Wind Tunnel Advice

[Geo]

Stan,

I would be glad to help you and answer any questions.   

Geo

[jl222]

Zach,

I live an hour from A2 Wind Tunnel,,, I jusr spoke with them last week and the 2011 prices have increased a bit.

$460 per hour.  I need to check a few things on my Stude and while there with all this spolier and safety discussion I was going to put my car in backwards and test to see how the rear lifts with altered style rear spoiler.  I was then going to test a hinged design and flaps in the spoiler,,

However after talking with them, the time involved to take the car out, re set it backwards and make the tests would cost another $2,000 that I don't have.

So I understand your budget concerns.

Good luck.

Charles

  All this discussion on wind tunnels got me to looking at my Chaparral book were Jim Hall had doubts about results from wind tunnels without rolling floors.
  It will be interesting if they can give you a correct pressure difference above and below the spoiler.

                JL222

[efenn611]

As for roof flaps, it is pressure differential that makes them work. When going forward the air flowing over the roof makes the flap try to raise( moving air = low pressure), while also pushing them down (flowing air pushing the surface down). When you go the WRONG direction the flowing air catches the lip that was raised by the low pressure,raising the flap, thereby GREATLY reducing the lift of the car. kinda like the spoilers on a performance sailplane.

[joea]

jl22 im with you...i just cant get myself to ignore the other half of the air
flow and its influence on the entire system.......

[krusty]

              " It will be interesting if they can give you a correct pressure difference above and below the spoiler.


      The A2 tunnel personnel can install a flow grid behind your radiator, for instance, and can assist you in putting other pressure taps in the places you need them. This needs to be coordinated with them prior to arrival. Many teams use their existing data acquisition systems in the tunnel (separate from A2's) to gain even more info. What leads you to think that they can't accurately measure a pressure differential? I've got a few old school delta p gauges that I could plumb and then record their readings with a lipstick cam if I should need to. Even the wind tunnel ain't rocket surgery...          vic

[Cajun Kid]

Vic is with me  !!!

I can always use another good man in the tunnel.

See ya soon Vic.

[sabat]

That's what she said. 

[jl222]

              " It will be interesting if they can give you a correct pressure difference above and below the spoiler.


      The A2 tunnel personnel can install a flow grid behind your radiator, for instance, and can assist you in putting other pressure taps in the places you need them. This needs to be coordinated with them prior to arrival. Many teams use their existing data acquisition systems in the tunnel (separate from A2's) to gain even more info. What leads you to think that they can't accurately measure a pressure differential? I've got a few old school delta p gauges that I could plumb and then record their readings with a lipstick cam if I should need to. Even the wind tunnel ain't rocket surgery...          vic

  krusty... have you ever seen the smoke collect behind a wind tunnel car as the dust does on the rear of a car at EL Mirage
or any car going down a dusty road? I havn't and that makes me think
  Also I was quoting Jim Hall were his design of a front end, hign in front sloping downward which  would act like an inverted airfoil, and proven in the wind tunnel [with no moving floor]  but testing at their track showed a bunch of lift and undrivable untill adding a snowplow chin spoiler which worked so good they had to trim it to keep the body off the tires.
  I'm sure they can come up with a number and if you can also test at the track and come up with the same number
GREAT .
 
                     JL222

[Freud]

The chin spoiler on the Treit/Davenport streamliner was the finishing touch.

Just Believe.

FREUD

[manifest]

I was always under the impression that the roof flap box was not vented into the cockpit but completely inclosed.  If it were you would have to have the same size hole as the flaps somewhere else to allow the air to escape else it would try to blow the windows doors etc. out/off the car.

Anyways, would foam, wood, etc. be better for building the scale model?

Zach

[Geo]

Zach,

You are correct in the flaps being enclosed in a box with a small vent hole.  The flap has TORSION SPRINGS on the hinge making it light weight and able to open with a small difference in air pressure.  The small vent hole limits the filling of the interior when going backwards.  You can also vent to the exterior and then not worry about the interior.  There are movement limiting cables to stop the open flap.

Geo