Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
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So that performance is at sea level?
Even then, the overhaul life is extremely conservative.People claim that the US air cooled engines in small aircraft have made no improvements in the last 70 years but they may have doubled their overhaul life.
A major market for these engines is currently as a replacement for older pistons. as such, something about hte same power and same weight is an advantage, as you don't need extra strengthening to absorb the power, or introduce C of G issues if the engine is too light.Most of the modern small diesels seem to barely equalling the power to weight ratios of the old gas engines and depend on their lower fuel burn and cheaper fuel for their market appeal. It some cases it may very well be a large advantage and nothing else is needed.
Well interesting thoughts. Motorcycle engines reving high!!! So on a turbo prop or any turbine the revs are very high. So what is happening is the torque output from a turbine is being multiplied many times by the gear reduction unit, gear drives are torque multipliers, and that torque figured against the final rotational rpms is what will determine the HP output, so there is a bit of cheating with the power out put of turbines.
Well interesting thoughts. Motorcycle engines reving high!!! So on a turbo prop or any turbine the revs are very high. So what is happening is the torque output from a turbine is being multiplied many times by the gear reduction unit, gear drives are torque multipliers, and that torque figured against the final rotational rpms is what will determine the HP output, so there is a bit of cheating with the power out put of turbines. So what is the reduction of a turbine like what is mentioned above? And in another thought can HP even be calculated the same with a turbine? I don't know. I just have a sneaky feeling the basic engine does not put out as much power with out a gear reduction unit unlike a recip.
I'm just curious about something . Is the Ranger 5,000 hp radial still the largest ever built ? And for inlines , what was the most powerful ever built ? I'm talking in terms of aircraft power-plants of course .
As a side note I remember flying a 200hp Ryan Navion . She was like trying to get a truck off the ground . But with the extra 60 hp with a 260 hp engine , she was a much better airplane . Amazing what a little extra horsepower can do .
Yawn !!! Scaling up you keep the basic cylinder dimensions the same, you just add more, for your motorcycle engine experiment. That is how multicylinder engines came about, especially aircraft engines. And stop with the gasoline stuff, no one says we have to use SI and gasoline. Dissipate heat ?, lets go adiabatic, oh just got another great idea, and can't give away all the secrets. Anyone have some out of the box solutions of how to force those pistons down the bores using less energy?Nice try at changing the argument. I was trying to explain why you are not going to get the power "density" or power per cubic in/liter out of a big engine (or one that uses big cylinders) that you can out of a small engine, or small cylinders.
61 cubic motorcycle engine moves 176.5cu/ft of air per minute (assuming 100% efficiency, it won't be). An old Lycoming 0-235 moves 190.4 cu/ft of air.(assuming 100% efficiency, it won't be). Motorcycle makes 145hp@10,000rpm Lycoming makes 115hp@2800rpm Obviously the motorcycle engine is more efficient. It should be, it uses a 12:1 compression ratio vs 6.75 (the Lycoming runs on 80 octane gas). The Motorcycle uses 5 valves per cylinder so we can assume that it is closer to 100% in filling it's cylinders than the 2 valve Lycoming. The older 1000FZRs used four 38mm carbs The Lycoming use one single barrel carb, again better breathing, the motorcycle is water cooled using everything they learned upto the late 80s early 90s. The Lycoming dates from 1942 (developed from a 1940 engine).
Motorcycle uses a 56mm stroke, Lycoming uses a 98mm stroke so obviously the the motorcycle can run almost twice as fast for the same piston speed.
As an experiment lets try scaling the motorcycle up to twice it's displacement. (or as an alternative trying to use it as a V-8). If we change the bore and stroke to 95.62 x 70mm we get a 2011cc engine, now will the 70mm stroke still let us rev to 10,000rpm???? Or will we be limited to closer to 8,000rpm?
the 1000cc engine had .571 sq ft of cylinder wall to dissipate heat through. The 2000cc version has .905 sq.ft of wall area. Or about 80% of the wall area per unit of volume. So poorer cooling IF were try to burn the same amount of fuel per CC or Cubic in per minute (lowering the rpm will help).
I am not going to try to figure out the valve sizes needed to flow the amount of air needed for two liter engine compared to the one liter but the valve "area" is the circumference of the valves times the amount of lift with a correction factor. Trying to fit 5 valves into a 95.62 mm cylinder that flow twice the amount of air as the 5 valves in a 75.5 mm cylinder may be a bit of a problem.
View attachment 507731
These are some of the fundamental problems in trying to scale an engine up and keep the same specific power output.
We can certainly do much better than the old engines but trying to use vastly different size engines as indicators as to what is possible is misleading.
View: https://www.youtube.com/watch?v=j2nD7Nqh7B4
Lots of weight and cost and fuel burn, for the turbine.
Duke engine 180 HP and 101.5 lbs. and that is a non production experimental.
awn !!! Scaling up you keep the basic cylinder dimensions the same, you just add more, for your motorcycle engine experiment. That is how multicylinder engines came about, especially aircraft engines.
Hmm, upset that your theory about commercial jets being the result of a government conspiracy might not be true?And stop with the gasoline stuff, no one says we have to use SI and gasoline.
Dissipate heat ?, lets go adiabatic
And then the costs involved to purchase and then the low TBO etc etc.The RR500 has a maximum continuous rating of 380hp and take-off power of 450hp for a weight of 225lb.
https://www.rolls-royce.com/~/media...vil-aerospace/rr500-turboprop-tcm92-11545.pdf
Rolls-Royce RR500 - Wikipedia