Torsion Powered Vehicle

[--Pete]

Hi,

. . . most common fuels yield around 40-45 MJ/Kg, . . .

Should be pretty easy to calculate a rough number for spring energy density. Pick a spring for which you have the constant, the max deflection and the weight. To a first approximation, the energy is simply 1/2 * constant * deflection^2. If this gives an energy density close (i.e., within an order of magnitude or so) to that 40-45 MJ/Kg (or whatever it is for state of the art batteries) then it is doable. If it is down by two orders of magnitude or more, it's probably pretty hopeless. In between would need more investigation. My guess, based on experience with mechanical systems, is that springs will fall far short of what you need.

Would it be possible to store around 2000-2500 MJ of energy in a lightweight serial sequence of torsion springs to replace the chemical fuel?

I wouldn't worry about the details (i.e., 'serial', 'torsion') until the overall concept pans out. If the energy density isn't there just considering material properties, then the details won't help you.

In order for me to calculate the possibilities I would need to research more about materials properties to understand maximum potential spring constants.

Give the spring engineers the benefit of the doubt. Assume they get close to ideal performance from the materials and designs they use. So just look at a few commercially available items to get a rough idea. And remember, exotic materials usually have exotic prices:)

If one could design such a series of springs, wouldn't this be a better option than batteries which are heavy, present their own chemical/electrical hazards and wear out rather quickly?

Yep. Which adds to my doubt of the viability. In a world where things like high speed rotors have been considered, I find it difficult to believe that no one has considered springs. That no one seems to be pursuing it makes me think that the potential is not there. But happy hunting;)

--Pete