the-moss

Does anyone know of a calculator or a relatively simple formula that will allow me to calculate a theoretical max speed on a straight at a road course.

What I would like to know in theory is this. Right now my car will hit 120mph along the straight when exiting turn X at Y track at 55mph before having to brake down to 45mph for turn Z. What I would like to be able to calculate is how much faster I have to exit turn X to enable myself to hit 130mph while still being able to make turn Z.

Clear as mud? Thanks in advance!

captain_pants

Seat of the pants guess: Exit turn Y at 70 mph.

Why?
1. You'll need to be 10 mph faster at the end of the straight.
2. Acceleration ability decreases with speed due to non-linear air resistance.
3. If you're going faster, you'll have to brake sooner to hit 45 mph by corner Z.

Sounds like a pretty tall order to increase straight speeds by 10 mph using only improved corner exit speeds.

the-moss

Yes it's not something I'm going to practically try to achieve, rather I want to use it to demonstrate how unlikely some claims actually are.

PedalFaster

I saw this posted in response to a similar question on another forum, but I took one look at the math and stopped reading.

http://phors.locost7.info/phors09.htm

patinum

[QUOTE=PedalFaster,Nov 9 2010, 02:37 PM] I saw this posted in response to a similar question on another forum, but I took one look at the math and stopped reading.

the-moss

Thanks pedal faster, that's exactly what I wanted to find. S2KI always comes through.

CKit

I'd think datalogging and getting real world data points would be the best way to cement the argument. There are so many variables depending on the track. We had a friend in a Miata that wasn't able to get over 107 mph on the front straight at Road America. We were at ~140mph in our AP1 when supercharged with crap exit speed on street tires. It'd be different without the uphill climb...

itrack

I know its a multiplier, ie 3mph more corner exit speed might give you 10mph at the end of the straight. DA is the only way to tell for sure at the track your driving.

PedalFaster

You inverted your multiplier. Remember that acceleration decreases at higher speeds, so given equal acceleration, whatever the speed difference is at the beginning of the straight, it will be smaller at the end of the straight.

mikegarrison

[QUOTE=itrack,Nov 11 2010, 08:52 PM] I know its a multiplier, ie 3mph more corner exit speed might give you 10mph at the end of the straight.