I recently discovered Mythbusters... fun stuff!
Anyway, I'm currently partway through Pilot #1 - the episode with the JATO Impala. They reenacted the fabled event with an actual Impala and three HPR motors fired in sequence. The results were impressive, but fell far short of the legend.
Just for giggles, let's look at the best case. We'll attach the rocket to the car and fire it off in outer space, thus eliminating air resistance, road friction, engine braking, and all that stuff.
If we apply 1500 pounds of thrust to a 3000 pound car for 15 seconds, that's, er, half a gee (call it 5 m/s2) times 15 seconds, or about 75 m/s. The handy-dandy units program says that's around 168 MPH. Faster than your average Impala, but hardly into mythical territory.
Curiously, the Mythbusters result is consistent with this BOTE calculation. Funny how that works out.
Oh, one thing grated: they kept referring to "pounds thrust" and "horsepower" as if there were a constant conversion factor. In fact, they're not convertible; thrust has units of force, and horsepower has units of force times distance per unit time, so instantaneous vehicle speed has to be factored into any conversion. Or, you can take the energy expended by the rocket to be your "horsepower" number, whether it's accomplishing anything or not. Remember, exerting 1500 pounds of force against a stationary object can be accomplished with zero horsepower in the steady state!
Later: Pilot #2 examines the tale of the autodefenestrating lawyer, and addresses the question: how could a window stand up to repeated lawyer impacts, and then one day succumb to the same impact? A structural engineer raised the issue of HVAC-related pressure differences, at which point two words sprang into my mind: Hancock Building. The issue of outside wind speed and building aerodynamics didn't even get mentioned on the show!
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