3/12/2010

03-12-10 - Friday Linkage

YouTube - SeatofEmpire's Channel - cool documentary about Seattle as the manifestation of American capitalist-military exploitation. This is just previews but they are fun and well made.

YouTube - Heel & Toe - best video I've seen of heel & toe technique. For racing, through a corner you want to go from braking hard directly into gassing hard with no coast time in between. It's actually much more important to do this in a turbo car or any car with a high narrow power band - in that case you need to actually shift while you go through the corner so that you keep the car in the power band, you can't wait and shift right before you power out at the apex because the RPM will have dipped too low.

YouTube - minutegongcoughs's Channel - good old music

Wheel Alignment A Short Course
Caster, Camber, Toe
The new 911 has some weird shit going on with the alignment to keep the tail from sliding out. I had no idea what camber or toe were or how they affected vehicle dynamics; crazy interesting stuff. Some people who race 911's make the alignment more neutral so that they oversteer more.

John Sizemore - Weird_Weird_Science on Dailymotion - awesome awesome videos of extreme zooms on materials all the way down to the atomic scale. How do they do this?.

Alan Turing - Wikipedia, the free encyclopedia
Turing biography
Of course we all know Turing from the Turing Machine and the Turing Test and his thoughts on AI and Computability, but he also did work on chemical pattern formation, abstract mathematics, and code breaking. I had no idea about his personal life story, though, which is quite shocking.

NOVA Sputnik Declassified A Tainted Legacy PBS - speaking of scientist biographies

Popular Science - Google Books Old Popular Science magazine is fucking awesome. Just the other day I was oiling up my bicycle and was wondering why we don't oil up cars the same way (oiling all the hinges and gears and such) - well of course in the past they did!

Pelican Technical Bulletin All About Motor Oil
A little bit archaic but pretty interesting.

Brian Beckman's Physics of Racing Series - really this is "Physics of Driving" ; it's mainly a review of the basic forces involved in cars. Pretty good stuff. I guess BB is at MS Research and may have contributed to "Forza 2" , though if it's anything like the typical MS Research video game "contribution" it means he sent them a link to his articles and they ignored it. (BTW just found this nice series of videos on basic car physics made by a dry narrator in a Seven).

Aircrew Survival Equipmentman 2 - Aviation theories and other practices - what to do when your plane goes down. Includes how to maintain or fabricate your parachute.

11 comments:

Autodidactic Asphyxiation said...

The Turing story is awful, but I knew it already. This dude comes up in Omnivore's dilemma:

http://en.wikipedia.org/wiki/Fritz_Haber

cbloom said...

Ah, wild, that's classic Greek Tragedy - create poison for your Fatherland, then have them use it against your family.

Tom said...

That's a neat heel'n'toe video. Thanks. The written descriptions I've read were never very good; looks like "heel" is a looser term than I assumed.

My car will be the one with its rear end stuck into the outside wall of some random bend...

(I guess the hinged-at-the-bottom accelerator pedals are better for this. I always wondered what they were for. My current car has one, and I like it, but I wasn't sure whether there was any real reason to have things set up that way.)

Tom Forsyth said...

The video shows heel&toe, but I think you're describing left-foot braking.

Left foot braking is the technique you're describing - making the front wheels brake while applying power to the rear wheels, which causes the back to step out and gets you into power-oversteer, and also keeps the power on ready to exit the corner. Even works in 4WD cars because brakes are almost always front-biased. Really only good for gentler corners - in hard corners you want the max out of the brakes, not have them fighting the engine.

The video demonstrates heel&toe, which is all about the ability to change down & match revs while still braking into or through a corner. As you change down, ideally you should be rev-matched with the wheels&gearbox at somewhere around 4k-6k revs. Note that the throttle blip is done while the clutch is applied - this is not about getting power to the wheels!

Without heel&toe, the engine is idling probably around 800 revs when you drop the clutch - a 5x disparity with the gearbox. Obviously this mismatch isn't great for the clutch, but far more importantly what you're doing is suddenly inducing a braking force through the driven wheels right at the moment you're already pushing them hard with the lateral force from the corner. They'll break free very quickly, and now you're spinning like a top. Don't ask me how I know - I'm still picking the grass out of the Seven's radiator.

With heel&toe, the clutch is dropped when the engine and gearbox are at about the right revs, and there's no extra forces on the wheel through the drivetrain - all the force is still through the brakes, under driver control.

cbloom said...

"The video demonstrates heel&toe, which is all about the ability to change down & match revs while still braking into or through a corner."

Yeah, that's exactly what I'm talking about.

"this is not about getting power to the wheels!"

It is though, it's about being able to accelerate out sooner. Not when you blip, but later on, because you blipped.

"Without heel&toe, the engine is idling probably around 800 revs when you drop the clutch - a 5x disparity with the gearbox."

Now this is an interesting and weird point. You are making the exact same statement that I've seen all over the internet and it really boggles my mind. You're presenting heel & toe as an alternative to just dropping the clutch. That's so weird to me. Of *course* I'm not just going to slam the clutch. That's not the alternative to heel & toe. The alternative is that I brake in to the corner, and just stay in the higher gear, and then when I want to accelerate out past the apex I then take my foot off the brake and blip the gas to down shift and get on my way. Or I just keep my clutch in as I brake, select my gear, then gas on out, no blip needed. For some reason racers think it's really bad to ever have your clutch held in, but I can't figure out why.

Tom Forsyth said...

> The alternative is that I brake in to the corner, and just stay in the higher gear, and then when I want to accelerate out past the apex I then take my foot off the brake and blip the gas to down shift and get on my way.

That works, but it's slow, and during apex you're in the wrong gear. If you're like me and have feet way too big to heel&toe (or maybe my car is too small), much faster to still change gear as you come into the corner (just like with heel&toe), but start braking a fraction earlier. This gives you time to, while still coming into the corner, clutch in, change down, come off the brake & blip the throttle, clutch out, back on the brake. Now you're going through the corner in the right gear and you can control both entry (brake), apex (neutral) and exit (power) without changing gear.

If you try to change gear during apex, you'll fuck it up, put extra torque through the wheels, and spin the car off the track. If you try to change gear during exit you'll be sad and slow right when you need max power.

Cars with FPGs, or the astonishingly clever Nissan 370Z, blip the throttle for you on downshifts, so there's no need for heel&toe.

cbloom said...

"Cars with FPGs, or the astonishingly clever Nissan 370Z, blip the throttle for you on downshifts, so there's no need for heel&toe."

Yeah this is all a dying skill as electronic gear shifts are the way of the present/future.

I wish the 370 was like 500 pounds lighter and just really raw. And more glass. And better seats.

Tom Forsyth said...

Actually re-reading your post I think I kinda see what you're getting at. Yes - you don't want to change gear after the apex - it's slow (abysmally so with turbos). But that's not an alternative racing technique that heel&toe solves - that's just shit and dangerous - never ever do that.

Always change gear before the corner, and what heel&toe does is let you start braking that little bit later.

Gilles said...

There is a great book, cryptonomicon by neal stephenson about WWII, cryptography,math, Turing.. You should read it.

MH said...

Time to rent a car and try that heel/toe stuff out.

Tim said...

Regarding Turing's work with chemical pattern formation, there's a BBC documentary about it: http://www.youtube.com/watch?v=HACkykFlIus

It's decent for a popular science piece.

old rants