Recent content by cyberdiver

I've been trying to make a Sondhauss tube lately. My setup is a 17-cm long Pyrex test tube with a small piece of steel wool as the stack. I've been holding the closed end over a gas stove on full heat with a pipe wrench, but absolutely no sound is produced. What I am doing seems to be no...

According to FuelCell Energy, compression (I'm assuming wallplug) efficiency is 95%, so charge-discharge efficiency should be ~90%? Lithium ion batteries get 80-90% by comparison. I'm not exactly sure how to go about calculating the energy density of such a system just yet.

Electrochemical hydrogen compressors (https://en.wikipedia.org/wiki/Electrochemical_hydrogen_compressor) basically convert an electrical potential difference into a pressure difference. Would it be possible to run one of these in reverse, i.e. using a pressure difference to create a voltage? If...

The equations I was taught in class are completely different. I will need to investigate this more thoroughly.

I just looked through the thread. Why does the equation only take into account the mass of the primary body if it is affected by both the primary and the satellite masses?

Why is the period of a satellite's orbit independent of its mass? I understand that its mass cancels out mathematically, but I don't understand it intuitively. The way I'm seeing this, if a satellite has a greater mass, it would have a greater pull on the body it is orbiting, and hence would...

I understand now. Thank you very much!

So the sail can only reach a state of equilibrium if its areal density is just right, otherwise it would drift?

But if the solar sail is heavy enough, it would start falling toward the star, wouldn't it?

Hold on. Is it because radiation pressure and gravity both follow the inverse square law, so the equilibrium is at all distances?

This is not actually a homework assignment, but something I decided to try in my own time. I wanted to find the radius from a star at which a solar sail would be held at equilibrium (radiation pressure = gravity), given mass per unit area and stellar luminosity at a reference radius. So I...

Would there be a point where rapidly spinning it becomes more mass-effective than simply making the supports thicker and thicker?. As for the structural strength of the ring, I'm not entirely sure what the ring would be made of or what structures would be required on it (coils, etc.), because my...

The hull won't spin. It will be support rings on the inside that spin, and magnets would transfer the centrifugal force to the hull to counteract exterior pressure. I'm basically trying to have a structure based on tension instead of compression. As for stealth, I conceived this idea thinking...

I'm not sure how else to refer to centrifugal 'force'. Well, I suppose that's why I'm up here in the first place, right? Interesting statement about magnetohydrodynamic effects. I've never considered that before.

If the walls of a submarine were supported by fast-spinning rings, using centrifugal force to prevent collapse or buckling, would this be viable engineering? I am assuming that the rings would be magnetically suspended to eliminate friction. This also seems like a self-stabilizing system with...