Thoughts on aero drag

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oldjohnno
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Thoughts on aero drag

Post by oldjohnno » Wed Sep 07, 2016 6:23 am

I've been thinking about the effects of the aero differences between TF cars and funny cars. The terminal speeds are about the same, though the dragsters are ET bit quicker. The FC is said to have less drag than the TF car and supposedly this is why it can match the top end speed of the dragster. Yet attempts at streamlining dragsters have generally been less than spectacularly successful. Comments?
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Re: Thoughts on aero drag

Post by j-c-c » Wed Sep 07, 2016 7:31 pm

Nothing to add, but I would like to know the amount of DF each has, and how that might effect et/mph in this discussion.

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Re: Thoughts on aero drag

Post by MadBill » Tue Oct 04, 2016 12:34 am

10,000# plus for a TF car, probably a little less for a TFC..
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Re: Thoughts on aero drag

Post by Olefud » Tue Oct 04, 2016 11:55 am

I don’t actually have either. But my thought is Engine Location. Better hookup with rear engine. And early speed in a run is more important than at the end.

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Re: Thoughts on aero drag

Post by j-c-c » Wed Oct 05, 2016 4:29 pm

MadBill wrote:10,000# plus for a TF car, probably a little less for a TFC..
Is that TF DF mainly wing (s), or are there other under body shapes involved in that number? If not, that means the rear wing is likely the majority contributor, say 70%(?), and that 7,000lbs is fighting the centrifugal force of the rear tires for contact patch. Can't see the front tires happy with 3K+ loading, but I don't know.

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Re: Thoughts on aero drag

Post by MadBill » Wed Oct 05, 2016 5:09 pm

it's mostly wing, but the exhaust thrust adds 1,000 lb.+ I'd guess you're about right on your numbers, the hugely long wheelbase means lots of leverage for the relatively low downforce front wing. (If a TF chassis fails, it often buckles upwards in the middle.)
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Re: Thoughts on aero drag

Post by j-c-c » Wed Oct 05, 2016 6:52 pm

MadBill wrote:it's mostly wing, but the exhaust thrust adds 1,000 lb.+ I'd guess you're about right on your numbers, the hugely long wheelbase means lots of leverage for the relatively low downforce front wing. (If a TF chassis fails, it often buckles upwards in the middle.)
Didn't think about that, and that is not speed dependent, bet losing a motor suddenly mid track and its 1000lbs of exhaust DF, could raise ones heart rate . :shock:

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Re: Thoughts on aero drag

Post by MadBill » Wed Oct 05, 2016 7:09 pm

Absolutely! Almost better to lose 8 cylinders than 1 or 2. Huge loss of directional control as the 3(2?) cylinder side of the car unloads... :shock:
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Re: Thoughts on aero drag

Post by crazyman » Thu Oct 06, 2016 1:07 am

Not directly related to the OP's question, but I picked up 2 highway MPG on a 1994 square S-blazer by ditching the bug shield on the hood and swapping flag mirrors for stock sport style mirrors. Little things make a huge difference in aero no matter what speed.

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Post by dwilliams » Mon Dec 12, 2016 7:36 pm

I kept track of mileage on my Mazda pickup when I got it. The previous owner had installed a camper shell, which was fine for keeping stuff from being stolen out of the back, but the windows would fog up or ice over, making driving in traffic dicey. So I took the shell off after a few months.

The result was impressive. Mileage dropped from a consistent 35 on the highway (55mph speed limit then) to 30. I guess the shell gave it a Kamm effect at the back.

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