Re: Obliterating the Rocket Equation with a Torusail


raphfrk@xxxxxxxxxxxx wrote:

> The difference between a rocket and the bomb track is probably not
> massive due to the fact that orbital velocity is only around double the
> exhaust velocity, so the exponential doesn't really start to kick in.

I concur. Planning my own mission, with V/Ve of 3 or so, I found that
the bombtrack equation offered twice the advantage of the rocket
equation. But carrying two tonnes of fuel onboard is much preferable to
capturing one tonne of fuel, accelerating it to ship speed, and then
using the energy of capture to post-accelerate the products out the
back again, which would be necessary for perfect "bomb-track"
operation.

Obviously there is a ratio of V/Ve where the bombtrack becomes
acceptable. The thread is about a ratio of 10, so of course the numbers
favour bombtrack in that situation. But they dont consider bombtracks
for interplanetary missions. Instead they consider rockets with higher
Ve, ion drives etc.

So the question becomes which is easier; to develop the bombot
technology or to develop more efficient rockets with better Ve.

The limiting factor with better Ve is the shear power of the rocket
required, since the ratio of momentum to power is inversely
proportional to Ve. I am pinning my hopes on nuclear-light-bulb with
hyper-efficient photovoltaic conversion and ion drives.

So I conclude that the bombtrack will only be better if there is a vast
technological advance in guidance systems but negligible progress in
nuclear rocket engines. Of course efficient engines with Ve of 0.08C
are currently fantasy. But there appears to be a great deal of effort
in the appropriate areas, ion drives, photovoltaic conversion, plasma,
fusion etc.

.

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