Near-infinite specific thrust from drive that ignores physics

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NASA is renowned for doing really difficult stuff. You want to drop a Mini-sized lander on Mars using a sky crane? Well, NASA will do that for you. There is a view of NASA as staid and conservative but, on the whole, I think the agency is full of innovative problem solvers, albeit sometimes crippled by political oversight.

The side-effect of being innovative is that some rather strange and unphysical ideas sometimes escape from NASA. This probably explains the Helical Drive.

Twisting the laws of physics

The basic idea of the Helical Drive, according to the author of that link, is simple. Imagine that you have a mass in a cylinder that is oscillating back and forth. Every time the mass hits the end of the cylinder, it will impart some momentum, accelerating it. Because the mass sequentially collides with each end of the cylinder, the net force is zero, and the only outcome is that the cylinder gets a massive headache.