The Davis wing is a

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

-era aircraft

wing A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expres ...

design that was used by

Consolidated Aircraft The Consolidated Aircraft Corporation was founded in 1923 in aviation, 1923 by Reuben H. Fleet in Buffalo, New York, the result of the Gallaudet Aircraft Company's liquidation and Fleet's purchase of designs from the Dayton-Wright Company as the ...

on the

Consolidated B-24 Liberator The Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models des ...

, as well as other models. The airfoil had a lower

drag coefficient In fluid dynamics, the drag coefficient (commonly denoted as: c_\mathrm, c_x or c_) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag equ ...

than most contemporary designs, which allowed higher speeds, and created significant lift at relatively low angles of attack. Its use in designs ended almost immediately following the

end of World War II End of World War II can refer to: * End of World War II in Europe * End of World War II in Asia World War II officially ended in Asia on September 2, 1945, with the surrender of Japan on the . Before that, the United States dropped two atomic ...

Development and use

Theory and testing

In the summer of 1937

Reuben H. Fleet Reuben Hollis Fleet (March 6, 1887 – October 29, 1975) was an American aviation pioneer, industrialist and army officer. Fleet founded and led several corporations, including Consolidated Aircraft. Birth and early career Fleet was born on Mar ...

, president of Consolidated Aircraft met with David R. Davis. Davis was a freelance

aeronautical engineer Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is si ...

who was looking for development funds for his airfoil design, the "Fluid Foil". Davis had designed the profile "in reverse", starting with a basic low-drag teardrop shape and then modifying it to provide 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 the new wing would offer reduced drag over designs then in use, and would offer considerable lift even at a small

angle of attack In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is m ...

. Additionally the thickness of the wing provided space for fuel storage, or even embedding engines, an idea that was in vogue at the time. He approached Consolidated to license it for their large

flying boat A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in that a flying boat's fuselage is purpose-designed for floatation and contains a hull, while floatplanes rely on fusela ...

s. The ability to generate lift at low angles of attack made it particularly attractive for flying boats because it would reduce the need to pull up the nose for takeoff and landing, which was limited in flying boats by the surface of the water. Neither Fleet nor Isaac M. Laddon, Consolidated's chief engineer, were impressed and Davis failed to convince them to try out his new design. A few days later, however, Laddon changed his mind and convinced Fleet to pay for construction of a model and wing wind tunnel test at the

California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

. They intended to compare the design to one that had been designed in-house. Initial results of the Caltech wind tunnel tests were disappointing. Test instruments did not support Davis' predictions. However, Davis and others determined that the Caltech wind tunnel's instruments were not sufficiently sensitive to detect improvements from the Davis wing tests, despite being among the most sophisticated of their kind at the time. After re-calibration of the Caltech wind tunnel instruments, tests showed significantly improved readings.Notes from a 1989 reunion of Consolidated Aircraft design engineers, San Diego, CA The results of the wind tunnel test were so good that the engineers were skeptical. Caltech recalibrated its wind tunnel and ran them a second time, and then a third time. When it delivered its report to Consolidated it indicated that the wing appeared to deliver everything it claimed, but Caltech also suggested it might be a wind tunnel fluke, something that gives good results only in the tunnel. This is a common problem since the tunnel's walls affect the results by increasing the effective aspect ratio, or the

Reynolds number In fluid mechanics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces. At low Reynolds numbers, flows tend to be domi ...

used could have been incorrect.

Real world use

Fleet allowed it to be used on Consolidated's new twin engine flying boat, the Model 31 XP4Y Corregidor. The Model 31 made its first flight on 5 May 1939, vindicating the Davis wing. By this point Consolidated was already working on a secret project for a new

bomber A bomber is a military combat aircraft designed to attack ground and naval targets by dropping air-to-ground weaponry (such as bombs), launching aerial torpedo, torpedoes, or deploying air-launched cruise missiles. The first use of bombs dropped ...

to improve on the

Boeing B-17 Flying Fortress The Boeing B-17 Flying Fortress is a four-engined heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Relatively fast and high-flying for a bomber of its era, the B-17 was used primarily in the European Theater ...

that was just entering service, and had selected the Davis wing for this project as well. The Model 32, which would become the B-24 Liberator, first flew on 29 December 1939. The same basic wing would also be selected for the

Consolidated B-32 Dominator The Consolidated B-32 Dominator (Consolidated Model 34) was an American heavy strategic bomber built for United States Army Air Forces during World War II, which had the distinction of being the last Allied aircraft to be engaged in combat duri ...

Limitations and abandonment

Only later was the reason for the Davis wing's performance properly understood. Largely through accident, the shape maintained

laminar flow In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mi ...

further back from its

leading edge The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...

, to about 20 or 30% of chord compared to the 5 to 20% managed by most airfoil sections of the era. Although later designs greatly improved on this, with some maintaining laminar flow to upwards of 60% of chord, the Davis wing represented a great improvement at the time. The thick profile of the wing quickly led to its being superseded. Although aerodynamic tests prior to the war had demonstrated that high-speed drag was strongly associated with thick wing profiles due to

wave drag In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (res ...

, it was only late in the war that higher speeds made that an insoluble problem. As speeds of aircraft increased, the Davis wing's reduced low-speed drag could not compensate for its increased high-speed drag.

References

{{Reflist

Bibliography

* ''The Davis Wing and the Problem of Airfoil Design'',

Walter G. Vincenti Walter Guido Vincenti (April 20, 1917 – October 11, 2019) was an American engineer who worked in the field of aeronautics, designing planes that could fly at hypersonic speed. He was elected as a member of several scientific societies, incl ...

, ''Technology and Culture'', Vol. 27, No. 4, Oct., 1986, pp. 717–758
The Dreese Airfoil Primer, Part 5: Laminar Airfoils Made Easy

External links

– correspondence in ''Flight'' Aircraft wing design