I Want to Build a Go Fast RC !

[DCastaneda]

ZeroPointBug is talking about a rear diffuser as with on F1 cars

[SunnyHouTX]

Rear diffusers in an RC car are only mildly effective IMHO.

The way that Nic has his car set up in the photo that PBO posted, and the way we set up our RC drag car bodies, makes the whole body act the same way as a diffuser, but at higher effectiveness, and the down force is distributed over much of the length of the car rather than just behind the rear wheels (which will cause the front end to pick up).

[DCastaneda]

Diffusers in the traditional sense may have negligible effect on our little cars but some slightly unorthodox diffuser designs will create a significant difference. You're basically trying to make a relatively flat front end and streamlined rear. A teardrop shape or airfoil of sorts but for ground effect. That combined with some vertical stabs and you're set. This is all very unnecessary to only hit 100mph but to go beyond this point they may be needed or atleast aid in maximizing speed with the power available.

[zeropointbug]

PBO, that's exactly what I'm talking about in the picture, nice streamlined, with channels to hold the low pressure and reduce eddy's. The openings are also something I had in mind, was looking for the term Venturi's, which makes alot of sense.

[SunnyHouTX]

Originally Posted by zeropointbug

... hold the low pressure...

^^^ Very key. Holding the sides of the body steady and not flapping around plays a big part here as well. Actually, something to keep the sides from being sucked in is all that's needed sometimes.

[SunnyHouTX]

Here's the back of my RC funny car showing an "aid" to evacuate air out the back of the car:



And same from my True 10.5/Pro Stock



Mind you, the funny car goes 90+mph and weighs at 48oz (3lbs) and hasn't been airborne at those speeds. That gives you an idea how effective low pressure under the body is. Also note that the angle of the wickerbill is not that extreme: just enough to be effective and not create a lot of resistance.

[PBO]

Originally Posted by SunnyHouTX

Here's the back of my RC funny car showing an "aid" to evacuate air out the back of the car:

That is in essence a diffuser...just a very large & efficient one, sucking the car down harder, the faster you go

[SunnyHouTX]

I don't consider it a diffuser in the strictest sense simply because the area of influence of the low pressure created is much larger here, but that's just me

But the important thing is that this all helps keep the car stuck to the ground

[PBO]

Hahaha...fair enough. Giant venturi is probably more acurate

[nitrostarter]

As far as aerodynamics, what do you guys think of the dirt oval body Ofna has?

Or any suggestions for the most aerodynamic body? My LHS guy did 112mph at ISC with a Ferrari body. I would get one but I want to be different than his.

[SunnyHouTX]

That dirt oval body should work fine, but will still benefit from rear stabilizers, splitters, diffusers, et cetera ad nauseum.

[Bondonutz]

When making these nessasary add on pieces can I make them of .040 or the .060 all the better ??

[PBO]

I'd use .040, plenty strong enough

I've used the same with 1/8 aluminium rivets before to great effect

[Bondonutz]

Originally Posted by PBO

I'd use .040, plenty strong enough

I've used the same with 1/8 aluminium rivets before to great effect

Thanks !

[Overdriven]

Correct me if I'm wrong here but, IMO, the dirt oval bodies should have decent front down force with their wedge shape. I'd think a splitter would be all thats needed in the front.

Bondo, PBO posted a pic at the top of page 2 that shows the vertical stabilizers mounted to the sides of the body. Thought I'd mention it if you missed it as its a simple way to do it and would make for a clean look on a dirt oval body.