Dealing with Pop-Offs
by Ed Anderson
aeajr on the forums
Pop-offs occur when your plane over rotates on launch and comes off the hi-start or winch tow line too early. This often happens shortly after launch when the plane has not achieved a lot of height and perhaps not a lot of speed. So a plane that has popped off can be very hard to handle.
Since the plane is going through a rotation and essentially starting a loop to the rear, I have found the best way to deal with a plane that has popped off is to help it finish this backward loop. I will add up-elevator, usually a lot, to help the nose over the top. Sometimes I will continue in a nice smooth loop, be it 6 feet over my head, or it will flip over at the top, in which case I get off the elevator and try to get the plane back to level flight, sometimes only a few feet off the ground. Then the priority is to set up for a safe, clean landing .... somewhere away from people.
Causes of Pop-Offs
If you are popping off, there are some things to check and to try, most of
which you have probably already done, but let me state the obvious:
1) Make sure the hook is not bent. I saw a very experience flyer pop off a
bunch of times during a contest. He retrimmed the plane, rebalanced, change
the receiver, ........, the hook was bent. Discovered it half way through the
contest.
2) Move your hook to the more forward position, approx 3/8" to 1/4 inch in
front of the CG for Sport and Novice competition flyers. Serious ompetition
positions may be even closer to the CG, on the CG or even behind the CG.
My Spirit 2M RES has three hook positions. One in front, one
on the CG and one behind the CG. On this plane, My hook is in the most forward
position - I never pop off and I get great launches.
3) If you have up elevator in your launch mix, take it out. If you want a quick fix for
pop-offs, dial in a few clicks of down elevator to keep the nose from overrotating, or
rotating too fast. Just take it out when you release, or perhaps after you
have passed the 1/2 point of the launch.
4) Last is to check stab position. My Spirit was popping off like crazy at
first. Did everything else. Discovered that the stab was up a little in the
back giving the plane a constant up elevator effect.
Give 'em a try and let us know if they help at all.
Here are some other links you might enjoy.
Learning to use a hi-start
http://www.flyesl.org/forums/topic.asp?TOPIC_ID=216
Sailplanes are wonderful!
http://www.rcflying.net/forums/showthread.php?s=&threadid=5356
Best regards,
Ed Anderson
aeajr on the forums
Long Island Silent Flyers |
Pop-offs
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Posted - 08/31/2006 : 08:09:25 AM
