Straightening a Twisted Fuselage

[Cliff Bastow]

Hi all,

I have begun to to try and rebuild a balsa/ ply model that I crashed a year or so ago and whilst it has gone back together fairly well I have noticed that when I put in the metal wing joiner it sits at an angle in relation to the tailplane.

Does anyone have any ideas how to take the twist out? The fuselage is film covered.

I cannot cut out the tube through the fuselage that the wing joiner threads through, to relocate it, because the wings fit into profiled slots in the fuselage sides.

Cheers Cliff

Edited By Cliff Bastow on 30/03/2019 21:27:06

[GrahamWh]

If you can do so without breaking anything and if the amount of twist is only a few degrees, then you could try twisting it back straight and a little bit more the other way, then holding everything like that perhaps in a jig, go over all of the covering again with a covering iron to re-set the covering. When it is all cool, release the jig and see if it is straight again. This can work for wings that are a bit warped. It may be a fix that you have to do again after some months or if the model sits in the sun for a long time and the film starts to sag and therefore release its tension.

[Peter Miller]

How far out is the tailplane. I have seen a few models with the tailplane at an angle to the wing.They flew perfectly well.

Alternatively, can you alter tailplane seating.

I did once build a scale model of a Dornier 217 which has a fuselage sheeting with 1/16" sheet. THis got a twist in it.

I jigged it up as described by Graham and left it a full week.That got it straight.

[Cliff Bastow]

Thanks guys,

The twist is quite noticeable to be honest.

I have soaked the fuselage internally as best as I can and jigged it up slightly past where it should be and I will leave it weighted down for a good few days and keep my fingers crossed.

Thanks again, Cliff.

Edited By Cliff Bastow on 01/04/2019 13:19:53

[Cliff Bastow]

well I left it in the jig for a little over a week and all seemed ok. The twist was much less and only just noticeable. great I thought lets press on with the rebuild.

However over the next couple of days I noticed that the twist had returned, nearly as bad as before!

So I have tried a different approach. I re-jigged it again but this time I heated the inside and outside of the whole fuselage as much as I dare with my heat gun. I had to be careful of the covering as it is the pre-printed type.

I then allowed it to cool and there was a bit of creaking and groaning from the model! This seems to have worked ok but I will have to see if the twist returns over the next few days.

 

Edited By Cliff Bastow on 11/04/2019 12:05:11

Edited By Cliff Bastow on 11/04/2019 12:06:02

[Don Fry]

I have bodged to straight as follows. Please sit before reading.

Build a frame, adjustable, so a crosspiece can be screwed/clamped to the back face if the fuselage, adjust so it's now bent the fuselage in the opposite direction the the twist, at least as far as your twist is out. Now see if you can see what looks out of line, and crack those joints. If you can't see what is out of line, crack some joints, and reglue. Ease the cross piece and see see if you are straighter, replace the crosspiece to its opposite twist position, and crack another joint or two, repeat untill straight.

This is a construction secret. Tell no one.

[Nigel R]

If you can stand an amount of rebuild at this point, then removing the underside of the fuselage will make Don's Trade Secret easier and more permanent. Releasing and reattaching the top deck even more so.