all moving tail help required

[Tim Mackey]

 Mrs T picked  up a "bargain" at the NATS in the shape of a BAE hawk for the slope - it was a pusher in anold life, but the seller converted it to glider only. Its a bit rough, and broken in a few places, but nothig a bit of work glue and balsa cant sort. It utilises an all moving tailplane which was operated via long pushrod from front mounted servo under the cockpit

( Lead has been fitted to the tail I intend to remove that, and fit the servo in the rear section).

However the surface was operated via a crummy and badly conceived ply horn arrangement which appears to have been simply epoxied onto the central axle, and this ( unsurprisingly ) has become loose, allowing a severe amount of slop - totally unsuitable.

The tail plane halves are one of the few areas which seem in pretty good structural condition, and I would like to avoid having to strip them out if possible....so...... the question to all you genius builders out there is how can I fabricate and fit a new horn onto the axle without removing it? Alternatively should / could I simply fit the servo in the fus side and fit a horn to the tailplane itself. ideas welcome. A picture of the assembly as viewed from below is attached .

[winchweight]

Tim. I have the tailplanes off of my F16. They have bushings and an arm which is then operated by a micro servo mounted on the fuselage side. Would they be any help / use? You can see them here.

[Andy Sayle]

Could you saw it in half, and then re-assemble it with a long "collet" type tube (that has a horn silver-soldered to it).  The collet would then clamp each side of the joiner using a grub screw or two (possibly gripping on some flats ground into the joiner ?

Cheers

Andy

[Tim Mackey]

Thanks guys.... Shaun, I think I will try and keep a single internal internal setup - and possibly modify the axle as per Andy's suggestion, after all, if I cut in half, then each half can be slid out and the axle ground and "worked on" before being slid back into place and joined.

If this idea fails, then I will maybe try the idea as seen in your pic - cheers.

[Bob Cotsford]

2 mm bolt through the tube  with a ball link on the end?  Is the tube large enough to take a thread?  Otherwise epoxy the bolt in.

[Former Member]

[This posting has been removed]

[Tim Mackey]

bob cotsford wrote (see)

2 mm bolt through the tube with a ball link on the end? Is the tube large enough to take a thread? Otherwise epoxy the bolt in.

Not really - only 4mm O/D solid rod. I like the idea of the 2mm threaded rod with ball link though, think this may well form part of the eventual design.

Eric...your right...sounds complicated and also appears to require two 2 "axles" and more modifying of the existing one ?

[Terry Whiting]

I was going to suggest a simula set up to that of Andy, but using brass tube only.

Cut the  rod central, find a peice of tube which is a sliding fit over the rod, about 20mm should be sufficient, silver solder  a brass horn to the tube, slide the finished item  onto one half  of the rod, then slide the tube back over the other half, centraise and soft solder in position.  

[Tim Mackey]

Yes I am still leaning towards Andys idea. However soldering it in situ may be little awkward, and I am unsure yet as to the exact material of the axle rod - I think it may be piano wire. This will be revealed when I cut it in half with my dremel and then each tailplane half can be withdrawn and I can work on the rod easier - I liked the idea of the "collet" style joiner as this also allows some retro adjustment for equalizing each T/P half. Alternatively I had considered a nice ight fitting sleeve which could be epoxied onto the cleaned up and roughened axle ends. I am also going to fashion up some new bearings for the fus sides where the axle exits, as the existing ones are merely bits of ply plate which have worn allowing slop. I think I will make up some thin bushes with a large "head" which can be epoxied to the fus inside, and allow a greater support area for the axle. I will then make the joiner tube the correct length to fit snugly between each bush - from  fus side to fus side as it were - which will prevent any horizontal movement of the assembly too.

As usual, I shall doubtless end up over engineering the damn thing, turning up new bushes and rods and threaded parts and so on on the lathe ....still keeps me happy

[Tim Mackey]

OK, update. I guess the pictures explain final job, just gotta fit the servo now ( after a quick flying session with Iawnski up the big rock this afternnon )

Seems fine, and allows me to adjust each tailplane half independantly if needed. 5 ox of lead was removed from the tail when I opend up the bottom sheeting so the weight is no problem, although I have tried to keep it as light as possible whilst retaining suffficient strength and meat for the set screws and modified 5mm bolt which has become the horn.

[Terry Whiting]

Nice bit of lathe work Tmbo, and a good tidy up.

[Tim Mackey]

Thanks Terry... yeh I just lurv playing around with stuff in the lathe / mill - very satisfying somehow turning metal.

Took me all day to just do this job, but then I do claim to be the worlds slowest model aircraft builder.