An experimental investigation of air cargo densities and some other operational factors related to transport aircraft fuselage design

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Content AN EXPERIMENTAL INVESTIGATION OF AIR CARGO DENSITIES AND SOME OTHER OPERATIONAL FACTORS RELATED TO TRANSPORT AIRCRAFT FUSELAGE DESIGN A Thesis Presented to the Faculty of the Department of Business Administration of the School of Commerce University of Southern California 1 In Partial Fulfillment ; of the Requirements for the Degree I Master of Business Administration i i by Captain George H. Christena 1 ' V United States Air Force January 1957 UMI Number: EP43459 All rights reserved INFORM ATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI EP43459 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346 Q.ov^ m /B A l 5^ C 5 5 ^ This thesis written by CAPTAIN GEORGE H. CHRISTENA under the guidance of the Faculty Committee, and approved by all its members, has been presented to and accepted by the Faculty of the School of Commerce in partial fulfill ment of the requirements for the degree of MASTER OF BUSINESS ADMINISTRATION Approved TABLE OF CONTENTS CHAPTER I . THE PROBLEM AMD DEFINITIONS OF TIMS USED . . . . The problem . . . . . . . . . . . . . ........ Statement of the problem . ♦ • . .......... Importance of the study . . . ........ .. Definition of terms used Cargo density . . . » « • • . . . ♦ Cargo envelope ........ .......... Design-point range . . .......... * . . . . Load density . ♦ ........... . . • ........ Logistics . .......... ........... Payload-cube efficiency • • • ............ . Pipeline • . ............ .. Stacking loss ...... .............. • Usable Cube.............. .................. Zero Fuel Weight . .......... • Organization of the remainder of the thesis • • j II. THE INFLUENCE OF CARGO DENSITIES 01 FUSELAGE ! DESIGN AND A REVIEW OF DENSITY INFORMATION . . A brief history . • ........................... The first recognition of the problem • • . . Present state of the density problem . . . . The Berlin Airlift experience Theoretical investigations CHAPTER Review of air cargo density information • • • Military air cargo density surveys • • • • Density surveys by commercial air 9 cargo carriers * * ............* * * . ♦ Surface carrier cargo densities * ........ Ill* MILITARY AIR CARGO DENSITIES * . ............ The approach to the air cargo density study • «•*••*.••••*• ........ Source of the raw data **•••••••• Criteria for the density study ..*•*. i j The density study................ • The raw data source * • * ................. Method of tabulation • •••*•••*•• Results of the density study *•*...* j Mail densities .............******** Analyses of the density study and some observations •*»•••**•*•••• ! IT* EFFECTS OF AIR CARGO DENSITIES 01 PRESENT j OPERATIONAL AIRCRAFT . * . . .......... .. ' Related factors .......... * Backlogging of cargo...............♦*♦ Stacking losses ••*••• .............. Stacking losses and work-rate .......... ♦ ; Present stacking losses ............. * . . 1 ! < CHAPTER PAGE Materials handling systems . • • . . . . 56 The people ......................... Payload-cuhe efficiency • ••••••• 59 The dependency on door size ..... • . 59 Payload-cube accomplishment ..... . . 62 ¥. FACTORS II CARGO AIRCRAFT FUSELAGE DESIGN OTHER THAI CARGO DENSITIES ...... . . 69 Size of the cargo compartment • . • • • . . 70 Shape of the cargo compartment . . . 74 Cargo entry doors ••.••••••• 79 The design-point range . . 80 Summary ¥1. SUMMARY AID CONCLUSIONS . ............... . . 84 Summary .••••• ................... Average cargo densities . . 85 i Other cargo information ....... . . 85 Other fuselage design criteria • • . ♦ . 86 Packaging and load unitization . . . . . 86 Conclusions . . . ........ .. Air cargo densities .•••••••• to • . Payload-cuhe potential of an aircraft . . 87 Load densities and stacking losses • . . 88 Materials handling systems ........ . . 88 BIBLIOGRAPHY............................... . LIST OF FIGURES FIGURE 1. Fuselage Properties versus Payload ....... 2. Cost Index versus Fuselage Diameter ...... 3. Pacific Area Route Patterns of the Military Air Transport Service ...••• . • • • • • 4. MATS Cargo Shipments to Pacific Areas by Number and Weight, August 1953 - July 1954 • • 5. Military Air Cargo Densities to Pacific Areas, August 1953 - July 1954 . . . ..... 6. Air Force Air Cargo Densities to Pacific Areas, August 1953 - July 1954 • • .......... 7. Army Air Cargo Densities to Pacific Areas, August 1953 - July 1954 . . . . . . . . . . . 8. Navy Air Cargo Densities to Pacific Areas, i i August 1953 - July 1954 ..... .......... ! 9. Cargo Loading Door Sizes of Operational j Transport Aircraft ..... ...... .... !10. Cargo Densities in Pounds per Cubic Foot * | Related to Transport Aircraft Payload-Cube 1 Capability ••••••• ............. .... 111. Cross-Sectional Fuselage Shape versus Cargo Envelope-Typical Sections of MATS Aircraft . ♦ (12. Payload versus Range of Some Turboprop Aircraft Designs •• ••..........••••• LIST OF TABLES TABLE PAGE I. Hand Computed Payload Capability of Turbo prop Designs versus Military Computed Capability............... . . . .............. 20 II* Extremes in Monthly Air Cargo Density Averages By Pacific Area, August 1953 - July 1954 ................................... 42 III. Baited States Mail Densities, 1947 - 1955 . . . 43: I IV. Military Air Cargo Shipments by Weight to j Three Overseas Areas, August 1953 - July 1954 ............................... . . 46; V. Cargo Densities of Loaded Aircraft as j Governed by Cube/Lift Capacity Ratio ........ 63^ VI. EATS Aircraft - Tonnage Effectiveness in Transporting Average Density Cargoes ........ 64 ACKNOWLEDGMENT The writer is indebted to the Douglas Aircraft Company, Santa Monica Division, for valuable assistance in i i i tabulating the statistical data included in this thesis. j CHAPTER I THE PROBLEM AID DEFINITIONS OF TERMS DEED Over the years the principles of warfare have not changed materially* They are basically still the same today as expounded by von Clauswitz in the early 19th century. The principles of mass concentration, surprise, and pursuit, coupled with the principle of constant supply, • j are the elements that still govern warfare. Or, as Civil War General Nathan Forrest aptly put it in a simple, oft repeated axiom, the victory will probably be won by the side that "gits there fustest with the mostest." But the techniques of arriving at the goal of victory have changed tremendously. The employment of the airplane has seen to that. Because of manfs conquest of flight, a field of battle is* not now limited to small | i areas, but potentially is any place on the earth. And into! our military thinking have been introduced the nebulous terms, "global strategy" and logistics. Whenever the mili tary strategists mention these terms in their planning operations, sure to follow, and in a way somewhat synony mous, will be a discussion of the problems of air transport• AKarl von Clauswitz, Principles of War, (Harrisburg, Pa.: Military Science Publishing Company, 1942), p# 46* Statement of the problem* In the design of our smaller World War II type transport aircraft, there was seldom a limitation on the carrying capacity imposed by the factor of air cargo densities. Usually the maximum allow able weight was reached before the cabin cavity was filled. However, in the newer designs of heavy and very heavy transport aircraft, the consideration of cargo densities I - o appears as an important problem to the airframe industry. Further, there has been no comprehensive study made of the subject of air cargo densities upon which the designers can rely as being accurate information for the present, nor upon which they can base trends to determine future requirements.^ In the past the engineers have gotten along, and somewhat successfully, by designing the airplane fuselage to meet the passenger seating requirements and then adapt ing the same fuselage for cargo hauling. In some of the i designs of around-194-8 to 1952, they were supplied with some "educated guesses" regarding cargo densities which were the results of the influence of spot checks and ^Stated by Colonel Edward A. Guilbert, Headquarters, Atlantic Division, Military Air Transport Service, United States Air Force, personal correspondence. ^Stated by Herman 0. Olson, Douglas Aircraft Company, personal interview. I 3 experience of various military and civilian operators of transport aircraft.^ Considering that the lack of such information may measurably affect the ultimate success of a design project involving several millions of dollars, it seems incomprehensible that concrete, detailed, air cargo density information has not been made available long before this* Importance of the study* It is generally conceded that the defense of this country, its assumed responsi bility in defending various portions of the world, and its ability to assume the offensive is based, in the main, upon air power superiority* This is evidenced every day by the public accent on air power and as one observes the continu ous streams of fighters, bombers, and transports rolling off the production lines to be deployed to bases in the United States, Europe, Africa, Asia, and the Arctic. In many ways the United States is becoming a t t have not1 1 nation in terms of scarce materials and skilled man power. With an inability to stockpile critical supplies and to train specialized personnel in sufficient numbers, j this country cannot scatter its military strength to these many parts of the globe in concentrations large enough to ^Engineering Report Humber LB215&0; A Study of General Cargo Handling Methods, YC0133 Airplane,1 1 (unpub lished engineering report, Douglas Aircraft Company, Long 4 sustain a military operation* In addition, the cost of war material has increased tremendously as technological advances come into heing, and the rate of obsolescense has risen sharply*-* For instance, the cost of a Pratt and Whitney 157 turbojet engine for a present day fighter air plane is approximately the same as the total cost was for a complete North American P-51 fighter during World War II, and the engine has perhaps half the life of the older fighter.^ Because of the problems raised by the lack of skilled manpower, shortages of raw materials, and costli ness of material, it becomes apparent why the United States should not spread its military strength too thinly. To solve these problems, the strategic planners have turned to the theory of the central striking force with a mobile i reserve, and to means of improving logistical methods to I ; reduce the intransit or "pipeline1 1 time. ■ In most cases, using the traditional means of sur face transportation,, as much as 15 percent to 20 percent Beach, California), p* 6. ^"Airlift Helps AMC Cut Logistical Knots," Air Material Command. USAF. (reprinted from August 16, 1953 edition of Aviation Week, McGraw-Hill Publishing Company, New York, 1954)> P* 45* 6Ibld. of the available supplies were usually found to be in the pipelines.^ Even then, the material often did not arrive when it was vitally needed. From the realization of this deficiency has come the plans for an improved logistical system known as the Air Force "Revised Logistical Concept.” The essential element of the concept is the reduction of inventories through the reduction of the time element ft between the request for and receipt of supplies.0 Even in the global deployment of a minimum of the countryfs forces, the long supply lines require either more items to keep them filled or faster delivery methods. The possibilities for major economies are tremen dous. A former Secretary of the Air Force testified that by cutting the pipeline time from 270 to 100 days (includ ing the repair cycle) through airlift of engines overseas, the Air Force will be able to accomplish a 25 percent savings in spare engines alone.^ Top Air Force logistics planners are now granting air priority to the 2 percent of ^Airlift Helps AMC Cut Logistical Knots,1 1 o p . cit.. p. 43* ^Colonel J. N. Sammons, "The Role of Air Cargo in Modern Logistics,” (Paper Number 54— A-216 presented before the American Society of Mechanical Engineers, New York, November 28, 1954)> p# 2. ^"Congress Sets Sights on Missiles, Airlifts,” Aviation Week. February 7, 1955, p. 13* the 725,000 items of Air Force inventory which makes up some 40 percent of the total inventory dollar value.^ One tool to satisfy the need for logistical expedi ency is, of course, the transport airplane. But, to go further, the tool must he a special one. The modern Air Force logistic concept requires the employment of a true logistics airplane, designed specifically as a cargo carrier, uncompromised for any other purpose. Every detail must he pointed toward maximum efficiency and economy in 11 the handling and delivery of cargo to its destination. The airplane must have certain operating characteristics, a certain desirable range, and a specified payload capac ity— all of which help to make up the design criteria. These design criteria are constantly under surveillance hy !the military, hy the airframe manufacturers, and hy out side consultants. One factor to be considered in the design criteria is the relation of the fuselage size and shape to the amount of payload the aircraft must carry. To determine this, the designers must have some knowledge of the size and type of cargo carried and, most important, the density of the cargo. Industry Spotlight,n American Aviation. January 17, 1955, p. 16. 11 ^ Sammons, on. cit.. p. 4* Therefore, it can he seen that the subject of cargo densities is only one— but a most significant— facet in the consideration of an adequate air logistical system. II. DEFINITIOB OF TERMS USED Cargo density. The weight of cargo in pounds per cubic foot. Cargo envelope. That volume of space which the loaded cargo physically occupies. Design-point range. That range in nautical miles which an aircraft is designed to fly with a design payload and adequate fuel reserves. Load density. Referred to also as the stacked cargo density. It is the gross density of an entire load of cargo as computed by dividing the total weight of the cargo i !by the cargo envelope volume expressed in cubic feet. i Logistics. A branch of the military art which i i embraces the movement and supply of military forces. Payload-cube efficiency. The degree to which the total usuable cargo envelope is employed to carry the maxi mum payload which structural and operational requirements permit. Pipeline. An expression used to denote the line of communication from one point to another through which per sonnel and materiel must flow to reach the point of use. The non-effective period of time during which personnel and materiel occupy the pipeline in the process is the flow I time• i i I Stacking loss. That difference between the load density of the entire cargo load and the sum of the indi vidual piece weights of the cargo divided by the Siam of the' cubages. Usable cube. That portion of the total cubic ! ! ;volume of the airplane fuselage cavity which is considered ! ! jto be usable for the purpose of loading cargo in it. j I | Zero fuel weight. The maximum an aircraft and its j i I entire load less fuel may weigh for flight. Any allowable j i weight between the zero fuel weight and the maximum gross j allowable take-off weight must be taken up by fuel only. i i I III. ORGANIZATION OF THE REMAINDER OF THE THESIS j t Chapter II reviews the air cargo density available and how the first approaches to the density problem evolved. It attempts to point out that existing informa- i tion is sketchy, that information on military cargoes has |not covered representative samples, and that an inadequate * attempt was made to answer the air cargo density requests of the aeronautical engineers. Chapter III explains the approach to the density survey, the method of obtaining the data, the reason why the particular source was selected, and sets up criteria for the study. The chapter records the results of the density survey and compares the cargoes of the different military services with some brief explanations as to their differences. It also attempts to analyze some of the sta tistical findings. Chapter IV points out some of the effects of cargo operation upon the limited aircraft of the present outmoded fleet and how the various factors concerning these opera tions effect utilization of this logistics fleet. It also enquires into some of the inherent disadvantages of the current designs. Chapter V explores some of the desirable design characteristics of future transport aircraft fuselages. Chapter VI summarizes the findings of the study and draws certain conclusions. I I CHAPTER II THE INFLUENCE OF CARGO DENSITIES ON FUSELAGE DESIGN AND A REVIEW OF DENSITY INFORMATION In transportation media other than air, the impor tance of cargo densities has long been recognized. The design of ocean vessels and freight cars has always taken cargo densities into consideration to determine their util ization and to provide a basis for construction of tariffs. As a general rule, however, the cargo density factor has been expressed as a figure representing the average of a variety of densities. For example, the measurement ton used as a basis for applying rates to ocean freight ship ments represents 40 cubic feet at a density of 56 pounds |per cubic foot. In the construction of rail tariffs, an J experienced examination of the volumes of tariffs will j reveal that many rates pertaining to low value items are i jbased upon their density as a primary base. Not so well i junderstood, apparently are the effects of densities, and also variations in densities, upon the tonnage effective ness of a fleet of cargo aircraft.'*’ ^■Colonel Robert W. Johnson, f ! Effects of Variations in Cargo Densities,1 1 (unpublished report to the Director of Transportation, Deputy Chief of Staff for Materiel, Head quarters, U.S. Air Force, Washington, D.C., April 1, 1955), P. 2. I. A BRIEF HISTORY The background* In the days of World War II, the transport''aircraft was in its infancy. First, converted bombers such as the B-24 were used to transport personnel and equipment in small quantities, and then, as production was allocated commensurate with the increasing importance of air transportation, the Douglas C-47 Skytrain and C-54 Skymasters were passed into the Air Transport Command of the United States Army Air Corps. Yet it is significant that these designs were conceived before World War II• Indeed, the C-47 was designed in 1933 and the C-54 in 1938. They were both originally intended to be passenger air craft carrying people whose density is roughly three pounds j per cubic foot, roughly 20 percent of the average cargo i ; densities which one might expect to find in logistic oper- ations. But because no other suitable types of aircraft were available, these two aircraft models became the pri mary air cargo carriers during the war and remained so until several years afterwards. The era became one of experimentation with logistical air transportation. %. Dixon Speas, Airline Operations« (Washington, D.C.: American Aviation Publications, 1948;, p. 324* 12 The first recognition of the -problem, A thorough search of available sources reveals no recorded public recognition of the problem of air cargo densities until one author did consider it in an air transportation textbook in The optimum design of a cargo airplane will pro vide sufficient cargo volume to carry the maximum load without penalizing the airplane’s performance. Obviously, a design utilizing a low density figure will require an exceptionally large fuselage resulting in increased drag and reduced performance. The high density extreme will reduce the quantity of low density cargo which can be carried, consequently reducing pay load volume. The design density to be used for a cargo airplane should balance these two considerations. The author then supplemented his remarks by saying that, in the interests of the commercial airlines, a con tinuing density study had a definite bearing upon ton-mile revenue. The Berlin Airlift experience. When the Russians i blockaded Berlin, Germany, in 1948, the Western powers organized a military airlift to supply the isolated city with food, fuel, and other supplies without which it could not survive. The basic aircraft with which the airlift was organized were the C-47 and C-54 types— all that were available. Since the flight to Berlin from the airfields of the ^Speas, o£. cit.. p, 321. 1948.3 f 13 j Western Zone, primarily in the Frankfurt-Weisbaden area, was a rather short one, a minimum fuel load could be taken. This, coupled with the fact that higher than normal combat gross weights were allowed, presented a comparatively high payload aircraft with relatively low cubic carrying capac ity. Officers in charge of the "Vittles" operation, as it was called, became quite concerned because the aircraft were not being loaded to their full allowable gross weight and thus vital airlift potential was being wasted. I Upon assigning an investigator to the problem, the j j discovery was made that the daily lift of large quantities | ! ; i of light dehydrated foodstuffs magnified the problem of j space limitations to one of major proportions. From there j the investigator determined the ratio of heavy cargoes to j i : ! light cargoes, and, as a result, the Air Force recommended , i ! I that the more dense commodities be mixed with the less ; i ! ! dense commodities in a ratio of three to one. Then the I ; ' Army Transportation Corps inaugurated a "marrying" opera- | i | tion at the airfield railheads whereby high and low density | cargoes were combined into the desired density loads.^ It ’ | was estimated that by this method of selectivity, approxi- ( | mately two thousand added tons of cargo were carried by all %jt. (jg) C. 1. Henn, "Operation Yittles-Study of Cargo Densities, Month of February and March 1949," (unpub lished report of the Office of the Director of Traffic, l Headquarters, Combined Airlift Task Force, Weisbaden, , u airlift planes during the month of December, 1948, which would have been left behind due to space limitation had all foodstuffs been straight-loaded by individual commodity as they were received aboard rail cars. The "Tittles® investigator summarily concluded that the density problem was already of sufficient importance, to require a planned solution at the policy making level. Theoretical investigations * Some engineering inquiry has been made into the air cargo density problem in more recent years than the time of the Berlin airlift. In 1952 the United States Air Force contracted with the Rand Cor poration of Santa Monica, California, to explore the per formance and capabilities of possible future transport airplane designs. The Rand engineers presented the find ings of the performance of over one thousand different designs which entailed the study of a multitude of varia bles. In the resulting report there occurred an acknowl edgment of the density problem through the study of aircraft fuselage diameters.^ The effect of cargo density Germany, April 1949), p. 6. ^Ibid., p. 2. 6Tv4^ ^ 11# ^Tom T. Jones and Associates, "Capabilities and Operating Costs of Future Transport Aircraft," (report to 15! I on cost index and take-off weight was investigated by designing aircraft having the same fuselage length, design point range and payload, airfield length requirement, and cruising speed, but having different fuselage diameters. Fuselage dimensions were determined by the size and weight of the cargo to be carried and were chosen from a survey of existing and proposed cargo aircraft designs. Comparisons of the fuselages chosen for the Rand study and those of existing and proposed designs are shown in Figure I. The Rand investigation noted that there was a sizeable increase in cost index as the fuselage diameter is increased. This result is illustrated in Figure 2. Rand then concluded that the effect of fuselage diameters on cost index is great enough that the importance of carrying very large objects should be very carefully considered before fuselage a diameter is selected. But in choosing fuselage diameters, i I Rand may have repeated errors of the past designs. | Howhere in the Rand report was a statement as to i j exactly what cargo densities were considered. A critic of the Rand report analyzed the particular findings pertain ing to the turboprop configurations and found that, with United States Air Force by Rand, Incorporated, Santa Monica, California, July 1953, p. 9• 8Ibid. FUSELAGE DIAMETER (FT) FUSELAGE LENGTH (FT) ioo 3 0 20 ALTERNATE FU SELA G E DIAMETERS IO FUSELAGES FOR ACTUAL A P R O P O S E D A IR P L A N E S ND BO 1 60 200 40 1 20 PAYLOAD W EIG H T (LB5/lOOO) FIGURE I FUSELAGE PROPERTIES VS. PAYLOAD (FROM JONES AND ASSOCIATES, CAPA BILITIES AND OPERATING COSTS OF POSSIBLE FUTURE TRANSPORT AIRPLANES). COST INDEX (CENTS / t o n - n a u t i c a l - m i l e ) DESIGN-POINT PAYLOAD * 5 0 ,0 0 0 LBS. 6 COM POUND-RECIPROCATING T U R B O J E T 4 T U R B O P R O P 2 4 8 12 16 FUSELAGE DIAMETEP (F T ) FIGURE 2 COST INDEX VS. FUSELAGE DIAMETER (FROM JONES AND ASSOCIATES, CAPA BILITIES AND OPERATING COSTS OF POSSIBLE FUTURE TRANSPORT AIRPLANES). 17 5\ %' * * * % . ■ Vv- , ? , ' u J - } V \ ) ' * ■ " V i , S ' * , /% I < < ^ l % , 1 ^■’ t 7 V’ ” ' * % * » " ........ . ^ ' * * , < : - ■ ; • * V ■ 'A*Vt S ' ' * * / * • ' * . „ J * 1 ' • A . , ' - V V ,, A x t t - ' ^ * * K * * ' ‘ 4 : "*! , £* \ ' *V ■ -J - * V » ' . f « ■ • r , >'•*. v * < S ' ^ u /;* V ‘ 1 ./■>„$*•" v 'V ' ' • - ■ " , » r* ‘ t . ' . * ' V » * ' * * * * i ^ r X ,J A \ % , / * ■ : * C * / 1 . ; ’i ~ tir ■ v - • • ' - . f v* * . J f c A . . . . . . . . , " . " f - v V , * ' " ' • ■ •" e - . V ' H , % g ,*•*.* ’ < - » ■ ' f , i ' < ’ t * * ' ??< *4 * \ •,, , , . 4 ' i ! j * ^ 4 , ! ' *d V ’' * „ V , ! » ■ - K . ' V / v ' - ^ V * * % ‘ . * ' - . , • ' , ' ' ' ' . » ’ ’ ' j i / ' % ' - w , ~ r r-> t . . r s : . . ¥ m ^ ! ^ U ’ s K *■■<- V ' • ! : ' - - ' - 1 v> < •* ^ % * t , 7 ^{! k !<r1‘ * V # * . , ■ : 6 ’ .^. r*{- . ' :f>v- ? „* v • ■ % -4 r .'Xf*.»* •••^-'•*;^ • ' - «. v\ .;•.? -'v.- t '4i ‘ v'1 * • « ? / & t e ' i ’ 1 :y » ’ - ■ K “ ^ '-’ • ‘ V! \,0* * . . - * • . * • " • ; * > . \ t , ' • -t, IB the exception of the 25,000 pound payload category, rated payloads (weight carrying capacity) could not be achieved i ! I with normal logistical cargo because of the severe cubage j Q I restrictions.7 Table I depicts the disparity of the actual! computed capability of Rand aircraft with the capability that has been assumed. The comparison serves to emphasize the essential relationship which must exist between den sities of cargoes and the aircraft designed to carry those cargoes. The chart indicates that the Rand report utilized i undersized fuselages and considered only circular shapes, j i This would have a considerable effect upon the productiv ity, weight, and cost of operation of each Rand aircraft. To reduce the payload of a set of given aircraft designs would have the effect of exaggerating the speed and utili zation factors.^® The computation for the actual computed capability !(space-wise) in Table I are based on the following rule of j : i :thumb formula: Payload equals the usuable cubage x 10 pounds per cubic foot load density. Usuable cubage is computed %jt. Col. Ben W. Hunsaker, ”An Analysis of the Rand Report,” (unpublished report to the Deputy Chief of Staff, Operations, Military Air Transport Service, United States Air Force, Washington, D.C.y November 16, 1953), p. 6. 10Ibid. 19 as (.60 x length of the fuselage - 4 feet) x (6 foot stacking height) x (.70 fuselage width - If foot safety aisle). Motdd with interest is the 10 pounds per cubic foot load density which appears in the formula. Although this figure of 10 pounds per cubic foot was not substantiated by any complete, detailed study of air cargo densities, it became accepted as a temporary standard in the Military Air Transport Service, and consequently it was used by at least one aircraft manufacturer in some experimental performance calculations. It represents a net average cargo density of 13*6 pounds per cubic foot minus a stack. The 13.6 pounds per cubic foot was arrived at through a number of spot checks of cargoes at different stations of the Military Air Transport Service. Another member of the Hand organization approached the density problem in a different but philosophic manner while questioning this specific area of the general problem; * 1 o of logistics and supply. * * 1 Lt. Col. George Hewitt and Associates, "Report of Field Trip to Lockheed Aircraft Corporation, Marietta, Georgia," (unpublished report to Deputy Chief of Staff, Operations, Military Air Transport Service, Andrews Air Force Base, Md., 23 April 1954)> p. 2. ■^Robert e. Bickner, "The Relation Between Cargo Density and Airlift Capacity," (unpublished memorandum of the Rand Corporation, Santa Monica, California, July 1954)9 p. 1. TABLE I RAID COMPUTED PAYLOAD CAPABILITY OF TURBOPROP DESIGHS VERSUS MILITARY COMPUTED CAPABILITY Rand Design- Point Capability Rand Maximum Capability Computed Usuable Cube Computed Space Limit Capability at Densities: 10 lbs./ft.3 12 lbs./ft.3 25,000 lbs 35,587 lbs. 3,264 ft.3 32,640 lbs. 39,168 lbs. 50,000 66,062 3,834 38,340 46,008 75,000 103,078 4,648 46,480 55,776 100,000 128,462 5,451 54,510 65,412 125,000 160,853 6,279 62,790 75,348 150,000 179,315 7,172 71,720 86,064 21 Given an aircraft type, a route, and an average cargo density, we may find the weight limitation is considerably more, or considerably less, restrictive than the cubage limitation. If so, the appropriate limitation may be kept in mind and the other limita tion forgotten. If not so, the dispersion of cargo densities about the average becomes relevant. The author of the statement further elaborated by explaining that if the weight limitation of an aircraft over a given route is 15 tons and, that if the cargo den sity is such, that on the average, 15 tons of cargo can be loaded in the available space, the chances of averaging 15 tons are nil.*^ Unless available space or weight lifting capacity is a free good, which may be the case for any narrowly defined problem, both limitations should become effective. They can become effective by selecting differ ent aircraft, selecting different cargo, modifying loading regulations, altering loading and tie-down techniques, altering packaging methods of altering operating character istics of the aircraft. The concept is in keeping with the Air Force requirement for a family of logistical trans- i port aircraft, varying in size, payload capability, and | range. Present state of the density problem. The state of the density problem is adequately described by a prominent Ibid.. p. 2. ^Bickner, op. cit.. p. 2. 22 aeronautical engineer before the 1954 meeting of the American Society of Mechanical Engineers*1- * In common with other aircraft manufacturers, we have been, and are still asking ourselves some rather searching questions regarding the nature and amounts of present and potential air cargo in order that our designs would better solve diversified logistics requirements. Airplane design as it relates to load ing and securing of cargo, as well as efficiency of space and weight utilization from off-loaded cargo is a subject of active design investigation. II. REVIEW OF AIR CARGO DENSITY INFORMATION A review of available air cargo density information | suggests that it has not been very searching nor has it been complete. In fact it is so scant that it is of little more value than to arouse the curiosity of interested per sons. The problem had not been a significant one until recent years, and there has yet to be sufficient time and resources devoted to any comprehensive study. Although some commercial carriers have made small contributions of j I i ] j ' data, it will remain for the military carriers to conduct ; the statistical research needed to provide the engineers ; I i with the data they have requested. The reason being that ^Robert W. Middlewood, nLockheed C-130A Transport in the Mobility Era,1 1 (Paper Number 54— A-227 before the American Society of Mechanical Engineers, New York, November 28, 1954)9 V* 5. Ithe great bulk of cargo is transported by the military, and general military cargo differs from the commercial counter parts in nature, type of packaging required, and loading considerations• Military air cargo density surveys. For the past three or four years the Military Air Transport Service has been feeling about for air cargo density information with out appreciable results* Surveys conducted by MATS have been nothing more than spot checks barely scratching the surface of available sources# However, MATS did acknowl edge that the average density of cargo handled by the MATS system had assumed an increasing importance, and that the extent to which available payloads can be utilized is *j £ . directly affected by this average density. | Past MATS experience had indicated that 10 pounds I |per cubic foot load density to be reasonably realistic and I ithat figure had been consistently applied as a planning factor in determining expected attainable payloads* never theless, the validity of the planning factor was questioned i !by industry sources. However, MATS officers at the policy i making level stated that more recent developments indicate wAir Cargo Density Survey,” (letter from Commander, Military Air Transport Service, Andrews Air Force Base, Md., to Commander, Atlantic Division, Military Air Transport Service, Westover Air Force Base, Mass., April 15, 1954), P. 1. a need to re-examine this density average to determine if i 1 7 it was still valid or whether it should he revised.*1 *' Even prior to this declaration there had begun a series of spot checks in the MATS system to gather air cargo density data. On one particular field survey by a representative of Headquarters, MATS, the reporter found that an examination of approximately 130 tons of cargo revealed an average density of 13*9 pounds per cubic On another occasion, the controller for the move of a bomber wing from the United States to North Africa reported an average density of 8.3 pounds per cubic foot for 250 tons of cargo airlifted.*^ A resupply project in support of this same exercise required 342 tons of cargo 20 having an average density of 12.08 pounds per cubic foot. ■^Capt . Ralph A. Ruebel, "Report of Field Trip to Westover Air Force Base," (unpublished report to Deputy Chief of Staff, Operations, Headquarters, Military Air : Transport Service, Andrews Air Force Base, Md., November 5, 1195a), p. 2. ^Capt. Don A. Waters, "Traffic Controllers Report— MATS Operations Order 5-54 and 7-54," (unpublished report to Deputy Chief of Staff, Operations, Headquarters, Military Air Transport Service, Andrews Air Force Base, Md., March 19, 1954), P« 4* ^Ocapt. Donald A. Waters, "Field Report— Review of Cargo Densities," (unpublished report to Deputy Chief of Staff, Operations, Headquarters, Military Air Transport Service, Andrews Air Force Base, Md., March 2, 1954), P« !• 25 In yet another sampling MATS personnel collected the densities of approximately 150 tons of presumably repre sentative cargo and found the average to be 17*1 pounds per cubie foot.^ Although the intent of MATS was commendable in instigating these samplings, they were relatively very small, they did not necessarily represent all types of logistic cargoes, and they covered only very short periods of time. Another military air cargo density sampling was conducted by a member of the United States lavy Bureau of Supply and Accounts. The investigator reported that Havy air Cargo had an average density of 14 pounds per cubic foot. However, there is no information available as to the size of the sampling, the amount of cargo included in 22 the sampling, nor the source. i Density surveys by commercial air cargo carriers. i To gain air cargo density information, two aircraft manu facturers turned to the commercial air cargo carriers, jmainly because of the accessibility. A tabulation of one I I I | I 2^wCargo Density Study,T f (letter from Commander, Atlantic Division, Military Air Transport Service, Westover Air Force Base, Mass., to Commander, Military Air Transport Service, Andrews Air Force Base, Md., April 27, 1954)> P ♦ 1 • ^Stated by Lt. Col. Ben W. Hunsacker, Headquarters, Military Air Transport Service, personal interview.________ 26 months! traffic through Slick Airways 1 Chicago terminal was made with Slick Airways by the Douglas Aircraft Company and' the Lockheed Aircraft Corporation. The average density of 4000 pieces of cargo was found to be approximately 21 pounds per cubic foot. Sixty-seven per cent of the indi vidual pieces were found to be over 20 pounds per cubic One of the participants in the project expressed the doubt that the information obtained would be of much material value use due to the fact that the time period covered was too short to furnish any kind of a represen tative sample and that the primary interest was in military cargoes since any new transports designed would be, in all likelihood, built for the military.^ Again, several other spot surveys have been made by the commercial airlines much in the same manner as the military carriers have done. But the commercial carriers have related air cargo densities to such things as the top 1 revenue producing commodities, size of packaging, et cet era, and have not considered overall net densities as foot and 75 per cent of the shipments were hardgoods 2%iddlewood, crp. cit.. p. 6. ^Stated by Herman 0. Olson, Douglas Aircraft Company, personal interview. While air cargo density information is desired and needed by the transport aircraft manufacturers for use in their design criteria, there has been so little available that its material value may be questioned. All that the engineers have had to go by are ”estimates of average densities to which influential individuals have become attached.2^ Surface carrier cargo densities. To complete the picture of available cargo densities, it may be well to present some surface carrier average cargo densities so that they may be compared with the samplings of air cargo densities. The average box car load of Army, lavy, and Air Force logistical supplies received at Westover Air I Force Base, Massachusetts, for overseas air shipment was 27 11.55 pounds per cubic foot for an unspecified period. The Association of American Bailroads reported the average 2%om Harris, 1 1 Air Cargo Densities,” (letter to Lt. Col. 0. D. Stafford, Headquarters, Military Air Transport Service, Andrews Air Force Base, Bid., March 8, 1954)* 2%ickner, op. cit., p. 2. 27*Cargo Cube/Density Study,” (memorandum of the Office of Director of Traffic, Deputy Chief of Staff, Operations, Headquarters, Military Air Transport Service, Andrews Air Force Base, Md., undated), p. 2. density for Air Force domestic movements of cargo to toe 2ft 15*94 pounds per cubic foot during 1953. This organiza tion also reported that the national average boxcar load of regular freight was 17.56 pounds per cubic foot.2^ These comparisons are shown as a matter of interest only. 2%bid. 29Ibld.. p. 3. CHAPTER III MILITARY AIR CARGO DENSITIES In conducting an experimental study such as was attempted in gathering data for this presentation, certain criteria must be set up beforehand and likened to the mode of pursuit of the information. This chapter presents the necessary background to the study, the results of the accumulation of data, and a brief analysis and observations pertaining to the data. I. THE APPROACH TO THE AIR CARGO DENSITY STUDY The first suggestion of conducting a density study was proposed to the writer in 1954 by Colonel Edward A. ' Guilbert in a letter in which he stated that in the matter of new design criteria for larger transport aircraft, the I density factor appears as an important problem. This ; i j jsuggestion was then presented to certain representatives of |the Douglas Aircraft Company and the Lockheed Aircraft Cor-| poration, two of the foremost builders of transport air- | i » j i icraft, and their comments were invited. In both instances i the reception to the idea of conducting an air cargo den- j sity study was enthusiastic to the point where active 30 2 cooperation was proffered* With such encouragement to j spur one on, the writer decided to undertake the project. Source of the raw data. In this particular instance, the source of the raw data was almost as impor- i tant as the criteria themselves. Such considerations as j travel time to obtain the data and the availability of J ! assistance to tabulate the data were of prime importance. | j With this in mind, it was determined that Travis Air Force ! Base, California, was the most logical place for the under-; taking to begin. ! Travis Air Force Base, approximately forty miles i . northeast of San Francisco, California, is the west coast Port of Aerial Embarkation for the Military Air Transport j Service, the logistical air carrier for the Department of j Defense. From there are dispatched practically all of the ! Jcargo, passengers, and mail to the farflung United States 1 |military bases in the Pacific. A map depicting the general route patterns to the major areas is shown in Figure 3. ,From these route patterns it may be seen that cargo is • shipped from Travis to tropic, semi-tropic, and temperate i |areas. Unfortunately for the purposes of the study Travis ^Stated by Herman Olson, Douglas Aircraft Company, and Charles J. Rausch, Lockheed Aircraft Corporation, personal interviews. ASIA U. S. A. r*Avis Are Ce n t r a l, pacific SOUTHWEST PACIFIC FIGURE 3 PACIFIC AREA ROUTE PATTERNS OF THE MILITARY AIR TRANSPORT SERVICE university of Soutnern Calirorma C d A/j M B f t '?7 does not serve as an Aerial Port for the Arctic area. | A query to the Officer in Charge of the air freight J terminal at Travis disclosed that there was, on hand, the j I air freight records covering an entire, year*s operation, j A portion of these records were current, and the remainder ! i were awaiting packaging to the records storage depot. The records could be made available for a short time. Criteria for the density study. Although it may be implied that the criteria were chosen to fit the data, rather than the data picked to meet the criteria, such is I i not the case. The fact remains that Travis was the only i accessible, representative source of density data which was« available to the writer. I After some deliberation in discussing the require- j ments of a density study with the representatives of Head- r quarters, Military Air Transport Service, and the industry people, the following criteria were arbitrarily estab lished: 1) The sample should be as large as possible to establish a base for future trends and predictions. 2) The logistical air cargo under study should be representative of the three services— Army, Navy, and Air Force. 3) The nature of the cargo and type of packaging should be examined. j 33 4) fhe study should include data pertaining to average densities and density variations. 5) The geographical areas to which the cargo was shipped should cover all possible climates and seasons of the year. 6) The cargo under study should, if possible, represent wartime logistical shipments. To meet all of the criteria would have resulted in an endeavor of no small proportions, requiring more time and facility than was available to the researcher. There fore, some limitations had to be placed upon the scope of the study. Since, as a beginning, basic density averages appeared to be the most desired by interested parties, the collection of that type of information was made the primary! aim. Generally, with some exceptions, the remainder of the criteria could be met. Rather than attempt to decide upon and pick a representative sample, random or selected, it was decided to tabulate and examine all records avail able. Thus there could be no criticism on the point. Since the cargo had already been shipped, the observations of experienced personnel at Travis were relied upon greatly to furnish information as to the nature and type of packag-. ing. As Travis was not a shipping point to the Arctic areas, a sample of arctic cargoes was not available. It may be recalled that the Korean conflict was Just termin- 34 ating in the summer of 1953, so possibly the cargo in the pipelines during the month of August may be considered to be wartime materiel. II. THE DEHSITY STUDY Haring limited the scope of the density study by considering the various factors, no time was lost in embarking upon the project. The raw data source. Each of the armed services has its own method of accounting for an identifying cargo in the process of transportation. The Air Force has its Shipping Requisition, the Army has its Shipping Document, and the Havy has its non-negotiable Bill of Lading. How ever, each of the three types of different documents con tain essentially the same information. Usuable information found in these documents for the purposes of the study was the destination of the cargo, date, weight, and cubic meas urements (expressed in cubic feet) of the Shipment. The documents were segregated as to branch of service, month ofj the shipment, and the area to which shipped. ! A total of 42,631 usuable documents was tabulated representing 12,848,858 pounds of cargo. Each document accounted for one or several shipments of one or more items. If more than one shipment was listed on each docu ment, then each shipment was counted separately. ' Method of tabulation. The method of tabulation con sisted of submitting the documents to a number of clerks who extracted the information each was assigned to extract. As a group of documents were completed, tapes from the machines being used were totaled and identified. Care was taken, of course, to keep the information segregated as to service, month, and destination. In addition, the machine operators were constantly spot checked for accuracy by the writer. Some documents were found to be unusable due to illegibility, alteration by air freight personnel in the case of split shipments, or omission of essential informa- j tion. A conservative estimate is that these unusable documents did not represent more than two per cent of the total. Results of the density study. The results of the density study are shown in a number of ways. First, a j breakdown of the shipments for each service giving the number of shipments and the total weight shipped is shown in Figure 4 to determine the comparative tonnages. By both | means the Air Force ranked first, the Navy second, and the i | Army last by a wide margin. i Next, the total average densities for each service j to the three major areas in the Pacific are shown in Figure. 5 along with the monthly variations and the overall average density figure of 14.52 pounds per cubic foot. The most AIR FORCE 2 5 ,2 9 6 5 9 .3 3 % AR M Y 3 015 17. NUMBER OF SHIPMENTS 8 V SERVICE T O TA L - 42.631 N A V Y 14,320 33,59 ° / c W E IG H T SHIPPED BY S E R V IC E T O T A L - 1 2 ,8 4 5 ,6 5 8 LBS. ARMY 6.19 °U AIR FORCE 6 ,9 9 9 ,0 9 8 LBS. 5 4 .4 8 °/o N A V Y 5 ,0 5 3 ,4 9 7 LBS 3 9 .3 3 % FIGURE 4 MATS CARGO SHIPMENTS TO PACIFIC AREAS BY NUMBER AND WEIGHT AUGUST 1953 - JULY 1954 I i i v& ' j' i o r S im tlte riT C a itro rrm tt % , T v # T : ^ ■ ■" ? > > W - v : > ' V^-TV'- ■ ' < t x * -' * s - , ........ v<; : ; t. V*V' ^ ' > ' . ? -*V . > • . . No. 6311, U n iv ersity B ookstore, Los A ngeles 371 v~- l a t t , Tf h . 11 t , „ ' " ' ' J ‘ V - Vjt5 )/.' V ’ '-'■ s i, * % * ^ : v , /,* r v n &;•**. - <5 , t t : ' ■ ‘ i - . t-iY,. / v - > 1 * k ' I ^ ^ ^ . ' " ' jr ■ " ‘ ^ ', **n ^ ' r ' } . •/ ^ *v- ..' v/j < 5' * ; , ' \t* ’ J * * r > -"v ; y , < «* v , *A > . i * * ( \ * ' * J ' . ' • ' 'v X*- - ‘ 1 „ , - V J > > ■y ■ <. 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I <;+ y j /^<c«./ « ' ■ • • • *N "' ^ > 1 1 % i ^ : ' - i f * 1 * i * f * . s - ■ a v * • » / . >\' ” ***£•- - / / ''■ , ' „ " •* v . .*. - 1 * - , • . ! > • , n <: - - • • • — V\v^ ^ \ * * - * -a , '< < • * /1 < ^ 1 “ % » ■ ' * « * X r t £ * r f i ' r\ * \ ' < , , . *- ' vt ‘.; V*>' ■■■•'.• • , v r / jf, h > ; f ( ^ tr , » T * ' ' f ‘ ' ’ 'V ■ . s>y: < • - - .< < *, V 1 , V 5 ' * *' v . ^ W VvA/\ " t S iC- ^ ^ ' I Vv^,*/ / / ^ V striking thing about this is that Army densities may be observed to be much greater than either the Air Force or lavy densities* In Figures, 6, 7, and 8, are depicted the densities j of the individual services to each of the three major areas* compared with the total overall average density of 14*52. Extremes in the averages will be explained in the analysis of the study. Finally, Table II is included to show the spread in the monthly average density variations of Figure 5* ! I Mail densities. In a logistical airlift operation conducted by the military outside of the continental United: i States, mail for the overseas personnel is sure to be i j transported. To the remote areas where ships infrequently iput in, even first class mail and parcel post is delivered by air. As much as 25 per cent to 30 per cent of the total i j cargo and mail tonnage may consist of mail.3 Obviously i | then, mail densities must be considered in such a study as i •this. Table III shows the densities of air mail, first I class mail, and air parcel post by year from 1949 through |1955*^ Although the exact proportions of air letter mail ^Stated by Major Joseph R. Rasco, Officer in Charge, Military Air Transport Service Air Freight Terminal, Travis- | Air Force Base, California, personal interview. ^E. J. Walsh, Director, Division of Cost Analysis, No. 6311, U n iv ersity B ookstore, Los A ngeles 39 i , . % • ; r * * * ** ” / , V « >, i ■ ; < / ^ ; • ^ • . * • ’ * V ‘ , ^. . - 4 ,’ '*;* * ‘ ^ e i ' ' eL’ « f ^ ■ * ■ ' - l ^~’ * . ; • / i i V v -At*i ' * • * • • ^ • • - '4 . * - v v < ' ' ,& ? , 1 4 , r * H „ 7 t » ; * " ^ - ' : • ' «V * “ • ‘ • y r l ' - t > " V \ * “ • ' < v * “ * v 7 * • . v \ ’ , r > * * 5 , - > k * ( • ^ t ^ r ' h » - 1 , _ ■ ‘ X I s ril ■ * • < , . » ' * «■».'*' 1 -v , ' " i " * * » * ^ * — ^ * , f t f * * * . ^ ^ * */ \ V ' ^ ^ ^ ' ”J V ^ ' * ? y v i i * v v ' * { - i v * * * * a , 4 V"" S'¥< > ' * V ,'v ■ r w t t . f , - - * & > < T ^ 4 r * ’ * * v *> W ^ M W ^ i r\v.V S 1 * > W x * * .r * * % » 5 / . /*4 k *:*? ^ *J' « * *l *»\t % / ■ s * /» f; :j^ '4^T* V v V ^ , I ( ' ' * V ' - " %'1 , ? 1 Vv J * ' > ^ ’'I? , ^ " * . > , , ^ >' >*\i '-XtA * • * ' * , % 1 * • ‘ ’" f " ' * > ^‘ r t ‘ , \ . v - i ' 4 ' J , , i ' ’ ■ < ’ v* ; , ; ; i~ , v • > , * r */ t*'" i - ■ ' ' -v ,.vAj; pv'3 7Vv> “4'"7.-"’iV*-^ , - ' i : v;;^.-,;, * ^ ’ v-i’ jJ . ; V ' /v v* v * ‘ . . # • * - . > l , : c - ’ V • - . < r ? ** " * " ' T L’ if-• \, : » ■ > \ *lt / , ^ 2 i . ' 1 * *>- 4 : '." 1 W * .. * > Y* * s t * * * 'r ' - , ;" s ' • ■ ( „ ' ■ : ■ ’* • <' T' " * v > " ^ f m J , ' J T » - * v , j ' r % . ■ • • : i ‘ - " / t ; . v . " * * ^ ‘ . * t ^ V ^ m m m m No. 6311, U n iv ersity B ookstore, Los A ngeles AO i * ' v v . / ^ - - ' " ; : i\- , & ' * • ' ■ V f i r * f • * % « y y ~ A ^ \ % ^ / < < J ' * , 4 * v> - - ;'4 ¥4 -> ’ ” 4. ‘ y~, W ' ■ - „ J ; ' •'* , • ■ ' 1 >♦ ’ - < - ,. •■ * > ? , , * * * » * s ' , , " 1 > ■ •' 4 » V H * y ■ ' » * > , >■ *y ■’ * / * ? > < ¥ - * v > ► i ' * ” - , f J < * A , * * „ > . *\4* * * . ' ’ ^ \ ' t , V ' V N % 4 % ' - fr . * v * ^ » 4 ^ * * k.\ ' M i ® t - ‘ * ' TA V ' s i 5 * * < , v 4' * ■ » * * 4 : ,» • . • * ’ " * » r < . < ' ’ " * : . * * * ' V * 4 5 < , , r o*7,4 * * v 4 % * ** . 4 v » s 7 * . > -*3 * . *>/; <A 4 . * 4 4 { ; • > • * ^ * 4 ‘ „ Vf'!« v , ’ > 4 , . , * * * ’ -f * i y - , . , • 4' - * . s . : . . . ; . - 44 v *\ ‘4 *4 ^ * 4 , v ' y , 4 ; • , , t * , 44. ii * * • - V * ^ : • - x - * 44 ' ' * ^ * * f f i H s ' , "44*> ? .K- f - n 4 ^-' f (;. v 4 v * ^ * f } J ■ vt , ^ v y - v '£ a. > V * 4 A>, - I » ; * ' * % J V ’ f » i v i' ^ \ \ ^ y ► ? i • » , t . , f J >' " a «} / t ; .4 4 ; . . * f ■ * > ^ ^ v . f * ' x ■ ■ r- ‘ * -&*? *< v ‘ 1 ivf, » f ' .Y-f S> ' { S j. it V , ■% ; , k < 4 ' v ■ *- 4v ;4ia* 4 4 ' - * ' ^ f ; , \ * . * ? ‘ f ’ s . xV V I" ^ * J * i > v f -’#»'* 4* ' ^ 4^? t f %» tt f t ^ , 4 S , V V * j ^ &?r '’ •'* f *,*'*'' ‘ * t *!> , \ y .i < / • ^ . 1 ' Vs. , m m m t w i MAW No. 6311, U n iv ersity B ookstore, Los A ngeles 4 . 1 jr 4 * s < r i t - . , * v , ^ * , ' ; v ^ ' 'V* : iiilIRiIiSK® - ,-r ' ,,*■ y ■ « . - < * • ' <\ < , «»-«■ •■ ■ ■ ^ , n , ^ ' \-s ^ • • ' • - , . A ; ‘ , r , '*< ‘ f / * ^ , V \ * V- • < • ’ » > v - » » ^ * ; v '! ‘ ‘ v* . V,'Va, 1V . . ( ♦ • ^ v * v ■ ' ‘ 4 • * . * - ; ' * ’ ♦ ) * ^ % a t * i ‘ ' ’ ‘ , * ; - , t , ^ V; ^ ■ < * , ' \f - 11 Vv r f c V ' 1 \ ' . 'Va* . : . » ; * f $1 * > * ?A v * :. ‘ ; . p;,‘ , y 5 „ ^ j* v ^ i' *-*»*»,, J > . < ,** 4 W *' '£» A W , ,' j ''■* * i , • s * - * ’ ^ \ ^ , i * * * * / * - > \ \ % V'p v 1 : * ^*4r v . .-V. TABLE II EXTREMES II MONTHLY AIR CARGO DENSITY AVERAGES BY PACIFIC AREA AUGUST 1953 - JULY 1954 CENTRAL PACIFIC WESTERN PACIFIC NORTHWEST PACIFIC Max. Min. Max. Min. Max. Min. 1 [Army 37.40 13*28 34.55 14.19 29.22 21.10 Navy 21.20 10.67 24.50 13.54 18.18 8.66 Air Force 16.95 11.27 19.78 10.10 19.72 9.93 Variation Variation Variation j Army 24.12 20.36 8.12 1 Havy 10.53 10.96 9.52 Air Force 5.68 9.68 9.79 ■ 1 i } 4 > - TJHITED TABLE III STATES MAIL DEHSITIES 1947 43 - 1955 Average Pounds tier Cubic Foot Fiscal First Domestic Air Mail Domestic Air lear Class Letters and Cards Parcel Post 1955 . 18.130 17.133 12.670 1954 18.484 17.426 12.269 1953 18.788 15.673 10.541 1952 18.682 17.196 12.408 1951 18.869 16.525 12.784 1950 18.758 16.395 12.436 1949 18.621 16.112 11.702 ; 194# 18.625 17.803 1947 18.275 17.822 ■(From Cost Ascertainment Reports, United States Post I Office Department, 1947 - 1955) u I to air parcel post are not given, it can be predicted, from i observations of Travis personnel, that total average densi ties may fall in the same range as the cargo densities for all services. i j Analyses of the density study and some observations. From the source data certain variations and deviations may J be explained. In other cases the experienced observation of air freight personnel at Travis was relied upon. An examination of Figure 4 shows that the Army shipped only a small portion of the total number of ship- ; ments and the total weight. Possible explanations of this : are that, a) the Military Air Transport Service consists of! t operational units of the Air Force and Uavy, and therefore j !these organizations have a greater voice in the allocation ! of tonnage capability; b) the Army is not yet as "air- minded” as the Air Force and Savy in the concepts of logis- i !tical and prefers surface supply lines; or c) the Army has • | fewer high value, critical items of supply as compared with I the other two services and is not as concerned with the 'reduction of pipeline times. ! It can be observed with interest that the density of, i I jArmy cargo is much greater than that of either the Air j .United States Post Office Department, Washington, D.C. !personal correspondence. 45; Force or the Wavy. Spot cheeks of Army Shipping Documents i revealed that a) Army tare weights appear to he higher due to the use of heavy duty surface shipping containers with packaging preservation for long-time storage; and b) a | i great majority of the Army shipments appeared to consist ofj ordinance,* signal, medical, and photographic supplies whichj seem to have a greater density than the average of the mul titude of diversified items shipped by the Air Force and I Wavy. | In Figure 7 where the Army cargo densities to the , i Pacific areas are shown in line graph form, there is indi- * cated a great spread in density variations. In fact, only : the plot of the cargo densities to the Worthwest Pacific j follows any degree of regularity about the average. This ! : j disparity may be explained by the reasoning that to the ;Central Pacific and Western Pacific areas there was not a | sufficient number of samples nor enough total shipment j weight to furnish a representative sample. The relatively !small number of shipments can be compared with all others i |in Table IV showing the total weights of all shipments to ■ i 1 the various areas. ! ! Figure 6 illustrating the Air Force densities to the! I various areas shows some differences in density averages i 1 that can be partially explained by observations by experi- | enced air freight personnel at Travis. The fluctuations to; the low side of the Air Force average were generally ' 46 TABLE IT MILITARY AIR CARGO SHIPMENTS BY WEIGHT TO THREE OVERSEAS ARIAS AUGUST 1953 - JULY 1954 Northwest Pacific Central Pacific Western Pacific Army 682,184 lbs. 31,961 lbs. 82,177 lbs. 1 Air Force 5,016.596 1,362,967 440,075 Navy 3,114,159 1,380,056 559,280 ! i 1 ! TOTAL 8,812,939 2,774,984 1,081,532 | I accounted for in the shipment of light aircraft parts— such| i things as wing tip fuel tanks for fighter aircraft which j have a density of approximately 6.5 pounds per cubic foot.^i Often, due to operational expediency, it was necessary to make large rush shipments of such items that are sometimes expended at an unpredictable rate. In attempting to J explain the peaks of the chart, it was thought that perhaps j abnormally frequent shipments of aircraft engines might J have driven the densities to highs for the particular j i months. On the contrary, an investigation of aircraft | ! i engine densities revealed that they hovered around or even i below the Air Force cargo average densities. Typical i engine densities, for illustrative purposes, are 10.24 j pounds per cubic foot for a Pratt-Whitney R-4360 recipro- j ! jeating power package; 11.33 pounds per cubic foot for a !basic engine of the same type in a steel shipping con- ! Stainer, and 17.55 pounds per cubic foot for a J-47 jet I / L . engine in a protective steel shipping container. The high peaks in the Air Force average densities ^Stated fty Major Joseph R. Rasco, Officer in Charge, i Military Air Transport Service Air Freight Terminal, Travisi jAir Force Base, California, personal interview. | ^”Cargo Cube/Density Study,” (Record memorandum of , Traffic Division, Headquarters, Military Air Transport I Service, Andrews Air Force Base, Id., 1954)# !• remain unexplained except for the possibility that during | i i the particular months there was a dearth of the low density! items mentioned previously. ! Navy average densities follow general trends much as! the Air Force averages do. Nevertheless, Figure 8 shows that during the month of September and October 1953, Navy cargo densities were considerably above the average. Again, Travis air freight personnel recalled that during j that period of time they received large quantities of heavy! 7 I ship machinery to the Western Pacific area.' Other excep tional monthly variations are not immediately explainable, but possibly, as with the Air Force, the low point months i I were ones during which there were substantial shipments of ; [relatively light aircraft parts and assemblies. i i i ^Stated by Major Joseph R. Rasco, Officer in Charge, Military Air Transport Service Air Freight Terminal, Travis; , Air Force Base, California, personal interview. CHAPTER IV EFFECTS OF AIR CARGO DENSITIES OH PRESEHT OPERATIONAL AIRCRAFT The way machines are finally developed to achieve the desired resnit is by experimentation and improvement j over the mistakes of the ones that have gone before. The engineer designs the machine and can predict its perform ance with a great degree of accuracy. But only operational! I tests and exhaustive experience data will prove whether or : j i not the machine is doing the job that it is supposed to do.i The airplane is such a machine. . i This chapter will concern itself with the relation j i of air cargo densities to the operational performance and capability of existing transport aircraft types. ; I. RELATED FACTORS I i i Before the subject at hand can be fully explored, ' certain interdependent factors must be examined. These ,factors deal with the efficiency and method of terminal operations. t i i Backlogging of cargo. This study has delved thoroughly into the matter of average air cargo densities . \ 1 as derived from a given set of raw data. Yet the question I |may be asked as to whether or not the densities of the ! 50 cargo on hand will approach the average. The answer depends upon the amount of traffic and the willingness to backlog cargo.1 At the busier terminals such as the Ports ! of Aerial Embarkation of Travis Air Force Base, California,, and Westover Air Force Base, Massachusetts, the volume of j traffic is quite considerable, and it is expected to I become greater as more emphasis is placed upon the new logistic concept. Into these aerial ports are fed the overseas supplies destined for shipment by air transporta- | jtion. The serial ports are the collecting points, and it | j is from these that the fleets of logistic aircraft of the ! !Military Air Transport Service operate to the overseas | |areas. From Travis more than one million pounds of cargo | ; ; per month were airlifted to the three major Pacific areas I Q ]alone.* From Westover, during 1954> more than four million | pounds of air cargo per month were flown to all stations i jserved by the Atlantic Division of MATS.^ ' Controlling the flow of cargo into the aerial ports I ^Robert E. lickner, wThe Relation Between Cargo [Density and Airlift Capacity,! f (unpublished memorandum of the Rand Corporation, Santa Monica, California, July 1954)> 1 p. 2* , %upra, p. 35* I ^"Traffic Airlift Accomplishments,(unpublished | statistical report of Atlantic Division, Military Air I Transport Service, Westover Air Force Base, Massachusetts, i 4 February 1955), p. 1. ( 51: from origins all over the United States is an undertaking j of appreciable magnitude. The job calls for close coordin-j ation and scheduling so that the flow of cargo will not be i intermittent with a resulting jamming or starvation of j backlogs at the terminals. The flow must be monitored ; carefully so that the cargo will not have to wait an excessive length of time for shipment, thus increasing the i pipeline time which the logistic planners are trying so j i earnestly to reduce. j i Under concepts of present terminal operations, it has been determined that a minimum of three days backlog of j cargo is necessary to provide a sufficient amount oh hand to account for variation in the domestic pipeline time to j ithe port, and also to provide adequate lading in case extra1 i 1 j airlift is made available for a short period. ^ j A three day cargo backlog assists in allowing a ; certain amount of selectivity in choosing aircraft loads. ; i For instance, at Travis it was evident that a minimum of 1 300,000 pounds of cargo was on hand at any one time to the three major shipping areas plus a considerable quantity of i t mail. At Westover, during 1954* the backlog was computed I to be even greater— a minimum of 400,000 pounds of cargo ^Stated by Major Joseph H. Rasco, Officer in Charge,| j Military Air Transport Service Freight Terminal, Travis Air Force Base, California, personal interview. 5 ! and over 70,000 pounds of mail per day. As transport air-! craft of greater carrying capacity become available, and i more material is transported by air, these backlog tonnages will necessarily increase, but the endeavor to decrease i backlog times must be pursued even more aggressively. ! Therefore, it may be seen that air freight personnel had a selection of cargo available most of the time to use in pre-planning loads of the proper densities to attain the i desired combination of weight and cubes that would normally! result in full utilization of the aircraft payload and j space capacity. Stacking losses. Another related factor in the 1 i utilization of the transport aircraft cabin capacity that I must be considered is the problem of stacking losses. i 1 Since the shape of the aircraft fuselage determines, to a i j degree, the ease of cargo placement in it, as will be ( » : pointed out later, the matter of stacking losses is not jwholly dependent upon efficient terminal operations. But i I for the purposes of this discussion, stacking losses must i I j be approached in a different manner. ^ In order to completely utilize the usuable cube of ^Traffic Airlift Accomplishments,1 1 op. cit.. p. 2. 6Infra, p. 7-4. 53; i the cahIn cavity, an almost hypothetical set of circum- i stances would have to exist* Each piece of cargo would have to fit into the load so that there would be absolutely no space between it and the adjacent ones. The situation is not peculiar to aircraft, since it is a problem which has long plagued the maritime shipper whose aim is to load a ship "full and down." Even in the case of a highly specialized tanker, the condition is possible only when its i lading consists of a fluid possessing a specific gravity ! 7 ^ for which the ship was designed. ; Those factors which limit the full utility of the i cubic capacity of the vehicle and which directly result in | i stacking losses are the choice of cargo and limited ground , jtimes. In pre-planning the cargo load, the loading super- 1 i i jvisor may not always have as complete a choice of cargo as i ! he may desire. So that the proper balance between the i density and the cube may be maintained, the loading super visor may often necessarily accept irregular shaped items 1 of cargo that cannot be placed within the cargo envelope without some loss of space. If sufficient small cargo or mail is not available with which to fill the void spaces i readily, then his loading problem becomes somewhat complex. Fragmentary studies in the past have been averaged 7 'Johnson, op. cit.. p. 27. 54 and it was determined in the earlier studies that stacking losses approximated 26 per cent. These surveys revealed that the stacked load densities averaged 10 pounds per cubic foot. By using an average cargo density figure of ' i 13,6 pounds per cubic foot, computation resulted in the 26 ! c > ! per cent stacking loss. The stacking loss percentage in | ( the HATS system has since been revised to 17 per cent.9 To maximum!ze the use of the airplane, loading times1 i must be closely controlled and kept to a minimum so that 1 l the schedule may be maintained. Then too, ground time of ! an aircraft is an unproductive part of the transportation process. The loading time is normally dictated by the ■ ! loading characteristics of the aircraft, the amount of pay-j i load normally handled, and materials handling practices. j ! Therefore, with limited loading times, there is little to i I waste in experimentally hand-fitting every piece of cargo i I so as to gain a perfect load. i I i | Stacking losses and work-rate. The importance of i I stacking losses versus the loading work-rate were illms- Col. George Hewitt and Associates, "Report of | Field Trip to Lockheed Aircraft Corporation, Marietta, ! 'Georgia," (unpublished report to Deputy Chief of Staff, Operations, Military Air Transport Service, Andrews Air Force Base, Md., April 23, 1954)> P» 2. i ! %a3or Kermit R. Pope, Headquarters, Military Air j | Transport Service, Andrews Air Force Base, Md., personal | 'Correspondence. __ ; trated by a portion of a preliminary loading study on the fuselage mock-up of the Lockheed C-130 aircraft* In attempting to demonstrate that the C-130 could be loaded i i with a maximum payload, the Lockheed people spent consider-! i able time in accumulating close to ideal cargo and assembl ing it into a near-perfect, symmetrical load with a stack ing loss of only 10 per eent. By meticulously hand-fitting and tailoring the load for the demonstration— -to prove that the airplane was not cube limited— the loading task was | accomplished in six hours with a work-rate productivity of i 1,145 pounds per man per hour* This excessive work-rate is compared with the normal MATS computed work-rate of over • 2,000 pounds per man per hour on C-118 transport aircraft j ; which is not even specifically designed as a logistical i carrier.***® 1 1 1 Present stacking losses. If then, the 10 per cent 1 ! :stacking loss Is unrealistic under present loading stand- ; ;ards, then the question might arise as to whether or not j the 26 per cent stacking loss, accepted as the standard, I 'was a realistic one. MATS planners questioned the figure i in 1954 and sent a directive to all stations outlining test. I ! :criteria for reporting net densities and stacked densities •^Hewitt and Associates, op* cit.. p* 7. 56, for a specified period. When the test reports were tabu lated, stacked densities were found to average 17 per cent which was a considerable improvement over the 26 per cent i j stacking loss factor used previously.11 If the air cargo density average found by this study1 i to be H.52 pounds per cubic foot is accepted as valid, j then the load density planning factor can be increased to j 12 pounds per cubic foot by applying the newer 17 percent j stacking loss factor* Although 12 pounds per cubic foot | [ may appear to be a relatively small increase over the 10 j pounds per cubic foot planning density previously used, it! jean easily be seen that there is a substantial difference ! 1 if applied to an aircraft with 4-000 cubic feet of usable jloading space. ! ! ! i ! - ; j Materials handling systems* Not yet touched upon i are the materials handling systems used in loading aircraft i 1 and their contribution to the efficiency of space utiliza- 'tion. Generally, the subject is too broad to be adequately |presented in a paper of limited scope such as this. How- ? i |ever, the physical handling of cargo and the methods used 1 . 1 !to put it in place cannot be ignored completely in consid- : 1ering the effect on cargo operations. 1 Major Kermit R. Pope, Headquarters, Military Air Transport Service, personal correspondence* At present, most cargo loads are put in place and stacked by hand. Of course, several moving devices have been employed for some time to maneuver items of cargo aboard the aircraft, but it still remains that most of the • i loading and stacking is accomplished by hand labor. Much i experimentation is now going on in the Air Force to improve; the system in the light of the proposed developments of cargo aircraft such as the Douglas XC-132 which will pur- i portedly transport 100,000 pounds at its maximum range and j i which would conceivably take several hours to hand load. ! Such innovations are being considered as the master pallet ! i . I system whereby pre-loaded pallets slide into the aircraft i on rails and actually replace the floor of the aircraft. jAnother proposition being pursued is the idea of the port- : |able pre-loaded air transportable van which can be rolled ! |into the aircraft, lashed down, and flown away in a minimum of time.- * - 2 But these ideas and many others have yet to be ! proved and adapted to operational use. The lack of modern i ’ materials handling methods points up the fact they are j f ilaging behind transport airplane design. 1 i The people. All of the discussion contained in the , ^Col. Robert W. Johnson, nA Physical Handling Sys- . tern for the Revised Air Force Logistic Concept,H (unpub lished report to the Director of Transportation, Head- jquarters, United States Air Force, Washington, D.C., 1954)> I p. 12. 5S' prior paragraphs have one thing in common: The success of the full utilization of the cargo carrying capability of i the aircraft depends upon— to a marked degree— the people J who do the work* And certainly there is no evidence that 1 the loading supervisor or the cargo handler will be elimin-' j ated in the near future. | I The optimum tonnage accomplishment of even the most ideal transport aircraft is not possible if the loading supervisor does not pre-plan his loads taking into consider-^ ation cubes and densities; if the cargo handler maltreats j the cargo so that heavy excess protective packing must be j ithe rule; or if the load is so ill-fitted within the fuse- i ' j ! ilage that it appears to be little more than a jumbled mass. i ! In 1952 an experiment was conducted to determine the I effectiveness of moving a tactical air wing several thou sands of miles from its home base and supporting it for a i (prolonged period of time by the exclusive use of airlift. ! As one result of observations on the success of the proj- i eet, observers made a report of the conduct of cargo oper- ; i ations.^ ! a. When loading crews were familiar with the air- ' craft and material being loaded, it was found that the loading and unloading time established by the project could very readily be met. From loading and unloading ; time studies • . . this fact was readily established and futhermore justifies the conclusion that loading ^Johnson, op. eit.. p. 19. 591 manuals should he written for mse in training cargo | handlers for wording on all types of aircraft* j b. It is recommended that specific crews . . . be schooled in the proper and efficient operation of materials handling equipment in and around cargo air craft and in the fundamentals and procedures of handling cargo packed for air shipment • . . c. It is recommended that these crews should have j definite job assignments of air cargo loading and unloading, which will insure continuing familiarity and know-how of the job to be accomplished. ! Thus it may be seen that without proper selection of J i terminal personnel and extensive training of the cargo [ i loading supervisor and his cargo handling assistants, even I the most ideal cargo aircraft will not be utilized to the full extent of its potential. II. PAYLOAD-CUBE EFFICIENCY I In order to determine the future requirements of |the aircraft fuselage, it is well to explore some charac teristics of present ones of airplanes being used in the ,logistics fleet. Most of the deficiencies have been elim- ! inated in airplanes which will replace those of the out- i dated fleet. ! The dependency on door size. One phenomenon that f i i appears to exist in the operating field of military air i logistics is that larger items of cargo have less density , ! i jper cubic foot than smaller items. This is substantiated I ; by the experience of the Military Air Transport Service as - reported by the Headquarters Traffic Division.^ The effect on the present fleet is very distinct. In choosing i the loads at the cargo terminals for various types of air- j i craft, the loading supervisor must constantly keep in mind j the maximum size package that may enter the loading doors. Thus there will be an automatic screening of cargo for air craft with smaller doors, and the remainder will await an aircraft with larger doors. It follows that the selection ; i of cargo densities is automatically governed-— greater than | average densities for aircraft having relatively small J doors, and smaller than average densities for aircraft j equipped with the larger doors. , For comparison, Figure 9 shows the cargo loading j door sizes of the various operational aircraft. The main 1 jdoors of the C-54&, C-118, and C-121 airplanes are in the j side of the fuselage while the doors of the C-124 and C-130 I are in the nose and under-tail section, respectively. The i point is that cargo which may not pass through the doors of the C-54G, C-118, or C-121 airplanes, may, in all likeli- jhood, be loaded into the C-124 or C-130. Again, the former ! |group of aircraft will carry heavier density cargoes than t ithe latter through the automatic selection process. ^Col. Robert W. Johnson, wEffeets of Variations in |Cargo Densities,n (unpublished report to the Director of Transportation, Deputy Chief of Staff, Materiel, Headquar- I ters, U.S. Air Force, Washington, D.C., April 1, 1955)9 C - 130 M A IN C A R G O LO A D IN G D O O R lO'X 9* C-118 M A IN CARGO L O A D IN G D O O R lO'^'X 6'6" C - 12.4- M A IN C A R G O L O A D IN G D O O R 11’8“ X ll'A" C - 5 4 MAIN CARGO L O A D IN G D O O R 7'HM X 5' 7" 8*7' IOOO LBS. /A .52 L B S ./F T 3 < * > U ) FIGURE 9 C-121 M A IN CARGO LO A D IN G D O O R . 9 'I" X 6 ' CARGO LOADING DOOR SIZES OF OPERATIONAL TRANSPORT AIRCRAFT University or SoutKern Calirornui C o m ^ 7 c s ~ s f 62 The suggestion has been made that, of the present fleet of aircraft, the high lift, low cube ones be reserved specifically for the carriage of high density items, and conversely, the large cube aircraft be assigned to the 15 carriage of low density items* ^ Especially in the case of the C-121 and C-118 airplanes, the automatic selection sys tem already does this to a degree. These particular high lift aircraft are models which are the result of the exten sion of design life of the older C-54 Skymaster and C-69 Constellation models which were improved by adding more powerful power plants and by extending the fuselages in addition to many other improvements. A brief survey was conducted to cheek the accuracy |of this basic proposition of automatic cargo selection by [examining the cargo densities of several aircraft loaded I |for departure on scheduled missions and the evidence pre- jsented in Table Y bears this out. i | Payload-cube accomplishment. Payload-cube accom plishment, as the term is used, is interpreted to mean the j | degree to which the total useable cargo envelope is ! employed to carry the maximum payload which the structure p. 7. • * • 5 Johns on, o p . cit.. p. 1, CARGO o.? TABLE V DENSITIES OF LOADED AIRCRAFT AS GOVERNED BY CUBE/LIFT CAPACITY RATIO Type Ho. of Average Aircraft Samples Cargo Density C-54 11 19.6 lbs/ft3 C-118 7 17.7 c-124 9 14.78 I TABLE VI MATS AIRCRAFT - TONNAGE EFFECTIVENESS IN TRANSPORTING AVERAGE DENSITY CARGOES Airplane Volume Density Weight Limit Payload Average Load Density Cube Limit Payload Percent Tonnage Effectiveness Note* C-54 13.6 19,500 12.0 17,220 88.3 1 C-118 10.0 23,080 12.0 27,600 83.6 2 C-121 11.5 33,150 12.0 34,740 95.4 2 C-124 10.7 45,000 12.0 50,400 89.3 2 C-74 14.1 48,000 12.0 40,800 85.0 1 C-97 16.7 45,000 12.0 32,400 72.0 1 *1 cube limited 2 weight limited (From Johnson, effects in variation of cargo densities) 65 or operational requirements permit* In Table VI is shown a comparison of payload-cube accomplishments of some trans port aircraft in operational use* The load density of 12 pounds per cubic foot has been applied to the data in the table and is an outgrowth of the density findings accumu lated at Travis Air Force Base. The cube limit payloads were computed from the formula shown elsewhere in this 16 study* From the table it will be noted, to the extent i that the largest, lighter density loads can be carried onlyj in the C-118 and C-124 airplanes, the density of cargoes j remaining for lift in the C-54 and C-121 aircraft is increased* The indications are, therefore, that the pay load-cube accomplishment percentages shown are minimum i 1 7 ^ I measures of true accomplishment. I i The comparison of payload-cube accomplishment is illustrated graphically in Figure 10* The intersection of |the cube and payload lines for each aircraft are plotted j | to show their positions with respect to the average cargo i density curve, while the C-118 and C-124 plots fall to the jleft, or light side. Only the C-121 plot is comfortably ! i close to the average density curve. The almost ideal cube- payload effectiveness of the C-121 loses some of its sig nificance when the fuselage shape is examined, however. i z xoSupra. p. 18* ^Johnson, on. cit., table opposite p. 9. USABLE CUBE 4 5 0 0 13 il4 4 00 0 3500 3000 2500 2000 Le g e n d 1 C-54 2 c-na ■ 3—tr^37“ 4 C-121 5 C -74 1500 IOOO 9 II 13 15 17 19 21 23 25 27 2 9 31 3 3 3 5 37 39 41 4 3 4 5 4 7 4 9 51 53 55 P A Y L O A D IN T H O U S A N D S O F P O U N D S FIGURE 10 CARGO DENSITIES IN POUNDS PER CUBIC FOOT RELATED TO TRANSPORT AIRCRAFT PAYLOAD CUBE CAPABILITY (FROM JOHNSON, EFFECTS OF VARIATIONS IN CARGO DENSITIES) r 66 : i t * • • ' k / * « j * * * 5 * • V./ . 1 * t f s t _ _ v v i r . " t ~5 >, f ;\ ( J i ' A* > - X • % ( 'O ’ 2 f - ' ' • ■ » - <* - - ‘' < . : ,/ „ y , v * ** , „ I ’ > * . * f % i i 1 » v . * -* < • ■ • ;• „ ■ i • i % * . * , < - ' * ‘ - « d S * ,' > V > X v X ^ < X „ ^ ' ■ f , V ' ‘ “ s/> w/ 1 ' ^ ' f ' ■>? K j v ; • * ' ' * y . . , , ' a- ’ - ’ " / V M ’ * , \ ‘ .'VfV * ^ ■ * vy t % “ , , > 3 ( r * \ A < * - 'V W V : > T ; ' 5 ' ' . r - ' i . ' • X f * » „ ^ ^ * , I* ‘ * '" X - ' „ ;„ - f; -*5* - /fe>. ^5^-* ’’ . „ . , • • * ' J- - , ; ' . * v ; . x , - * • , X r V ^ ^ ar ^ < • , * V • ., , ^ J V » > y * v > -J* J\ , ' V V ^ * -,..•* . . ••« .*/;. ly-,, :J yf'V . . v f*y » • ' , 4 * * . ’ w * \ » * v ; ; . k • t * * < v, ° ' % , • ‘f>'**• v * *v - I - ' ' V * ' ; . * • k\ S • - * > . . - ■ . . . . , .. ., ' ' . < ',3 , tf " ■ , , ! , “ 4 - < > } ^ f ; v-^ \ . * J 2k' %*,'** J. . J /> 'ir „ ' 1 ’ < \ v j> .„ ' ^ ' '! ' t t ^ ^ ,w < V ' « I v V( * i >x >' f' x * * - fivr;--'. •: ^ - ■ > x*?*5 y . ; . ' ! • '-.V: ••• 1 | V < * 8 r * » . * i I S. i ''h1 ^ ^ *Vu’ J t * * > {J \ . x ? ' x M Xi ' ‘~ ■V t * ’' » -ir - * ' * K 5 67 Because of the round cross-sectional profile of the fuse lage presenting limited vertical clearances, the C-121 loads must he partially pyramided to take maximum advan tage of the useable cube. Optimum loading of the C-121, and, to a great extent, of other round fuselage airplanes, is achieved only by careful hand-stacking and load-shaping, and will rarely be realized in normal practice. Under actual conditions the C-121 plot would then be possibly somewhat misleading and would fall further to the right in 1 the figure. As progress is made with palletization and 1 unit load programs, it is probable that the actual cargo envelope will more closely resemble a rectangular section. : i Under such conditions the payload-cube accomplishment of round fuselage designs is considerably l£ss than those of | the rectangular ones. I As may be seen, in the case of those aircraft whose i volume density plots fall on the heavy side, increased pay-, load-cube accomplishment may be achieved only by extension ; !of range, at the expense of payload, or by the carriage of i 1 cargoes in the heavier density ranges.MO Of interest, in fconnection with this last statement, is the fact that the I C-54 and C-124 airplanes have a design point range of roughly 1900 nautical miles in comparison with the present l ft xo«Tohnson, ojd. cit., p . 8 requirement for a 3500 nautical mile design point range. It must be concluded that if the average density figure is the governing factor then there would be no ho of improving performance of the present, out-dated fleet ^JTones and Associates, c>p. cit., p. 13 CHAPTER V FACTORS IN CARGO AIRCRAFT FUSELAGE DESIGH OTHER THAI CARGO DENSITIES ! As has been stated before, until the last decade the' military has had to rely upon the converted passenger type aircraft then available to perform its airlift missions• But with a new emphasis on the design of transport air craft, two rather surprising factors come up repeatedly.*** | i 1) There is as an ever-widening gap between the j conventional type carrier and the military air cargo carrier as there is between a bus and a truck or between a i 1 I ;railroad boxcar and a Pullman. I 2) The trends constantly revert to parallels in ! i highway, rail and marine transportation. In those fields, i !differences exist between freight and passenger carriers as: I to speed and provisions for loading and unloading. The 'military services can no longer pay the multiple penalties of excessive weight, slow loading, and high cost for an ! i jall-purpose airplane. i i With the specialized aircraft trends influencing the 1 designers, the fuselage becomes rather complicated when the I ^Walter Tydon, "Military Air Cargo Trends," Aeronau-: : tical Engineering Review. July 1953, p. 39. types of carriers and their missions are considered. | Throughout the discussion of any criterion of aircraft j design, it must constantly be borne in mind that aircraft j design is a series of compromises between the realistic requirements, the structural possibilities, and the aerody-; namic possibilities.2 For many years the aircraft engi neers designed an aircraft with only very broad functional criteria in mind, but today the great emphasis is placed i upon the rigid design performance specifications set down j i to begin with. In the case of cargo aircraft, considera- i jtion of the fuselage design greatly influences the versa- ! itility and economical use of the aircraft. I i i j Size of the cargo compartment. The size of the 'cargo compartment must be conducive to efficient interior loading operations and possess sufficient usuable cubage to I I contain the largest amount of average density cargo expected i !to be carried on the projected routes during normal opera- i i It ions. Anything less in the way of usuable cubage will res- i trict the productivity of the aircraft in the event of tailwihds (lessening the fuel carrying requirements, thus increasing the weight carrying capability to a limit), low h,t. Col. George Hewitt, ! r Loadability as Applicable to Transport Aircraft Design,f ! (unpublished paper presented before the annual meeting of American Society of Mechanical; (Engineers, Hew York, lovember 1953), p* 1* j 71 density cargo, or normal operations over routes shorter than the design point range. Of course, beyond the maximum landing weight or the zero fuel weight, fuel and payload are not interchangeable. Just how much of the cubic capacity of the fuselage i may be defined as useable is a nice question. Some of the | o I factors have been discussed in previous chapters.-' Con- j ceivably, the cargo cavity could be used to its measured j j capacity, but such is not the ease in practice under pres- j ent accepted loading methods and limited loading times j which must be adhered to in dispatching the aircraft in the! scheduled stream of flights. Therefore, at busy logistical terminals and turnaround stations, the efficiency of cube l i | utilization will depend upon the experience and proficiencyj i f of the loading crew in "building" loads and also the type i |of cargo they are loading. Only under the most ideal com- , i j bination of cubes and weights and cargo characteristics can maximum cube utilization be realized. , In addition, other requirements peculiar to cargo aircraft operations are that passage ways must be left open' ! from front to rear for accessibility to the aft portion of i ; the aircraft in the event of emergencies on overwater 1 routes; room must be allowed for lashings over cargo to I------------------ i ^Supra. p. IS. hold it securely in place; some cargo cannot normally be stacked against the interior walls of the aircraft; and, of course, straight sided containers cannot be stacked in a | circular fuselage shape without some loss of space. : i Restricted useable cubage also impedes or restricts i the ^growth factor” of an aircraft. One of the greatest ! i operational problems is precipitated by the fact that j power plant improvements from time to time add to the per- ; formance of existing aircraft and allow a greater weight carrying capacity.^ If some projected allowance for this i increase could be made, based on past experience, to make ■ !provision for forseen growth, the design would have a much i [greater, economical life. In some of the older designs I i I * i 'such as the Douglas DC-4 and the Lockheed Constellation ! |series, the design life has been prolonged by the addition i | !of fuselage sections to increase the cabin length, and, i I although the practice is a common one today, it may not be i | a feasible one in future designs.-* i It was reported that the Pratt and Whitney Aircraft Corporation recently withdrew its proposed 1-34 turboprop engine from the Lockheed civil transport Constellation ^Hewitt, cit., p. 3. j ^stated by Herman 0. Olson, Douglas Aircraft : Company, personal interview. 73 turboprop project when Lockheed lengthened the model 1449 fuselage designs both 40 inches and 60 inches after payload and space studies indicated that the turboprop Super Con stellation could carry a heavier load than could be stowed j under average densities* Pratt and Whitney representatives! claimed that Lockheed wanted to pull too much cruise power 1 i & out of the T-34 for the new model. A Lockheed represent a- ( tive countered that the project was dropped by Lockheed because the engine design did not live up to promised powers and specific fuel consumptions which would have per-! mitted realization of design point ranges with maximum passenger (not cargo) loads. The point of illustration is that as more improved | ipowerplants become available, the growth potential of the ! j | (existing designs is greatly enhanced. The statement has ibeen made that the cost of air transportation can be con- i distantly lower in the future than it is today if a well -integrated plan of aircraft and engine development and i i growth is aggressively pursued.0 ^Lockheed Gives Up Turbopropped Connie,” Aviation ;feek, April 4, 1955. ! * 7 Stated by Charles J. Rausch, Lockheed Aircraft Corporation, personal correspondence. %om Y. Jones and Associates, ”Capability and Opera ting Costs of Future Transport Aircraft,” (United States Air Force project by Rand, Incorporated, Santa Monica, California, July 1953), p. 2. 7 A Shape of the cargo compartment* One consideration i pertaining to the shape of the eargo compartment is that ofj i the length to width ratio. From a materials handling j standpoint, a length to width ratio of ahout four to one is the most desirable to shorten the distance between the Q front and rear loading doors.7 Also the wider cabin will allow a greater freedom of movement and is conducive to faster loading times. Then too, a wide cargo compartment j provides the accessibility necessary to facilitate loading j i and unloading operations at intransit stations without | causing extensive load shifting due to the necessity of j balance limitations of a longer aircraft fuselage with i correspondingly longer moment arms. ! j The matter of aircraft balance begs some explana- j ;tion. An aircraft must be kept within certain balance ! 1 limits in order that it may perform as it was designed to ; ido. These balance limits are expressed in terms of a per- 1 ; centage of the mean aerodynamic chord of the wing as com puted by the designer. Balance computations of a cargo i load are expressed in terms of moments (distance of the i 'cargo from the reference datum x weight of a specific piece , of cargo) or by the formula: Moment = arm x weight. In ! ^Lt. Col. Ben W. Hunsaker, nA Transport Aircraft jEvaluation System,w (unpublished report to the Commander, j :Military Air Transport Service, United States Air Force, 75 practice a cargo aircraft is divided into compartments and the weight is tallied in each of these. By means of a com puter constructed on the principle of the logarithmic slide i rule, the loader may easily compute the center of gravity i change of the airplane as each compartment is loaded. When1 i the total load is aboard, the center of gravity must fall within the specified design limits. If it does not, the airplane cannot be flown safely. Since the moment is a function of the weight (fixed), and the moment arm (vari- j able), it may be seen that the shorter aircraft fuselage j will be easier to load within center of gravity limits than! a longer one. . An examination of the fuselages of most existing and' i planned logistical aircraft show that the goal of a four to; one length to width ratio has not been attained. Most have |length to width ratios of around 8 to 1, and the Douglas i ,C-133, the latest logistical transport to be ordered into I * i f \ ■ production, has a length to width ratio of 7.6 to 1. » Nevertheless, a lower length to width ratio is a goal that j Washington, B.C., December 1953), P* 6. | ^Engineering Report No. LB-21580; A Study of General Cargo Handling Methods on the YC-133 Airplane,0 : (report of Douglas Aircraft Company, Long Beach, Calif ornia, November 1953), p. 6. cannot be abandoned. | j The height of the cabin is largely an efficiency j i factor• The current thinking is that any height above ninej feet may be considered excessive for normal or planned 1 i military needs through the foreseeable future, and there- ; 11 fore constitutes an aerodynamic and structural penalty. The nine foot maximum height is predicted on the assumption that, although six or possibly seven feet is the maximum practical height to which a man can hand-stack a load, the I air transportable vans and unitized pallet loads of the j future will require a vertical clearance of eight feet plus; necessary head room. On many occasions there has been a | need to transport items which would require higher cargo I I I ■compartments, but those instances are not so numerous as to' jwarrant the economical building of an entire fleet around 1 12 them. i The cross-sectional profile of an aircraft is jdirectly tied to the efficient placement and stacking of cargo and, to a large degree, determines the space utiliza- I ition of the cargo compartment. The most prevalent shape in 'the past has been the circular or near circular section. i iIn recent years some cargo aircraft, notably the Douglas ^Hewitt, erg. clt.. p. 4. -^Hewitt, on. cit., p. 3* 771 C-124 Globemaster, were built with a nearly slab-sided, j almost rectangular shaped fuselage, that being recognized ! as the most efficient container for cargo* Some current J i shapes of transport fuselages are shown in Figure 11. But : with the advent of the turbo-prop engine which requires ; operation at altitudes around 30,000 to 40,000 feet for * best economy, even cargo compartments must be pressurized. This is because a great deal of the cargo carried, such as i toxics, gases, and anything in sealed containers can become1 dangerously explosive at high altitudes in unpressurized cabins. The most simple structure used in airframe con struction, from an engineering standpoint, to pressurize is; I the cylinder. Pressurization of a slab-sided fuselage j |requires additional reinforcement which would induce a I 1 3 ; i severe weight penalty that could be ill-afforded. Hewer !designs which incorporate pressurization, such as the C-13Q i again have a nearly circular cross-sectional profile but with a slab-sided interior in some sections which makes it i ! compatible with rectangular cargo envelope loading. i | The lack of a relatively long constant fuselage j section in most airplanes is also a deterent to an effi- i cient loading system. Tapering fuselage sections in both ^Stated by Charles J. Rausch, Lockheed Aircraft ' Corporation, personal interview. I --- ~1 C-118 .C-54 C -1 2 4 FIGURE 11 CROSS SECTIONAL FUSELAGE SHAPE VS. CARGO ENVELOPE TYPICAL SECTIONS OF MATS AIRCRAFT (NOTES NOT DRAWN TO SCALE) 781 * & % i ■ ' , . ■ * * ^ k . s r , « , ' t 1 " * 5 f k ' i ' ■J V - ; v ~ 1 * ' ' h , 'i > ^ ' ' * / « * , ’ . . 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"’ •<■ 1 ' - ; V ‘V: fe%s • • < , , ? J '4‘ . ^ ' -<^5,'^ ,4 ' W ; . ^ .K J - • ' 't« T ~ *> lV> ' % . . s % , •'-’ ’■/■ ■ • ’ • v y * \V' * . ' , --’ i , * ‘ t ” l L ‘ ‘ ■ i ' ' . ; > ■ « ' ‘ . * , ' • » , f j" * + V ' / » ' k r > ' r . ' , ' \ ' V , * * 5 , , ^ 1 ' “ * V * > » ' ^ h kx f t * *y t'-v’r. „ >v- n'v / ^ :4‘ 4 ,rWi *%* *' . . « «> ' ’ j}' r ’ *F.^r4: v' : • « , ’ v V . , * . V ' f , k ' * * ? , c ^ , • . ' ' ; j A - * 1 ;• • ^ ^ V \ .* * ' -v ’ 79 | | the front and rear of the aircraft prevent uniform stacking j methods which add to the loading time* Especially in the j case of palletized loads, much usuable space can be wasted*| I Therefore, a fuselage with as nearly as possible a long i constant cross sectional profile is the most desirable* I i Cargo entry doors * The cargo entry doors to the I i fuselage determine, naturally, the maximum package size that the fuselage will accommodate. The most desirable ' entry door is one which opens the fuselage to the full j dimension of its interior height and width. Present fuse- ' lages of logistic airplanes have their openings on the i side, in the front, or in the rear. ! Side doors are unsatisfactory because even the larg-| » jest doors do not open sufficiently to accommodate the iarg-' jest package by width and height measurement which will fit i lint© the fuselage cavity. Long, bulky cargo must be maneu vered around a corner to bring it parallel with the longi- Itudinal axis of the fuselage and the size of a piece of i 'cargo that can be thus maneuvered is limited. Doors 'located in the nose section of the aircraft are unsatisfac- i ;tory because they cannot be opened in flight to allow i jettisoning of cargo in an emergency. i The last possibility, therefore, is the rear cargo idoor* This type door has been incorporated in the two latest production cargo aircraft designs, the C-130 and the. 80 C-133, in which the doors are installed ornder the upswept tail. Divided horizontally in the middle, the bottom half of the door swings down to form a ramp, and the upper por- i tion swings up flush with the top of the cargo compartment j thus allowing a maximum door size access. ; ] I The design-point range. Closely allied to the fuse-! lage size, yet somewhat apart when considering performance,j is the matter of the design-point range. An aircraft, due 1 i to structural and power limitations and aerodynamic fea- j jtures, ean lift a certain maximum load and it can carry j this maximum load a certain range measured in flying hours. i I But if the aircraft is to travel further than this maximum ; i 1 i J j distance with the maximum load, it can do so only by j jexchanging payload for fuel. If the payload-range curve is; plotted, somewhere along the curve will lie the design- | !point range. j Shown in Figure 12, is the payload versus range tplots of nine different turbo-prop aircraft investigated as i Ia part of the Rand project. On the payload-range curves, tthe sloping lines through the design points are lines of jconstant take-off weight which show the results of exchang ing fuel and payload. The lines of const suit payload show the greatest loads that the airplanes are designed to carry. In the Rand study these capacity payloads are i limited by wing strength with the airplanes loaded to maxi- No. 6311, U n iv ersity B ookstore, Los A ngeles f - ill 5 - v ^ * * . - ‘ j S * " ' * i \ * , ' , / $ , v • > r ; ‘ -'^;V , : • > # ■ ' - i » ',. * 4* 4 ' « * - v o * w A ‘ i sf'vj s t > 4 82 mum take-off weights and carrying 65 per cent of the design point fuel loads by weight Thus the design point, under the Rand philosophy, intersects the payload-range line approximately 35 per cent below the maximum payload limit line* As one analysis of the Rand report brings out, there is actually a costly and exorbitant investment made in extra structure, drag, and power that is seldom required.^ The author of the analysis contends that the design point of an aircraft should fall near the intersection of the cubage (payload and structure) limit line (horizontal), and the optimum range line (vertical)Therefore, the range line should intersect the range payload curve approximately 10 per cent below the cubage (payload) limit line to allow ;for low density cargo, tailwinds, and occasional operation 17 jof the aircraft at shorter than optimum ranges. Summary* lost of the considerations of fuselage •^Jones and Associates, ojd. cit* * p. 11. *^Lt. Col* Ben W. Hunsaker, t f Analysis of the Rand Report,n (unpublished report to the Deputy Chief of Staff, Operations, Headquarters, Military Air Transport Service, Andrews Air Force Base, Md*, 16 November 1953), p. 2. 16Ibid.. p. 3. 17Ibid.. p. 3. 83 i shape and size have dealt with the loading problem with but a brief insight into the design applications. Basically the entire process of air transportation is one of materi als handling, and contributes nothing to the usefulness of j the item carried. But, when the chain of transportation j i events is broken down, the loading and unloading steps are the most unproductive parts of the procedure. Therefore, time spent in loading and unloading is idle time for an i i expensive aircraft which must be flying through the air to j i 'be productive. Through the competitive demand for the air-j ,craft industry to solve the materials handling problems 1 j [ I inherent in older designs, the engineers have, of late, ' ^ I begun to come up with designs which more nearly meet the I ■ requirements of the operators. The fuselage cavity, being ' !the container for cargo, is one deciding factor in the 1 | success of cargo aircraft designs. CHAPTER VI SUMMARY AED CONCLUSIONS T i The goal of the Air Force Logistics Concept for 1956, briefly, is to reduce inventories through reduction i of pipeline times. In order to do this, with economy of operation, there is a requirement for a fleet of logistics aircraft carrying greater amounts of cargo at greater speeds over the longest forseeable routes at a reasonable j cost. Although this is obviously an over simplification of! 1 the logistics problem, it is, nevertheless, true in essence. I I | Many, Many, design factors enter into this nebulous j i - !requirement. There are the aircraft performance consider- | I I J ations relating to aerodynamics, power, and speed; and the 1 | operational demands for a suitable vehicle of desirable jloading characteristics, range, and capacity. To weigh ! all of the factors, compromise what can be designed with the present state of design art, and what must be designed, 1 , and then to come up with a vehicle that satisfies the , requirements, must be a tremendous job indeed. It is i | little wonder that the engineering costs constitute a great portion of the total aircraft costs, nor is it surprising ^Sammons, op. cit.. p. 2, 85 " j that no sooner is an aircraft ready for operational use than it has heen made obsolete by newer designs on the drafting boards, I. SUMMARY ! Average cargo densities. The theme of this study, J although much necessary digression has taken place, has been that the average cargo densities are important in the overall planning of aircraft fuselage design criteria. At j large terminals which shall support the logistic fleet, ! there must be ample cargo backlogs to keep the pipeline ; flow at an even rate and to furnish lading for the sched uled fleet. Therefore, there will be available such a wide i jselection of cargoes on hand that the average density j I I jbecomes a significant factor when considering the capacity : i i |of a cargo fuselage design. These present average densi- ' Ities at a typical military logistical terminal have been determined to be 14*52 pounds per cubic foot, i i Other cargo information. Although there has been i no comprehensive investigation into the characteristics and i 'type of the typical cargo transported, such as frequency of certain items, frequency of size ranges, or type of packag- i ing required, such information would be helpful in deter mining the correlation of the cargo characteristics to i . .future cargo densities. 86 I _ Other fuselage design criteria. All indications are that average cargo densities shall, in the future, influ ence transport fuselage design to a marked degree, but other factors are also present. The shape of the fuselage j ! for aerodynamic and pressurization requirements must be in 1 balance with operational demands such as the length to width ratio, ease of access, ease of uniform load place ment, and interior shape. The size of the fuselage depends upon the usable cubage requirement plus other spaee required for safety aisles, headroom, and allowance for I \ design growth. ; i ! Packaging and load unitization. The people who i ! i ! operate the terminals are also cognizant of the fact that j the aircraft designs are striding ahead of current materials t 1 ! handling methods. The operating staffs are groping for ! jbetter, lighter, and cheaper packaging to reduce tare i weight. They are devising means of reducing or eliminating, individual packing by consolidating loads into vans which need no packaging or by unitizing shipments into palletized1 loads which can be easily handled and minimize stacking | losses. Nevertheless, there still remains an atmosphere of i reaction at the terminal level due to lack of education in the job, lack of physical resources to improve the mate- ; ,rials handling methods^ and a certain indifference which i 'results in the airplanes being loaded in much the same manner as they were ten years ago* II. COHCLUSIONS Air Cargo densities* The cargo density data collected for this study is only a beginning, but at least i it is that* It does not cover a long enough time span to i I allow trend predictions, nor is it by any means conclusive.j ♦ However, it is representative, factual data which fortifies, the **educated guesses’ * of some authorities and tends to j l disprove those of others. | i With a great emphasis being put on air logistics ; through the official recognition of air transportation as j a normal mode of conveyance, conceivably the nature of air ; cargo will change as will the methods of preparation for carriage, as mentioned in the summary. The value of air cargo density information being recognized by military representatives and the airframe manufacturers, then such a study must be continuous to predict future trends. i Payload-cube potential of an aircraft * The payload-’ cube potential of a cargo compartment is a function of its structure, dimensions and arrangement, and of the density factor selected as the design density. This payload-cube potential is independent of the range and payload capacity i of the vehicle in which it is incorporated. Maximum pay load-cube effectiveness of a cargo compartment is attained ! only when the actual load density is identical with the design-point density factor, and is adversely affected by extensions of range beyond the aircraft design point j mission, or by the carriage of cargoes of lighter density i than that for which the cargo compartment was designed. i i Load densities and stacking losses. The matter of stacked cargo densities and the difference in the net den- | i sities and the stacked load densities, i.e., stacking losses, has only been explored briefly and perhaps inade- ! quately. More conclusive data is necessary concerning ; * * |stacking losses. For the time being a stacked density of I ; twelve pounds per cubic foot appears to be acceptable as a : i planning guide based upon a stacking loss factor of 17 per-j ! cent. But both of these figures will undoubtedly require • ; continuous examination as materials handling methods and i ■ efficiency of loading methods improve. j ! In some designs, there is too great a disparity | between the payload capability of the airplane and possible true accomplishment because of existing cargo density and I 1 the dictates of handling and loading practices. This dis parity may result in an exorbitant investment in structure, drag and power that is seldom required. Materials handling systems. All present transport ! fuselages are dependent upon hand-loaded methods with per haps a machine assist. Such systems as the air transport- able van or the master pallet replacing the aircraft floor are proved and utilised, their effect on loaded cargo den sities must also be examined. Yet it still remains that the effective implementation and success of any system will continue to depend upon the recognition and treatment of the cargo loading crew as one of its most critical ele ments. BIBLIOGRAPHY A. BOOKS Speas, R. Dixon. Airline Operations. Washington, D. C.: American Aviation Publications, 1948. von Clauswitz, Karl. Principles of War. Harrisburg, Pennsylvania: Military Science Publishing Company, 1942. B. PERIODICALS "Congress Sets Sights on Missies, Airlifts," Aviation Week. ' February 7, 1955, p. 13. j 1 "Industry Spotlight," American Aviation. January 17, 1955, . p. lo. j 1 "Lockheed Gives Up Turbopropped Connie," Aviation Week. j April 4, 1955, p. 15. Tydon, Walter. "Military Air Cargo Trends," Aeronautical Engineering Review. July 1953, pp. 39-42. ; "U. S. Hot let Ready to Give Up Leadership," American j Aviation. September 13, 1954, P* 21. ! j C. UNPUBLISHED MATERIALS I '"Airlift Helps AMC Cut Logistical Knots," Air Materiel | Command. USAF. Reprinted from August 16,1954, edition , I of Aviation Week, pp. 44-48. |"Air Cargo Density Survey," letter from Commander, Military • Air Transport Service, Andrews Air Force Base, Mary- | land, to Commander, Atlantic Division, Military Air ! Transport Service, April 15, 1954* 'Bickner, Robert E. "The Relation Between Cargo Density and Airlift Capacity." Unpublished memorandum of the Rand Corporation, Santa Monica, California, July 1954. 92] "Cargo Cube/Density Study," memorandum of the Office of the Director of Traffic, Deputy Chief of Staff, Operations, Headquarters, Military Air Transport Service, United States Air Force, Andrews Air Force Base, Maryland, undated. | "Cargo Density Study," letter from Commander, Atlantic Division, Military Air Transport Service, Westover Air Force Base, Massachusetts, to Commander, Military Air Transport Service, United States Air Force, Andrews Air Force Base, Maryland, April 27, 1954* i "Engineering Report lumber LB21580; A Study of General Cargo Handling Methods, YC-133 Airplane." Unpublished report of Douglas Aircraft Company, Long Beach, California, November 30, 1953. j Harris, Tom. "Air Cargo Densities," letter to Lt. Col. 0. j D. Stafford, Headquarters, Military Air Transport | Service, United States Air Force, Andrews Air Force j Base, Maryland, March 8, 1954* j Henn, Lt. (jg) C. L. "Operation Tittles— Study of Cargo ; Densities, Month of February and March, 1949." Unpub lished report of the Office of the Director of Traffic,! Headquarters, Combined Airlift Task Force, Weisbaden, j Germany, April 1949. I I |Hewitt, Lt. Col. George. "Leadability as Applicable to Transport Aircraft Design." Unpublished paper pre- j sented before the annual meeting of American Society of Mechanical Engineers, Hew York, lovember 1953. i ;Hewitt, Lt. Col. George, and Associates. "Report of Field < ; Trip to Lockheed Aircraft Corporation, Marietta, | Georgia." Unpublished report to Deputy Chief of Staff, ! Operations, Headquarters, Military Air Transport i Service, United States Air Force, Andrews Air Force j Base, Maryland, April 23, 1954* Hunsacker, Lt. Col. Ben W. "An Analysis of the Rand Report." Unpublished report to the Deputy Chief of Staff, Operations, Headquarters, Military Air Transport1 Service, United States Air Force, Andrews Air Force Base, Maryland, lovember 16, 1953. 93 Hunsacker, Lt. Col. Ben W. ”A Transport Aircraft Evalua tion System.1 1 Unpublished report to the Commandder, Military Air Transport Service, United States Air Force, Andrews Air Force Base, Maryland, December 1953. Johnson, Colonel Robert W. ”A Physical Handling System for the Revised Air Force Logistic Concept.” Unpub lished report to the Director of Transportation, Head quarters, United States Air Force, Washington, D. C., 1954* Johnson, Colonel Robert W. nEffects of Yariations in Cargo Densities,0 Unpublished report to the Director of Transportation, Headquarters, United States Air Force, Washington, D. C., April 1, 1955. > Jones, Tom Y., and Associates. ’ ’Capabilities and Operating; Costs of Future Transport Aircraft.” Unpublished i report to United States Air Force by Rand, Incorpor- I ated, Santa Monica, California, July 1953. ! Middlewood, Robert W. ”Loekheed C-130A Transport in the i Mobility Era.” Unpublished paper Humber 54— A-227 | presented before the annual meeting of American Society of Mechanical Engineers, New York, November 28, I 1954. ! [ | Ruebel, Captain Ralph A. ”Report of Field Trip to Westover Air Force Base.” Unpublished report to Deputy Chief of i Staff, Operations, Headquarters, Military Air Transport ! Service, Andrews Air Force Base, Maryland, November 5, I 1952. I I j Sammons, Colonel J. M. ”The Role of Air Cargo in Modern I I Logistics.” Unpublished paper Number 54— A-216 pre- I i sented before the annual meeting of American Society of Mechanical Engineers, New York, November 28, 1954* | Waters, Captain Don A. ”Field Report— Review of Cargo | ! Densities,” Unpublished report to Deputy Chief of j i Staff, Operations, Headquarters, Military Air Transport Service, Andrews Air Force Base, Maryland, March 2, 1954. Waters, Captain Don A. ”Traffic Controller’s Report— MATS 1 Operations Orders 5-54 &nd 7-54.” Unpublished report to Deputy Chief of Staff, Operations, Headquarters, Military Air Transport Service, Andrews Air Force Base,1 i Maryland, March 19, 1954- > i i . ... 94, ^Traffic Airlift Accomplsihments,” unpublished statistical report of Atlantic Division* Military Air Transport Service* Westover Air Force Base, Massachusetts, February 4> 1955. D. PERSONAL INTERVIEWS AID CORRESPONDENCE Guilbert, Colonel Edward A. Deputy Chief of Staff* Traffic Headquarters, Atlantic Division* Military Air Transport! Service, United States Air Force, Westover Air Force | Base, Massachusetts. j Hunsacker, Lt. Col. Ben W. Office of the Deputy Chief of j Staff, Operations, Headquarters, Military Air Transport! Service, Andrews Air Force Base, Maryland. j Olson, Herman 0. Douglas Aircraft Corporation, Santa s j Monica, California. ; iPope, Major Hermit R. Office of the Deputy Chief of Staff,' ! Operations, Headquarters, Military Air Transport j j Service, Andrews Air Force Base, Maryland. , I | jRaseo, Major Joseph R. Officer in Charge, Military Air ; I Transport Service Air Freight Terminal, Travis Air | Force Base, California. 'Rausch, Charles J. Lockheed Aircraft Corporation, Burbank,: ! California. I i ! Walsh, E. J. Director, Division of Cost Analysis, United | States Post Office Department, Washington, D. C. E. AIR FORCE REGULATIONS ^Policy on the Use of Air Transportation, * * Air Force 1 Regulation Number 76-16, March 30, 1954* tatverSity of Southern California

Asset Metadata

Creator Christena, George H. (author)

Core Title An experimental investigation of air cargo densities and some other operational factors related to transport aircraft fuselage design

Contributor Digitized by ProQuest (provenance)

Degree Master of Business Administration

Degree Program Business Administration

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag OAI-PMH Harvest,transportation

Language English

Advisor Goodwin, John L. (committee chair), Libby, Phillip A. (committee member), Rausch, Charles J. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c20-144025

Unique identifier UC11261943

Identifier EP43459.pdf (filename),usctheses-c20-144025 (legacy record id)

Legacy Identifier EP43459.pdf

Dmrecord 144025

Document Type Thesis

Rights Christena, George H.

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

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