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From what I have read, I cannot see actual efficiency figures for the engine they are describing (or how they would compare with other rotary engines, such as the wankel engine, of gas turbine engines).
The efficiency of a rocket is connected to the mass that it is throwing out of the back. the force you get from throwing something out is proportional to the mass times the velocity where as the energy you use is the mass x velosity2 so the more mass you throw out the back the slower it needs to go so the less energy you need to have the same effect.
The normal IC engine achieves its reasonable thermal efficiency due to the high temperature of combustion compared to exhaust, Wankel engines have an additional problem apart from seals which is the shape of the combustion chamber which makes it hard to achieve a good expansion ratio (commonly called compression ratio) without pre-ignition.
anothersomeoneWell, all I can say is that you have not gone through the web-site.
A Wankel Engine for your information is just a glorified version of the Rotary vacuum pump, that has been around for more than a hundred years, while the rotary vacuum pump is extremely efficient, since it runs in an oil bath for effective sealing, the Wankel engine, dealing with much higher pressures, tries to do the smae thing in reverse in air! It is a huge scam, on which a lot of money has been spent.
Tell that to all the people who seem to love the performance of the Mazda RX7.
I find it difficult to make any serious criticism of the so called pulse jet engine, compressed air provided by a separate compresser! (I guess a turbo charger could be used), poppet valves operating at 2000°C the exhaust valves in an IC engine have a hard enough time coping with the exhaust gases after they have cooled by expansion.How are inlet and exhaust valves to be operated (if they could be built) on these moving conbustion chambers?, I think the request for funds to develop it says it all!
Belt driven compressers on IC engines have been obsolete for thirty years superseded by ceramic turbos.
Rocket engines may be very powerful and the only way to achieve thrust in space but they are not thermodynamically efficient and that is the most important figure when it comes to fuel consumption in terrestrial vehicles.To properly calculate the true thermodynamic efficiency of an internal combustion engine one needs to calculate the temperature and pressure of the high pressure gases and temperature and pressure of the exaust gases and the efficiency with which the expansion of these gases have been converted into useful work.Think of a normal car the velocity of the exhaust gases do provide in theory a useful thrust out of the back of the car but this is miniscule in proprtion to the much more effective thrust via the expanding gases pushing the cylinder down inside the engine.
Think also of modern aircraft engines. they are all high bypass ratio turbofans in which most of the energy in the gas turbine is used to suck air from the front of the aircraft and push it out the back and the jet thrust is only about ten pecent of the total thrust of the engine.
The jet engine example was just to show that the high bypss turbojet engine can create much more thrust by using the heat enrgy to move more air than just using the heat energy to create thrust in its own right like a rocket.
while the rotary vacuum pump is extremely efficient, since it runs in an oil bath for effective sealing,
Otto got it right first time, he did have the experience of 50 years of steam locomotives to draw on.Wankel engines have been around for about 100 years but have only caught on for niche applications
I wonder if and when nanotechnology will ever give us an internal combustion engine.You could imaging all sorts of advantages (and problems, of course) with a distributed engine with, in effect, thousands of tiny reciprocating parts, all working independently and thinking for themselves (well you know what I mean). No vibration, easy cooling and easy replacement of parts. Sounds a bit like muscles.
Otto got it right first time, he did have the experience of 50 years of steam locomotives to draw on.Wankel engines have been around for about 100 years but have only caught on for niche applications, about every 10 years an eccentric rotary design is published but none ever get built.
You cannot compare a gun to an engine of this type.
But a recoiless rifle needs several times more propellant, and therefore several times more energy, than a conventional gun of the same design. This is why recoiless weapons are restricted mostly to infantry weapons that are not fired very often so the lighter weight of barrel is more of an advantage than the much heavier ammunition that you need to fire in it. If you are going to fire a lot of rounds it rapidly becomes easier to transport a heavier gun and lighter ammunition.
....and have you an answer about the efficiency yet..?
....May I suggest for your reading....
Depending on specific thrust (i.e. net thrust/intake airflow), ducted fans operate best from about 400 to 2000 km/h (250 to 1300 mph), which is why turbofans are the most common type of engine for aviation use today in airliners, as well as subsonic/supersonic military fighter and trainer aircraft. It should be noted, however, that turbofans use extensive ducting to force incoming air to subsonic velocities (thus reducing shockwaves throughout the engine).