Guys I have what I suspect is a control linkage problem with my Buso Jaguar project. The flap horn holes are drilled at 1.25” and 3/4” spacing. The elevator horn has one hole drilled at 1”. I have the bellcrank connected to the 1. 25” hole in the flap horn. The 3/4” hole in the flap horn is connected to the 1” hole in the elevator horn. I have more flap movement than elevator. I don't really understand control horn geometry so I don't know how my model will respond in flight because of this issue. What should I do (if anything) to correct the perceived problem?

The stab is not yet glued in but the wing is glued to the fuselage. So I can still make some adjustments if necessary.

The hole in the elevator horn has to be closer than or equal to the flap horn.  As I see it you have two choices.  Swap the connections on the flap horn or drill a hole closer to the hinge line on the elevator.  Personally I would swap the flap horn since that should produce a 30/45 flap/elevator which I like but if you want a 1:1 you need to move the elevator hole to 3/4".  The plane will fly As Is but I don't think you will like how it corners.

Ken

Tape a piece of thick cardboard , wraped around the stab , while youre t it with the drill .
Better to chew that up , rather than good timber .

Center punched , and a sharp bit , with some LUBE , should see it go thru clean .
Ive had to do the same , using a 6 in drill & hand drill . Then needle file .
If youre bushing it , a bit of angle drilling wont hurt , The knob at the center of the drill reemoves , to reduce the angle .
or undersize & use a final size drill to ream , with a hand holder - like a large blade knife handle for the bit .
( if your soldering in a bush , a damp rag around the area , and a wet tissue to quench  a.s.a.p. . My 80 W iron will get in guick . a slow one'l heat it more ,
Pre Tin - so youre not faffing about . )Actually a long ' brass toob' , so its STRAIGHT , then trim ( razor saw ) and dress ends . Little paint brush & adequate acid helps .
Another dry towel to mop excess , so we dont acidifdy the wood ! . 

Seen recently something where he had more flap than elevator travel . Unusual but ' in trim ' , whatever it was on .

Other option 'd be halve the flap chord . 

1 : 1 is usual with an aftish C.G. .

What is the aeroplane there ? .

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Picture of DRILL before hoodlum has wrenched centre support knob free ! .

Yea. Looks like thats by far the easyist option.

If you remove that cockpit flooring ( maybe leave the edges , as per aft ) youll get better axis.
If the JB Welds fairly recent its unlikely fully cured.
Ive removed JB WEld from a G 51 Bypass port with a chisel & patiance. Came out in big lumps.
Its not titainium .

You may need a bit more pushrod clearance in the top wing sheeting, aft.

Ratio'd be 1.25 to 1  . Elev / Flap . Theres a thing .

Thanks for all the help guys (and your knowledge). I was able to drill a 3/4" hole in the horn with very little difficulty. I would have preferred the hole to be threaded but running a tap into it would have been too difficult. I will JB weld the bolt head onto the horn for a little extra strength.

By Jove I think he's got it.

Just for future reference, you can put a 4-40 tap into a pin vise or get a small file handle,  Horns are thin enough to tap w/o much force.  I have even done it by clamping a small vice grip to the tap and doing it by hand.

Ken

It’s great that you were able to solve the problem without having to break loose the JB Weld.
In future if you have to loosen an epoxied connection I have had great success heating it with my soldering gun and undoing the nut while still warm and the glue is softened from the heat.

1" from the pivot to the bellcrank hole is more than enough to keep Mr. Nezband happy

Or it could be less than enough.  Leverage over hinge moment does not depend on control horn height or bellcrank output hole location.

I think we both made bad assumptions.  My point was that, for a given ratio of bellcrank to flap travel, you could have any flap lever arm length if the bellcrank lever arm is proportionally long.  You are correct that some of the other things are equal.  I presume that Dennis isn't going to mess with the bellcrank, so my point is moot. 

We don't have sufficient information to tell where either linkage is relative to the "Netzeband wall", namely whether the ratio of leadout travel to control surface travel is adequate.  The "wall" is squishy.  Inadequate ratio of leadout travel to control surface travel makes it difficult to fly a given loop radius in the presence of turbulence or mistrim, even with tension on both lines.  And, as you and Ted have observed, what ratio of leadout travel to control surface travel you need is a function of airplane mass.  Swapping holes in the flap control horn would certainly reduce the ratio of leadout travel to flap travel.  It may or may not make the plane a lot harder to fly, but I sure wouldn't do it.  We discussed the mass effect in https://stunthanger.com/smf/open-forum/question-on-the-netzeband-wall/msg342263/#msg342263 .

There is nothing universal about a 1:1 flap-to-elevator ratio.  The ratio you need depends on the design.  The Jaguar plans should tell you what to use.  It's too late for Dennis's airplane, but most folks I know now use an elevator control horn with a slot so the length can be varied as needed.  It's another trim tool.

This is how I try and set mine up.  I get the elevator to 1:1 with the horn adjusted just below center on the elevator horn.  I have left a few at 1:1 but mostly I and up at somewhere around 35:45 degrees.  I am taking caution to make sure it cannot slip since I experienced one of those "it can't happen and if it does it won't be me" crashes.  The adjustable horn started slipping and by the time I got to the Clover I only had 15 degrees left and I was too low to make the 4th loop.  If it had just slipped all at once I would have noticed it.  I had just done some extensive work on the plane and I must have forgotten the thread lock.  I once asked if there is a limit to how many stupid things can make a ship crash and I am going to answer my own question - no limit.

Yup.  There's no doubt a safer way to make an adjustable control horn. I've been lucky so far. 

The combait (sic) guys use control horns like that without any problem, but I don't think their control load is as high and the dreaded Netzeband Wall is way off in the distance if the engine is running. I don't see how you could adjust the thing when it's enclosed in a stunter's fuselage. It would be cool if you could, tho. The other thing about that is watching out for differential to creep in. I'm not all that crazy about the current slotted elevator horns, and wish somebody would engineer something better, more precise, and less dangerous.   

Honestly, I didn't think control ratios were any more complex than grade school math. As I recall, fractions and ratios were taught at about the same time. Some folks are baffled by fractions, but not those of us who bought balsa sheets and sticks!    Steve

Honestly, I didn't think control ratios were any more complex than grade school math.

High school math.  The bellcrank-flap relationship is a 3-dimensional problem.  You need a formula for the intersection of a circle and a sphere.  I'm not up to it, but I came up with a crude iterative method.  If you ever build anything, I'll send you a copy of the program. 

   Interesting, we had the same problem trying to determine the intersection of a cone and sphere, the cone being the scan path of an earth sensor, and the sphere being the earth (we know it isn't a sphere - in fact the reason we cared was to determine the correction necessary for the oblateness of the earth, *compared* to a sphere) which we simplified by realizing that we only really cared where the edges were - meaning our sphere was now circle, and the oblate earth was ~an ellipse.  When we where solving it as a sphere, we, too, only managed an (unsatisfying) iterative solution. And yes, the fact that the 8000 mile diameter earth is fatter at the equator by a mere 28 miles does matter, it's actually a huge effect compared to our other error sources and can't be ignored.

    Brett

If you were successful in creating a formula to plot a moving cone on a rotating unequal sphere I will never question your math again!

Ken

It's an *extremely* sensitive adjustment and even .010 of an inch difference (out of about 1 1/4 overall length) can have a very big effect on the control feel and response of the airplane.

How on earth does one accurately and reliably move a slider by 1/100 of an inch?

How on earth does one accurately and reliably move a slider by 1/100 of an inch?

Scribe a line on it before the move.  Kinda calls out for a threaded fastener somewhere in the mechanism, doesn't it?

What do you do when your glasses don't focus on the horn by the time the tail wheel hits you in the forehead?

You know that you could have had a V-8.

Ken

It's easier and much lighter to make new flaps that are the right size, and that's not critical at all.

Brett has approached my airplane with an X-acto knife in his hand and a mischievous look in his eye.