DigitalWidgets

We all know the 1g+ lateral force skid pad performance for many of the Corvette models. But a recent discussion got me thinking about other g forces and now I'm curious if anybody would have a little more trivial knowledge they'd be willing to share:

The brakes on my GS are really awesome. Hit em hard and hold them right before ABS kicks in, and you can feel the blood rushing to the front of your face and arms. I've also noticed that the subconscious tightening of the grip and gut muscles on a spirited launch is necessary to keep from getting slammed to the back of the seat.........so, out of curiosity:

Does anybody know what kind of g forces the body is subject to in a 4 sec. 0 to 60 launch, and/or a 100 foot 60 to 0 stop?

Seadawg

If you look at youtube videos, with some of the vettes having data loggers on the tracks, they will hit 2 - 3 G's for very brief moments.

I'm sure one of our physics students out here will calculate the stopping and accelleration G's for us too

I know that I've bruised chests with the seat belt, even when warning women to brace themselves when stopping really quickly.

Gearhead Jim

I'm sure that a gentleman like yourself would offer a comforting massage...

DigitalWidgets

wayback

If he wont I will.

DigitalWidgets

The only comparable numbers I could find on the Net so far:

Formula One car, maximum under heavy braking: 5+g
Bugatti Veyron from 0 to 100 km/h in 2.4 s: 1.55g
Top Fuel drag racing world record of 4.4 s over 1/4 mile: 4.2 g
Death or serious injury likely: >25 g

Source: http://en.wikipedia.org/wiki/G-force

50 4Ever

So, if these cars get any better we'll need a G-suit...

talon90

It's going to be much less than you will imagine. I have been a passenger in a Corvette during testing of both a manual performance launch and a launch control system launch for 0-60 and 0-100. On the same test run we completed a 0-150-0 distance test. The car was a 2012 ZR1 with Pilot Sport Cup tires (maximum grip for reference). During the acceleration testing we were simply talking as if we were sitting having coffee. I would estimate the g load to be something less than to about 1.0 g and for the braking tests I would estimate it to be less than 2 at maximum braking.

Just as a frame of reference, a Navy pilot during a carrier catapault launch will experience an initial g spike of 6 g's and the load will level off to around 3 and on landing, the load in to the harness will be around 3 durind a smooth landing. The astronauts experience 3 g's during a Space Shuttle launch. A formula one car can achieve 4 or so g's during max braking from max speed.

DigitalWidgets

This is inline with what I would expect. Although, 2g's is nothing to sneeze at....it turns a 250 lb. fat guy like me into 500 lbs. of fat guy! Hmmm....may have to upgrade the seatbelts!

racebum

tires have to be included in this chat. it would not surprise me at all to see north of 1.5g on slicks

of course high g tires can be real problems for wet sump engines

MisterMidlifeCrisis

Acceleration in G is in units of meter/second squared, and 1G is rough 9.8 m/s^2.

60 miles per hour is 26.8 meters/second, so if you do it in four seconds, that's an average acceleration of 26.8/4 = 6.7 m/s^2. Divide by 9.8 and you have an average acceleration of 0.69G for a four second 0-60 run.

Braking is a bit more than double this, probably around 1.5-1.7G for a Corvette with warm, sticky tires.

DigitalWidgets

I'm glad at least one of us paid attention in high school! Thank you for the lesson.....I knew v=m/s and a=m/s^2, but I just wasn't sure how to frame the question as a math problem.

So now I'm wondering why it's so easy to break traction with the back tires on acceleration (at .69g), when braking can handle so much more force (1.6g) without loosing traction. I know acceleration is just rear wheel drive and braking is all 4 wheels...but with weight transfer, I've heard that 80%+ of braking force ends up falling on the front wheels.

Just some more stuff to ponder while washing her this weekend!

Mad*Max

v = u + gt

(60x1.6x1000)/3600=gx4 (converting 60 mph to metres per second)

g=6.67 m/s2

this is the g-force on a 4 second launch based on basic physics formula (this assumes constant acceleration though)

MisterMidlifeCrisis

I think that if you had AWD and enough horsepower, you could accelerate as fast as you can brake. But it's probably also more complicated to maintain traction when accelerating than when braking, because you don't have the ability to route power to each wheel individually in the same way as ABS can modulate the braking force on a single wheel.

But the 0.69G is just an average. I'm not sure what the peak forces are, but they're probably in excess of 1G.