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Rudder and tail wheel control horn

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Chris Walby19/06/2017 14:30:51
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1325 forum posts
332 photos

Advice please.

I have a BH Mosquito that uses a long tail wheel rod that goes through the tail wheel bracket (plastic block), through the fuselage through a steering arm and then up through the fuselage bent 90 degrees with the rudder (epoxied in).

The issue is no matter how tight I do the screw the steering arm slips on the tail wheel rod on the bench and moving

it about.

No a problem if the tail wheel moves, but as its part of the rudder I don't fancy flying with a large dose of rudder in set on way and my thumb on the stick in the other!

Options

Take the screw out, Loctite the arm and a long grub screw in place

Try in the very limited space to move the arm an file a bit of a flat on the tail wheel rod

Engineer it so the tail wheel is not part of the rubber/steering arm assembly

Anything else?

Each option has some merit and a downside, but what have others done with success?

Thanks for your time

Denis Watkins19/06/2017 14:58:31
4632 forum posts
129 photos

dsc02120.jpgOne solution

A picture is worth a 1000 words

The mount is added upside down to hold as a bearing

And the tiller passes through  a grommet for strain relief

dsc02119.jpg

Edited By Denis Watkins on 19/06/2017 15:01:48

Chris Walby19/06/2017 15:32:42
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1325 forum posts
332 photos

Dennis, thanks for the post, I' take a photo and then you'll see the problem I have!

Chris Walby19/06/2017 16:20:47
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1325 forum posts
332 photos

tail wheel.jpg

Denis Watkins19/06/2017 17:10:02
4632 forum posts
129 photos

Right Chris, thanks. Mechanically your wheel lever is longer than your control horn, so the wheel has a

Mechanical advantage over the control arm.

I have, in the past, on thin bar like this, replaced the soft Philips screw with socket cap head bolt that allowed greater tightening,

and reduced the advantage at the wheel by shortening that leverage.

Alternately, the whole assembly could be built up and bent to shape from thicker piano wire

And a flat area ground on for the control arm location

Chris Walby19/06/2017 18:23:58
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1325 forum posts
332 photos

Cheers, the issue is compounded by the fact that tail wheel rod is also goes up into the rudder.

Plan A unless anyone would like to chip in, Replace the screw for a Allen cap head and Loctite it on.

Other options seem to require significantly more/complexity, but if I do then move collar up & remove tail wheel, then fit castor type behind original.

Despite having both props in same direction it does not yaw on take off so a bit of rudder & castor wheel should be ok.

Martin McIntosh19/06/2017 20:12:33
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3544 forum posts
1220 photos

Simply cut the rod, bend it to hook and fit a spring from the hook to the rudder, fixing the end into the rudder with a self tapping screw. Works great.

Denis Watkins19/06/2017 20:14:57
4632 forum posts
129 photos

Keep the steering Chris

A twin will castor all over the place

Ground loop for sure

Former Member20/06/2017 01:03:16
3577 forum posts

[This posting has been removed]

Former Member20/06/2017 08:12:33

[This posting has been removed]

Chris Walby20/06/2017 10:44:33
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1325 forum posts
332 photos

Cheers chaps there are some good ideas, I'll stick with option A for the summer and book her in for some bench time in the winter for a more elegant & permanent solution.

Chris

Peter Coleman 104/08/2018 14:38:17
1 forum posts

Hi Chris, I have exactly the same problem with my BH Mossie. What a kack design! Seeing as I bought the plane secondhand by unflown is probably why it is still in one piece as I saw another post where the plane spiralled into the ground on its maiden. Problem is once the plane is built you can't get this horn out so I have opted for filing a flat on the bar to stop it from turning. How did you fix your problem? Peter.

Biggles' Elder Brother - Moderator04/08/2018 19:11:16
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Moderator
15748 forum posts
1460 photos

Another possibility might be is to provide separate servos for the rudder and the tailwheel and put them on separate channels. You could then do the file a flat on the tail wheel trick. Mix it in your tranny so the tail wheel is a copy of the rudder (not the other way round!) and bob's yer uncle, no danger of a mechanically stuck tail wheel pulling your rudder over and no dodgy epoxy joint between the tailwheel and the rudder system.

BEB

dave windymiller13/08/2018 22:27:53
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113 forum posts
149 photos

Be warned.

If a tail wheel can cause the rudder arm to slip, 100% it will on the first bump. The mosquito flight will be very short! ask me how i know.

I bought this nice model off the estate of a fellow club member but this one fault has been its downfall (3 times). Each of my improvements proving inadequate.

The grub screw was swapped for a cap head screw but even this didnt give enough grip. Loctte also failed. Mine has now a cap head screw locating onto a flat on the shaft, holding a solid brass arm and has been silver soldered too.

Best solution is independant tail wheel servo which i will try if theres another iteration of this problem!

The mossie now sports an easy to repair night fighter black with home made spinners!

imag0087.jpg

 

imag0234.jpg

 

Edited By dave windymiller on 13/08/2018 22:32:59

Chris Walby14/08/2018 06:28:15
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1325 forum posts
332 photos

Nice one Dave and glad to hear you have (hopefully) sorted an inherent issue with this model.

I have to admit that I done nothing yet as I don't like the idea of all the aggravation of another servo and the consequential grief to get the C of G back to where it should be.

If you have any photos of your mod it would be appreciated.

PS what set up are you running?

dave windymiller15/08/2018 13:20:25
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113 forum posts
149 photos

Unfortunately I cant show any photos as its hidden inside the fus until its next crash!

Im not sure of the plan its built from but I think its an adapted version of the BH plan. Its 69" span and the fus is in two sections, the rear half is stepped behind the wing and behind the cockpit. Its got 2 X la40s swinging 10x5 3-blade props from master airscrew (about 3 quid each from hobbyking via hongkong!) .

When it all goes well its beautiful in the air. I have the ailerons up a few degrees to prevent tip stalling plus both engines point outwards a few degree to hopefully minimise yaw on a dead engine. Its got no flaps! It did have a clear nose section but since its first crash, its now the fighter solid nose version(never got round to adding cannons). The eagle eyed would spot the wrong canopy for the NF version!

It became a labour of love after 3 rebuilds!  I felt I owed it to Tony Bowler (RIP) who built it.

Edited By dave windymiller on 15/08/2018 13:25:41

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