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Aviation History
1945
1945 - 0862.PDF
47« FLIGHT MAVJRD, 1945 Cargo Aircra A Study of the Efficiencies of Various Designs : Wing Loadings Range fron\J^to~26^P^^ds per and Power Loadings from 15 to Ih^/Pounds per Horsepower /By ROBERT J. AS it is .always possible, to achieve great seeeds for agiven price with sacrifice in economy (this^ijgwever,^ not being the best solution to the problem), a has been prepared on the air cargo transportation economics as affected by speed increases resulting from higher wing loadings and lower power loadings. It is recognised that, in passenger transportation, the passenger could, and probably would, pay premium prices for time saved due to higher speeds. This will not be the case in cargo and freight transportation. It is not believed that a customer would want to pay the cost of, say, 30 per 'cent, higher operational expenses for saving 45 min. time on a 5-hr, total time ; that is, flying plus handling, on a 500-mile trip ; or. say for 3 hr. saving on 15 hr. total time necessary for a 2,000-mile trip. In cargo and freight transportation, the service of picking up and delivery of the goods by truck must also be taken into account This will further extend the time required for such service, and will therefore reduce the advantage of higher speeds obtained in the aii. For these reasons, it is believed that the advantages of air cargo transportation, as compared with ground trans- portation, will not be great enough to operate at distances truck, so th>t<deliyery of the goods by either method of transptwtation could be made early in the morning. It is Terefore only at distances approximating 500 miles that, a substantial portion of a working day would be saved by aircraft. As is seen from the above figures, the handling time is a very important factor in aircraft cargo transportation, and every effort must be made to facilitate this. A typical example of such excellent arrangement is a railroad box car. Its floor is level and located at the most convenient height above the ground. Its capacity and size should alsc ^ be taken into consideration in the design of a cargo aircraft," but not necessarily its height. Basic Design Features In order to satisfy these requirements, the logical cargo aircraft therefore would be : High wing so that there is easy access to the fuselage and its cargo holdA Tricycle landing gear must be used so that the fuselage floor is level and of approximate height of a truck platform for easy loading. The door opening, which would best be located in the rear, should be approximately 9ft. wide and 7ft. high; and the length of the cargo hold, which must be unobstructed. much shorter than 500 miles. For example, for a distance should be anywhere from 30ft. to 60ft., depending on the of 150 miles, approximately 4 hr. will be required for truck^^size of the aircraft. For handling mail, compartments service, this including pick-up and delivery. For an air- craft, I hr. will be required for flying, and approximately 2 hr. ground handling time, this including the time required for pick-up and transfer of cargo between the service truck and aircraft at point of departure, and unloading and accessible from the outside should be placed under the main cargo floor, with possibly some arrangement for the use of parachute containers for mail in localities where the aircraft would not land. The design should be such that the distribution of cargo delivery time at the point of destination. Therefore, the^/for freight in the cargo hold would allow great variation time required for aircraft service will be 2+J, totalling so that the airlines would not have to go through any 2-f hr. The difference between the two means of trans- lengthy centre of gravity computations. For example, it is portation would be only ij hr. For twice the distance, tht quite feasible to provide variation of C.G. limits of such time required would stilr be only overnight travel of ar^i"magnitude that either the forward or aft half of the cargo 3 o HU. O s f- o S o o * 7 4- 3 ^- • *-" "OhIP 2 ««* -^- 4O( «*• •MM ^-4* lO H H V3 B , •• 12 C O I* •M 2 •E — - "1 J4- ..: 5-' roH -B S3 p 5- S9 • i -A 7OOO:; 1- I C4 B 1 = H c 9 3 -\ ; • s | ["1 ] • ' Slii = i> ** C2 I IMP ^»^- ——/V/b »-« <** rW/S4O w/s WS26 2O"P 4" Mi 0 33 > —I \opoo I5POO 20,000 30O00 50,000 CROSS WEICHT OF AIRCRAFT. LBS. 100,000 Fig. 1. Variation of specific wing structure weight with gross weight and wing loading.
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