How much throw do I really need?

[Matthew Brown]

Like the title says, how much do I need?
During assembly of my Oriental ARF, I got the elevator hinge line a bit tighter than I intended and now have only about 30 degrees throw each way. Flaps are plenty good but the elevator concerns me. Since I've never flown a true stunt plane I'm not too sure.

Thanks, Matt

[Mark Scarborough]

30 degrees should be plenty fine. I have done some experiments and its unlikely that you will ever need more than that, ( if you even need that much)

[Steve Helmick]

Twenty degrees each way is plenty. The question is, how hard (line tension) is it to get to the amount of deflection you need. Did you use pinned hinges, or those horrid CA hinges that just flex?   Steve

[David_Stack]

Thread down in the "Design" section:

http://stunthanger.com/smf/stunt-design/elevator-deflection/

r/
Dave

[Tim Wescott]

Twenty degrees each way is plenty. The question is, how hard (line tension) is it to get to the amount of deflection you need. Did you use pinned hinges, or those horrid CA hinges that just flex?   Steve

I have some extra-horrid pinned hinges that I turned into CA hinges with CA at the Fireballs' fun-fly.  It was Robin's plane and she didn't get a chance to fly.  She was being very nice about not getting torqued with me.  (I offered to let her fly the Atlantis -- but only because I knew the answer would be "hell no!").

[Dan McEntee]

Like the title says, how much do I need?
During assembly of my Oriental ARF, I got the elevator hinge line a bit tighter than I intended and now have only about 30 degrees throw each way. Flaps are plenty good but the elevator concerns me. Since I've never flown a true stunt plane I'm not too sure.

Thanks, Matt

      In reading your post, I get the impression that you are saying that you have more flap deflection than elevator. That may be a problem. I don't know of anyone that ever had more flap through than elevator throw. It's either 1:1 or 3/4:1 flap to elevator. The control surfaces don't deflect more than 15 or twenty degrees if everything is in trim. I would work on it some more to get them even.
   Good luck and have fun,
   Dan McEntee

[Randy Powell]

Sort of depends, I'd say. The farther forward you carry the CG, the more throw you need.

[Matthew Brown]

For reference, I just glued in the hinges. There's no pushrods connected yet. For that matter neither the wing nor stab is installed into the fuse yet.
My initial intent was to use the CA hinges but someone in one of my other threads poopoo'd them so bad I went ahead and used some Dubro pinned hinges I had in stock.
The elevator hinges are plenty free for about 20 degrees then get gradually stiffer till the elevator hits hard stop about 30 degrees.

Matt

[Dane Martin]

For reference, I just glued in the hinges. There's no pushrods connected yet. For that matter neither the wing nor stab is installed into the fuse yet.
My initial intent was to use the CA hinges but someone in one of my other threads poopoo'd them so bad I went ahead and used some Dubro pinned hinges I had in stock.
The elevator hinges are plenty free for about 20 degrees then get gradually stiffer till the elevator hits hard stop about 30 degrees.

Matt

When using the pinned hinges, I like to draw a straight line all the way across the TE. Then I can align the hinges.  If they are not perfectly straight, they will bind.
With that being said, still sounds like enough throw. I try and set up my surfaces to fall under their own weight all the way to the stop. Not always easy. ..lol

[Mark Scarborough]

For reference, I just glued in the hinges. There's no pushrods connected yet. For that matter neither the wing nor stab is installed into the fuse yet.
My initial intent was to use the CA hinges but someone in one of my other threads poopoo'd them so bad I went ahead and used some Dubro pinned hinges I had in stock.
The elevator hinges are plenty free for about 20 degrees then get gradually stiffer till the elevator hits hard stop about 30 degrees.

Matt

I think it was me that poo pooed the CA hinges,, among others no doubt,,they are not good for CL
anyway, back to the point
that free movement until 20 degrees is what you are looking at, I would suggest that you see if you can determine what is making the hinge get stiffer past 20 degrees, its possible there is glue spots on the hinge barrell that oozed out from the hinge slot and that can cause resistance. Its also possible that if the control horn, or surface is not perfectly flat, it is working hard to get past that point and it will "pop overcenter" for lack of a better term..
20 degrees is about the minimum amount, and I would prefer to have more free play than that even though you likely wont want to use it.

[Matthew Brown]

I think it was me that poo pooed the CA hinges,, among others no doubt,,they are not good for CL
anyway, back to the point
that free movement until 20 degrees is what you are looking at, I would suggest that you see if you can determine what is making the hinge get stiffer past 20 degrees, its possible there is glue spots on the hinge barrell that oozed out from the hinge slot and that can cause resistance. Its also possible that if the control horn, or surface is not perfectly flat, it is working hard to get past that point and it will "pop overcenter" for lack of a better term..
20 degrees is about the minimum amount, and I would prefer to have more free play than that even though you likely wont want to use it.

I know what caused it! I always cut a recess for the barrel of the hinges so that the surfaces essentially touch. I cut a couple of the recesses a bit too deep so the hingeline is really tighter than I like. I normally use playing cards to set the gap but I got rushed as my epoxy was curing a bit faster than I planned and failed to set the gap with cards.

Matt

[Tim Wescott]

I know what caused it! I always cut a recess for the barrel of the hinges so that the surfaces essentially touch. I cut a couple of the recesses a bit too deep so the hingeline is really tighter than I like. I normally use playing cards to set the gap but I got rushed as my epoxy was curing a bit faster than I planned and failed to set the gap with cards.

Matt

If you get desperate for more throw, put a straight-edge in the gap and close the surface on it hard.  That'll crush the balsa a bit, and give you more throw.

If you're cringing at what that'll do to your wood and your hinges -- well, that's why I said "if you're desperate"!

20 degrees throw should be enough.