TB993tt

Thanks Jean......so not that much difference then ? I expected the arches to have a greater effect.

Jean

And since I know what you are thinking... With your current engine and aerodynamics here are the results:

100-160kph: 3.0 seconds
100-200kph: 6.1 seconds
200-300kph: 15 seconds
60-130mph: 6.9 seconds

With stock 993TT bodywork:
100-160kph: 3.0 seconds
100-200kph: 6.0 seconds
200-300kph: 14.5 seconds
60-130mph: 6.8 seconds

Jean

TB
I don't know how much impact the flares have on the CD and Area, it is just an estimate between the 993 GT2 and the stock TT.

Jean

Just noticed, this is the same as the RUF RT12 from 200-300kph despite your aerodynamics and you are faster by 0.3 seconds on the 100-200kph with 2 gear changes !!

Red rooster

Dificult to see the correlation from all these numbers posted .
Aerodynamic drag is proportianal to area x speed squared .
Drag power is proportianal to drag X speed which then becomes proportional to area X speed cubed . That cubed law means that top speed becomes more and more difficult to raise .
Does that basic law equate to all these numbers measured and calculated ?

Geoff

Jean

Red Rooster,

The question was what would be the times with different aerodynamic setups, the best (and only?) way to calculate it is to establish what is the rate of acceleration that the car has at every point in its travel in a drag-less environment, based on engine dyno and vehicle characteristics (weight distribution, rolling resistence, mass, gears, tires etc..) and do the same for aerodynamic drag but in the opposite direction, and then substract them and arrive at the revised "real" acceleration rate.
As you can imagine, this is a huge spreadhseet, but the results are surprisingly accurate vs. datalogger info.

As far as the formulas you mentioned. Remember I am not calculating Power, this is force.
Power = Force x Velocity

So if you want to establish the HP/KW correlation to drag, you use Power, but I am establishing the time needed to achiveve a certain speed.

In terms of power, horsepower lost goes up by 8 times as speed doubles, due to the cubic relationship, so certainly increasing top speed requires substantial HP, but most of our cars have enough Power to beat drag up to 300kph. However that would not help us determine the time needed to achieve a run.

Aerodynamic drag,
((Vkph/3.6)^2)x Air density x Cd x Area
Multiply by 0.5 X mass and you get the force which is what I am using..
Multiply by velocity and you get the power required.

Finally as I always say, I am not an engineer, if there is a better way to do this please share it with us, maybe on the other thread that I linked earlier to avoid further hijacking, it is an interesting subject! Here it is;
https://rennlist.com/forums/showpost...76&postcount=1
Thanks

leonsamonas

Jean,, you are even more full of sh** than toby is, if you are suggesting toby's car is quicker than an RT12 between 100 and 300km/h then you need your head examined, of course i would expect such optimism from both of you.. but it just makes you seem so desperate

Jean

Leonsamonas, I knew you were an idiot from listening to everyone who met you, but I think they were being nice. I don't know what agenda you have with TB, but whatever it is keep me out of it you ignorant snob.

leonsamonas

Ignorant is a word you must be very accustomed to judging by your analysis, no agenda with tb just bemused at the amount of **** you both get away with of this forum..

Jean

Definitely, I would not expect you to understand any of this, when you grow up come back again and you might then learn a thing or two.

leonsamonas

Seems like geoff doesn't understand either, I wonder why??

p.s of the few things i have learnt , one is to regard your analysis as inaccurate and greatly optimistic.

Jean

Go burn more rubber with your RT12 in parking lots kid, you are wasting bandwidth here.

Red rooster

Jean,
I will have a go at re reading your numbers !
My idle thought was that the higher the speed range being looked at ,the much more important aero drag / weight would become .
All interesting stuff but does it just shift the emphasis heavily to the two key area and hightlight some 993tt shortcomings ?
I always remember the RUF narrow body cars having seriously high speed performance when compared to a normal wide body car.Maybe that is the direction the serious cars should be moving ?

Geoff

Jean

Red Rooster
That is exactly my point, there is no doubt in my mind that any high performance car targeting high speeds should be aerodynamically fit, i.e. narrow body and low drag dynamics (rain gutters, narrow tires etc..). Problem is it will have a narrow track and poor cornering, so the right balance needs to be found depending on the targeted usage. Not everyone is out there to beat speed records at the expense of handling.

I covered the Yellowbird example earlier:
The distance needed to cover 200-300kph with the stock body is 1920 meters (6,300ft.) vs. 1680 meters (5,511 ft.) for the CTR body, I consider that to be substantial, especially bearing in mind that I am maintaining 993TT weight in this simulation, not CTR weight. Once we put this into perspective we should realize how important aerodynamic improvements are for anything beyond 200kph (124mph).

Stummel

I can somehow follow why Leon is rejecting all this theoretical estimates based on his believes and the money he put down for the Ruf cars.

The only thing that he has seen first hand is that his old Ruf has beaten TBs RS car. The thing here is that I am sure Leon does not believe TBs car was in limb mode back then.

As the RT12 outperforms the R Turbo for sure it makes no sense for him that TBs car should outperform the RT12... (Being faster in a straight line is at least a transitive function.)

The only solution besides ignoring all this shyt is to have the RT12 race against TBs RS 993tt.