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Old 11-25-2012, 08:14 AM
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partisan
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Default Radical tail wheel idea

I have been wondering if any one has ever not tied the tail wheel into the rudder. Basically the tail wheel would be free to swivel any way it wants to, the plane would turn only by the air passing over the deflected rudder.

Would this work or should I forget about it.
Old 11-25-2012, 08:33 AM
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Villa
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Default RE: Radical tail wheel idea

Hi partisan
I do that with my Yak 54 and it works perfectly.
Old 11-25-2012, 08:40 AM
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LesUyeda
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Default RE: Radical tail wheel idea

The only issue you have, is with ground handling. It is virtually impossible to taxi "hop" a tire over a pebble with a free wheeling tail wheel. The wheel will just pivot around the rock.

Les
Old 11-25-2012, 08:54 AM
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Default RE: Radical tail wheel idea

I like a dolly wheel on grass runways, its a CHALLENGE on any harder smooth surface.. or should I say nearly impossible? :P

One of my preferred setups is to run the rudder with a servo. Then have another short control rod run from the rudder to the tail wheel steering arm, I use a semi flexible piece of plastic control rod. If you mount the rod close to the surface of the rudder, and further out from the pivot point on the tail wheel.. you end up with a slow forgiving steering on the runway.. and still have plenty of rudder in the air.


And the flexible steering rod helps protect your servo like a servo saver..
Old 11-25-2012, 09:05 AM
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flyinwalenda
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Default RE: Radical tail wheel idea

Depending on the plane two words typically sum it up.......Ground Loop !
Old 11-25-2012, 10:12 AM
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da Rock
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Default RE: Radical tail wheel idea

Radical idea?

Lots of full scale tail draggers have 'loose wheels' in back. A lot of them have a way to lock 'em too. How many have steerable tail wheels? No that's a radical question.
Old 11-25-2012, 10:15 AM
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Default RE: Radical tail wheel idea

Hi!
Like the Spitfire for instance! Only locked the tailwheel at take of.

I have used it on many models during my 36 years in this hobby.
Old 11-25-2012, 10:35 AM
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Gray Beard
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Default RE: Radical tail wheel idea

Nothing radical about it at all, it's done all the time, so are fixed skids. A lot of the smaller electric ARFs come with the free turning tail wheel.
Old 11-25-2012, 12:01 PM
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bogbeagle
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Default RE: Radical tail wheel idea

Castoring tailwheels allow you to manoeuvre in very confined spaces. You can "stand on the brakes" and spin around the main wheels.

Other than that, they are bad news.

IMO.
Old 11-25-2012, 12:13 PM
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Chad Veich
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Default RE: Radical tail wheel idea

Yes, castoring tail wheels are common on full size airplanes. So are differential brakes! That's what allows them to be common on full size airplanes. Despite some success in a modicum of applications there is a reason why they are NOT common on model aircraft. That's my .02 cents anyway.
Old 11-25-2012, 12:52 PM
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partisan
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Default RE: Radical tail wheel idea

Well, it's on a GP extra 300 .60 kit. I will leave it as is. I fly off of grass and it isn't what you would call a smooth field. It is also windy sometimes and I think that would make it harder to taxi with a cross wind.

At least with it steerable, I can give full up elevator when taxing and push the tail wheel into the ground to help in the wind.
Old 11-25-2012, 02:16 PM
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kwblake
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Default RE: Radical tail wheel idea


ORIGINAL: Chad Veich

Yes, castoring tail wheels are common on full size airplanes. So are differential brakes! That's what allows them to be common on full size airplanes. Despite some success in a modicum of applications there is a reason why they are NOT common on model aircraft. That's my .02 cents anyway.
DC-3 or C-47 for one very common one.

Old 11-25-2012, 02:46 PM
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THERCAV8R
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Default RE: Radical tail wheel idea

.
Old 11-25-2012, 06:23 PM
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OliverJacob
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Default RE: Radical tail wheel idea

+1 on the full scale plane you have left and right brakes, even with a steerable nose wheel you have to use one brake sometimes to make a turn.
Some small airports do not have taxiways and you need to turn around on the runway.

I would think a castering wheel might be hard to control, it depends on it's geometry, the weight of the tail, the rudder size and deflection and the amount of air...or better - every plane is different.

Maybe worth a try, but a steerable wheel gives you better control


Old 11-25-2012, 07:16 PM
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Default RE: Radical tail wheel idea

Most, if not all of the first generation of trike-gear airplanes (P-38, B-25, B-29) did NOT have steerable nosewheels. They simply free-castered. This only works if you have brakes that can be applied only to one side or the other to force the airplane to turn. A free-castering tailwheel works the same way. Without the brakes, turning will be haphazard at best and the airplane will decide the direction of the turn at least as often as the pilot does. Just to make matters worse, a taildragger on the ground is directionally unstable to begin with. Letting the tailwheel do as it pleases is akin to shooting an arrow feathers-first.
Old 11-25-2012, 07:20 PM
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Jetdesign
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Default RE: Radical tail wheel idea

I may be missing something, but I don't see an 'advantage' to a castoring tail wheel on a model airplane, other than for scale appearance.
Old 11-25-2012, 07:29 PM
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Default RE: Radical tail wheel idea

I use a castoring tailwheelon nearly all of my models at some point. The only issues with it are.

1. If you have a small rudder or very little rudder deflection, ground handling is nill.
2. If the crosswind is really strong, ground handling can be a bear.

Otherwise, i dont have a problem with castoring tailwheels.
Old 11-25-2012, 07:33 PM
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Default RE: Radical tail wheel idea

I did that once and only once. My idea was to keep stress off the servo gears, it wasn't worth it. I had to go back and hook it up.
Old 11-25-2012, 08:11 PM
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PLANE JIM
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Default RE: Radical tail wheel idea

How about a crosswind landing gear like the Cessna 195?
Old 11-25-2012, 09:18 PM
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John Sohm
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Default RE: Radical tail wheel idea

I tried it once on an Ace 4-40 Bipe just to see how it works out. It was interesting to say the least. Pebbles were a pain in the ***** as was any form of crosswind. With no brakes on the planes, it was a real pain and I swore I would never do it again.

I do remember having a Futaba AcroStar 60 that had an interesting setup. The rudder hingepin went all the way through the fuselage and exited the bottom. It was keyed and had a bellcrank on it that had a spring on each side that attached to another bellcrank on the spring loaded tailwheel. The springs took up any shock to the wheel protecting the servo gears from any direct shock. I thought it worked very well. I tried to upload pictures but got a "500 - Internal Server Error" message. I'll try later.

Old 11-25-2012, 11:22 PM
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eddieC
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Default RE: Radical tail wheel idea

Castering nosegear on fullsize twins work very well. Real pilots use differential power for turns, and brakes for mistakes. [8D]

For our small taildragger stuff, it depends on the aircraft and its geometry, fin/rudder size, etc. i have an Extreme Flight profile Edge 540 60-size with free-swivel tailwheel and it's well-behaved. But it has a huge rudder...
Old 11-26-2012, 05:51 AM
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JohnBuckner
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Default RE: Radical tail wheel idea

The majority of general aviation full scale twins actually use rudder pedal coupled nosewheel actuation although there are just a few with limited swivel nosewheel and rely entirely on brakes. Of course brakes and differential thrust are used as additional aid in ground taxi of most all.

Plane Jim the Crosswind gear you are refering to Allows the taildragger Maingear (not the tailwheel to pop out of forward position into predertermined indents This allowing the pilot to land in compelely crabbed position much like the legendary Ercoupe which utilized a main gear with an extended trailing link to allow it to be landed in the same manner.

I have flown both C-195 as well as c-185 which had the aftermarket Goodyear crosswind gear installed and it was to say the least unique with the required crosswind technique. The worst situation was pedaling into an excessive sharp turn while taxing and worn spring ratchets would allow both mains to pop to the outwards position.

None of this really applys to the original posters question though and it is my opinion that a fully free swiveling tailwheel on a conventional model taildragger will cause excessive ground handling problems. While yes on some over powered types that typically are off the ground in a few feet are not a problem but most others are.

This problem with the free swivel tailwheel is made worse with the type of runway surface with the grass being the least problem but hardpan earth and of course hardtop or concrete the worst case.

For the fellows who want to use a swivel tailwheel I always recommend a drip of CA in the bering block to make it non steering or swivel or even just a tailskid. Agine just my opinion even a tailskid is preferable to a free swivel tailwheel in the majority of cases.

John
Old 11-26-2012, 10:06 AM
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Default RE: Radical tail wheel idea

I tried it once. Ground handling was atrocious. Even the slightest cross wind would make the plane weather vane into the wind and there was no way to control it. The rudder could not ovecome the force of the wind. Maybe making the rudder the size of a barn door would have helped, but making the tail wheel steer helped even more. I see no reason to try it again.
Old 11-27-2012, 04:34 AM
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Default RE: Radical tail wheel idea

I haven't done it...I've seen it done...works ok with power on but slower taxi speeds aren't so good....did ya all know that the A-4 Skyhawk was a free castoring nose wheel? yep no nose wheel sterring.....differental breaking and aileron into the wind landing with a cross wind.
Old 11-27-2012, 05:14 AM
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JohnBuckner
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Default RE: Radical tail wheel idea

DC-6B had a large knob by the pilots left knee that provided power steering for the nosewheel. Separate and uncoupled ground steering for RC proabably not a great idea though[8D]



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