THSCC Forums

ok... so now with the changes, shouldn't you

1) Not have to slow as hard for the Carousel, T8, T11, T14 (new pavement in all turns, re-config for T12, T13, T14) since you're able to carry more speed through them

2) Let the brakes cool a little more between T8 and T11, then again from T12 to T14

I'm not suggesting it will be as forgiving as VIR, it's a full 1-mile shorter. But by the same token, you can't really complain about it being worse right? You have to deal with it the best way possible... ducting, driving style, pad compound. Obviously, you can't (shouldn't even) be able to run the same pad compound at CMP that you would at VIR.

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Stacy King
Midlife Crisis Participant

An unpopular opinion perhaps, but one thing I'l miss about CMP as a learning experience for people is that it teaches you how to save the equipment. With CMP 1.0, if you go out and tear arse for 30 minutes, you *will* notice a difference in braking with your car. Pretty much any car. These were lessons that served me well in endurance racing.

The new layout, obviously, is TBD.

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Karl S.
2014 Baby, 2014 House, 2013 Ford Focus ST, 2013 BMW 328i, 1994 Mercedes E320
(Insert passive aggressive signature line here)

i don't recall anyone having any braking issues in the 3hr enduro on friday...also pretty sure the car i co-drove on friday went on to finish the rest of the weekend (2 qualis, 2 sprints, and some practice time) on the same pads/rotors that we ran in the enduro...these were hawk ht-10's

the new layout seemed to be easier on brakes...not easy on brakes but better than before...

with the new pavement in many turns, corner speeds are higher and the new configuration elminates one brake zone and gives a lot more time for brakes to cool before braking for t14

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David White
95 M3 - #275 BMWCCA JP, NASA GTS-3
02 M3 - street/track
05 Suburban 8.1L

Matt,
While I realize you are an engineer and I am not, I am having a hard time with the logic of the KE of the formula you posted. Yes, KE goes up as the square of V, but the F of the de-acceleration is the same as long as the change in velocity is the same. So a 50 MPH change of a 2800 lb car is the same (not given assistance of Wind Resistance) as long as the time is the same. The KE comes into effect if the velocity is not the same. I remember the change in the kinetic energy of an object is equal to the net work done on the object. So KE comes into play when KE is converted to force or work.

Ie:
W(net)=1/2*MV^2(second) – ½*MV^2(initial)


But actual force used to cause the change in velocity should be the same otherwise the standard F=MA formula doesn’t apply. So the actual force applied to the pads should have not changed.

Maybe I am remembering all this wrong.

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Marty Howard
2011 NASA SE Factory Five Challenge Champion
Track Events Logistics Coordinator - TZC/THSCC
2007 Factory Five Challenge Car.
http://www.mh-motorsports.com

Marty,

You hit the nail on the head without realizing it -- the acceleration (or deceleration in this instance) is missing a time component. The rate of the change is the difference.

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Has no responsibility whatsoever.

Or to think of it another way --

Energy = Work = Force * Distance

During threshold braking from 100MPH to 50MPH you'll be braking with the same force, but a longer distance, than you would from 90MPH to 40MPH. Thus more energy.

Same force, same delta V, but longer distance, and thus more work or energy. Due to the higher initial V.

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Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

Per Stacy's scenario:

Old config: 90-40 mph
new config: 100-50mph

Thing is, you're NOT slowing completely from 90mph, you have to subtract the amount out that you're not slowing, which is 40mph. So the equation for the old way looks like this:

Work(old)=.5M(90)^2-.5M(40)^2

The new way is the same thing, with higher velocities for both Vs.

Work(new)=.5M(100)^2-.5M(50)^2

Now, .5M is a constant (same car), so we can just drop that out of the equation, since we're looking for the change.

W(new)/W(old)=(100^2-50^2)/(90^2-50^2)

That says Delta W is 15%. Same change in velocity, but that whole squared thing really kicks your butt....



Very fair. I only have 1 data point so far. But it was a bad one...

I'm having trouble here. Are Mike, Wes and I in agreement? It kinda sounds that way....

Yeah, but, it's 15.34% more energy

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Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

I think that we're saying the same thing using different words.

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Has no responsibility whatsoever.

Hmm. Odd. I get 15.38%.

One of you has a calculator that is out of calibration.

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-Jeff

R1 Powered Locost 7
ITB '90 Honda Civic under construction
2004 F250 Super Duty
http://www.project-seven.goof.com/

I don't have a calculator. I have a phone that occasionally adds shit up...

Well there's your problem Matt. Your calculator isn't SFI certified. I'm guessing Mike's is.

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Todd Breakey
STS 42 - 1992 Sunburst Miata
Dammit!
"You souldn't play leap frog with a porcupine. You might get hurt." - Eliza

Ryan mentioned my data logging info. If anyone is interested I can send the file along. You can download the viewing software (traqview) from Tarqmate's web page. Its a bit difficult to find so I can also include the address. Send me a note directly: ron.e.spencer@gmail.com

Its quite fun to see exactly what speeds are being carried into braking zones and through corners. DL keeps one from telling "big tales".

Ron