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Old 12-10-2009 | 12:41 PM
  #14  
erazz
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Default RE: What size engine - A poll


ORIGINAL: basimpsn


ORIGINAL: erazz

You're saying you want more thrust in smaller package, right? Even if the fuel draw is horrible?
Very generally a 40# engine in a 30# case will draw fuel like a 50# engine.
Well.. A smaller engine size(25#thrust for a S/M F-18E example) will put your throttle setting above haft the whole flight. But with a bigger engine your throttle just above idle & better fuel consumption.

P.s In my opinion

Hehe...
Efficiency doesn't work that way. Consider 2 engines. Both 40# thrust. One has a 120mm dia case and one has 100mm. The larger diameter will have better efficiency. It will use less fuel to push the same thrust.


I can understand why the thrust-to-weight or thrust-to-size numbers produce better sales. But on the efficiency side having a wide and short engine is much better.