a race car system development

In message , Jack Crenshaw writes

Banning traction control does not mean they won't have it. It just will not be labelled as such.

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\/\/\/\/\ Chris Hills  Staffs  England     /\/\/\/\/
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Chris H
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Which bit is flawed? I use it fine

Reply to
bigbrownbeastiebigbrownface

They do not kill power, what a stupid suggestion. They do however shift upand down without clutch sometimes. Same in car racing.

Reply to
bigbrownbeastiebigbrownface

google

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\/\/\/\/\ Chris Hills  Staffs  England     /\/\/\/\/
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Chris H

Are you _KIDDING_ me? Granted that all mfrs will cheat if they can figure out how to do it without getting caught (witness McLaren's use of a new kind of shock with mass component, the FIA watches them like hawks. They made Ferrari stiffen their front wing mounts because they were flexing (slightly) under the 1000+ lb aerodynamic loads. They said that made them a "variable aerodynamic device."

If you saw the 2008 races, you know how twitchy the cars were under acceleration. Spins galore. If Ferrari were using traction control in

2008, someone sure forgot to tell Filipe Massa.

Jack

Reply to
Jack Crenshaw

Stupid? STUPID?

You could have worded that a little more tactfully.

On a motorcycle, it's easy to shift up without the clutch, if you roll back the throttle. But the kill button allows for much faster shifts. The transmission is capable of withstanding bang-shifts with no decrease in power, but doing this on a road course is a good way to end up on your butt.

I'm pretty sure that F1 cars do all shifts without the clutch, but they've got million-dollar electronic controls, not to mention $1M transmissions.

Jack

Reply to
Jack Crenshaw

Not at all. I know someone personally involved in checking the software for the FIA for many years.

That is my point.

They do and it is quite a game. There is a LOT of money at stake and everyone enjoys the intellectual challenge (said that without mentioning hacking :- )

I bet that was a complete surprise to Ferrari who hadn't noticed it. :-)

Yes.

:-)

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Chris H

Oh, sure, all shifts up-down are possible if you take your time, shift into neutral, and synchronize RPM with car speed. The trick is to do it quickly. With F1 transmissions shifting 600 HP in sub-ms times, things are a little different.

Then again, I guess I don't know what kind of racing the OP is talking about. Maybe not so high-tech?

Jack

Reply to
Jack Crenshaw

... snip ...

I suspect that is because a bike engine can reduce rpm faster (with the throttle closed) than the bigger and heavier automobile engine. Also, racing gearboxes have much closer gear ratios than automobiles.

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 [mail]: Chuck F (cbfalconer at maineline dot net) 
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Reply to
CBFalconer

Well, what I've been trying to say is, you don't want any sudden impulses -- throttle or kinetic -- into the rear wheel. I suppose it doesn't matter for motocross -- those guys are constantly in wheelspin anyhow. But on a road course, with your knee scraping the ground, any sudden addition of torque is going to put you down in a hurry. Bike racers learn quickly not to do anything sudden.

It might seem counter-intuitive to suggest that something as impulsive as a kill button would make a smoother transition than just bang-shifting at full throttle, but that's my impression. It might be for the reason you suggest -- the rotational inertia of any race-useful engine is usually small, and at least on my bike there was some cushioning in the hub.

OTOH, back in the 70's a friend of mine had a kid who made something of a name for himself in "little league" motocross. His starting technique: Put the bike in neutral, rev the engine to wide open throttle. When the flag drops, stomp the shift lever into 1st gear.

Ouch!

Jack

Reply to
Jack Crenshaw

Hello, we did a fuel injected CBR600 engine for formula SAE at Uni of Qld in 2003. It had a gas actuator running on CO2 to rotate the gear select shaft. When we did a shift we asked the Motec ECU to stop sparks for 100ms to cut engine power while the gas actuator banged the gear through without a clutch. Make sure you get the timing right so power is cut for the whole time the shift is happening. Use some data acquisition gear to measure that the shaft has rotated all the way before resuming sparking. Ours was open loop we just delayed for a time relative to the switch for up shift that always allowed the shift to complete.

We had a clutch cable that we operated by hand when we launched the car. It had traction control which also was handled by the Motec ECU. To launch we would hold the clutch with one hand and have the other on the steering wheel to hit the up shift button and hold the wheel straight. The Motec was set to hold 5000rpm at the launch and once the wheels were rotating it would monitor the tyre slip front and back and drop sparks to an increasing number of cylinders to drop power when we were starting to slip. After a bit of trial and error we came up with these launch parameters.

We won the event for fastest accelerating. We had a spool too instead of a differential. So we had less transmission losses and lower rotational inertia which probably contributed most to this.

We heard one team had problems getting clutchless shifting happening on a Kawasaki ninja. Something about first to second being tough to bang through. We really hurt our first gearbox by not getting the engine depowered for the whole duration of the shift. It was coming back on part way through the gear engagement which wore the corners off the dogs. We had to replace the engine on the night of a competition which wasn't fun. If I had to do it again I'd make a gizmo external to the ECU to cut sparks until the gear was selected (with a timeout in case the gear change fails). Better a quick grind than setting there dead in the water. I can't remember if we had to cut sparks on downshifts.

at

the

switch

Reply to
MarkC_Bris

Excellent good! That's exactly what I was trying to suggest. A manual kill switch worked fine for me, but we're still talking about times in the 100ms -300ms range.

Make sure you get the timing right so power is cut for the whole

Yeah, another excellent idea. You learned the hard way that 100ms is not long enough .

FWIW, I've been following the adventures of Formula SAE for awhile. It seems like a great adventure (now, about Road Atlanta...). In another lifetime I drove a "Micro-Midget," which then was limited to 250cc. Not nearly as big as the ones in Formula SAE, but with a fully modified engine (compression ratio 22:1) in a 300-lb car, and running alcohol and nitro, it will definitely get your attention. I once got to drive a friend's nat'l championship car on a crushed limestone track -- softer than asphalt, harder than dirt. There was not one place on the track, especially including the straightaways, that I could use full throttle. To do so only made the wheels spin faster.

Today, they have micro classes for 600cc and 900cc engines. _THAT_ must surely ring one's bells.

I've been trying to think of a way to automate downshifts, but can't think of any possible way. As we've discussed, it's easy if the transmission has a neutral position, but motorcycle transmissions are progressive. In braking you have the engine revs going down, but have to blip the throttle to make the transmission.

I dunno, maybe it would work. What you're really trying to do is not to synchronize the engine RPM with the speed -- the trannie can sort that out -- but remove the torque from the engine, going up or down. So maybe some kind of "anti-kill" solenoid that could blip the throttle, just for long enough to engage the next gear.

Timing isn't nearly as critical on downshifts, either. Today's brakes are grest, and the front wheel does all the work anyhow. The only reason for downshifting, anymore, is so you're in the right gear on exit from the corner.

That being the case, perhaps the trick here is to be smooth and gentle. Slowly ramp up the throttle to neutralize the torque on the tranny, give the shifter plenty of time to engage, then ease the throttle back down again.

Hm. Sounds like we need a torque sensor, too.

Speaking of up gears and down gears: Years ago I had the thrill of watching the FIM races at Daytona. They had classes for all sizes of engines, right down to 50cc. To see a 50cc bike going 110 mph is something to behold.

Those bikes had very peaky 2-stroke engines, with something like

13-speed transmissions and VERY close gear ratios. A reporter asked one of the riders, "How do you know what gear you're in?" The rider said, "We don't, but it doesn't matter. Wherever you are on the track, there's always at least one gear up and one gear down."

Jack

Reply to
Jack Crenshaw

... snip ...

All my _bikes_ have always had a false neutral between each gear, whether shifting up or down. This enabled downshifts quite nicely without a clutch.

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 [mail]: Chuck F (cbfalconer at maineline dot net) 
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Reply to
CBFalconer

IIRC this is inevitable for standard motorcycle gearboxes (don't know the english term):

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Falk, never^Walways racing his Enfield Diesel ;-)

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Falk Willberg

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