RC India

RC Equipments => Tools, Materials and Building Techniques => Topic started by: topalle on December 01, 2017, 12:23:22 PM



Title: Reducing control surfaces play and flutter
Post by: topalle on December 01, 2017, 12:23:22 PM
Hi everyone,
I'm working on a project which is an autonomous plane. Which follows waypoints and is controlled by a pixhawk. So for that, I need a very stable Air-frame and the control surfaces need to have very little play.
Can you post how you make your control surfaces and attach them to the servos?
Till now, I used to glue on my control horns using CA or Hot Glue.


Title: Re: Reducing control surfaces play and flutter
Post by: AL HAM SHARI on December 26, 2017, 05:55:34 PM
Bro it totally depends on the type of plane. If it's a park flyer and made of foam. Most of us use control horns with  ca. But for something that lasts. I think string driven control surfaces are more precise than control horns.


Title: Re: Reducing control surfaces play and flutter
Post by: AL HAM SHARI on December 26, 2017, 05:56:18 PM
I mean control rods


Title: Re: Reducing control surfaces play and flutter
Post by: AL HAM SHARI on December 26, 2017, 05:56:52 PM
So the servos won't necessarily be near the control surfaces


Title: Re: Reducing control surfaces play and flutter
Post by: AL HAM SHARI on December 26, 2017, 05:59:42 PM
You can use nylon or Kevlar strings as you wish and. The only difference is that there  are two control horns on either side of the surface and two strings attach to the servo.


Title: Re: Reducing control surfaces play and flutter
Post by: AL HAM SHARI on December 26, 2017, 06:00:25 PM
So how is the progress so far Bro?


Title: Re: Reducing control surfaces play and flutter
Post by: AL HAM SHARI on December 26, 2017, 06:02:29 PM
This is may help you: https://m.youtube.com/watch?v=AiTk5r-4coc it's the real deal.


Title: Re: Reducing control surfaces play and flutter
Post by: K K Iyer on December 26, 2017, 07:11:51 PM
the control surfaces need to have very little play.
Can you post how you make your control surfaces and attach them to the servos?
Till now, I used to glue on my control horns using CA or Hot Glue.
Hi Srinivas,
Assuming that the TE of the fixed surface (wing, stab, fin) and the LE of the control panels (flaps, ailerons, elevator, rudder) are hard (ie, balsa, not foam), the best way to ensure minimum play is to round the edges that meet, and tie them together with figure of eight stitching using appropriate thread.
THIS HAS NO SLOP AND NO FRICTION. Better than any hinge!

Use 5 min Araldite Klear to stick the control horns into full depth slots in the control surfaces.

Another source of play is the pushrod end (clevis or Z bend) being a loose fit in the hole in the control horn.
To cure this you need a bush in the horn. You can cut slices from the plastic tube in Johnson's Ear Buds  ;D
Hope this helps.
Regards

PS. Let us know if you are considering using cables instead of pushrods. Cables have their own issues!


Title: Re: Reducing control surfaces play and flutter
Post by: saikat on December 26, 2017, 07:33:37 PM
load one side with a spring - and use a non stretch string (like kevlar) for movement on the other side.

it will have zero slop(play)

practically speaking - a little play will make no difference , unless you are flying at very high speeds




Title: Re: Reducing control surfaces play and flutter
Post by: K K Iyer on December 26, 2017, 08:41:41 PM
@saikat sir,
"I lean on old familiar ways..."
(With apologies to Simon and Garfunkel)
Regards


Title: Re: Reducing control surfaces play and flutter
Post by: AL HAM SHARI on December 27, 2017, 05:08:39 PM
Yes i have thought about that too @saikat sir