David Cooks wheel pants

[Scott Hersha]

Come on guys. Where's the discussion on the aerodynamic affects of the hole in the back of David Cook's wheel pants??? I'm doing the finishing work on my RV-8 wheelpants now and need that extra knot that will propel my past Jon Thocker and let me claim the title of 'the fastest RV-8 on the airport' (HAO)... oh yah, did I mention, I don't have my wheel pants and intersection fairings on yet? That might help too. What do you aerodynamicists have to say? Is there pressure build up inside the pant that slows you down? If so, then I think the hole will help. If it's just to drain water, maybe the hole should be a little smaller. If this subject has been addressed somewhere else here, please help this poor fiberglass dust-fazed rvator find it.

Scott Hersha
Phase I test 31 hours
RV-8 Fastback

[jthocker]

Just so no one's confused, all Scott was missing were the intersection fairings! I think you should be methodical about this Scott, do the intersections first. Then cut the hole.

For those that may be interested Scott and I have recently completed RV8's with nearly identical setups.

Brand new ECI Titan engines built by Jimmy Brod of JB Aircraft Engines
Tapered Barrel cyl.'s
9 to 1 pistons
Carb.'s....... Scott's is a 4164 mine is a 3878
Van's latest baffle kits, I would say our baffling is identical.
Oil coolers on the aft baffle, Scott's is Van's oil cooler II, mine is a SW 8604?
Our basic Avionics package is the same except for Scott's Icom A210 and my Garmin SL40
Dynon D180/AP 74/ Dynon non heated pitot tube
Garmin 496
Garmin 327
Safe Air... non flush static vents and pitot/static/AOA tubing kit

When we fly side by side our airspeed,altitude, OAT, and TAS are identical. My airspeed in the cruise regime has been found to be accurate via numerous calibration runs while breaking the engine in, to be dead on + or - 1 knot.

The key differences in our planes are: Scott's is a fastback and he's running 1 Lightspeed electronic ignition.
Scott has a Whirlwind 2 blade prop, I have a Hartzell BA 7497 prop.

I hope to do a formation start up, taxi, and takeoff, then full throttle climb to 8000 to 10,000 ft. Recording or downloading #'s from the Dynons.

Maybe we can put to rest the debates on Carb. nozzles, and oil coolers.

If Scott should turn out ultimately faster than me, be assured that it will be at the expense of his health, due to massive fiberglass/micro/ flox dust ingestion in the pursuit of maniacal fit and finish!!!

[sierradelta]

I keep coming back and checking on this post......I can't think of this Mod being that important. I guess even if it is a little, it is worth the increase because its a small/easy Mod. Can anyone explain how this works? I really am curious.

[Bob Axsom]

I do think all the RV Blue Class racers should implement the mod though. Well, all but Race #71

Bob Axsom

[jthocker]

I brought this mod up to a friend that races at Reno(formula 1, biplanes) today and his response was, if you provide for outflow you effectively increase the wetted area. Meaning you not only have the exterior of the wheel pant wetted area you now have the inside wetted area also. So there might not be a net benefit.

[SportAvServ]

(I brought this mod up to a friend that races at Reno(formula 1, biplanes) today and his response was, if you provide for outflow you effectively increase the wetted area. Meaning you not only have the exterior of the wheel pant wetted area you now have the inside wetted area also. So there might not be a net benefit.)




Did ya think about the fact that the pants are lighter?

F=L/d wt x hambuger x L2 + ###= OU812

[Howie]

If you cut a slot instead of a hole, would it whistle?

H

[az_gila]

Originally Posted by SportAvServ

(I brought this mod up to a friend that races at Reno(formula 1, biplanes) today and his response was, if you provide for outflow you effectively increase the wetted area. Meaning you not only have the exterior of the wheel pant wetted area you now have the inside wetted area also. So there might not be a net benefit.)

.....

...sucking air up from around the wheel opening and expelling it at the new rear hole....

Perhaps the reduction in turbulence around the wheel (assuming there is a reduction......) can outweigh the increase in wetted area?

The hole is in a low pressure area and will tend to suck air out of the wheel pant.

[Webb]

Originally Posted by az_gila

...sucking air up from around the wheel opening and expelling it at the new rear hole....

Perhaps the reduction in turbulence around the wheel (assuming there is a reduction......) can outweigh the increase in wetted area?

The hole is in a low pressure area and will tend to suck air out of the wheel pant.

Gil - I have to disagree with you. There is a support wall (call it a rib if you will) on the inside of a main wheel pant. In other words, even with the hole, it is not possible to have a continuous air flow unless there has been a hole cut in the support wall.

[Barry]

Perhaps he intends to fit a couple of those small jet engines now used for model aircraft, one in each wheel pant. It may be possible to get an extra 30lbs of thrust! Would also help at high altitude.