First generation acrowot tail fin

[Morgs]

Hi all can anyone help me, I've completely snapped off my tail fin on my acrowot there is no damage to fin but where the fuselage tappers down to fin needs replacing both sides. So need plenty of advice from the experts please on the best way to repair it please.

[Ronaldo]

Would be helpful if you could post a photo of the damage Mark.

[bert baker]

Clean it up as best as possibly and glue it back on

[kc]

Presumably this is the kit built 57 inch balsa version? Those of us canny enough always draw around every component in the kit onto a bit of lining or wallpaper before starting construction. Then every component can be made again or even a complete model. So someone will have every component drawing for this popular model. But just gluing the remains back together with some slight reinforcemment may work well enough.

At the top of this page you will find 'Features' then' Building technique ' then Don't Bin it Fix it' which is Peter Millers guide to fixing broken models. This covers reinforcing the broken parts.

[Bruce Collinson]

Keep it light.

BTC

[Morgs]

Thanks for your responses tried to upload photos but can't work it out, fin is complete just needs gluing back on and a repair to one side of the rear fuselage.

[Morgs]

Thanks kc found the Peter Miller guide I'm on it

[Morgs]

finally worked out how to upload pics lol, would thick ca sort it.

[Jon H]

I would probably glue it straight back on with some epoxy and then sort out the missing parts after that.

[Peter Miller]

You can use thick CA but I would reccomend Aliphatic resin glue. THis is more gap filling. IT is also much harder that PVA when set

I would also get some1/4 (6mm) dowel and insert a couple of pegs in the base of the fin and drill matching holes in the tailplane.

This would add reinforcement in the event of a future tumble.

[David Davis]

I agree with Jon. Glue it back in place with epoxy then find some light balsa block, cut it roughly to size, glue the block into position and shape it to the fuselage contours. The covering looks like Cub Yellow to me.

[Nigel R]

I would use epoxy to stick the fin on. Then some soft block to fill the missing area on the one side of the fuselage.

[Morgs]

Thanks everyone.

[alex nicol]

Agree with above, epoxy the fin back on and make sure it is straight. If you have the other broken bits glue them back in and it'll be fine. Alternately if you don't have the broken bits make a rectangular block from some very soft 1/2inch balsa sheet, carve and sand it to fit and you'll be good to go. (speak to clubmates somebody will more than likely have a bit of scrap balsa that'll do the job and should be able to give you a steer)

[kc]

I see that in the original Acrowot instructions there should be a hinge on the rudder very near to and slightly above the rudder horn. There seems to be no sign of it in your photo. Make sure you replace this hinge - perhaps choosing a nearby alternative position to avoid digging out the old hinge if it ever existed.  No sign of it being pinned unlike the other hinges which are clearly pinned.

Edited By kc on 22/01/2020 11:12:02

[Martin Harris - Moderator]

Don't forget to re-check the C of G before flying - additional weight added while repairing/modifying at the tail can shift the C of G significantly.

[Morgs]

thanks all, where is the C & G on the Acrowot.

[kc]

These sort of repairs are so much easier if you collect all the bits of balsa .......with the missing bit it will just glue in and look almost like new. Without it's quite a lot more work. Easier to look around for the missing curved bit!

Without the hinge by the rudder horn any blow to the rudder or even using the rudder in the air will tend to pull the fin to one side. With a hinge in the fuselage itself it will help a lot.

Cof G in the origiinal 57 inch is shown as three and a quarter inch back -plus or minus one quarter inch- measured from bulkhead ( dowel hole bit)   Thats 82.55mm plus/minus 6.35mm I think.  

 

Edited By kc on 22/01/2020 13:43:48

[Morgs]

Will put in that hinge when I repair it, also got missing piece but some of it missing.

[Bob Cotsford]

that will glue back together easily enough, then a dash of filler before patching the covering if you want it to look posh. As kc said, it really does need that missing bottom hinge fitting.

[Morgs]

Is it best to glue fin on first then the sides, or do sides first then the fin. Or do it all in one go.

[Denis Watkins]

Posted by Mark Morgan 2 on 22/01/2020 17:04:39:

Is it best to glue fin on first then the sides, or do sides first then the fin. Or do it all in one go.

Dry fit 1st Mark

Make sure that all the bits fit back in place without undue force

Then rehearse your best assembly tactic and lay the parts in order

I then wipe all contact surfaces with epoxy

Assemble

[kc]

First fix the ( new, lower ) hinge into the rudder and arrange matching slot in fuselage. Hinge must be inline with the other 2 hinges to avoid binding. Slot in fuselage must be central otherwise the fin wont be inline.  Let the hinge glue set on just rudder, pin the hinge then glue the fuselage side when you install fin. Pin fuselage side later.

The fin needs to be down the centerline and square to the tailplane so that is probably first, but glue the curved fillet part on while the glue is still wet, otherwise a lump of dried glue may displace the fillet. The fillet piece needs to reinforce the fin. A slow drying glue like PVA or Aliphatic will give time to get precise alignment but will need pins or something to stop the fin sagging whilst it dries.

I pin hinges with cocktail sticks sharp end thro drilled holes, thro both balsa and hinge. When glue dries I nip the excess length off. Nail clippers work ok to nip the ends off but eyeprotection is needed as the bits fly off.

Edited By kc on 22/01/2020 17:38:27

Edited By kc on 22/01/2020 17:42:21

Edited By kc on 22/01/2020 17:49:27

[Bruce Collinson]

Anyone said, clean off all glued surfaces with solvent last thing before gluing up? Particularly if I/c powered.

BTC