Quote:
Originally Posted by RedDevil
The Lightyear is an even more extreme design than the XL1, with hub motors and no engine. So yes, I do believe they can make a car that only uses 75% of the energy an XL1 needs.
Let's do the scaling on that thing though. Make it 3 times as big, it then has 9 times the drag - and it would be longer than the Lightyear 1.
Move it 4 times as fast for 100 km/h; the air resistance would increase 16 fold but friction, drive train losses and rolling resistance would not, so averaging that at 8 times more, multiply by the size factor and we have 72 times more energy to move the scaled up racer at 100 km/h.
That's only a fraction more than the 65 from my assumption, but we'd get there if we scale up by 2.8 times or drive at 94 km/h. That's faster than I usually drive anyway.
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-Scaling up the body will increase its mass, which will also increase its rolling resistance
-energy required correlates to the
cube of velocity for aerodynamic drag force and linearly with velocity for rolling force, since energy is the integral of force. 71 times more drag force (since we're assuming constant rolling resistance between the TUfast and its scaled-up version, even though this would not be true in reality) means an order of magnitude more energy required to overcome that force.
-Then, add in that the Lightyear 1 has a drag coefficient twice that of the TUfast, and more mass (read: rolling resistance) for its size, especially if it's carrying 4 people.