Half a croissant, on a plate, with a sign in front of it saying '50c'
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thin gap rotary engine

fuel burning in "circle" causes expansion and pressure
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See image in link.

Rotor has small triangles with one leg diagonal and one vertical like in a ratchet, which catch the gasoline/air mixture. It is ignited only in one place, the combustion spreading in one direction only.

As it starts burning in a "cycle" the exhaust valve is opened, and thrust is created in that opposite direction of the exhaust trail pushing the rotor.

When the fuel is burnt, new fuel is pumped in and ignited.

pashute, Jul 22 2013

illustration https://docs.google...xY/edit?usp=sharing
[pashute, Jul 22 2013]

Similar but actually works... http://www.google.c...1.21.hp.Z3x7RbCv0ms
Wave disc engine, uses shockwaves from combustion. [neutrinos_shadow, Jul 22 2013]


       It appears to me that your diagrams don't show // with one leg diagonal and one vertical like in a ratchet //   

       I'm not sure simply having a fixed rachet shape will allow the combustion to travel only one way. The triangles would need to be able to compress when there was pressure on the diagonal leg.   

       Alternately you might be able to use a Tesla valve, though those do have some leakage.   

       And besides that, I don't see how this would actually work.
scad mientist, Jul 22 2013

       ooh! neutrinos, thanks for the link! scad, say with a tesla valve why not? And your correct that the ratchet shape is not shown. I'll fix that.   

       The ratchet shape should cause most of the energy to be directed (reflected) in one direction rather than the other. Why wouldn't it work? Its similar to a turbine rotating in an air flow.
pashute, Jul 23 2013

       // [pashute] The ratchet shape should cause most of the energy to be directed (reflected) in one direction rather than the other. Why wouldn't it work? // Let’s assume the gasoline/air mixture burns ideally, producing uniform pressure, that leakage between “notches” is zero, and that the wheel is so much bigger than each notch that the calculationg for curvature can be ignored. For simplicity, let’s assume the angle of the diagonal walls are 45 degrees. Consider the inside of one notch consisting of a vertical and a diagonal wall. The force on each wall is pressure time area. The area of the diagonal wall is sqrt(2) time that of the vertical wall, so the force on it is also sqrt(2) time that of the vertical wall. Forces on a wheel have a radial (outward) and angular (rotating) component. The radial component of the force on the vertical wall is zero, the angular one 1 time the force on it. The radial and diagonal components on the diagonal wall are both 1/sqrt(2) times the force on it. Since the force on the diagonal wall is sqrt(2) that of the force on the vertical wall, the net radial force on the wheel from the two walls is zero. So the wheel won’t turn due to it.   

       If the exhaust is directed some way other than straight out, the wheel is simply a fuel-powered aeolipile similar to the steam powered one Hero of Alexandria was said to have made ca 50 BC. Burn enough fuel fast enough, It’ll turn, but the notches inside don’t help it.
CraigD, Jul 24 2013

       For the sake of explanation, I'll add an almost completely closed wall inside the wheel, just before the beginning of the burning cycle.   

       The exhaust leaves the wheel at this point.   

       After filling with fuel and oxygen, that point is ignited. You are correct that the total force in all directions will eventually cancel itself out, BUT, at the first stage, the shock wave hits the vertical wall pushing the exhaust against that wall.   

       The exhaust then exits the wheel from the side, NOT working as an Aeolipile. The returning force of the exhaust is now much less in the the diagonal direction, due to the loss of energy during the exhaust escape. I hope you agree till now.   

       If I'm correct, then, you can remove the wall, and just have the single exhaust valve or perhaps multiple exhaust valves, with the combustion happening each time inside the next "ratchet" chamber.   

       - The efficiency could be improved in several ways, but first lets agree that it would work.   


       By the way, today I tried a first version of the rainbow wind generator. It turned beautifully when disconnected, but wasn't able to make a 6 volt bicycle dynamo budge.
pashute, Jul 24 2013


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