bearmech

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Hi Everyone:

I'm building a Thunderbug 40 and converting it to a tail dragger. I'm using a halco gear for the mains and looking for different methods for the tail wheel. This will be my first tail wheel installation so should I use a free castoring assembly, use a more conventional assembly attached to the rudder like a sullivan or wire assembly glued straight to the rudder. Also will I need to increase the rudder size for this conversion, if so, how much?
Thanks in advance for your help!

RobStagis

If the plans show where to mount main gear for a tail dragger, that's the hard part. It should go ahead of the CG, right? Not a whole lot forward - but forward. I'll tell the story of the evil-handling old-timer I had - wouldn't take off cuz of ground-looping...the gear was too far forward.

Anyway - the old-timer had a skid for a tail'wheel'. It landed so slow that nothing else was necessary, but you had to lift the tail with prop blast and down-elevator to turn the plane.

My Balsa Stik - all I did was purchase a wire tailwheel (DuBro?). The wire from the tail gear was stuck up through the pivot, then bent back to lie alongside the rudder, then 'sewn' onto the rudder with copper wire.....easy-teasy.

My Goldberg Cub used springs from a rudder-pivot arm setup to steer its Klett tailwheel. That isolated the rudder (and its servo) from bumps.

A bigger rudder? Nah - not in MY book. Real planes are taildraggers!

bearmech

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Thanks

The main gear was easy! I put it just ahead of the wing leading edge with the sweep forward. If that don't work I can still turn the gear around which will move the wheels aft. Its just that pesky tail wheel thats bugging me! LOL

David Cutler

Hi,

Whatever system you decide, it's a good idea to make sure none of the loading from a heavy landing is transfered to the rudder. That is, don't support the wheel by attaching it to the rudder; just take a non-supporting wire, spring or cable from the rudder to provide the turning action.

Did that make any sense?



-David C.

JimTrainor

The Sullivan tail wheel works well in my single experience with it.

You can set it up to castor, and if that isn't working well then just add the little spring that connects the it to the rudder.

LSP972

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This post and the next one give two variations of the same theme; an easy-to-install, quickly replaceable tailwheel assembly.

While the pix are pretty well self-explanatory, don't hesitate if you ahve any questions.

Steve

LSP972

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That was on a Four Star 40. This one is a Somethin' Extra.

bearmech

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Thanks to all!! Is this a great site or what?

Steve what you have is what I had in mind except clip the shaft right above the bearing, solder on a washer and let it free caster.

LSP972

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>

Why, when it is soooo easy to bend a "tiller bar" and fit it to the rudder?

Steve

RobStagis

Taildragger-only trick: While at idle in the middle of the runway and no innocent victims (or witnesses) around, do this:

Full aileron (in direction)
Full rudder (in the same direction)
Start advancing the throttle. The plane will rotate in the rudder's direction.

NOW - add a touch of down elevator to pick the tail up.

NOW - add more throttle.......

If you're successful, you'll end up with a whirling dervish in the middle of the runway.

Warning: This is a prop-eater.....

bearmech

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Steve I was a little worried about the tiller bar breaking out the rudder on those less than perfect landings. Maybe I'm just over stressing here! I think I'll just build it, fly it, repair it, and repeat as necessary! lol
Thanks for the help!

RobStagis

My 'tail-dragger only' trick never broke nuthin'.....but I never tried it on something even remotely fragile. The Balsa USA Stik 40's tail is a balsa plank.......

David Cutler

The tiller could be arranged so that it doesn't transfer any load to the rudder during a hard landing. Maybe a pivot, or the fact that it's a long lever would then isolate the upward movement that happens during a hard landing from the rudder.

-DC

bearmech

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David,

I think you might be right, the tiller arm longer than the arm of the wheel = less leverage hence less stress on the rudder. Would that be right?

MinnFlyer

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Or, you can attach it with a rubber band or spring:

pettit

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Here's a way, as long as you have a tail post that's substantial.

Drill a 1/8" hole, maybe 1.5" deep, from the bottom into the tail post, making sure it is parallel to the rudder line.

Fill the hole with thin CA. When it sets up, drill again. more thin CA, etc. You want to harden the tail post.

Then insert a piece of 1/8" brass tube in the hole and secure it with a drop of thin CA.

Make up a 3/32" music wire tail wheel wire that will slip into the brass tube. The wheel goes on the bent up end. Put a 3/32 wheel collar to act as a stop to keep the wire from going too far into the tube. Use a 4-40 bolt, maybe an inch long, instead of the set screw, pointing toward the rear.

The wire will now fall out, unless you take a section of fuel line, put one end over the bolt, now called a tiller bar, and fasten the other end to the bottom of the rudder with a pin or a screw. Keep the tubing a bit long to give some mechanical isolation between the rudder and the tail wheel. The wheel assembly will be held in place by the tubing and you have a steerable tail wheel!

bearmech

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WOW so many good ideas! I gotta get more planes so I can try them all! LOL
Thanks guys.

SST

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I like the Klett tailwheel.

LSP972

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bearmech,

Take a closer look at those pix. There is a washer soldered on the strut that butts up against the bottom of the plastic bearing.

The washer takes all of the weight/impact loads and prevents it from being transferred to the rudder.

Dick's idea is neater and probably looks better; mine is the quick'n'dirty method...<G>

Steve

bearmech

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Steve

Here's what I have so far. I think the lower wheel collar will take the load. I plan to glass the doubler that the tail wheel bracket attaches to, and attach the tiller to the rudder like minnflyers pixs!

http://www.rcuniverse.com/gallery/sh...t=1&thecat=500

Steve Campbell2

Already cut the wire too short, didja??<G>

That should work just fine. Use thread locker on those collar screws, though.

Steve

bearmech

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That tail wheel wire was salvaged from someone elses crash! The wire that came with the du-bro mount seemed to be to weak! It will get loktite on every thing at final assembly.

thanks