Clark Y is the name of a particular

airfoil An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more Lift (force), lift than Drag (physics), drag. Wings, sails and propeller blades are examples of airfoils. Foil (fl ...

profile, widely used in general purpose

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

designs, and much studied in

aerodynamics Aerodynamics () is the study of the motion of atmosphere of Earth, air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dynamics and its subfield of gas dynamics, and is an ...

over the years. The profile was designed in 1922 by Virginius E. Clark using thickness distribution of the German-developed Goettingen 398 airfoil.Piccirillo, Albert, "The Clark Y Airfoil - A Historical Retrospective," SAE/AIAA paper 2000-01-5517, presented at the World Aviation Congress & Exposition, October 10, 2000, San Diego, California. The airfoil has a thickness of 11.7 percent and is flat on the lower surface aft of 30 percent of chord. The flat bottom simplifies angle measurements on propellers, and makes for easy construction of wings. For many applications the Clark Y has been an adequate airfoil section; it gives reasonable overall performance in respect of its

lift-to-drag ratio In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the Lift (force), lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficie ...

, and has gentle and relatively benign stall characteristics. The flat lower surface is not optimal from an aerodynamic perspective, and it is rarely used in modern designs.

The Clark YH airfoil is similar but with a reflexed (turned up)

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 1997. ...

producing a more positive

pitching moment In aerodynamics, the pitching moment on an airfoil is the Moment (physics), moment (or torque) produced by the aerodynamic force with respect to the aerodynamic center on the airfoil . The pitching moment on the wing of an airplane is part of ...

reducing the horizontal tail load required to trim an aircraft.

Applications

Aircraft

The

Lockheed Vega The Lockheed Vega is an American five- to seven-seat high-wing monoplane airliner built by the Lockheed Corporation starting in 1927. It became famous for its use by a number of record-breaking pilots who were attracted to its high speed and lo ...

and

Spirit of St. Louis The ''Spirit of St. Louis'' (formally the Ryan NYP, registration: N-X-211) is the custom-built, single-engine, single-seat, high-wing monoplane that Charles Lindbergh flew on May 20–21, 1927, on the Charles Lindbergh#New York–Paris flight ...

are two of the better known aircraft using the Clark Y profile, while the

Ilyushin Il-2 The Ilyushin Il-2 ( Russian: Илью́шин Ил-2) is a ground-attack plane that was produced by the Soviet Union in large numbers during the Second World War. The word ''shturmovík'' (Cyrillic: штурмовик), the generic Russian term ...

and

Hawker Hurricane The Hawker Hurricane is a British single-seat fighter aircraft of the 1930s–40s which was designed and predominantly built by Hawker Aircraft Ltd. for service with the Royal Air Force (RAF). It was overshadowed in the public consciousness by ...

are examples of mass-produced users of the Clark YH.Lednicer, David
The Incomplete Guide to Airfoil Usage
The

Northrop Tacit Blue The Northrop Tacit Blue is a technology demonstrator aircraft created to demonstrate that a low-observable Stealth technology, stealth surveillance aircraft with a low probability of intercept radar, low-probability-of-intercept radar (LPIR) and ...

stealth technology demonstrator aircraft also used a Clark Y. The Clark Y was chosen as its flat bottom worked well with the design goal of a low radar cross-section.

Model aircraft

The Clark Y has found favor for the construction of model aircraft, thanks to the flight performance that the section offers at medium

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

airflows. Applications range from free-flight gliders through to multi-engined radio control scale models. The Clark Y is appealing for its near-flat lower surface, which aids in the construction of wings on plans mounted on a flat construction board. Inexperienced modellers are more readily able to build model aircraft which provide a good flight performance with benign stalling characteristics.Martin Simons, ''Model Aeroplane Aerodynamics'', Model & Allied Publications 1978. Chapter 7 - 9, Aerofoil Sections.

Cars

An inverted Clark Y airfoil was used on the spoilers of the

Dodge Charger Daytona Dodge produced three separate models with the name Dodge Charger Daytona, all of which were modified Dodge Chargers. The name was taken from Daytona Beach, Florida, which was an early center for auto racing and still hosts the Daytona 500, NASCA ...

and

Plymouth Superbird The Plymouth Superbird is a highly modified, short-lived version of the Plymouth Road Runner with applied graphic images as well as a distinctive horn sound, both referencing the popular ''Looney Tunes'' cartoon character Road Runner. It was th ...

. (29 June 2005)
From NASA to NASCAR
retrieved 29 April 2017

Aircraft

Some of the better-known aircraft that use the Clark Y and YH: ;Clark Y *

Aeronca 50 Chief The Aeronca Model 50 Chief is an American light plane of the late 1930s. Consumer demand for more comfort, longer range and better instrumentation resulted in its development in 1938, powered by a 50-horsepower (37-kilowatt) Continental, Frankli ...

* Avia B.122 *

Consolidated PT-1 The Consolidated PT-1 Trusty (company designation Model 1) is a biplane primary trainer used by the United States Army Air Service (USAAS) in the 1920s. Design and development In 1921, Colonel Virginius Clark, chief designer of the Dayton-W ...

Fleet Fawn In the 1930s, Fleet Aircraft manufactured a series of single-engined, two-seat training aircraft, based on US designs. The Fleet Model 7B and Model 7C, known respectively as Fawn I and Fawn II were purchased by the RCAF as primary trainers. Afte ...

(all intermediate designs used the same section) *

Curtiss P-6 Hawk The Curtiss P-6 Hawk is an American single-engine biplane fighter introduced into service in the late 1920s with the United States Army Air Corps and operated until the late 1930s prior to the outbreak of World War II. Design and development Th ...

(most of the Curtiss Hawks used the same section) *

Heath Parasol The Heath Parasol is an American single or two seat, open-cockpit, parasol winged, homebuilt aircraft, homebuilt monoplane. Design and development In 1926, Edward Bayard Heath, a successful American air racer and the owner of an aircraft parts ...

Orion Orion may refer to: Common meanings * Orion (constellation), named after the mythical hunter * Orion (mythology), a hunter in Greek mythology Arts and media Fictional entities Characters and species * Orion (character), a DC Comics c ...

(all intermediate designs used the same section) *

Polikarpov R-5 The Polikarpov R-5 () was a Soviet Union, Soviet reconnaissance bomber aircraft of the 1930s. It was the standard light bomber and reconnaissance aircraft of the Soviet Air Force for much of the 1930s, while also being used heavily as a civilian ...

Ryan Brougham The Ryan Brougham was a small single-engine airliner produced in the United States in the late 1920s and early 1930s.Taylor 1989, p. 772. Its design was reminiscent of the Ryan M-1, M-1 mailplane first produced by Ryan in 1926, and like it, was ...

and related types including the

Stinson Reliant The Stinson Reliant is a popular single-engine four- to five-seat high-wing monoplane manufactured by the Stinson Aircraft Company, Stinson Aircraft Division of the Aviation Manufacturing Corporation of Wayne, Michigan. Design and development ...

Vultee V-11 The Vultee V-11 and V-12 were United States, American stressed-skin monocoque monoplane attack aircraft of the 1930s. Developed from the Vultee V-1 single-engined airliner, the V-11 and V-12 were purchased by several nations for their armed forc ...

* Waco Standard and Custom Cabin series ;Clark YH * Currie Wot *

and Il-10 *

Mikoyan-Gurevich MiG-1 The Mikoyan-Gurevich MiG-1 () was a Soviet fighter aircraft of World War II that was designed to meet a requirement for a high-altitude fighter issued in 1939. To minimize demand on strategic materials such as aluminum, the aircraft was mostly ...

and

MiG-3 The Mikoyan-Gurevich MiG-3 () is a Soviet fighter- interceptor used during World War II. It was a development of the MiG-1 by the OKO (opytno-konstruktorskij otdel — Experimental Design Department) of Zavod (Factory) No. 1 in Moscow to rem ...

Miles Magister The Miles M.14 Magister is a two-seat monoplane basic trainer aircraft designed and built by the United Kingdom, British aircraft manufacturer Miles Aircraft. It was affectionately known as the ''Maggie''. It was authorised to perform aerobatic ...

Nanchang CJ-6 The Nanchang CJ-6 ( zh, c=初教6) is a Chinese basic trainer aircraft designed and built by the Nanchang Aircraft Factory (now Hongdu Aviation) for use by the People's Liberation Army Air Force (PLAAF). Development The CJ-6 (Chu Jiao 初教 ...

Polikarpov I-153 The Polikarpov I-153 ''Chaika'' () is a late 1930s Soviet sesquiplane fighter. Developed from the I-15 with a retractable undercarriage, the I-153 fought in the Soviet-Japanese combats in Mongolia and was one of the major Soviet fighter types ...

* Potez 39 * Stolp SA-900 V-Star *

Yakovlev Yak-1 The Yakovlev Yak-1 () was a Soviet fighter aircraft of World War II. The Yak-1 was a single-seat monoplane with a composite structure and wooden wings; production began in early 1940.Angelucci and Matricardi 1978, p. 239. The Yak-1 was a man ...

, 3 and 9 * Yakovlev Yak-50

References

{{reflist

External links

Clark Y airfoil at airfoiltools.com
including coordinate data
Clary YH airfoil at airfoiltools.com
Aerodynamics Aircraft wing design