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WmInce

Effects of engine droop on aircraft climb/cruise performance

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Designed engine droop angle for the CTSW is 5° nose low.

How does that droop angle affect climb and cruise performance?

What if the engine droop is more or less than 5°?

Why is there any droop in the first place?

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It is designed to aim into the airstream in level flight (you're actually slightly pitch up in level flight) to try and neutralize p-factor. Many aircraft designs also aim these to the right (in a clockwise rotating engine).

Where did you get this?

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8 minutes ago, Anticept said:

Where did you get this?

Diagram is from Flight Design AIRCRAFT OPERATING INSTRUCTIONS CTSW, page 2-2.

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The 5 degree "droop" isn't necessarily with respect to the relative wind when the airplane flying in the cruise configuration.  it is possible that while in flight the bottom edge of the stabilator is 5 degrees below the center of the spinner resulting in no engine droop (again, with respect to the relative wind) when actually flying.  

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The purpose of the down thrust is to keep the airplane from having large pitch changes with changes in power. It is a balancing act between the lift of the wing, the down force of the tail and the direction the thrust is pulling on the front of the airplane.

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16 hours ago, FredG said:

The 5 degree "droop" isn't necessarily with respect to the relative wind when the airplane flying in the cruise configuration.  it is possible that while in flight the bottom edge of the stabilator is 5 degrees below the center of the spinner resulting in no engine droop (again, with respect to the relative wind) when actually flying.  

They often are though.

Many designs, aside from engine offsets, use wings with chords that are not aligned to the fuselage as to increase angle of attack, therefore lift, in level flight, so the fuselage can be levelish in flight. Without it, they would be slightly nose up to generate the required lift.

What tom said is the first time I've heard of that purpose for droop, but doesn't surprise me.

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