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ELEVATOR CONTROL STOP POSITION
1) Perform a one 'g', wings level, straight ahead stall with sufficient
power to maintain level flight. Slowly pull the control stick back to full aft stick. This
should result in a nose high attitude with a "pitch bucking" that can vary from
hardly noticeable to quite vigorous, perhaps "one buck" per second, with a deck
angle change of several degrees per "buck.'. This is normal and will vary depending
on the cg. If, however, you notice a strong stall break (canard stalls) and the nose comes
down through the horizon until you are in a stable shallow dive, even though you are still
holding full aft stick, the speed may build up to over 100 KIAS before the EZ begins to
climb again. This very long period pitch "bucking" can be as long as 30 seconds
per cycle and is indicative of too much elevator trailing edge down travel. You can verify
this by releasing back pressure on the stick during the nose down phase of the cycle and
gently raising the elevator trailing edge perhaps 1/8" at a time.
This should allow the canard to develop more lift and pitch the nose up. Try to determine by experimenting with elevator position, where CLmax is, then set your elevator stop at that position.
2) Another classic symptom-may be noticed during a take-off. At full
aft stick, it may take a longer take-off roll to lift off than it does at, say, slightly
forward with the stick. If you have ever noticed this, it should be corrected. Under
certain circumstances, this could become a serious problem. A Long-EZ builder/flyer in
Alaska, attempting to take off on a rather short runway, discovered that he was rapidly
approaching the end of the runway and, even though he was holding the stick all the way
back, was not rotating. Realizing he was not going to make it, he backed off from the full
aft stick stop and, to his surprise, the airplane literally jumped into the air! Again,
his trailing edge down elevator stop was set for too much travel. This same scenario has
also been reported to us by a San Diego VariEze pilot.
What causes this? If the elevator stop is set so that at full aft stick your canard can develop its maximum possible lift, this will result in the lowest possible rotation speed for take-off and a good, clean canard stall (limiting the main wing angle of attack) or classic "per the book" stall at full aft stick in flight. If, however, you have set your elevator stop for too much travel (perhaps you thought you could lower your rotation speed?!!) what happens is that you are now on the "back side" of the lift curve, lift is less than maximum and the elevator is creating lots of drag. The result may be running off the end of the runway. Keep in mind that this condition could be aggravated even further if it were raining.