Engine Thrust Line

This is another area of "Black Art" when it comes to trimming aircraft. However it is actually simple to get the correct results even if you did not build it in to the aircraft.

Most of us nowadays use bolt on engine mounts, these give you a great deal of flexibility in making small adjustment to engine thrust. So why do you need it, well you don't, but the aircraft will fly better if you do.

So what are the symptoms; 

Too much engine down thrust.
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The model jumps up from straight and level flight when the engine is suddenly cut.

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The elevator requires excessive up-trim to maintain level flight.

Not enough engine down thrust or slight engine up thrust.
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The model goes into a dive from level flight when the engine is slightly cut.

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The engine requires down trim for level flight.

Not enough engine right thrust.
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During a steep climb, the model tends to pull up to the left as it loses speed.

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Model tends to pull to the left near the top of a loop.

Too much engine right thrust.

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During a steep climb, the model tends to pull up to the right as it loses speed.

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Model tends to pull to the right near the top of a loop.

Use the above to make the adjustments as required to your aircraft to get the right results. You can add small amounts of packing behind the engine mount to make the required changes. 

Just keep adjusting until it does not react. 

10/05/2004 09:50:29 PM

 

Suggestions? Corrections? Remarks? e-mail - Craig Tarlington.
As I get quite a number of messages, it might take some time until you receive an answer and in some cases I get lost in the flood and you may even receive no answer at all. I apologize for this, and if you have not lost patience, you might want to send me a copy of your e-mail after a month or so.
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