Jetrader - November/December 2010 - 23

by a former employee, Jack Northrop. (Northrop became a famous airframe manufacturer in his own right; those of you who attended that ISTAT Airshow will remember his piston-engine quarter scale ﬂying wing for Northrop’s jet powered ﬂying wing bomber. The prototype was used in the ﬁlm of the “The War of the Worlds” by H. G. Wells.) More importantly, unlike the Boeing 247, the wing spars had to pass under the cabin ﬂoor and the passengers had to have comfortable seats with plenty of leg room. The Douglas design team met far into the night for over a week and arrived at the

Boeing 247D. Photo taken by Bill Bath from a B-17 bomber at a 2001 airshow.

following features listed in the AIAA 2002 book by John D. Anderson Jr., The Airplane, a History of its Technology. 1. Be a low-wing monoplane. (TWA had suggested their tri-motor could also be a biplane.) 2. Use a modiﬁed version of the Northrop Wing. 3. Be a twin-engine airplane, not a trimotor. 4. Have retractable landing gear housed in the engine nacelles. 5. Have some type of ﬂap to permit a slower landing speed. 6. Use the NACA engine cowling to increase cooling and decrease drag. 7. Locate the engine nacelles well ahead of the wing leading edge so that the propeller slip stream over the wing would not induce it to twist. After some weeks of hard negotiations in New York between Arthur Raymond with Vice President Harry Wetzel of Douglas and TWA President Richard Robbins and his team, which included TWA Vice President Frye and Charles Lindbergh as technical consultant, a

contract was signed for one prototype at a price of $125,000 and the option to purchase 60 more for $58,000 each. The contract was 42 pages, of which 29 were detailed technical speciﬁcations. Note that TWA’s original speciﬁcation was only one page; the same as the Wright brothers speciﬁcation for the Wright Military Flyer to the U.S. Army 25 years earlier in 1908. In the end, Douglas got the contract over its competitors by focusing on the engine-out concerns of the TWA team; calculations showed a 90 percent certainty of a safe takeoff and climb from all of the airline’s airports. Only by building a prototype and testing it could the uncertain 10 percent be proven to also safely make a takeoff with an engine failure. What followed were 200 tests in the California Institute of Technology’s wind tunnel. A weight increase during design work shifted the center of gravity aft and the tests revealed the aircraft would be unstable. By adding that now familiar sweepback to the DC-1, plus outer wing panels and consequent slight rearward shift of the aerodynamic center of lift, ﬂight stability was restored. The ﬁrst ﬂight of the DC-1 took place less than a year after that TWA letter was received by Donnell Douglas; subsequent to solving the engine cut-out mystery in climb, it met all of TWA’s route and operating requirements. The ﬁrst production model was labeled the DC-2. By adding two feet to the fuselage, it could now carry 14 passengers and was delivered to TWA on 14 May 1934. A total of 156 of these planes were ordered worldwide.

were also changed. Its ﬁrst ﬂight was on 17 December 1935 with a 30 percent greater payload than the DC-2, plus a 50 percent heavier gross weight. The initial production models had Wright R1820 engines rated at 1000 hp, but the military version (C47) had the Pratt & Whitney R1830 rated at 1200 hp, which eventually became the standard for the DC-3. Removing the sleeper bunks, Douglas had a commercial winner with 21 seats and sold 803 to the world’s airlines. Production of the military C47 totaled 10,123. Author’s Note: In June 1944, as a 13-year-

Removing the sleeper bunks, Douglas had a commercial winner with 21 seats and sold 803 to the world’s airlines. Production of the military C47 totaled 10,123.
old living in Brighton on the south coast of England, all civilians had been conﬁned to the town for more than a month. Around 2 June, the 140,000 Canadian troops moved out with their tanks and artillery in the middle of the night, and on 5 June a violent storm caused waves from the English Channel to explode dozens of the land mines buried in the beach. By night the storm abated, and the roar of Merlins and radial engines from ﬁghters and medium bombers passing low overhead kept all awake. In the early gloom of daybreak on the 6th, I looked out the window to see a gaggle of C47s heading out towards Normandy struggling along each towing a glider. The show was on and the Douglas C47 was playing a major role in the initial assault behind enemy lines.

Further Douglas Developments
It was Cyrus. R. Smith, the president of American Airlines, who was the father of the famous ﬁnal model, the DC-3. It took a $300, two-hour phone call from his Texas ofﬁce to convince Donald Douglas that he was serious about ordering 20 DC-2s for a transcontinental sleeper service, which would commit the airline to an order for which it did not have the money. However, Smith got a $4.5 million loan from President Franklin Roosevelt’s New Deal. Reconstruction Finance Corporation and design work for the Douglas Sleeper Transport (DST) with California Institute of Technology wind tunnel assistance created what was a new airplane. The fuselage was longer and wider with a greater wingspan; the ﬁn and rudder

References:
Principal reference: John D. Anderson Jr., The Airplane, a History of its Technology. AIAA, 2002 Graham White, Allied Aircraft Piston Engines of World War II, SAE, 1995 WWW: Wikipedia.com/Douglas/DC-1 etc WWW. Numerous: DC series with P&W Wasp & Wright Cyclone engines Jetrader 23

http://www.Wikipedia.com/Douglas/DC-1

Jetrader - November/December 2010

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