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Old Nov 21, 2012, 07:08 PM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
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Quote:
Originally Posted by robert_houdin View Post
.....In this design, the entire wing will be rotated, with the servo shaft attached directly to the spar, so I probably don't need to worry about the sloppiness to which you refer, but I'm just curious.
That will provide you with far too much pivoting travel. Past designs that utilize "wingerons" typically move the wing through about a 4 to 5 degree total travel.

To achieve this sort of travel reduction the common method is that the wings are set up so that they pivot on a joiner rod which acts as the load bearing center joiner and as the pivot rod. Brass tubing is then used as inner and outer bearings with a bit of oil or grease on the steel rod.

Note that the joiner rod/pivot must be at or VERY close to the 25% MAC position of the wing. Typicaly this is not where the spar is located. So you may want to alter the design to either add a little taper and sweep or some other trick so that the spar at the root portion of the wing is located where you can put the sleeve for the joiner/pivot rod between the spar caps.

The servos are then connected to stubs attached at the leading edge that sticks into the inside of the fuselage where the servos are arranged to move these stub pins up and down and achieve the total travel of around 5 degrees.

5 degrees doesn't sound like much but the one model I saw and got to fly briefly had about that much and it was VERY aerobatic for a glider.
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Old Nov 22, 2012, 04:01 AM
Twisted and Confused
flyonline's Avatar
Joined May 2003
4,309 Posts
Quote:
Originally Posted by BMatthews View Post
That will provide you with far too much pivoting travel. Past designs that utilize "wingerons" typically move the wing through about a 4 to 5 degree total travel.

...

Note that the joiner rod/pivot must be at or VERY close to the 25% MAC position of the wing.

5 degrees doesn't sound like much but the one model I saw and got to fly briefly had about that much and it was VERY aerobatic for a glider.
Check out my onboard vid of my 2m Orca pitcheron for some idea of wing movements. Mine are a little more than suggested above, something like 20deg total if I remember rightly (plane is now dead ) but that is generally not all used excepting high speed rolls, and sharp turns. My records show that all my pitcherons (yet to seriously build a wingeron) are all at about that rate or slightly less, though it pays to have low rates set up for the first flight!!!!!!

Tail Cam - Orca pitcheron (3 min 23 sec)


I've also flown a largeish 2m pitcheron with the wingrod/pivot point @ 33%MAC and a wingloading of ~20oz/sq' without trouble but I had large powerful servos - I wouldn't do it again by choice though I never actually had trouble with it, but I wouldn't want to push it. Modern high speed airfoils with the thickest part at around 25-30% make it a lot easier to put the spar/joiner at that point, the SD7003 is a favourite partly for this reason.

One great and simple method of making a bellcrank is something like this, you can then clamp down on the drive pin in the wing making it nice and tight.



Steve
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Old Nov 22, 2012, 10:51 AM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
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Steve, your video actually matches what I saw and felt during that one day with that other guy's model. I noticed that even with minor roll inputs that your response is DARN quick. And the spots where you put in full travel it makes the world look like a washing machine window....

They wingeron model I tried was being set up for thermal soaring. So it didn't really need the same crazy roll rate you're getting.
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Old Nov 22, 2012, 11:02 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,279 Posts
Quote:
Originally Posted by robert_houdin View Post
Thank you very much to everyone for the responses. I now have a much better understanding of why servos are suited to RC aircraft applications.







In this design, the entire wing will be rotated, with the servo shaft attached directly to the spar, so I probably don't need to worry about the sloppiness to which you refer, but I'm just curious.











Any chance you could post a quick sketch of the wing ?









Stuart
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Old Nov 22, 2012, 11:02 AM
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United States, CA, Brentwood
Joined Jun 2012
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Quote:
Originally Posted by pmackenzie View Post
Just like you would in a motion control application you can get around the feedback problem by doing an origin return on power up.
But not sure I would want that for a control surface application.

Pat MacKenzie
Zero return switches on a plane, now that's getting complicated. I can still see a loss step mid flight. That would be real bad to try and zero return mid flight. One hellava snap roll me thinks
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Old Nov 22, 2012, 11:44 PM
Twisted and Confused
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Joined May 2003
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Quote:
Originally Posted by BMatthews View Post
Steve, your video actually matches what I saw and felt during that one day with that other guy's model. I noticed that even with minor roll inputs that your response is DARN quick. And the spots where you put in full travel it makes the world look like a washing machine window....

They wingeron model I tried was being set up for thermal soaring. So it didn't really need the same crazy roll rate you're getting.
That's true for roll, but they're not normally known for a big elev response. I've got a high speed 60" model that I can't count the roll rate in real time with ease, and have to come out of a drill bit roll with caution so I can work out if I'm up, or down
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Old Dec 21, 2012, 01:31 AM
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Vespa, "are you smoking crack" been around for ~40 years and your not seeing the reality of physics, Sorry bud
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