McLaren F1 transmission

[jediali]

Originally Posted by Kultag

It's a pity car makers' employees don't come to these forums to answer these questions. Or F1 owners...

Im with drakkie..id still come on here and discuss issues if I had the pleasure of working in automotive engineering. Perhaps secrecy comes into it, but for vague surface issues like this its unlikely youd be divulging confidential info. If anyone finds a particularly good forum I could also visit where there is a particularly rich community of automotive engineers please share! At the moment the best I can find is through the IMechE and its not as good as here.

Originally Posted by Kitdy

Do you derive some sadistic pleasure form constantly putting him down?

you still alive Kitdy?

[Wouter Melissen]

Originally Posted by Matra et Alpine

Remeber what was said LONG time ago .... drag increases exponentially.
So there are always limiting points ... so for example a car with static downforce will likely have high drag at the higher speeds and so the forces at the contact patch are MUCH higher and hence slip will occur.

Cars like the Veyron and Porsche CGT have dynamic aero to be abel to reduce the drag and adjust the downforce to optimise across wider range of speeds and so limit the lip potentially.

I tihnk if you do the math on all those you'll find them significatn -- tho' I concur that quic mental estimate finds it difficult to see >10% that you're witnessing.

The only thing that might explain this anomaly is clutch slip, but if the clutch slips this much it won't last 2 minutes. Drag is irrelevant as this is more a theoretical issue.

His calculations show that the gearing of the McLaren allow for a theoretic top speed of 459 km/h at 7500 rpm. Of course this is not possible because of the aforementioned issues with drag. All that is irrelevant though because Andy Wallace indicated he hit the limiter at 380 km/h. Do you really think that the clutch would slip to the extend that it would loose 80 km/h of top speed?

So either McLaren changed the gearing or their numbers are wrong. That was the poster's point / question.

[Kultag]

Originally Posted by Matra et Alpine

Remeber what was said LONG time ago .... drag increases exponentially.
So there are always limiting points ... so for example a car with static downforce will likely have high drag at the higher speeds and so the forces at the contact patch are MUCH higher and hence slip will occur.

Cars like the Veyron and Porsche CGT have dynamic aero to be abel to reduce the drag and adjust the downforce to optimise across wider range of speeds and so limit the lip potentially.

I tihnk if you do the math on all those you'll find them significatn -- tho' I concur that quic mental estimate finds it difficult to see >10% that you're witnessing.

Ehm... back to the point, if I can. So still: no-no-no. Drag means just a force. But the engine rpm and the rigid shafts and cogs in the transmission dictate a strict (compulsory as I called it) speed at a given engine rpm in a given gear. Others talk about clutch and wheel slip, which I call negligible or at least insignificant. This means if the above data are correct, the car cannot do 380 km/h in 6th at 7500 rpm. What you are talking about is a second question, whether or not the car has the power to reach that speed or another.

Think of a bike: if the front sprocket has 30 wheels and the rear has 10, wheel rpm to leg rpm (or what ) ratio MUST be 3, always. I just calculated that the Mac has to reach redline in 6th at 459, so if it goes with 380, engine rpm must be lower. So: something's wrong.

Edit: ...the front sprocket has 30 TEETH...

[Wouter Melissen]

Originally Posted by Kultag

Ehm... back to the point, if I can. So still: no-no-no. Drag means just a force. But the engine rpm and the rigid shafts and cogs in the transmission dictate a strict (compulsory as I called it) speed at a given engine rpm in a given gear. Others talk about clutch and wheel slip, which I call negligible or at least insignificant. This means if the above data are correct, the car cannot do 380 km/h in 6th at 7500 rpm. What you are talking about is a second question, whether or not the car has the power to reach that speed or another.

Think of a bike: if the front sprocket has 30 wheels and the rear has 10, wheel rpm to leg rpm (or what ) ratio MUST be 3, always. I just calculated that the Mac has to reach redline in 6th at 459, so if it goes with 380, engine rpm must be lower. So: something's wrong.

Are you absolutely sure about your calculations? If so, I'll ask around if the figures are correct.

[Matra et Alpine]

Depends on HOW you measure speed
If it's from the driven wheel then the speed-revs ratio is as you surmise.
BUT when the speed is taken electronically or off a non-driven wheel then the slip on the driven wheels DOES show.
Rally cars have had this issue for decades since the invention of the Halda

[Kultag]

Originally Posted by Wouter Melissen

Are you absolutely sure about your calculations? If so, I'll ask around if the figures are correct.

They should be okay. As I wrote, they work with all the other cars. I checked the cardata files in Need for Speed 6, calculated what the top speed should be in each gear with each car using this formula, and NFS6 did exactly those speeds. It also worked with other programs, so others use this as well. Also the input data should be correct (not mistyped at least) as they write these everywhere. If you think of Diablos, the VT models are 4 wheel driven, so gearbox and diff ratio is useless without transfer gear which I did find on the net. Without them the redline speed of the 5th gear would be 575 km/h with the 6.0 VT. The spreadsheet showed big, obvious errors, but it can't reveal minor ones. That is, who knows, how many other cars are missing a few information?

[Kultag]

Originally Posted by Matra et Alpine

Depends on HOW you measure speed
If it's from the driven wheel then the speed-revs ratio is as you surmise.
BUT when the speed is taken electronically or off a non-driven wheel then the slip on the driven wheels DOES show.
Rally cars have had this issue for decades since the invention of the Halda

IRC they measured speed with a radar at Ehra-Lessien, so the above don't count. And again, this difference is too big (19 %) to be slip.

[Matra et Alpine]

Kultag, it would count... If they are measuring the speed EXTERNALLY then the revs to speed ratio you use won't match IF there is slip.
However, as said earlier, I concur it shouldn't be as large as 20% or if it was the driver woudl be aware of that amount of driven wheel slip !!

[jediali]

Originally Posted by jediali

you still alive Kitdy?

Im sure Kitdy is alive..but his post aint (neither is Drakkies)! Glad we have a delete and forget policy here

[Wouter Melissen]

Originally Posted by jediali

Im sure Kitdy is alive..but his post aint (neither is Drakkies)! Glad we have a delete and forget policy here

Off-topic posts were removed from the thread.

[Rockefella]

Originally Posted by jediali

Im sure Kitdy is alive..but his post aint (neither is Drakkies)! Glad we have a delete and forget policy here

It wasn't worth keeping the posts around, otherwise this thread would have exploded into a 15 page war. A war I was ready to fight. But won't since I'm a cool guy and such.

Speaking of the McLaren F1 Transmission..