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New log flap drive crank idea

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Mark wood:

--- Quote from: Howard Rush on November 12, 2021, 07:15:53 PM ---Here's a discussion of similar mechanisms:  https://stunthanger.com/smf/stunt-design/interesting-bellcrank/

--- End quote ---

That's a very interesting discussion. Thanks for sharing Howard.

Istvan Travnik:
Dear All,
I have read this long discussion from beginning of 2012. Sometimes I was laughing loudly. That time I haven't read that, I do not know, why.
But I remember well, how many times we discussed with Jan Skrabálek in the '90s, on that theme "expo, or logarithmic", at the "Józef Gábris Memorial" contests, in Bratislava. I knew which is better for me, (expo), I worked it out, and reconciled to that fact, I will never be so talented as Jan, or some years later, Igor. 
My Hungarian comrades -not being mechanical engineer, or too innovative minded- always observed nothing else, what is more succesful in the world. And then copied, or bought that. So I walk my way technically alone, at least from1982.
But, when somebody is interested, I do not hide nothing.
Istvan 

Ken Culbertson:

--- Quote from: Mark wood on October 26, 2021, 02:39:23 PM ---One of the observations I have is that stunt models seem to use much more flap deflection than is necessary and / or desirable.

How to test this premise? Make a configurable flap drive. Have CAD. Have 3D printer. It can be done. I've spent a bunch of time working on this model, maybe a bit more than I should but it is addictive. I've also made several iterations along the way. The primary difference between what I have and Igor's is that I have turned the drive crank around and turned the flap horn into a "flap drive horn" which is connected independently to the flaps. With four turnbuckle connecting rods between the bellcrank the flaps independently and the elevator the entire system can be tweaked at one location accessed by a single hatch.

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Mark, I thought you might like to see your brainchild installed and working.  Exceptionally solid, no slop and totally smooth.  Forgive the balsa bellcrank.  I do this before installing the real thing so that I don't have to redrill holes when I change my mind and also to mock up a way to drive a small canard.  I like to tinker too.  Completely removable and adjustable.  I made a full length structural bottom hatch.  Electric lets you do things like that.  No vibration to loosen things and no oil to destroy them!



Ken

Mark wood:
All I can say is that is ubercool. How is it flying? Send me a note via my home email.

Mark

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