>From: "George Schiro" <gschiro@lni.net>
>To: "Phil Martin" <pmartin_vacation@hotmail.com>, <htc@MNSi.Net>,
><Bricklin@autox.team.net>
>Subject: Re: How not to go fast
>Date: Thu, 28 Dec 2000 12:12:46 -0500
>
>I suspect this JATO story is an urban legend as well. However, regarding
>the melted brakes, it isn't the weight of the car that matters but the
>momentum.
I was trying to make two kind of related points, but in retrospect I didn't
make them very clearly:
1) If a car can stop at almost 1g, and it weighs ~3500lbs, then
the brakes & tires are capable of generating a retarding force
of about 3500lbs. This almost certainly exceeds the the thrust
of the JATO, which means that the brakes should be able to slow
the car.
2) Even if the car got up to 300mph (which I think it wouldn't,
since with a thrust approximately equal to its mass, the best it
could hope for is terminal velocity in freefall, which I think
would be less than 300mph), you won't melt the brake rotors
and/or drums. The pads (or shoes) will partially vaporize,
and the brake fluid will also boil pretty quickly, which will
severely limit the effectiveness of the brakes. No matter how
much kinetic energy the car had, you'd never be able to put
enough of that energy into the rotors/drums to melt 'em.
I've gotta say, this is my favorite urban legend, and I can't tell you how
many times I've thought about trying it myself, just to demonstrate my
premise that overall this would be a pretty innocuous exercise.
Maybe once my Brick's roadworthy. I do have to agree with HTC that the
story's better with a Brick - looks more like a spaceship! ;)
--
Phil Martin
"It ain't no sin to be glad you're alive"
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