Presented by Nine Lives Racing
1 2
stafford1500
stafford1500 Dork
7/7/19 6:16 p.m.

In reply to Adrian_Thompson :

I have heard that the Brabbhams had an interesting response when you revved the engine in the garage or pits. The car would pull down and slowly recover as the engine revs came back down. Either way using existing hardware to do another job is the hallmark of creativity in motorsports. Always make sure every part does at least two jobs.

Also anytime you get a rule written against whatever you are doing, you have made it in motorsports (Stampie, looking at you for this one...)

Keith Tanner
Keith Tanner MegaDork
7/8/19 8:20 a.m.
stafford1500 said:

I recall Keith Tanner setup a DRS style wing for one of his cars. Simple and effective.

Actually, it wasn't DRS, it was an air brake. When I hit the brake pedal, the wing flipped up and stalled out. Loads of extra drag and (if I understand this right) the center of aero pressure moved way back. This not only slowed the car, but added stability. I got the idea after following a McLaren MP4-12C around a complex of corners and saw the factory aero dancing around.

I'm not convinced DRS does much on a car that isn't running massive aero with the drag that goes with it. Guys build it because it's an F1 thing, but that's funky reasoning.  IIRC F1 cars will decelerate at close to 1g from drag alone, so reducing drag at nearly 200 mph is really effective. On my Miata (a modified street car with an engine that more than 4 times as powerful as the stock one), I can pull my aero through the air well enough but I need help stopping. 

One big problem with my setup is that I lose visibility out of the rear window when it engages. 

Lemons still allows some active aero. The most clever I've heard of is an ironing board that was "activated" by a bowling ball in the trunk. Hit the brake, ball goes forward, "wing" goes into high AOA. Accelerate, ball goes back, wing flattens out. I don't believe it was raced for obvious reasons but I love the concept.

Johnny_at_NineLives
Johnny_at_NineLives New Reader
7/8/19 9:04 a.m.
Keith Tanner said:
stafford1500 said:

I recall Keith Tanner setup a DRS style wing for one of his cars. Simple and effective.

...i 'm not convinced DRS does much on a car that isn't running massive aero with the drag that goes with it....

 

Yes and No, 

 

On a single element wing Yes having a DRS won't do much. As you can see on our CFD chart here of the wings we make. @ 140 mph there is a 22Lbs of drag swing at 140 mph. your average sports car like a Corvette makes around 400lbs of drag at a similar speed.  add the drag from the cart to the 400lbs base, we get the following. Going from 417 too 439lbs of drag is only a 5% swing.  in our experience, the stopwatch will like that, but drivers will only notice about a 7% change. You, as a driver,  not being convinced does correlates to our findings.  

Where the big change is on Dual elements.  like ours pictured above. the main wing is set at 0 AOA and you adjust the second element for downforce. now our chart doesn't show drag with the second element open but it would only add a few lbs anyway. knowing that, we can use the chart as an example of what might happen. since we are talking about hypotheticals anyway it won't hurt. @140 mph if you opened the second element you could change your drag from 63 too 17 lbs of drag. That would take the corvette drag from 463 lbs of drag to 417 a 11% reduction. Frankly speaking, anything we see that's over 10% change is a really big deal. So a driver would definitely notice that. 

Keith Tanner
Keith Tanner MegaDork
7/8/19 10:14 a.m.

Thus my comment about massive aero. DRS would let you stack a lot more wing on the car for the times you need it, but you'd have to design for it from the start. Multi-element wings are still pretty unusual in the converted street car arena.

It would be interesting to see on the stopwatch which would be more useful, 10% less drag on the straight or a whole bunch more drag under braking. My Traqmate unfortunately committed suicide when I put my air brake on so I don't have data, but I know that my confidence level was a lot higher under braking with the airbrake engaged.

Robbie
Robbie UltimaDork
7/8/19 10:27 a.m.

60 lbs of drag using f=ma means about .02 g of braking, right?

Edit, assuming a 3000lb Corvette.

pinchvalve
pinchvalve MegaDork
7/8/19 10:37 a.m.

Smokey Yunik built a 7:8 scale version of a Chevelle for NASCAR.  In truth, Smokey moved the body of the car backward three inches for better weight distribution, raised the floor and smoothed out the underside of the car for better aerodynamics, and made the bumpers and fenders flush with the rest of the body.  It looked stock and it won, and people have called it a 7:8 scale, even though it was just clever manipulation. 

I think you could take a 2-Series and swap over a lot of M3 parts and do the same thing. What?  It's a stock M3? Does it look smaller?  I don't think so.  

1 2
Our Preferred Partners
OLs4j68TnakLR4wgn6oy93RAoMzWU3HGTH7mTIpK4HnMGZjGTyYrHhTQBa4Hd325