Comments by "H. " (@LocPH.) on "Liquid Piston Rotary Engine - Yet Another Engine That Changes Everything?" video.

@iddqd339 Except for the fact that turbines are VASTLY more expensive and far less efficient. Which is why they're not in use for cars.
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@iddqd339 what are you talking about? Small turbines are the absolutely WORST out there in terms of efficiency. They rarely exceed 20-25% while piston engines operated in a specific region can exceed 40% (CI engines). You are confusing small turbines with large, stationary ones. The larger ones have at least twice the efficiency of the small ones.
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@Appletank8 exactly my point
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@brianb-p6586 yes but it uses synchronizing gears that will be heavily loaded during combustion and expansion due to the force direction = reliability issues.
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@clivestainlesssteelwomble7665 They made a video of one of their smaller engines on a drone. The last thing you would call it is quiet. Also the propeller makes the majority of noice. As for fuel efficiency, it's really not special at all. The haven't even passed 35% TE for the gasoline one last I checked.
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@crezychameau I think the purpose was to use the rotor inside as an overexpansion chamber. But I find that to be really weird - the exhaust will be open to the atmosphere while this is happening and the same force applied on the the wall inside the rotor moving towards rotation will also be applied on the opposite wall - no net force. It's like keeping the exhaust valve open in a regular engine while also making the head move with the piston. How are you extracting work from that?
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@iddqd339 helicopter engines are in the range of a few 100hp to 1000s of hp continuous power. You can find the lists of BSFC numbers and calculate TE easily, and I did just that quite a long while ago. The 55% figure is familiar, it is for one of their engines in the 1000s of hp range, so not a microturbine at all. I don't remember the exact one though. Efficiency sharply drops off from there. For a car you need a few orders of magnitude less than that. No more than 50 hp continuous. There is no turbine in the world in the 100s hp range, let alone under 50 that comes anywhere closer to the 55% figure. They don't even go above 35%. I suggest you Google these tables, Wikipedia is one place to find them. If you somehow find a turbine with around 50% TE around the 50hp mark, please share you source. That would be very interesting to me.
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