servo placment
#1
Thread Starter
Join Date: Mar 2006
Location: mt shasta, CA
Posts: 412
Likes: 0
Received 0 Likes
on
0 Posts
servo placment
When building a wing is there a formula to where the servo goes. Like one third of aileron or just as close to wing root as possible. Thanks Steve
#4
Senior Member
My Feedback: (2)
Join Date: Nov 2003
Location: MT SHASTA,
CA
Posts: 384
Likes: 0
Received 0 Likes
on
0 Posts
Thanks Bob!
I have followed several of your threads over the years, Mostly at the other forum sites, LOL. Your willingness to help others and this hobby is greatly appreciated and I know my building skills have improved as a direct result of your work.
Mike
I have followed several of your threads over the years, Mostly at the other forum sites, LOL. Your willingness to help others and this hobby is greatly appreciated and I know my building skills have improved as a direct result of your work.
Mike
#5
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
Posts: 12,425
Likes: 0
Received 22 Likes
on
19 Posts
I've seen references to the idea that you don't want to put the control horn where the inboard and outboard portions are evenly divisible. So don't put the control horn at the 50% point or the 1/3 point. Instead make it an oddball number like 45% or 28%.
The theory being that exactly even or related divisions can promote flutter. Sort of like the old Tacoma suspension bridge. By putting the control horn at some oddball location along the span length you break that possibility.
And of course at that point you put the servo just ahead of the horn if using outboard servos with one on each surface.
To avoid high mass moments in the wing I like to put the servo as inboard as possible within reason. So I look to put the horn at around 27 to 30% out from the inboard end of the surface. That puts the servo out far enough that I don't need to worry as much about flex and I avoid the 4:1 ratio of putting the horn at 25%. But the outboard mounted servo is not so far out that it builds on making the tips heavier too badly.
The theory being that exactly even or related divisions can promote flutter. Sort of like the old Tacoma suspension bridge. By putting the control horn at some oddball location along the span length you break that possibility.
And of course at that point you put the servo just ahead of the horn if using outboard servos with one on each surface.
To avoid high mass moments in the wing I like to put the servo as inboard as possible within reason. So I look to put the horn at around 27 to 30% out from the inboard end of the surface. That puts the servo out far enough that I don't need to worry as much about flex and I avoid the 4:1 ratio of putting the horn at 25%. But the outboard mounted servo is not so far out that it builds on making the tips heavier too badly.
#6
Senior Member
A good rule of thumb is to place it at an odd multiple of the span; i.e. 1/3, 1/5, 2/5 2/3 etc. This minimizes the chance of flutter as it tends to cancel out some of the possible flutter frequencies. For best use of the forces required of the servo, the farther out on the wing the better.
#8
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
Posts: 12,425
Likes: 0
Received 22 Likes
on
19 Posts
A good rule of thumb is to place it at an odd multiple of the span; i.e. 1/3, 1/5, 2/5 2/3 etc. This minimizes the chance of flutter as it tends to cancel out some of the possible flutter frequencies. For best use of the forces required of the servo, the farther out on the wing the better.
What's needed is a real oddball like 1:3.2. The surface may still flutter but with a non integer based ratio such as this it'll be due to other factors than resonance due to the horn location.