Gurney Wickers

[jcorsico]

Does anyone use these on their FE wings? The rules changes a few years ago allowing people to run them, but I can't recall seeing anyone actually using them.

[S Lathrop]

I don't know what the FE rules are.

But a quick way to evaluate the effect of a Gurney is to place a digital level across a wing with the trailing edge of the level on the top of the trailing edge of the wing and then again on top of the Gurney. The difference in the angle of the level will be a very good estimate of the effect of the Gurney.

Say the Gurney changes the angle by 2 degrees vs. no Gurney, then you have the option of changing the wing angle 2 degrees or add a Gurney that gives a 2 degree angle change. The effect on handling will be very close.

I always use a 1/8 gurney as a minimum. I have used Gurneys an high as 1 " when I could not change the angle of the wing.

I also have used Gurneys in various lengths. Usually I start at the outer edge of the wing, the portion in front of the tire. This is done when I have very tall Gurneys.

Just to confuse you, you can use a 1/2 Gurney on the outer 6 to 8 inches of the wing or use a 1/4 inch Gurney over the entire length of the wing. The effect might be the same for front down force but there might be quite a difference further down the car. At the rear, Gurneys are just as effective and full width is not the only option.

Have fun guys. And I thought the FE guys chose that class to avoid just this kind of stuff.

[Peter Olivola]

Here's the FE Front wing Gurney wording from the GCR:
Wicker bill (Gurney flaps) are
permitted as an option for installation on the trailing edge upper
surface of the front wing secondary elements only, not the wing
main plane. They must be attached in a secure fashion, without
modification to the wing element except for mounting hardware.
Total height is .500”. Maximum number of mounting locations on
front flaps is 2 on each flap and maximum hardware size is #8
(.156). Gurney flaps, where attached, shall be 90 degrees and
parallel to the upper surface of the wing element and no taper or
“saw toothed” Gurneys are permitted.

And similar wording for the rear wing:
Wicker bill (Gurney flaps) are permitted as an option for installation
on the trailing edge upper surface of the wing element. They must
be attached in a secure fashion, without modification to the wing
element except for mounting hardware. Total height is .250” on
one or both elements. The Gurney flap only, may extend beyond
the parameters of the end plate. Maximum number of mounting
locations is 5 and maximum hardware size is #8 (.156). Gurney
flaps, where attached, shall be 90 degrees and parallel to the upper
surface of the wing element and no taper or “saw toothed” Gurneys
are permitted.

[J Leonard]

This one by Adrian Newey might not be legal

[S Lathrop]

Here's the FE Front wing Gurney wording from the GCR:
Wicker bill (Gurney flaps) are
permitted as an option for installation on the trailing edge upper
surface of the front wing secondary elements only, not the wing
main plane. They must be attached in a secure fashion, without
modification to the wing element except for mounting hardware.
Total height is .500”. Maximum number of mounting locations on
front flaps is 2 on each flap and maximum hardware size is #8
(.156). Gurney flaps, where attached, shall be 90 degrees and
parallel to the upper surface of the wing element and no taper or
“saw toothed” Gurneys are permitted.

And similar wording for the rear wing:
Wicker bill (Gurney flaps) are permitted as an option for installation
on the trailing edge upper surface of the wing element. They must
be attached in a secure fashion, without modification to the wing
element except for mounting hardware. Total height is .250” on
one or both elements. The Gurney flap only, may extend beyond
the parameters of the end plate. Maximum number of mounting
locations is 5 and maximum hardware size is #8 (.156). Gurney
flaps, where attached, shall be 90 degrees and parallel to the upper
surface of the wing element and no taper or “saw toothed” Gurneys
are permitted.

As I read this, there is a glaring omission that would make a significant difference in the performance of the Gurney. They give a maximum height but not a length of the Gurney along the wing surface, and especially beyond the trailing edge of the wing. At the rear, they allow the Gurney to extend beyond the end fence. The Gurney can be used to increase the cord of the wing under these rules.

[RobLav]

Nice catch Steve.

[dsmithwc04]

Steve, you spilled the beans!!!!