3 ms·

I"m not following why you think the wheel generator will produce more power than is required to spin the wheel in the first place. Friction is a pretty big iss

I"m not following why you think the wheel generator will produce more power than is required to spin the wheel in the first place. Friction is a pretty big issue in your scenario. It seems orthogonal to the actual results.

Gravityloss 12y ago
The whole thing was a thought experiment to show how extraordinary the supposed result is. Power of the wheel = thrust * rim velocity. That's just basic physics you should learn in high school. P_1 = F * v This means if your force, that is, thrust, is constant, you generate more power the faster you go. That's also why cars accelerate faster from 20 to 30 km/h than from 120 to 130 km/h - they have constant power which means they have more force at lower speeds and thus higher acceleration at lower speeds. The claimed thruster produces a constant thrust for a certain power, let's use a factor k for that: P_2 = k * F Now if we want perpetual motion, we can set P_1 = P_2, and solve F * v = k * F v = k If we let the speed be faster, we can actually generate power from the wheel in excess of what the thruster uses. We can also have some friction, let's say the wheel generator is 50% efficient. We then need to run the wheel twice as fast to get the same effect. There actually exists a trivial "reactionless" thruster if we use a flashlight and the light pressure. But it turns out the velocity is the speed of light then.
- gus_massa 12y ago
  I totally misinterpret your first comment. It looks like "This is even more amazing! We have a perpetual mobile machine!!" but it's really is "This also break the energy conservation law! So we have a serious problem." In special relativity, momentum and energy are much related, so if you break the conservation of one of them, you break also the conservation of the other. (It's not very clear if the authors say that this device break the momentum conservation, all the information is very confusing.) But the example is nice. Just get two of these devices and put them in the opposite sides of a carrousel or a spinning space station so you don't have to worry about friction.
  - Gravityloss 12y ago
    Thanks for the comment, now I realize the post was not very well written in that regard. It is hard to express these contradicting ideas in a small space: 1. If this works, forget spacecraft. Free energy for everyone! 2. I think it's a measurement error. There are other reasons to think so as well, a person said that the "out there" advanced space propulsion research community traditionally gives a lot more leeway than some other research disciplines where this might have come up.
- ghshephard 12y ago
  I've read this half a dozen times over the last days, trying to understand exactly what you are getting at. I think what you are saying is that you could use the power generated by the wheel to power the thruster, which would in turn spin the wheel. The part I don't understand is why you think this "Wheel Generator" would impart any significant thrust to the wheel. That is, let's say (for the sake of argument), that you needed 1 watt to generate 1 newton of thrust. And, that one newton of thrust could get a wheel spinning at 10 m/s. Now, we hook that wheel up to a generator, and it's capable of generating 1/10th of a watt of energy, but in doing so, obviously comes to a halt without external energy being imparted (because obviously the generator uses up its momentum to generate energy) - but, the energy being created by the spinning wheel (1/10th of a watt), only can get the wheel spinning at 1 m/s. The entire system comes to a halt quickly. I'm not suggesting that the entire idea of a reactionless thruster doesn't have huge holes in it - but it certainly doesn't seem to (at least) suggest that you have a perpetual motion machine.

Gravityloss 12y ago

The whole thing was a thought experiment to show how extraordinary the supposed result is. Power of the wheel = thrust * rim velocity. That's just basic physics you should learn in high school. P_1 = F * v This means if your force, that is, thrust, is constant, you generate more power the faster you go. That's also why cars accelerate faster from 20 to 30 km/h than from 120 to 130 km/h - they have constant power which means they have more force at lower speeds and thus higher acceleration at lower speeds. The claimed thruster produces a constant thrust for a certain power, let's use a factor k for that: P_2 = k * F Now if we want perpetual motion, we can set P_1 = P_2, and solve F * v = k * F v = k If we let the speed be faster, we can actually generate power from the wheel in excess of what the thruster uses. We can also have some friction, let's say the wheel generator is 50% efficient. We then need to run the wheel twice as fast to get the same effect. There actually exists a trivial "reactionless" thruster if we use a flashlight and the light pressure. But it turns out the velocity is the speed of light then.

gus_massa 12y ago
I totally misinterpret your first comment. It looks like "This is even more amazing! We have a perpetual mobile machine!!" but it's really is "This also break the energy conservation law! So we have a serious problem." In special relativity, momentum and energy are much related, so if you break the conservation of one of them, you break also the conservation of the other. (It's not very clear if the authors say that this device break the momentum conservation, all the information is very confusing.) But the example is nice. Just get two of these devices and put them in the opposite sides of a carrousel or a spinning space station so you don't have to worry about friction.
- Gravityloss 12y ago
  Thanks for the comment, now I realize the post was not very well written in that regard. It is hard to express these contradicting ideas in a small space: 1. If this works, forget spacecraft. Free energy for everyone! 2. I think it's a measurement error. There are other reasons to think so as well, a person said that the "out there" advanced space propulsion research community traditionally gives a lot more leeway than some other research disciplines where this might have come up.
ghshephard 12y ago
I've read this half a dozen times over the last days, trying to understand exactly what you are getting at. I think what you are saying is that you could use the power generated by the wheel to power the thruster, which would in turn spin the wheel. The part I don't understand is why you think this "Wheel Generator" would impart any significant thrust to the wheel. That is, let's say (for the sake of argument), that you needed 1 watt to generate 1 newton of thrust. And, that one newton of thrust could get a wheel spinning at 10 m/s. Now, we hook that wheel up to a generator, and it's capable of generating 1/10th of a watt of energy, but in doing so, obviously comes to a halt without external energy being imparted (because obviously the generator uses up its momentum to generate energy) - but, the energy being created by the spinning wheel (1/10th of a watt), only can get the wheel spinning at 1 m/s. The entire system comes to a halt quickly. I'm not suggesting that the entire idea of a reactionless thruster doesn't have huge holes in it - but it certainly doesn't seem to (at least) suggest that you have a perpetual motion machine.