Down force and zoomies

[wideopen231]

 Noticed on another thread where Jon was talking about down force from zoomies. I know for fuel guys its big and with our little injected motors not so much, but still there. Being the always inquizitive type I got to wondering how much down force? Best angle and if there's enough thrust force to make any et difference,talking .0__ or .00__.It all helps and sometimes t takes cpl thing to equal noticeable difference. Heck if not for fun of tuning more out of it than next guy there would be no need for timing systems.

Anyone ever done ABA testing with zoomies or just tried different size and or angle. I can see where smaller tube having more velocity make make difference also.

[Roger]

From Alan Ellis after switching from headers to zoomies on his Pro Stock 500" engine in his AA/A last year:

"The down thrust from the new zoomie style headers proved to be a tremendous advantage to the launch of the car. It allows us to apply more power early in the run which equates to quicker ET's."

[gregm784]

"Able to apply more power" or had to make more power without header scavenging in effect?

Interesting topic for sure.

[glofria]

Zoomies will have an affect in steering a (short wheelbase) car.  it will not have an affect on a longer wheelbase car.

I believe that the optimal angle would be 45 degrees to the ground as an even trade off on down forces vs. thrust. As with the recent issues with nitro funny cars lifting the front end down track with too much thrust, down force is important. But not to the point of sacrificing performance and strain on the engine.

FYI, I am not am engineer, but I do understand certain concepts. So if my information is incomplete...

[glofria]

Okay, I just read the other thread and i think Jon was referring to the back of the car washing out vs. steering. Canards will create down force (drag) on the back tires and that will keep the car straight down track. Had a conversation with Walt Stevens of the High Speed Motorsports N/TF team a few years ago about the canards they designed. It has definitely improved their performance.

For your reading pleasure:

https://www.nas.nasa.gov/About/Education/Racecar/physics.html

[noslin]

These are the subjects that interest me with racing and trying to improve performance.  F1 has a lot of good information too.  i was researching different wing design for the vw i had as even though i raised the wing (engine cover actually) i still had rear lift at 160mph even as heavy as it was.  you could see it in the ride height sensor i had on the shock.

anyways, i'd like to stick cannards on my ride as i think it helps with appearance but i have been told they really dont work till over 200 mph.  but when you look at some of the F1 designs or basic premise on the kind of downforce they get i wonder if you could do a design to get downforce at a lesser speed so it is worth while to put them on other then astetic points. 

you look at TF wings (modern wings) and they follow this principle for design somewhat.  its basically just up side down wing.  think of a jet when you take off, there the main wing, the flap and then there is another little one past the flap.    i wonder for slower speeds then 200 if putting another smaller wing above the last one would create some downforce for >200mph


im getting ready to fab up some headers, ill use 45 deg for angle.  i was wondering what angle to set them at. 

ty
dean

[wideopen231]

Noslin I think best way to see effects of zoomies or canards would be data recording and watching tire slippage. I have been told FED's need down force added  little before 200 mark. Sometimes it takes very little to make big difference. I know on our TA/FC we added a 5/8" lip at 15* to rear deck and car went from hunting arou nd at finish line to being on rails and straight as arrow. If car looses speed with canard or wing then odds are too much attack angle and excessive drag. I know the wing I had on my TA/D had 400 lbs at negative 2* and went up from there.It also went up in drag and drag jumped big time compared to down force after 8* attack.

I have front canards on fed and they are set for 1*.One they look cool IMO,two they should help stabilize front end on top end w/o much drag. I have car setup for rear canards in case needed. I have three settings.2,4 and 7 degrees. I also have lot of aero trick pieces on drawing board that I want to try later. Have been told pointless,but xxxx trying new things is what I love about race car. A fed is probably the least aerodynamic  race car there is,which means lots of room to improve.

On header thing.I am thinking about build two more sets with big difference in angle and try some ABA test to see if any difference. That is after I get trailer to get car to track.LOL

[jeff/21]

i ran cars with wings on the top, angle,placement, adding a wickerbill either 1" or 2"changed the handling big time  so canards must work but not as noticeable below 200 MPH but the angle of attack must be important and if they have side-boards to control the air stream and  stop spillage

[aafa760]

Weed Sweepers Baby the real test of spectator hearing!

besides dumping all our bad juju infrontof the tires!!
Wow I am old!

[JrFuel Hayden]

The reason I posted about zoomies, and conards is because of the photo of Curly's car, with a real sharp angle conards, even NTF don't have that much angle. I'm sure they slow the car down [ie hold the car back] , they look kool, but slow his car down. which is OK if he is running brakets and can't run run quicker than the bracket.
THe other thing I noticed are his collector pipes, which work good on gasoline, but all the info I've seen is no advantage burning alky, jusy heavier, and no down force.
Also the reasdon we put conards on our Heritage Jrfueler is I saw RPM spikes on my RacePak about half track, and looking at another teams RacePak at the same track / same lane and he had no RPM spikes on a good run, they had conards.  Indicating too much tire spin after the shift on our car. So we put low angle conard, with good size spill plates,  now we have better traction after the shift. And the low angle high spill plates don't seem slow the MPH. 

Just my 2 cents
Jon

[wideopen231]

Jon estimated mph at shift?  Unless your the baddest Jr. fueler in world you are way below 200 then and still seeing effectiveness of canards and wondering where that point might be.  What angle of attack?


One thing some do not consider when setting angle of wing is how tire growth will effect it down track especially topend where it can be sustanual .