Yeah, but you're forgetting about the 5 hp Honda generator and the leaf
blowers! He could easily be up into Land Rover acceleration territory once
that thrust is added! He DID say he'd had it up to 85 mph but had to slow
down due to the speed rating on his tires!
Perhaps an early April Fools joke?
Chris Eck
59 TR3A
59 Bugeye
In a message dated 3/7/01 4:52:33 AM Eastern Standard Time,
mporter@zianet.com writes:
> Randall Young wrote:
> >
> > All that work, and the thing only develops 190 lbf of thrust ? It was a
> > whole lot faster before he modified it !
> >
> > Unless my envelope slipped a digit somewhere, his 0-60 mph time should
> > be something like 40 seconds ... the thing only makes around 1/2 as much
> > power as my TR3A, and doesn't have any torque multiplication !
>
> Pretty close. Sort of fun to try to remind myself of some basic
> acceleration stuff and some international units I've long forgotten from
> disuse. But, it goes something like this:
>
> Ignore rolling resistance and aerodynamic drag. Assume 2100 lb. curb
> weight + driver = 2250 lb, or 1020 kg.
>
> 1 Newton(f) = 0.225 lbf
>
> One Newton is the force required to accelerate 1 kg of mass at one
> meter/second/second, or:
>
> 1 Newton(f) = 1 kg(m) x 1 m/s/s (F=mA)
>
> 190 lbf = 844 Newtons
>
> Using the standard Newtonian force equation:
>
> F=mA
>
> 844 Newtons = 1020 kg x 0.827 m/s/s
>
> To sort of bring this into perspective, let's take 1/4-mile performance
> as an example:
>
> To determine final velocity starting from rest for the quarter mile,
> divide 1320 ft by 3.275 to get meters = 403. Not yet knowing the elapsed
> time, the acceleration equation from rest for final velocity over
> distance would be:
>
> Vsubf = square root of (2a x delta d), where Vsubf is final velocity in
> m/s, a is rate of acceleration in m/s/s and d is distance, or
>
> 403 x 2 x 0.827 = 667
> Sq rt of 667 = 25.81 m/s, or 84.6 ft/s. Taking the shortcut to calculate
> mph, 88 ft/s = 60 mph, so this guy's trap speed in the quarter is 57.65
> mph, less a bit for total drag.
>
> Working backwards from the final velocity to distance result, the
> equation for elapsed time is:
>
> Vsubf = a x t, or t = Vsubf / a
>
> therefore, this guy's elapsed time in the 1/4 mile is:
>
> t = 25.81 / 0.827 = 31.21 seconds (neck and neck with a stock Renault
> Dauphine, I would guess...).
>
> Let's hope this guy's specific thrust estimates are way low--otherwise,
> he's probably invented the world's slowest jet-powered car.... <smile>
>
> Cheers.
>
> --
> Michael D. Porter
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