Budd RB Conestoga The RB - 1 Conestoga was a twin - engine , stainless steel cargo aircraft designed for the United States Navy during World War II by the Budd Company of Philadelphia , Pennsylvania . Although it did not see service in a combat theater , it pioneered design innovations in American cargo aircraft , later incorporated in modern military cargo airlifters . Design and development . World War II created a great demand for military transport aircraft in the United States . Because of initial fears of a shortage of aluminum , the War Department explored the use of other materials for aircraft construction . Budd , the developer of the shotweld technique for welding stainless steel and a manufacturer of stainless steel railroad cars , automobile , bus , and truck bodies , hired an aeronautical engineering staff and worked with the U . S . Navy to develop a new twin - engine transport aircraft constructed primarily of stainless steel . The U . S . Navy accepted the proposal for the new aircraft , and placed an order for 200 , to be designated RB - 1 . The U . S . Army Air Forces ( USAAF ) followed with an order for 600 , designated C - 93 . The Conestoga was a twin - engine high - wing monoplane with tricycle landing gear . The elevated flight deck was contained in a distinctive , almost spherical nose section . Its two Pratt & Whitney R - 1830 - 92 air cooled 14 - cylinder , twin - row , radial engines , the same engines fitted to the C - 47 , drove three - bladed Hamilton Standard Hydromatic constant - speed , full - feathering propellers and powered a 24 - volt electrical system . While the fuselage was thin - gauge stainless steel , only a portion of the wing was made of the metal ; the trailing section of the wing and all control surfaces were fabric - covered . Innovations . The RB - 1 / C - 93 was radical for its day , introducing many of the features now standard in military transports . The flight deck could accommodate three crew members , pilot and copilot side - by - side , the navigator behind them . Stairs connected the flight deck to the cargo area , which was long with an unobstructed cross - section of 8 × 8 feet ( 2 . 4m ) throughout its length . Cargo loading and unloading could be accomplished in two ways : through 40 × 60 inch ( 102 × 152 cm ) doors on both sides of the fuselage or by an electrically operated 10 × 8 foot ( 3 . 0 × 2 . 4 m ) ramp at the aft end of the cargo area under the upswept tail , a similar development to what had been initially fitted to the Germans ' own Ju 90 four - engined transport aircraft as their " Trapoklappe " ramp in 1939 . The RB - 1 ' s loading ramp , accessed by manually operated clamshell doors , along with the tricycle landing gear , meant cargo could be loaded / unloaded at truck - bed height . A manually operated two - ton ( 907 kg ) hoist for unloading trucks and a one - ton winch for pulling cargo up the ramp were also provided in the cargo area . The aircraft could accommodate : Operational history . The prototype first flew from the Budd Red Lion Factory Airfield in Philadelphia , Pennsylvania on 31 October 1943 , piloted by Guy Miller . The prototype had a takeoff run when empty of just 650 feet , and could carry a maximum payload of 10 , 400 pounds with a takeoff run of 920 feet . However , the aircraft demonstrated greater than expected fuel consumption ; the range with a standard payload was only 700 miles , 650 miles with a maximum payload . Three prototype aircraft : " NX37097 " , " NX41810 " , and " NC45354 " were built ; one was used for testing radio equipment , while the other two were used for flight test evaluations . During testing , a few aircraft had difficulty with the simultaneous deployment of the right and left landing gear . With the same engines as the C - 47 , but with 3 , 000 pounds more weight ( empty ) , the aircraft was relatively underpowered ; it was reportedly said that for an aircraft built by a railroad car company , it indeed handled like one . At the Budd factory and airfield in Philadelphia , Pennsylvania , there were construction delays due to cost overruns and problems with stainless steel fabrication . By late 1943 , aluminum production had been increased with the construction of new processing facilities , and other more conventional cargo aircraft ( such as the Curtiss C - 46 Commando and the Douglas C - 47 Skytrain ) were being produced in large numbers . This caused the Army to cancel its order for the C - 93 and the Navy to reduce its RB - 1 order from 200 to 25 , of which 17 were delivered in March 1944 . On 13 April 1944 , during a Naval Air Training Command ( NATC ) evaluation flight of RB - 1 prototype U . S . Navy " NX37097 " at Patuxent River NAS , Maryland , the aircraft crashed , killing one of the crew . The aircraft was damaged beyond repair and written off , but the pilot reported that the stainless steel construction of the aircraft contributed to saving his life . Production RB - 1 aircraft never entered squadron service with the Navy , but a few were briefly used by Naval Air Station s as utility aircraft . With only 17 aircraft in inventory , the RB - 1 was not feasible to maintain on the active list , and it was retired from U . S . Navy service in early 1945 . The extant RB - 1s were then transferred to the War Assets Administration ( WAA ) to be sold as war surplus . In 1945 , the WAA sold 12 Conestogas to the National Skyway Freight Corp for $ 28 , 642 each at a time when new C - 47s were selling for approximately $ 100 , 000 each . The new company , founded by members of the AVG Flying Tigers immediately sold four RB - 1 aircraft to other buyers , which paid for the entire WAA contract . The seven remaining National Skyways aircraft were used to transport a variety of cargo , shipping fruit and furniture from its base in Long Beach , California . Pilots reported that the Budd transports were temperamental ; in particular , exhaust stacks kept falling off and causing engine fires . There were three more crashes of the Conestogas while in service with National Skyway Freight , one each in Virginia , New Mexico , and Michigan . The crash in Virginia was a belly landing at a country club brought on by fuel exhaustion as the result of weather - related problems . The Albuquerque , New Mexico crash was apparently due to pilot error when the exhausted pilots fell asleep ; they awoke in time to make a forced landing , but pilot and copilot were killed when they were thrown through the windshield and the aircraft skidded over them ; the flight engineer survived . In 1947 , the U . S . Army ( and later the U . S . Air Force ) gave National Skyway Freight a large contract for trans - Pacific freight , for which it leased military aircraft . The company changed its name to Flying Tiger and replaced the RB - 1s with C - 47s for its U . S . freight routes ; the RB - 1s were sold off to other buyers . One of these aircraft , a prototype RB - 1 , " NC45354 " was sold to the Tucker Motor Company to transport its demonstration 1948 Tucker Sedan to auto shows around the U . S . ; it was reportedly later abandoned at an airfield in Oakland , California after repeated mechanical troubles . Survivors . A single unrestored Budd RB - 1 is on display at the Pima Air Museum in Tucson , Arizona .