Words: Michael York
Flying-wing and delta aircraft can be very sensitive to pitch. It’s especially important to have the correct thrust line on a high-speed pusher prop to prevent unnecessary corrections in pitch during different power settings. Not only is it annoying if the plane reacts adversely every time you move the throttle stick up or down, but it can also keep you from hitting top speed due to the drag caused by the extra amount of trim required to compensate for the thrust vector. Here’s a quick and easy way to see if the angle is set correctly:
- Have the aircraft trimmed for hands-off flight at full throttle.
- Cut the throttle and see what happens.
- If the plane climbs, it means too much downthrust and there was uptrim to compensate.
- If the plane descends, it means too much upthrust and there was downtrim to compensate.
- If the plane gently transitions into a glide, you’re spot on. With the design of the FunJet Ultra motor mount, adjustment is a simple matter of loosening the two mounting screws slightly and turning the lower screw in or out for either an increase or decrease in angle. Once set, retighten the mounting screws and go up to check your settings.
It may take a few flights to get it just right, but once you do, you can go from full throttle to idle with almost no change in pitch.
some one in my flying club gave me a flying wing approx 40″ wite rear motor mount no cut out for prop, when I looked at the m mount it has at least 10 degrees up trust to me prop facing upward away from bottom. , other wings I own have at teh most 4% up thrust should I trust this motor mount with that much up thrust or shim it downward a bit?
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