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FT Delta - is it me?

#1
Did anyone else have an issue with the elevon control horns being too far forward. Maybe it was something in my setup but I had a weird elevon thing where they kind of went over center in the up position. That locked the one elevon full up. I had the control rods in the lowest position.

It didn't look like the hole for the rod was in front of the hinge line, not over it. I clipped the horn off and drilled another hole back further. What I think is more directly over the hinge line. Test flight soon.

Personally, I think it might just be another instance of my rush to finish building style.

Brent
 

xuzme720

Dedicated foam bender
Mentor
#2
With the rods in the closest hole to the control surface, you are getting maximum throw, just like closest to the servo pivot gives maximum throw. You may know this already but thought I'd point that out in case that could be part of your issue.
 

skeplin

Senior Member
#5
Thanks xuzme720, though I'm not sure I understand why a down elevon would push the wing up. Isn't it the opposite effect with ailerons?
 

xuzme720

Dedicated foam bender
Mentor
#6
No, it's the same effect as an aileron, at least as far as roll is concerned. In practice, the aileron/elevon on the down side is increasing the camber of the wing and generating more lift. By contrast, the up side is creating reflex or decreasing camber and lift.
 
#7
With the rods in the closest hole to the control surface, you are getting maximum throw, just like closest to the servo pivot gives maximum throw. You may know this already but thought I'd point that out in case that could be part of your issue.
I did have my mental pic of how things work messed up. I was thinking close to control surface is least throw. So wrong. I'll adjust. You said closest to servo pivot is max throw. I'm betting you miss typed. Close to servo shaft is minimum throw. Unless after really thinking about it I'm still messed up! Could be, LOL

I should have retained physics from dirt bike days. Small engine sprocket and big rear wheel sprocket is lower gearing. Or "less throw"
 
#8
On the servo end, it's how far the control rod moves for a given angle of servo movement. Farther from the center gives you more movement. The distance moved along an arc for a given angle is directly proportional to the radius of the arc.

On the control surface end, it's how far the control surface rotates around the hinge for a given amount of control rod movement. Closer to the center gives you more rotation. The angle swept by an arc for a given distance moved along the arc is inversely proportional to the radius.

See, geometry is good for something. :D
 

xuzme720

Dedicated foam bender
Mentor
#9
I did have my mental pic of how things work messed up. I was thinking close to control surface is least throw. So wrong. I'll adjust. You said closest to servo pivot is max throw. I'm betting you miss typed. Close to servo shaft is minimum throw. Unless after really thinking about it I'm still messed up! Could be, LOL

I should have retained physics from dirt bike days. Small engine sprocket and big rear wheel sprocket is lower gearing. Or "less throw"
It was a typo...should have been"closest to servo pivot is min throw" but it looks like you got it sorted.