Analysis of information sources in references of the Wikipedia article "Gurney flap" in English language version.
Liebeck conducted wind tunnel tests on the effect of a 1.25% chord height Gurney flap. He used a Newman-type airfoil, which had an elliptic nose and a straight line wedge for the rear section.[permanent dead link]
Once Gurney had confirmed they were alone, Unser told him the rear was now so well planted that the car was pushing (understeering) badly, hence the poor lap times.
So successful was this deception that some of his competitors attached the tabs projecting downwards to better protect the hands.
Gurney flaps are known already since 1931, when they were first patented by Zaparka (USA).
And I remembered having spent a lot of time with these little tabs on the back, or spoilers and so forth, and I thought to myself – well, I wonder if one would work on a wing? We already had wings on these in 1971. Sure enough, that was the beginning of the Gurney flap.
Liebeck stated that race car testing by Dan Gurney showed that the vehicle had increased cornering and straight-away speeds when the flap was installed on the rear wing.
through the proper use of Gurney flaps, the aerodynamic performance of a simple design, easy-to-build airfoil can be made practically as well as those of a modern, high performance, complex design.[permanent dead link]
One of the critical flight conditions is a high-powered climb. The negative angle of attack of the horizontal stabilizer can be as high as −25°, whereas in autorotation it may be +15°.
These devices provided an increased region of attached flow on a wing upper surface relative to the wing without the flaps.
One candidate technology is the Gurney flap, which consists of a small plate, on the order of 1–2% of the airfoil chord in height, located at the trailing edge perpendicular to the pressure side of the airfoil.
Race-car driver Dan Gurney used this flap to increase the downforce and, thus, the traction and potential cornering speeds generated by the inverted wings on his race cars.
...the intermittent shedding of fluid recirculating in the cavity upstream of the flap, becomes more coherent with increasing angle of attack.... Comparison of flow around 'filled' and 'open' flap configurations suggested that [this] was responsible for a significant portion of the overall lift increment.
Liebeck stated that race car testing by Dan Gurney showed that the vehicle had increased cornering and straight-away speeds when the flap was installed on the rear wing.
Liebeck conducted wind tunnel tests on the effect of a 1.25% chord height Gurney flap. He used a Newman-type airfoil, which had an elliptic nose and a straight line wedge for the rear section.[permanent dead link]
The first theoretical investigations were published by Liebeck who introduced the concept of trailing edge devices to aircraft aerodynamics.
When hot-wire anemometry is used, a tonal component in the spectrum of the velocity fluctuations downstream of the Gurney flap is shown. This points to the existence of a von Kármán vortex street.
...the intermittent shedding of fluid recirculating in the cavity upstream of the flap, becomes more coherent with increasing angle of attack.... Comparison of flow around 'filled' and 'open' flap configurations suggested that [this] was responsible for a significant portion of the overall lift increment.
The problem is to create, in landing, a region of turbulence on the lower side of the wing near the trailing edge by some obstacle to the air flow.
{{cite conference}}: CS1 maint: location (link){{cite journal}}: Cite journal requires |journal= (help)...the intermittent shedding of fluid recirculating in the cavity upstream of the flap, becomes more coherent with increasing angle of attack.... Comparison of flow around 'filled' and 'open' flap configurations suggested that [this] was responsible for a significant portion of the overall lift increment.
And I remembered having spent a lot of time with these little tabs on the back, or spoilers and so forth, and I thought to myself – well, I wonder if one would work on a wing? We already had wings on these in 1971. Sure enough, that was the beginning of the Gurney flap.
One candidate technology is the Gurney flap, which consists of a small plate, on the order of 1–2% of the airfoil chord in height, located at the trailing edge perpendicular to the pressure side of the airfoil.