FED Aerodynamics

[adrianphicks]

Hi all.

I've been wondering whether some small changes to bodywork on a FED might achieve some downforce at the rear without increasing wind resistance.  Not sure if anyone is doing this already.

Being that funny cars run low side skirts my thought was to run the side panels (from the engine plate back) down relatively low, say 3" from the ground, & maybe with a small lip folded outwards.

Added to that, seeing as blown cars need a tray under the engine, the tray could be part of a bellypan from the front of the engine to the rear of the car, with the bellypan sweeping maybe half way up the driver's back, or at least to the rear seat cross member.

And one more addition of a small spoiler at the front of the engine tray, down to the regulation 2" from the track.

Would this create a venturi (lower frame rails angled up slightly from the engine plate) & provide some down force, maybe requiring smaller wings resulting in less overall wind resistance?

Your thoughts?

Adrian

[rooman]

Adrian,
           it sounds good in basic theory but there are a few problems.  Venturi style aero requires that the side of the tunnel be close to the ground but as the slicks grow on the top end that goes away and air leaks under the car from the sides negating the effect. Turbulence off the tires also hurts and the fact that the tunnel is relatively narrow is also a negative. The current funny car package works because the front of the car is relatively wide and smooth and the teams are able to put the front lip pretty much on the ground from half track on. A front motor dragster starts out being very dirty with the wheels axle/wishbones  etc being the first thing to punch a hole in the air--even with a full body you have broken up the airflow right from the start.
  Years ago Pete Robinson experimented with a wide sweeping arc shaped package mounted ahead of the motor and opinions vary as to whether that contributed to his fatal crash as it definitely appeared to by pulling the car down on the top end. It was wide enough and low enough that it did appear to create the sort of low pressure area that you are talking about but trying to do it further back with the tire turbulence and car attitude change may be a problem.

Roo

[dreracecar]

Genreraly in our relm, the marginal gain is not worth the effort-expense-weight for it to be practical.
Based on the fact that at our level there are so many racing variables that any conclusions of success would take a lot of passes to even see some kind of pattern.
 What you do is this , build your car and the body the chassie both ways. Purchase a 20channel racepack unit and the $600 ride hight sensor and mount it to the lower framerail and start making passes in both configurations about 5 each with and without. resist changing anything about the setup. Come up with and best average of tire plant & ET between the 2 versions and go with the better.
 I built all that aero crap for a N/TF dragster before including the "duck-butt" and there was no indication of any measurable improvment on this dragster, All the design info came from Aero Guy that has worked for some major teams out there and when questioned on some hard numbers, he just shrugged his shoulders and said he didnt no unless he put it in a tunnel.
Do it because you like the look, but there is no real advantage

[wideopen231]

I have some ideas on few items for aerodynamics .That said most of them even I don't think will have enough effect to out wiegh the weight added,but if it equals out and I get added look I want Im cool with that.

  For me the trick is figuring out how to set it up so I change from having the extra pieces to not having them and seeing what effect is. Being the picky type I want to be able to change them w/o screwing up the look of the car.

 My deal is mainly built for bracket and minimum weight is not a big of issue as it will be for heads up. I would like to come up with front end that did as Rooman stated about the funnycar fronts.Punch nice hole in the air so I can drive thru it. I do not see anyway of making a FED super slick just too much stuff out in the wind. Still fun to try new stuff as long as you keep a eye on safety side of it.

Pretty sure the rear canard help with down force with minimum drag. For one they have to out weigh the weight because the weight shaving master Parks has them and if they weighed more then they helped I doubt he would have them on the car. I have some wild looking side pods that I am working on to swap out for rear canards using same mounts.Look aerodynamic as  all get out. Are they helpful still to be seen.If you come up with something try it.Worst thing you spend few bucks to find out it does not work.Just keep in mind how it might effect handling.

[dreracecar]

Unless you have proof that your tires (new tires and nothing on the track) are spinning going down the track (data recorder rpm spikes) cannard wings are just expensive billboards/number plates. Any amount of downforce they produce imposes drag.One would be better off just adding weight equal to the weight of the wings to the rear of the car.

[wideopen231]

My canards cost less then 100 bucks and total weight maybe  6 lbs to 8 lbs. Not much weight to add to rear to help with traction. A properly designed wing/canard has very little drag until you get stupid and add too much angle of attack. I try to keep wing or canard below 8* angle of attack and would rather it be around 4. I do agree its hard to tell how much effect it has other then data recorder. I have added 3/4" piece of aluminum to  rear of funny with 15* angle and it went from running 1/2 mile to 1/4 mile straight as arrow. Recorder showed very little but straight is quick.ET was better but hard to say that was why.

IMO if you can make back to back runs with very close to same condition and either MPH or ET pickup or drop thats the best indicator of works or don't work. If car goes straighter after change would be another good indication. Kind of like changing leanout and seeing what differance is.

[masracingtd1167]

How about a small wing mounted on the roll cage like the comp cars have ? I have thought about doing this to make my car more stable at speed . I t seem's like 190 mph is when these cars start to become un stable . Any thoughts about this? Bill

[dreracecar]

Been 205 with my car without "ankle biters"  Very stable at the big end
Without added downforce the tires grow= MPH
I feel that front stability is more important on the long w/b cars. If the front end wanders you are always playing catch-up and it feels like the back end isnt hooking up whereas if the front is going down the track you just need to correct the attitude of the rear end

[wideopen231]

Bill,

 Did you call Mr.Jr. fuel Parks and ask him what he thought would best correct it. His canards are pretty cheap and his kits even cheaper.Might be worth try. Since Scott has run some high 190's he probably would have some good input .

[coupemerc]

I discussed the use of canards with Frank and Scott when my car was under construction. Scott likes the feel/stability of the car with them on. Remember...his deal is 1350 lbs, 12" wide tires and 195 mph so they run them. Frank speculated that they may become mandatory in Comp in the near future and they give you another "tuning knob" on a marginal track. Mine are mag skin with CF spill plates. The whole assembly is about 10 lbs total and can be removed from the car in about 30 seconds.

[masracingtd1167]

Chuck I think that the problem is that the cars are so light and the small tires make it worse . If you remember back about ten years ago A lot of the Comp Eliminator dragsters were crashing especially the B/ED cars very light and small tires . NHRA made it mandatory to have a rear wing on all Comp dragsters from C/ED on up and I think it helped a lot . The only thing I can say for shure is we put one on my son's rear engine dragster and you can feel the difference with it and with out it . The car is much more stable at speed.