dear friends, i know this is not STUNT, but i understand that the knowledge on design is in this place, so i came asking for help:
i am working on a high wings scale model, that i want to use for Control Line, and i plan to build a full depth cockpit, so the only places available to hide the bellcrank are under the seats, close to the bottom of the fuse, or worst case, into the wing.
itīs a Citabria, a high wing model, with dihedral.
i have made a rough sketch with a J3 front view to show where i plan to install the bellcrank.
itīs not intented to do any pattern, just to fly straight, wing over and loops (maybe)
i know that the bottom position would be bad due to the CG of the fuse, but what should i expect from that?
thanks in advance for the input

I know first hand the Citabria (7KCAB) is a wonderful airplane.  

I think that having the lead-out support that close to the fuselage might be a problem; could result in the wings wagging.

The lead-outs in the wing would be more stabile as far as roll and give a cleaner look.  A trim tab could be used to get wings level if needed.

Or, you could mount the bell crank below the seat and run the lead-outs to a wingtip mounted lead-out guide that drops down to the exact vertical CG, as determined by hanging the plane with wings vertical.  The lead-outs would bend going thru the guide, but shouldn't be a problem for the use you described.

As you stated, your model is not for stunt for the stunt event.  Now, you might be considering to do various maneuvers (inverted, loops and figure eights) in the scale event.  (After all it is a Citabria, the full size ship is stressed to be fully aerobatic).

It is interesting to note that Dick Mathis did a profile Citabria designed for Stunt.  (Flying Models, April, 1973)  His design had the bellcrank in the wing, dihedral, no flaps, with the leadouts coming out the wing tip.  About a 52" span for .29 to .40 engines.  In his article, Mathis wrote about all of the supposed taboos against a high wing stunt ship.  He wrote that it "flies just fine. In fact, it flies just like any other good sport stunter, or better than most."  Mathis used the "Equivalent of 10 pennies" in the outboard wing tip.  If you are not planning to fly your Citabria in a stunt contest, you do not have to worry about optimum flight trimming for keeping the wing from doing strange things in inside and outside loops and inverted flying.

There is another construction article by Michael Garmon for what he calls "HI-Cub/Citabria" inj Flying Models, March, 1997.  There are two models here representing a Citabria and a Cub, built up fuselages, .40 size engines, high wings, flaps, no dihedral, bellcrank and leadouts in the wings.  Flew and placed in an Intermediate competition in high winds.

I am aware of several people building the Bob Palmer/Ted Goyet Hi Boy.  (Model Airplane News, August, 1954)  This has a high wing, no dihedral, flaps, bellcrank and leadouts in the wing, designed for stunt.  Some have experienced the outboard tip flying high upright and down while inverted but still capable of flying the pattern.  Some of that could be minimized by small trim tabs on the wing TE.  Certainly a more desirable and more simple solution than placing the bellcrank in the fuselage and leadouts though a guide suspended below the wing.

So, these high wing airplanes can fly with the bellcrank and leadouts in the wing.  They might not give stellar Nats winning performance in stunt, but for scale, they can be made to fly without going to the problem of mounting the bellcrank in the fuselage and having to deal with a leadout guide suspended beneath the wing somewhere.

Good luck with whatever your decision is.

Keith

The greenhouse window on the Citabria was a factory option on the earlier planes.  I had a first year Citabria (serial #59), and mine did not have the greenhouse window.  You don't have to have one if you don't want to.

Mark

This has been a good Thread, important information from many informed modelers.

Fred,

I hope you don't mind but your Thread brings a question to my mind.

I see models with extreme swept back leading edges, they attach an "extender" stick at the tip allowing for attachment of the lead outs well in front of the wing tip.

Could this stick be eliminated and have the lead outs exit the LE, say 50% of the span of the inboard wing?

An example:  If the inboard wing was 30", the lead outs would exit at 15", half way between the root cord and the tip.

You would still have 45" of wing behind the lead out exit point.

CB
 

I have a similar problem with my Monogram Cub special. The original design had the U shaped bellcrank acting as a lead out guide placed under the inboard wing with a wire running through the wing to a small 90deg crank that connected to the elevator push rod. The revised plan calls for mounting the BC in the cabin with lead outs running through the cabin window. Plan calls for omitting the window, but with the O&R 23 the exhaust residue would fill the cabin area with oil. I lowered the BC crank just enough that would put the lead outs exiting just above the lower window sill. I plan on gluing a piece of wood in the lower window area to allow the cable to exit and still be able to close the window with plastic. I'm using wire guides at the inboard wing tip inline with the BC position. CL high wingers do present different problems, but most of these designs are sport planes anyway. Richard

Check the rulz for the event you're building for.  I'm pretty sure that for all but the pickiest events the insides of the cockpit don't matter.  And while I'd have to read them to really know, I'm pretty sure that they all say that the judges are to ignore the leadouts for static judging.

Putting that observation aside, you could put the bellcrank in the wing with just the end protruding into the cabin space, with the pushrod running down the left side of the fuse.  It would show through the window, but it wouldn't look at all bad.

indeed thereīs no need for a full cockpit, just my own satisfaction. however it needs to show the pilot bust
still thinking the wing bellcrank would be the slick solution...will work on that further

indeed thereīs no need for a full cockpit, just my own satisfaction. however it needs to show the pilot bust
still thinking the wing bellcrank would be the slick solution...will work on that further

Fred,

Someone mentioned a tad of weight to bring the outboard tip down if necessary.

I'd like to see a great cockpit interior on the horizon. I know you can do it. 

CB