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Nicely done.Armstrong-Siddeley Cheetah
Measured how?????
Least material used per hp?
Least man hours per hp?
Least investment in tooling per engine?
And I have no idea where to look for the statics except the price per engine divided by power, and that will always favor the big engines.
So if you use a criteria that favours the 003 and 004, by a miracle the 003 and 004 beats all the others.Find out the manhours per each engine. Then find out lbs of different metals were used in each engine. Keep in mind that some metals were in very short supply for certain countries, so you might want to have a correction factor for that. Once you've done all this research, come up with some sort of performance metric for engines and weight the manpower and material cost against that.
I strongly suspect that the 003 and 004 would beat all others.
Those engines required significantly fewer manhours to build. Off the top of my head, the 004 was under 600 hours when introduced, under 400 hours near the end of the war and Junkers claimed they could get it under 300. By comparison the Jumo 213 was >2000 manhours. Its pretty hard to beat that sort of a discrepancy.So if you use a criteria that favours the 003 and 004, by a miracle the 003 and 004 beats all the others.
Not really. The issues with the 004 and 003 engine life were related to alloys. When the Soviets made copies with better alloys the life went way up.Perhaps the number of hours to build correlates with the number of hours before failure.
Early German jet engines had a life of 25 hrs, so to compare to an engine that goes 300 hrs before it needs a major service you need 12 engines or 3,600 man hours.Those engines required significantly fewer manhours to build. Off the top of my head, the 004 was under 600 hours when introduced, under 400 hours near the end of the war and Junkers claimed they could get it under 300. By comparison the Jumo 213 was >2000 manhours. Its pretty hard to beat that sort of a discrepancy.
Added to this is that most of the work done for those jets was sheet metal operations that low skilled labor could perform. Piston engines required a lot of skilled labor.
As could be seen when the small gas turbines replaced the 300hp and up piston engines in helicopters, AG planes and light transports. Purchase price went up but longer times between overhauls made them more economical in the long run. The 300-400hp range was the cross over.All this often makes the construction of asimple gas turbine more complicated than a piston engine.
Again alloys matter a lot. German piston engines of the time had lifespans significantly shorter than 300hrs, I think well under 100hrs was probably typical in the late war period. That is more like 4 engines for equivalent life.Early German jet engines had a life of 25 hrs, so to compare to an engine that goes 300 hrs before it needs a major service you need 12 engines or 3,600 man hours.
Mechanically, gas turbines can be considerably less complex than internal combustion piston engines. Simple turbines might have one main moving part, the compressor/shaft/turbine rotor assembly, with other moving parts in the fuel system. This, in turn, can translate into price. For instance, costing 10,000ℛℳformaterials, the Jumo 004 proved cheaper than theJunkers 213 piston engine, which was 35,000ℛℳ,[26]and needed only 375 hours of lower-skill labor to complete (including manufacture, assembly, and shipping), compared to 1,400 for theBMW 801.[27]This, however, also translated into poor efficiency and reliability. More advanced gas turbines (such as those found in modern jet engines or combined cycle powerplants) may have 2 or 3 shafts (spools), hundreds of compressor and turbine blades, movable stator blades, and extensive external tubing for fuel, oil and air systems; they use temperature resistant alloys, and are made with tight specifications requiring precision manufacture. All this often makes the construction of asimple gas turbine more complicated than a piston engine.Gas_turbine.pdf
View Gas_turbine.pdf from SCIENCE 227 at University of Notre Dame. Gas turbineA gas turbine, also called a combustion turbine,is a type of continuous flow internal combustionengine. The main parts comwww.cliffsnotes.com