Why doesn't F1 use Top Fuel style clutches for launch?

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
riff_raff
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Joined: 24 Dec 2004, 10:18

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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TF cars don't shift gears because they don't have a conventional transmission. The engine is coupled to the rear end only by the clutch pack. A TF car has two forms of "CVT" that it uses to allow a change in speed between the engine and wheels. One is the change in diameter of the rear tires due to CF as they spin faster when the car accelerates down the track. The other is the gradual reduction in clutch slip (or progressive lock-up) as the car drives down the track and can handle larger amounts of torque without losing traction.
"Q: How do you make a small fortune in racing?
A: Start with a large one!"

J.A.W.
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Joined: 01 Sep 2014, 05:10
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Re: Why doesn't F1 use Top Fuel style clutches for launch?

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Gear changes via a 'transmission' per se - in T-F have not been utilized for many competition seasons now..
& r-r, that circumferential tyre growth/'gearing' - is initially due to power on, but down track is vehicle speed related..
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

Brian Coat
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Joined: 16 Jun 2012, 18:42

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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"tyre growth/'gearing' - is initially due to power on"

It's very interesting what happens. At initial power on, the tyre/gearing actually gets *shorter*.
This is due to weight transfer causing the tyre to be squashed flatter. The front wheels have momentarily left the ground at this stage. The tyre pressure is one of the factors determining the launch 'gearing'. The tyre is very non-round at this stage.

Then it gets taller as the car comes up 'on the tyre'. To achieve this is very tricky because there must be sufficient angular velocity to allow the tyre to become round and avoid tyre shake (stick-slip adhesion) but not so much as to cause tyre spin.

At the top end a combination of various forces etc. means that the tyre becomes very non-round and a lot taller. It's actually' and very visibly, the shape of a UK 50p piece! Another interesting phenomenon is the way that the car "arches it's back" at the top end, again, due to a combination of moments and forces.

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bdr529
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Joined: 08 Apr 2011, 19:49
Location: Canada

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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The video is a few years old now, but I still think it gives the best overview of how these machines work
the bit about the clutch starts at 9 min. and is fallowed by info on the tires


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Ciro Pabón
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Joined: 11 May 2005, 00:31

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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Thanks, Brian, mighty interesting, I had no idea of those subtleties about the initial squatting and the back arching.

Thanks to you also, bdr529, I had a nice lunch of junk food (fried potatoes and sausages) while I watched the video.

Actually, I saw it twice (and went back to the kitchen to make a second round of fried things, so if I have a heart attack these days it's partially your fault).

Misteries of the NHRA: how the f*ck do you fry Pepsi?
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Ciro

riff_raff
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Joined: 24 Dec 2004, 10:18

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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Diameter growth in TF rear tires is due to CF and thus is related to wheel speed. At any time during a run a TF car never wants to lose rear tire traction and experience spin. So at launch there should ideally be no tire spin or loss of traction that would cause growth in the tire OD. The same is true as the car goes down the track, except that the rotational speed of the tire progressively increases as the car accelerates. So an increase in tire OD will occur.

The only time you would see a TF car intentionally spinning the rear tires is when they perform a burn-out before their race pass.
"Q: How do you make a small fortune in racing?
A: Start with a large one!"

Brian Coat
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Joined: 16 Jun 2012, 18:42

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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riff raff has reminded me that a very small amount of tyre spin *is* actually required throughout the run for the same reason as on an F1 car at launch - this is what yields the maximum acceleration.

On the drag strip you can see this : a record breaking run always black stripes over the full 1000 ft.

Blanchimont
214
Joined: 09 Nov 2012, 23:47

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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I think it's time to bring up this amazing slow motion video. Watch the sidewall and the tyre slip at the start and don't miss the tyre deformation at the end of the run, unbelievable.

Dear FIA, if you read this, please pm me for a redesign of the Technical Regulations to avoid finger nose shapes for 2016! :-)

gruntguru
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Joined: 21 Feb 2009, 07:43

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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Brian Coat wrote:riff raff has reminded me that a very small amount of tyre spin *is* actually required throughout the run for the same reason as on an F1 car at launch - this is what yields the maximum acceleration.

On the drag strip you can see this : a record breaking run always black stripes over the full 1000 ft.
Does anyone know the optimum slip ratio for a typical drag slick?

I know the number for circuit slicks is usually somewhere between 5% and 10%.
je suis charlie

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Ciro Pabón
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Joined: 11 May 2005, 00:31

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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As this thread is becoming a thread on NHRA clutches, just in case you're interested (and you will) there you have a nice video about how to build a light clutch (for funny cars, only 1.800 HP), American old school style, if I may add.

The legendary Crower Clutches


This design have been used in races for the last 48 years.

Now that you've been enlightened about how to make a light clutch, you can appreciate the complexities of a heavy one...

...and, over all, the accent you have to have to understand what you're doing. 8)


Then you have to set the clutch.

This means that no matter how good you think you are, things are so competitive, differences are so minute and decisions have to be made on the spot about how the clutch will work that theories about how much slip you'll get (with all due respect, which, if you allow me to put it in this way, is not a lot of respect) are, well... wishes more than theories.

Talking about complains about the noise of engines, that abound in F1 these days, notice how the people in the background is desperately trying not to become deaf.

The nitro burns through the screen directly into my eyes... oh, my eyes! :cry:


If you're kind of nerd, like me, you might want to watch these to realize that with a multiple stage clutch you multiply the torque capacity by the number of plates: you are, in effect, distributing the torque among all the surfaces of the different plates.

...so you don't have to increase the diameter of the clutch or the pressure of the springs.


Now, to try to answer the question posed by gruntguru (hi, grunt!), I don't have the answer (duh), but I know how TF crews know it.

A driver has two gauges in the cockpit, one shows the engine RPM, the other one shows the driveshaft RPM.

Yes, I know, you've never seen this in Formula One.
Formula One is for sissies... :D



Of course, if you know the time, and hence the speed, and you also know the driveshaft speed you can quickly deduce the slip ratio (in case you're interested in that: probably you're more interested in the end result, that is, time).

Now, what happens when the clutch is not well set, rebuilt or managed? Do you lose one tenth, like in F1? Perhaps two tenths?

Well, it's kind of simpler. The clutch explodes.

Do you find Hollywood explosions exagerated? Well, lemme tell you you're a tad naive


I guess you are starting to understand why TF clutches are not used in Formula One: if the grid had a couple of explosions like the previous one at every race start, ratings would go up to the sky!

Frankly, comparing the complexities of Top Fuel launches with Formula One launches is kind of offensive, if I'm allowed to say it so.

In our next thread: why doesn't F1 use Truck Racing turbo compressors?
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Ciro

gruntguru
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Joined: 21 Feb 2009, 07:43

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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Nice post Ciro. My question was about "tyre" slip ratio ie how much faster the tyre is rotating than true ground speed.
je suis charlie

riff_raff
132
Joined: 24 Dec 2004, 10:18

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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The amount of power and slip a TF clutch is subject to is modest compared to the Lift Fan clutch used on the F35B. The air-cooled carbon clutch used to drive the lift fan on the F-35B transfers close to 30,000 hp and provides a variable speed ratio of over 10,000rpm
"Q: How do you make a small fortune in racing?
A: Start with a large one!"

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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Yeah r-r, got any references to cite - that give cost, serviceability, TBO & etc, facts on that F-35 VTOL?

Are any of them actually operational yet?

Maybe Auto-Gyro will chime in here & opine that the F-35 makes F1 look sensible.. budget-wise..
& T-F present as paragons of well-sorted economical longevity - by comparison
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

hpras
15
Joined: 12 May 2009, 06:15

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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F35 is impressive, but it is a push button operation that takes 15 seconds to accomplish. It's pretty unlikely that that turbine is transferring anything near 30000 HP when clutch lockup is happening as it would be idled down quite a bit. The transfer from horizontal flight to vertical would be conducted under a very strict regime, not something you would slam the plane into... unlike the Harrier where going to full reverse thrust was a tactic to cause the adversary to overshoot you (as I understand it). The RPM's that need to be dealt with are pretty spectacular all the same. Top Fuel F1 application.. not much. But impressive engineering all the same for what it needs to accomplish in the time frame allowed.

edit - excess words... honest

Brian Coat
99
Joined: 16 Jun 2012, 18:42

Re: Why doesn't F1 use Top Fuel style clutches for launch?

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I agree.

I would expect the level of engineering (and $) that goes into the F35B Lift Fan system is very much higher than F1, let alone TF.

According to Wikipedia, the lift fan system is a $28m per unit optional extra - the base model being 'only' $114m (at launch volumes).

The total lifetime program cost of F35 is estimated as US$1.0165 trillion.

http://en.wikipedia.org/wiki/Lockheed_M ... ghtning_II

We may think Teams+Sponsors have deep pockets but they are lo-budget compared the the US DoD.