New thread: powered aero

[Blue]

Quote from: jl222 on May 07, 2009, 01:34:17 PM
  Panic
 It seems a lot of racers have forgotten Jim Hall, the Chaparral racers and all their inventions for downforce.
 Or they may of never heard of him as this happend before some were born.
 Their adjustable spoiler design can still be used and the so can the sucker [on streamliners[ might get clogged fast though tongue
 This is why I post articles about WW11 supercharging and water injection because it can be forgotten or never realized information
is out there.
The two absolutely awesome car aerodynamic inventions of the past half century (wings are older) are moveable aero and powered aero.  Both were outlawed and both are good ideas that belong in modern vehicle design.
-----------------------------------------
I moved this to a new thread because I believe powered downforce deserves its own discussion.  FYI, "powered aero" is called "active circulation control" in the industry.  "Circulation" refers to the circulation of of the vector change in airflow around an airfoil or car body.

IM<HO, all LSR cars at speed have enough downforce to balance the traction vs. power required based on their inherent design.  Downforce increases with speed, so downforce-limited vehicles really should have more alpha or wing to hit their top speed. 

I believe there is a benefit to adding powered downforce to improve traction during acceleration and get up to speed sooner.  Any power used for the downforce should come from the "prime mover" engine that is regulated by the class rules.  In this manner, we could avoid all of those pesky "2nd engine/stored-power" issues.  Any electrically powered accessory should be proven to run off of the alternator power, not battery.

Of course, electric vehicles run only off of battery and would be likewise prohibited from having little combustion engines for "accessory" loads.

[tortoise]

Aren't you one who questions the safety of flat-bottomed, low clearance designs?

[maguromic]

I remember Jim Fueling showing me the canards on his liner and they were some how activated by air speed and would have different angle of attack at different speeds.  Also I think it was adjustable from the drivers compartment depending if he wanted more down force.  Anybody have more info on this setup.  Sure do miss Jim  

[Blue]

Aren't you one who questions the safety of flat-bottomed, low clearance designs?

Yes, I hope my post was understood to mean that we should have more ground clearance, not less; and deal with the flow under the car as an asset to downforce.

[Milwaukee Midget]

Any power used for the downforce should come from the "prime mover" engine that is regulated by the class rules. 

It has been years since I thought about the 2J Chaparral.  Correct me if I'm wrong, but weren't the fans powered by separate engines?

Getting to your point, Eric, if you were to drive a hypothetical LSR vehicle's active circulation control device off of the engine/drivetrain, you would be burdening the engine at precisely the time that you need peak horsepower for speed.  A  variable speed transmission on the device might work (or pitch control?) - especially if the vehicle design does indeed create greater downforce at greater speed, but transmissions eat power, too.

Possibly a design that would completely shut down the active circulation control at a point that aero downforce takes over?   

[Peter Jack]

The Chaparral fans were powered by a single JLO snowmobile engine.

Pete

[Dr Goggles]

I remember Jim Fueling showing me the canards on his liner and they were some how activated by air speed and would have different angle of attack at different speeds.  Also I think it was adjustable from the drivers compartment depending if he wanted more down force.  Anybody have more info on this setup.  Sure do miss Jim  

ain't there something in the rules about "aero devices controlled by the driver"

[interested bystander]

Don't forget the Gordon Murray designed Brabham - Alfa that had an engine -driven fan for downforce, er, cooling.

It WON a GP before the FIA banned it

[tortoise]

. . . downforce-limited vehicles really should have more alpha or wing to hit their top speed. 

Until some of the faster streamliners follow at least this advice, is it time to think about the second phase?

[jl222]

I remember Jim Fueling showing me the canards on his liner and they were some how activated by air speed and would have different angle of attack at different speeds.  Also I think it was adjustable from the drivers compartment depending if he wanted more down force.  Anybody have more info on this setup.  Sure do miss Jim  

ain't there something in the rules about "aero devices controlled by the driver"

 I can't find anything about moveable aero devices in the rulebook
 
I know of two streamliners being built with wings and I'am trying to talk one of them into
a movable one connected to shift points like those lakester guys from Minden Nevada.

     JL222

[Ron Gibson]

I think Arfons had them on the front his jet bike liner in the mid 80's. IIRC they were connected to the front suspension with linkage. If the body lifted, it applied more wing to keep it down.
He also had an automatically controlled movable vertical  dorsal fin that was supposed to keep it stable. Don't know what went wrong, but as he started on one of his first runs, the fin was slowly spinning, (not a good thing). It was gone the next day.

Ron

[desotoman]

Having owned v-drive boats since 1973 all with adjustable cavitation plates operated by foot pedels. I have always wondered why someone has not done the same thing with their car if they have a wing. The one thing you would have to watch would be too much downforce and overloading your tires. Just a thought.

Tom G.

[McRat]

Have rear wheel torque control the angle of attack on a wing.  If the torque falls, the wing becomes more aggressive.  This way, you use only as much downforce as is necessary for locomotive traction. 

[Rex Schimmer]

Instead of doing some sort of mechanically driven sucking device would it not be easier to have some small adjustable pitch angle canard wings maybe a set on the front and the back and run them fairly low so that they are in ground affects and then adjust the pitch, angle of attack, to produce the amount of down force you want at what ever speed you are running. If you use a "standard" foil shape, calculating the amount of down force is pretty straight forward. So you start out with lots of angle and then flatten them out based upon your speed. Both drag and down force are square functions of the speed so you probably don't need much angle at 300+ but running them low so that they are in ground affects makes them much more efficient.

Of course the ultimate control would be to control wing angle with your now legal traction control system!

Rex

[maguromic]

It shouldn't be that tricky to build a controller to operate a movable wing and tying it into a traction control strategy.  The trick would be to find some actuators to move the wing fast enough to compensate for the bad traction. Tony