I understand the C-39 was/is still considered a DC-2 derivative rather than a DC-3 Derivative.
I guess the DC-3 at that time in the late 1930's was still considered a DC-2 derivative as well, the "DST" was intended to be an enlarged "DC2" sleeper versiom, the fin and other mods were for handling and performance, the fuselage changes to fit the sleeping berths etc, the "DC3" was the day passenger version if this "improved DC2", the later success of the DC3 has since overshadowed the DC-2, but in the mid 1930's it was the DC-2 that was the most famous and well known of the two types and was the real ground breaking aircraft. - 1934 Air Race, etc
http://www.aarg.com.au/DC2.htm
Quote:
"The DC-2 was developed from a 1932 TWA Airlines requirement for a replacement for its aging wooden airliners due to the cost of operations and maintenance. TWA’s competitor, United Airlines had ordered Boeing’s 247 Airliner, and locked up production for others until their own needs were met, risking a significant competitive disadvantage to TWA.
Douglas, who had previously only built military aircraft, was keen to secure work for the airlines and responded with the twin engined DC-1, The DC-1 had a design cruise speed of 190 MPH, 30 MPH faster than the Boeing 247 (20% faster), and could carry 14 passengers compared to 10 in the Boeing 247 (40% more load).
As TWA was currently operating trimotor airliners to ensure added safety they demanded demonstration of the DC-1 on single engined performance. A novel demonstration on September 1933 saw the DC-1 depart Arizona's Wimslow airport and cut one engine immediately on takeoff, climb to 8000 feet and cruise to Albuquerque on one engine, arriving there 15 minutes ahead of the TWA Ford Trimotor scheduled flight that had departed Wimslow before it.
TWA immediately ordered twenty DC-2 aircraft which incorporated minor changes to the DC-1 Prototype, before 1934 was over all but one of the major US airlines had the DC-2 on order or in service, and Boeing was unable to sell any further Boeing 247 Aircraft. A total of 198 DC-2 and its military C33 & C39 versions were built before it evolved into the larger "sleeper" DST and DC-3 design as the worlds most successful commercial airliner.
The C33 was a militarised version of the DC-2, 18 were delivered between between May 1936 and January 1937, the C33A, redesignated the C38, was a one off improved C33 with "DC3 tailplane, nacelles and undercarriage.
The C39 was the production version of the C38, 35 were delivered in 1938.
Obviously from the USAF Museum photo, all or the later C39's had rounded fuselages, but perhaps of the original length?
There are major differences between the DC-2 and DC-3, in fuselage shape, width, and length, wing centre-section, wing outer panels, fin, rudder, engines etc.
http://www.aarg.com.au/DC3.htmQuote:
"The DC-3 was intended to have 85% commonality with the DC-2, although in the end the DC-3 was quite different and only able to utilise about 10% of the DC-2's components. Differences included a rounded fuselage to create a 66cm wider floor space, 76cm longer fuselage, increased wing span, more powerful 920 HP Wright Cyclone single row 1820 engines, and enlarged fin and rudder to overcome handling problems in the DC-2. The prototype first flew in December 1935 and only 50 DST aircraft entered service before the DC-3 in standard airliner form caused a revolution in the industry, with a DC-3 costing little more to operate than a DC-2, but offering a 50% increase in payload from 14 to 21 seats, it quickly caused the retirement of most other types such as the 10 seat Boeing 247 then still in United Airlines service."
Quote:
" By December 1941 when the USA entered the war, 500 DC-3's had been built and a further 369 were on order, the USAAC impressed 10% of operational airline aircraft, and requisitioned new airline aircraft direct from the production line, with those aircraft being designated C48, C49, C50, C52 dependant on the source and engine configuration."
The purpose designed military versions were the C53 "Skytrooper" Troop Transport and the C47 "Skytrain" Cargo Transport. "
The C47 had large cargo doors, strengthened metal floor and tie down points, Pratt and Whitney twin row 1830 engines, stronger landing gear and a glider towing cleat, and first flew in January 1942, with an eventual 9,500 being built. C47/Dakota's served in every allied air force, including the RAAF, which operated 124 lend-lease Dakota's (C47's) under its "A65-" number series and recently retired its last examples after 60 years of service. "
hope that clarifies
regards
Mark Pilkington
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