Slow motion movie of an rc car

[Dunc]

Originally Posted by Jonny_H

<grin> Who said anything about speed? I just said "it would look like full size"...

The problem is acceleration. Basically a 1/10th car still accelerates (in any direction) at about 1g - but the size is scaled, so if it falls (after jumping) at 10 m/s^2, it looks like 100 m/s^2 or 10g, because it's ten times as many car lengths per second.

Similarly for cornering, assuming the tyres produce about 1.0 coefficient of friction.

Slow it down by the square root of the scale, and the acceleration (jumping/falling and cornering) should make it look like it's full size.

There is some serious confusion going on here between acceleration and speed/velocity. The acceleration of any falling object will be equal to gravity; so how can a buggy 'look' as though it is accelerating 10 times faster than it is? You may be able to convince me its velocity appears increased, based on car lengths.

I think your main flaw is that you are trying to compare/factor dimensioned units (some of which are constant, like gravity). I suspect the only way to achieve a true comparison (assuming it is even possible) would be to use non-dimensional parameters.

Originally Posted by Jonny_H

Buggy: 35 mph => 112 mph 'scale'. WRC cars go how fast?
Touring car: 45 mph(?) => 144 mph 'scale'. Sound about right?
Velodrome / oval racer: ~60mph => 192 mph. NASCAR?
'Insane Run' record: 100+ mph => 320 mph. Maybe that's still a bit fast... but if you put the 1000 hp Penske-Mercedes Indycar (or a Can-Am / Group C prototype) on the bowl at Nardo, how fast could it go?

These are probably just a happy coincidence (remember you've scaled velocity by a factor 'derived' from acceleration).

.... then again, I could be completely wrong. This is just my feeling.