Chip,

I have used the three most common methods of controlling the elevator. Pull/pull, c.f rod to a MK bellcrank and most recently the .070 c.f rods set in a ladder type arrangement like Troy newman does.

What are your thoughts on each of these and what is your preferred method or tried and true way?

Wayne Galligan

Did you like the .070 pushrods with the ladder and do you think it was worth the trouble?
.070 sure looks small for this big of an airplane.

tommy s

THats what I thought at first. But the c.f. rods are very stiff and light weight. There are mininum connections between the servo and elevator horn. The MK set is good but there are 6 connections plus you have the bell crank horns that can flex.

I do not care for the MK setup or pull pull at all for elev. The little carbon rod system looks good to me, however I cannot see it really being superior to the tried and tru pushrod. My dad did it in 1986 on our Zlin and it did not feel any more solid then the Dalotels did at the time. Also seems like a lot of work.

Chip

Chip,
Why do you not like the MK bellcrank set up?
Other than more connections are there other issues?
Thanks

I like the PULL-PULL so that when the hinges deteriorate on the control surface, They will be in the same smoking pile as the rest of the model and you need not go chasing after them!!! LOL

The MK bellcrank set up is probably a couple of ounces more weight than
a good carbon fibre pushrod set up, and since it is made of plastic there is
the potential for flexing. I've got two of them working and haven't seen any
problems yet but I do think when I build my next airplane I will use the
double .070" carbon fiber pushrods. Less linkage to hook up and less to go
wrong although the initial set up takes a little more time.

tommy s

If you use the MK bellcrank DO NOT use stand offs from the control horns when using a ball link. This just adds to the leverage and twist on the control horn. Otherwise they are a pretty stiff setup when using the c.f rods and titanium ends. Also pricer then the pushrod setup or pull/pull.

I have tried the double .070 c.f pushrod on my latest setup and so far so good. Very light and I think it eliminates and variable like the pushrod flexing at the "Y". However like Chip said a good pushrod setup is about as good as any.

I know a a fellow who recently had problems breaking his stab at the center joint. He was flying a pull/pull setup and the control horn was not directley over the hinge line. It was set ahead of the hingeline causing the lines to tighten as the surface was moved. He broke the stab twice before someone discovered this and then the after the fix his servo rail failed(from previous stressing I assume) and ended up re-kitting the airplane. So there are some important thingsin a pull/pull system that need to be followed. A pushrod eliminates those possible conditions. Only thing about a pull/pull I like thought is the small adjustment settings one can make with it.

Wayne G.

More parts, more play, short stiff push rods last longer.