Drag racing physics discussion

[ArtQ]

It really doesn't get more tech than this: Torque, inertia, center of gravity

It was amusing how heated the discussion got, yet...Polite..

 

[zipperhead]

Good read .. thanks

 

[fdjizm]

Awesome info!

 

[bigstick]

It was amusing how heated the discussion got, yet...Polite..

Robin Parsons: This statement makes some kinda strange non sense to me...

Wimms: First, this wasn't polite.....

I kept waiting for the gloves to come off and that was the worst of it.

Damn. S197 has ruined me.

 

[ArtQ]

I kept waiting for the gloves to come off and that was the worst of it.

Damn. S197 has ruined me.

YES! That did seem to be the worst of it...HaHa

 

[psfracer]

Ok I only understood about half of that.

 

[ArtQ]

Ok I only understood about half of that.

HaHa, yeah, kinda gets your brain moving around...

 

[Sprayin Blue 3V]

I couldn't help but notice the almost complete lack of grammar in that thread. Horribly misspelled words, and one of the guys almost went the entire thread without using the word "the." English probably wasn't his first language, but it made the read more difficult than the terms and ideas they were speaking about.

 

[Norm Peterson]

What they are is a bunch of physicists, and English is not the first language of all of the participants. Even among the English-as-the-first/only-language folks, it's not all "American English". "Crown wheel" is definitely of England/Great Britain origin. You kind of get used to the language difference thing when there have been people from all over the world working in your office for 30 years or so.

What they aren't is engineers (vehicle dynamicists, to be more specific), and what they're trying to describe requires some knowledge of suspension kinematics (think instant center locations and anti-squat). In a roundabout way I think the discussion finally stumbled across the concept that the speed at which the initial loading hits the tires - and how suspension stiffness affects that - might matter.

I didn't thoroughly read it all, but it seems like way too much is being made of minor effects. Energy loss does happen in the shocks (not the springs), because you can't recover the energy spent by forcing the shock oil through tiny passages which heats it up. But that's a tiny amount compared to what's available.

Just to pick a few nits with one of the main players,

for inertia to be the effective lifter of the car, the car MUST travel forward, if you have ever watched drag racing you will have observed that dragsters lift their front ends RIGHT FROM THE START LINE, (not enough forward motion for inertia to have worked with the kind of force required) torque from the axle/chassis combination (matches, same as, the ring/pinion example)

He is missing the point that a large acceleration happens before there is much visible forward motion, that the body inertia force is directly in response to that, and that it is purely rearward/parallel to the track surface. He's a LONG way from realizing that the chassis of a rail can intentionally be made flexible for the front wheel droop condition.

Oh yes, BTW russ, I learned aout COG's in High school physics classes that occured when I was in grade 10. That was waaaaaaay back when I was ~15/16 years old, or ~1971/72, OOOOOooops that's right, you were not even born yet!

Please, forgive my overt rudeness, (or not, your choice) and beware OLDER MEN (and Women!) as they have had more time to learn more "things".

He got the gloves a little loose at that point. But he's still a kid relative to some of us, and I hope that he's been paying attention to his own advice. Never mind that he should at least remain open to learning regardless of the source.

PS Russ, from the start line, to the finish line, the real, and actual, 'COG' moves towards the rear of the car(!!), without question!

Except for rearward fluid slosh, rearward compression of the driver's body against the seat, and compression of any seat padding, he's way off base. I could tell him that a microscopic amount of longitudinal chassis compression actually does occur, but that he'd need to know more in order to be able to say whether that effect by itself would increase or decrease the rear tire loading.



Norm

 

[Diabolical!]

Except for rearward fluid slosh, rearward compression of the driver's body against the seat, and compression of any seat padding, he's way off base. I could tell him that a microscopic amount of longitudinal chassis compression actually does occur, but that he'd need to know more in order to be able to say whether that effect by itself would increase or decrease the rear tire loading.
Norm

That was the biggest thing I noticed as well. Center of gravity does not change. As for the rest of the thread, my thoughts varied between "What the hell is that guy talking about?" to "That guy has no idea what the hell he's talking about," lol.