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Permalink Reply by William D. Phillips on October 23, 2019 at 11:20am

Who knows how many degrees the flaps drop per 360 degree turn of the flap motor screw gear? Seems like a bunch of fellows should know this. Best Bill 

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Permalink Reply by John Austin on October 24, 2019 at 9:09am

I haven't looked at my flap gear motor in-motion in quite a while, but isn't the screw internal and not visible?  Here's a YouTube video of the motor in motion - I don't see any externally rotating parts that could be used to count revolutions: https://www.youtube.com/watch?v=S3KEz2N-ngI

John

N750A

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Permalink Reply by Jim and Amelia Isaacs on November 1, 2019 at 7:25am

Not sure why the question, but would this help? Flaps up, mark flap position (zero reference line) and flap motor arm length.  Activate motor for one second, measure flap deflection angle achieved in degrees with your smart phone or whatever. Measure flap motor shaft distance travelled. Record the data, Repeat in one second intervals until flaps are full down, then go back full up in the same manner.

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Permalink Reply by John Austin on November 1, 2019 at 12:09pm

Hopefully not to creep the thread, but a piece of potentially useful trivia:

Years ago, I verified with Caleb, the then-engineer at Zenith, that the gear motor as supplied by Zenith has internal limit switches, so there is no harm to holding the flap switch as long as you want at either end of the up or down limits.  On my STOL 750, it takes exactly 4 seconds to go from full up to full down flaps. So rather than have a flap position indicator, or look out the window and use my Mark I eyeballs, I can hold the switch and simply count "thousand and one, thousand and two" and know the flaps have traveled 2 seconds or 50%, etc.  If you lose track of whether they're up or down, you can simply hold the flap switch in either direction for 4 seconds and you know they're fully up or fully down, whichever direction you selected, and then reverse the direction and count seconds to get them where you want them.

John

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