G-force sensors?

Oper8r Al

I was hoping to find a way to measure the g-forces that are produced by brother-in-laws race cars, as they travel around the track. They race in different classes on a 1/2 mile oval, and I would like to be able to compare the two.·I was looking at an accelerometer but from what I·have read I'm not sure if that would work. It seems to be more for tilt and up/down g-force, not linear. I may be wrong about this and thought I would ask. I appreciate any help.

Al

Jon Williams

You can in fact use an accelerometer -- that's what they're good for. You'll need to select one that can measure g-forces great than can be tolerated by the car. A typical street car can handle 1-g, an Indy car can hanlde upwards of 5 g's in a corner. I'm betting your brother's car is somewhere in between.

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Jon Williams
Applications Engineer, Parallax

LoopyByteloose

Fighter jet pilots black out between 5 and 7 g's.
They even wear a special pressurized flight suit that drives the blood out of their limbs so their brain gets more in combat situations.

So that is about the limit unless you are building a SCRAM jet or something else government doesn't want yu to have.

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G. Herzog in Taiwan

steve_b

Not to brag, but that suit was made in Canada. For years, Canadian pilots wore it, where American pilots would do that "GRUNT" to keep going.
They've measured some pilots (a special few) that have made it through 10g's.

I can't remember the guys name, but there was a scientist "back in the day" that wouldn't allow any other live persons to be tested...just himself.
he lived through something like a 40g deceleration (those rocket sleds). He was in bad shape...but lived! 2 detached retina's, a whole lot of hemoragging.

A little off topic there.....
John, being that the race car, just guessing, will be driving a cambered track (25deg banks) howwould you go about calculating proper g forces. Guess you'd have to know the angle of the bank.....or use a 2 axis sensor and have one axis up/down and the other axis side/side...and then do some vector math?!?!

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·

Steve

"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."

Jon Williams

Actually, you'd want a 3-axis sensor to deal with a banked track, that way you can get accel/decel from one sensor, and side-to-side g's based on the vector between the x and z axis sensors.

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Jon Williams
Applications Engineer, Parallax

Oper8r Al

Thanks for the adivce. It looks like I will have to do a lot more reading up on the subject. The track is banked but not a high bank.

Al

LoopyByteloose

I guess you could also use those little sensors to gain data on how a car is pulling Gs through a corkscrew jump [noparse][[/noparse]like in the movies]. This is an interesting application.

Speaking of test pilots, my favorite is the guy in the 50s that took a balloon ride to outerspace and jumped. He did a long freefall [noparse][[/noparse]I think almost an hour] before he was clear to open his chute. He had oxygen with him, but he almost didn't make it because his bottom froze to the seat in the balloon gondola. When he got up to jump, he found he was stuck.

Those were adventurous times.· He was the first and last to actually freefall from outerspace to Earth.· Anybody wanna try it?

I really want to get two more Memsics to have a complete set of 3. It seems that you really can't appreciate them without an X, a Y, and a Z axis working together.

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G. Herzog in Taiwan

shandar

There was an article about that jump in a swedish magazine a few days ago, being a skydiver myself I found it to be very interesting [noparse]:)[/noparse] The freefall the guy did lasted 17 minutes before he opened his chute (it took an hour to get to the altitude of 31 km). And i found 30 seconds to be a long time in free fall!

The problem was that the pressurized suit he was wearing did not work properly (the left hand wasn't pressurized) resulting in bubbles of oxygen in his blood, which caused som serious pain. Other than that the jump went perfectly!