I was just watching the 2012 Valencia FP1 and a Torro Rosso does a practice start out of the pits next to Martin Brundle, about 32 minutes into the sky sports coverage. When the car first takes off it sounds much like a normal car taking off with a slipping clutch and constant revs, but after about a second (second phase?) the engine starts to sound wobbly. I actually suspect that they have some engine map which varies the revs very quickly up and down. I think they do this for the same reason that cadence braking works.
Interesting observation. Did it sound like the rev limiter (pit lane speed limiter) or was it different. If anyone can post a recording I'd love to hear it.
However given that weird engine maps are somewhat frowned upon or even banned (like the throttling in corners to energize the diffusers), and given the fact that I think that the throttle is strictly only allowed to be operated by the (human) driver, upon further thought it is far more likely that, rather than the engine doing something funny it is more likely to be the clutch doing something funny. Maybe they have made a clutch mode in which the clutch engages and disengages very quickly to the same effect as I suggested in the opening post.
Can I just say that splitting a video is the hardest thing I've done in my life. Lot's of programs, none does what it advertises. Well, I succeeded in the end.
It sounds weird to me, and not clean at all, neither when idling or accelerating.
This is a test, so compliance with the rules would not be required. I would also assume that they do not want to do a bunch of starts, so maybe the system uses some form of traction control while mapping the whole exercise/event. You go back afterwards and determine where you want to set thinks.
hardingfv32 wrote:This is a test, so compliance with the rules would not be required. I would also assume that they do not want to do a bunch of starts, so maybe the system uses some form of traction control while mapping the whole exercise/event. You go back afterwards and determine where you want to set thinks.
Brian
nah, heard the same wobble the topicstarter is talking about on a bunch of cars during race starts, I'l see if I can find some other footage. Been wondering myself what causes this.
Then I would say that is the sound of the engine hitting or on the rev-limiter.
In the case of the F1 start test maybe the throttle can not be controlled even during tests under the current rules. So, to remove a variable during the test the driver just goes to full throttle and the clutch travels through its range under computer control.
5.7 'The bite point finder strategy'. What is meant by this term: Does this describe the activity of finding the proper clutch release setting for the start or is the application of using a set clutch level during the start?
Thanks much for posting the clips. I don't know what's going on.
Here's a thought-- Remember a few years ago when Honda started doing weird MotoGP firing orders? They were called a "big-bang" engines because two or more cylinders fired together instead of in an evenly-spaced sequence. This gave better straght-line traction because the tires somehow gave better overall traction with the BANG-slack-BANG-slack method rather than the traditional bang-bang-bang-bang method.
The odd noise in the clips seems to occur when the engine is probably not delivering full torque. In this situation you can run the engine at, say, 50% throttle or you can run a high-frequency on-off-on-off throttle cycle that delivers an equivalent average torque. This would be roughly analagous to the Honda big-bang firing order. It may also be easier for the driver to modulate this type of thing. All guesses here.
I think the Honda thing might be a myth, with a 15000 rpm (2 stroke?) engine how could such high frequency (differences) in the delivered torque even be transmitted through the tyre to the contact patch ?
I think it was more to do with crankshaft design (a cover story ?)
Anyway, chain and sprocket transmission must generate its own torque ripple, and a ripple device could be built in (if it was wanted).
Current 4 cyl MotoGP bikes (and a road bike) are described as 'big bang', having cross-plane cranks to give equal spacing of inertia (recip) loads at the expense of uneven firing interals (like a Detroit V8 cut in half, NSEW)
This gives a more slender crank than the traditional flat/single plane NSSN crank design (thus smaller bearing diameters and less friction) for the same required crankshaft torsional frequency. As in any halfway modern engine the max inertia forces are far bigger than the max combustion forces.
MotoGP is a fuel-limited formula so bearing friction is important.
Off-road bikes have been made big-bang, the Triumph was once tried with simultaneous firing, also a US market 2stroke.
But anyway, the right kind of electronic/computer implemented torque ripple for traction/cornering grip sounded good, you'd think that it would have been tried by someone sometime (or it could be done mechanically ?)
