Downthrust
11-02-2002, 07:32 PM
#1
Downthrust
What effect does downthrust have on an airplane? My dynaflight mustang is set up with some.
i amost didnt catch it on the plans. its about 1/8 off an inch diff from the front of the spinner to
the back of the engine.
thanks for any help
Dan
i amost didnt catch it on the plans. its about 1/8 off an inch diff from the front of the spinner to
the back of the engine.
thanks for any help
Dan
11-03-2002, 12:15 PM
#2
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Downthrust
Downthrust is supposed to minimize the trim change needed for different throttle settings. As you add power, the plane speeds up and the decalage (incidence difference between wing and horizontal tailplanes) tends to drive the nose up. The downthrust counters that effect.
On high wing planes, the effect of throttle pullng the nose up is aggrivated by the center of drag being above the thrust line.
It almost never exactly correct at all speeds.... but you'd need to range the full trim setting range n a non-computer TX in flght without the downthrust. With the correet amounyt of downthrust just 2 to 4 clicks of trim differential between full throttle and slowest level flight speed is normal.
On high wing planes, the effect of throttle pullng the nose up is aggrivated by the center of drag being above the thrust line.
It almost never exactly correct at all speeds.... but you'd need to range the full trim setting range n a non-computer TX in flght without the downthrust. With the correet amounyt of downthrust just 2 to 4 clicks of trim differential between full throttle and slowest level flight speed is normal.
