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Old May 09, 2005, 08:49 PM
Just Keeping UP
United States, ID, Moyie Springs
Joined May 2004
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Beech Staggerwing Design / Build, Part 2

Since part 1 has now gone over 500 posts, I'm starting a part 2.

Part 1 can be found here:
http://www.rcgroups.com/forums/showthread.php?t=229942

Nick
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Old May 09, 2005, 09:13 PM
Just Keeping UP
United States, ID, Moyie Springs
Joined May 2004
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Ground Looping

I appreciate all of the advice!

I've reset the toe-in and its looping tendancy is less now. However, I suspect that all I can really do is add power faster to get rudder effectiveness before it has a chance to change direction very much.

The design has the wheels in the scale position with a scale castering tailwheel. The Staggerwing has a narrow stance with short tail moment, which is, I believe, causing the problem. Back in the '70's, I flew a tail dragger without this problem, so the whole thing is somewhat of a new problem for me. Since it's probably not practicable to design a controllable lock for the tailwheel, the best long term solution will be to make the tailwheel steerable.

As I see it, the easiest way to make the tailwheel steerable would be to add another pushrod from the rudder servo. This would require some surgery to do. If the fuselage were not already built, it would be possible to drop a connection from the rudder for an internal pushrod from the rudder. In any case, this would be a bear to adjust.

I'm looking forward to hear some experience from the other beta builders!

Nick
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Old May 09, 2005, 09:37 PM
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OK Nick:
I'm over here now waiting to hear how the flights go.
Rick
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Old May 09, 2005, 10:18 PM
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...any chance of just attaching the wheel to the rudder with a rubber band?... this is my preferred tail wheel hookup as it dampens the shock loads on the servo.

...if there's no obvious hook on the tailwheel, maybe a rubber band either side of the axle, to a small hook on the bottom of the rudder. May be enough to get it done to see what's what for flying.

For taking off, one could also offer the tip that when the tail lifts up, that a little down elevator is applied to keep the plane planted on the ground until you're sure you're above airspeed and that the plane is listening to the rudder instead of the wheels. Worst case scenario for this is that you get too eager on the down elevator and crack a prop.
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Old May 09, 2005, 11:02 PM
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Nick,

trailing along with the others.. have you heard from Paul??
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Old May 10, 2005, 12:30 AM
Just Keeping UP
United States, ID, Moyie Springs
Joined May 2004
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theKM, there's no simple way to connect the rudder to the tailwheel: it's due to the design of the Staggerwing. The tailwheel is well forward of the rudder and the rudder doesn't extend below the top of the fuselage. The entire structure of the tailwheel and its mount is below and forward of the rudder. Any system to connect the rudder to the tailwheel will need to be internal to the fuselage.

For me, the big question is: "Should I design a system to couple the rudder and tailwheel for steering?"

Will the other three betas encounter the same problem?

What do you other beta builders think?

Does anyone know of an off-the-shelf steering arm that will connect to a 1/16" wire for a steering bellcrank?

Nick
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Old May 10, 2005, 02:08 AM
Just Keeping UP
United States, ID, Moyie Springs
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Gearup, I haven't heard anything about trying to fly from Paul. I keep hoping that he'll fly his and tell me all is well!

Nick
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Old May 10, 2005, 07:36 PM
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Tail Wheel Coupling

My 64 inch Staggerwing is designed with the rudder and tail wheel coupled as shown in the attached diagram. The tail wheel is connected using a Y-Connection off of the rudder push rod. This may give some ideas on how to couple the rudder and tail wheel on Nick's model.
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Old May 11, 2005, 12:48 AM
Just Keeping UP
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Tailwheel Steering

Thanks for the drawing Victor! That's exactly what I meant when I talked about droping a connection from the rudder.

This system would be buried in the fuselage, so it's one you would want to get right before covering!

Since my tail cone is full of lead, there would be no room for this system in my beta. For my beta, I'll have to leave it as is, lock the tailwheel or add another pushrod from the rudder servo.

To make my tailwheel steerable, I'd need to:
remove the stringers from fuselage between last two frames;
add bellcrank;
add pushrod;
replace stringers and recover.

At least this would be adjustable after it's all sealed up.

Weather has been stormy here. We seem to be stuck back in February! When the weather breaks, I'll try to fly again.

Nick
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Old May 11, 2005, 12:50 AM
Just Keeping UP
United States, ID, Moyie Springs
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Kite Status

I've completed updating the laser cut files. I need to clean up the wing fillet drawings and everything will be ready to order kits EXCEPT FOR FLIGHT TESTING.

This is taking forever!

Nick
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Old May 11, 2005, 12:54 AM
Just Keeping UP
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I suppose I need to get started rewriting the assembly instructions. I intend to copy the sequence from the beta build part of the thread, adding & improving as required. But, some kits could be ordered and sold using the build part of the thread as instructions.

Now would be a good time for anyone with suggestions for the build instructions to post them.

Nick
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Old May 11, 2005, 07:06 PM
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Nick, I will go over the original threads tomorrow( I have a half day off)...
I wonder if you might go ahead and just FIX the tailwheel for right now... its not necessary to cople with the rudder, it should help track the model, and if it skids, its not going hurt the tail section..
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Old May 11, 2005, 07:40 PM
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Quote:
Originally Posted by gearup
I wonder if you might go ahead and just FIX the tailwheel for right now...
That's a pretty good idea
Set it to track straight, you will still be able to stear it with the rudder. When the tail comes up, it doesn't make much differance anymore, as the rudder is now the primary directional control anyway.
Rick
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Old May 12, 2005, 10:55 PM
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Fixed Tailwheel

Locking the tail wheel is only a "band aid" for the problem. If the tail wheel is locked, it will cause taxi problems on grass fields. The plane will handle like one with a skid vs a tail wheel. At best, it will make very wide turns. You will only be able to taxi straight ahead until the tail wheel clears the ground. Therefore, you will have to carry the plane out to the runway and set it "straight" down the runway. UGLY for such a nice Staggerwing.

Having said that, the locked tail wheel is problably the lesser of two evils. It will problably minimize ground loop problems.
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Old May 12, 2005, 11:45 PM
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well right now, I think the major point is flying the airplane...
I got the biggest kick out of Piper when they introduced the "tramahawk" in 77' the demo pilot was all a quiver about showing me how well it taxied in confined area... when we were at 3500' and I was stalling the airplane, I took a quick peek as to how the T Tail was handling the disturbance,... Disturbed was a good choice of words.. it was shaking like a $12 lap dance.... first and last flight in one... ( no offence to those who love it... just not my my kind of bird).... Fix it, Forget it for now, and Fly it Nick.....

JM
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