Davis wing
Low-drag wing used on B-24 Liberator; abandoned after WWII.
The Davis wing was a World War II-era aircraft wing design used by Consolidated Aircraft on models including the B-24 Liberator. Its airfoil produced less drag than most wings of the time, allowing higher speeds and generating lift at small angles of attack. Its use in designs ended almost immediately after World War II. Reuben H. Fleet, president of Consolidated, met freelance engineer David R. Davis in mid-1937. Davis sought funding for his "Fluid Foil" airfoil, which he had designed by starting with a low-drag teardrop shape and modifying it for lift. In comparison with conventional designs, Davis's design was relatively thick, having a short chord while still being deep enough to allow a high aspect ratio. Davis claimed it would reduce drag and provide lift at low angles of attack, and its thickness could house fuel or even engines. He approached Consolidated to license it for large flying boats, where low-angle lift would help during takeoff and landing on water. Fleet and chief engineer Isaac M. Laddon were unimpressed and initially declined. Days later, Laddon changed his mind, and Fleet funded a model and wind tunnel test at Caltech to compare the Davis wing with an in-house design. Initial results were disappointing, but Davis and others concluded the tunnel’s instruments were not sensitive enough. After recalibration, tests showed significantly improved readings. The results were so good that engineers were skeptical. Caltech recalibrated and ran the tests twice more, then delivered a report indicating the wing performed as claimed, though it warned the results might be a wind tunnel fluke. Fleet allowed the wing on Consolidated’s new twin-engine flying boat, the Model 31 XP4Y Corregidor, which first flew on 5 May 1939 and vindicated the design. Consolidated was already working on a secret bomber project to improve on the B-17 Flying Fortress and chose the Davis wing for it. That project became the Model 32, or B-24 Liberator, first flown on 29 December 1939. The same wing was later used on the B-32 Dominator. The wing was thinner than the B-17’s, and many B-24 units suffered heavy losses because heavily loaded wings often failed structurally when hit by gunfire. Its height required a tricycle landing gear, which made ditching and belly landings more difficult.
- Designer
- David R. Davis
- Developer
- Consolidated Aircraft
- First flight aircraft
- Consolidated Model 31 XP4Y Corregidor
- First flight date
- 5 May 1939
- First flight bomber
- Consolidated Model 32 (B-24 Liberator)
- First flight bomber date
- 29 December 1939
- Laminar flow range
- 20 to 30% of chord
Lore & Background
In the summer of 1937, Reuben H. Fleet, president of Consolidated Aircraft, met with freelance aeronautical engineer David R. Davis, who sought funds to develop his 'Fluid Foil' airfoil. Davis designed the profile 'in reverse,' starting with a low-drag teardrop shape and modifying it to provide lift. The wing was relatively thick with a short chord, allowing a high aspect ratio and space for fuel or embedded engines. Davis claimed reduced drag and lift at small angles of attack, which appealed for flying boats. Fleet and chief engineer Isaac M. Laddon were initially unimpressed, but Laddon later changed his mind and funded wind tunnel tests at the California Institute of Technology. Initial tests were disappointing due to insufficiently sensitive instruments; after recalibration, results were so good that Caltech ran tests three times, though they cautioned it might be a wind tunnel fluke. Fleet allowed the wing on the Model 31 XP4Y Corregidor, which first flew on 5 May 1939, vindicating the design. Consolidated then selected it for the secret Model 32 bomber project, which became the B-24 Liberator, first flying on 29 December 1939. The same wing was used on the Consolidated B-32 Dominator. However, the wing was thinner than on the B-17 Flying Fortress, and heavily loaded B-24 wings often failed structurally when hit by gunfire. The high wing required a tricycle landing gear, which made ditching and belly landings harder. Later analysis showed the Davis wing maintained laminar flow to about 20 to 30% of chord, compared to 5 to 20% for most contemporary airfoils. Although later designs achieved laminar flow to 60% of chord, the Davis wing was a great improvement at the time. Its thick profile led to its supersession: prewar tests linked thick wings to high-speed wave drag, and as aircraft speeds increased, the Davis wing's low-speed drag advantage could not compensate for its high-speed drag penalty.
Reader's Guide
The Davis wing's significance lies in its laminar-flow performance, which was accidentally achieved and represented a notable advance over contemporary airfoils. It enabled the B-24 Liberator to achieve higher speeds and lift at low angles of attack, contributing to the aircraft's success. However, the wing's structural weakness under gunfire and its thick profile, which caused high-speed wave drag as aircraft speeds increased, led to its abandonment almost immediately after World War II. The article notes that the wing's performance was initially met with skepticism, and Caltech warned it might be a wind tunnel fluke, but real-world use on the Model 31 and B-24 vindicated the design. Ultimately, the Davis wing was superseded by later designs that maintained laminar flow further along the chord, and its thick profile became a liability at higher speeds, ending its use.
Did You Know?
- The Davis wing was designed 'in reverse,' starting from a low-drag teardrop shape.
- Initial wind tunnel tests at Caltech were disappointing until instruments were recalibrated.
- Its thick profile caused high-speed drag that led to its abandonment after WWII.
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