Precedent T180 Restoration

Probably relying on the fact that the centre section is sheeted Eric.

OOPS - I thought we were on about the MAINplane, not the tail!
Balsa and fully sheeted will be strong enough.

Build progress. Nothing glued yet, and won't be till I'm sure all the fit is right.

When I place the old tail on the plan, it's about 5mm narrowing from front to back. So I think the plan might be scaled slightly. But I don't suppose it'll matter much as it'll all be built off the same plan.

I'm considering doubling up the ribs in the center section to strengthen it, as I've read the tail is a weak spot on this model.

On the topic of glue, my plan was to place all the ribs, then spot the ends with thin CA where they join the spars. I've seen that done.

Is that a sensible approach?

I wouldn't worry about the plan being a very slightly different size. They can grow or shrink by a small margin during the reproduction process.
Unless the printer specialises in model plane plans they will worry more about the quality if the printed lines rather than maintaining the same overall size.

Would adding ribs actually increase the strength of the tail section? It very much depends on the 'what, where and how' it fails as to what will provide the extra strength.
It is that middle spar and any sheet covering that provides the majority of the strength rather than the ribs. Ribs primary function is to give the wing its 'shape'.

Ah, ok. I'll not double them up then. It seemed like the damage was from the tailplane "ripping" off the fuselage. The tailfin slots into the tailplane. But it seemed to be mainly the sheeting that was attached to the fuselage with 2 spars running along the sides.

I have a plan to extend the tailfin down through the tailplan more, into the fuselage to secure it. I'd built some foam planes that way.

I'll try drawing it out beforehand and get some opinions.

Personally I wouldn't use cyno, it's brittle, I use a good quality wood glue, I've currently got a bottle of evostik "resin w" and bottle of gorrila glue on the go, both excellent products.

Thanks. I see CA being used whenever I watch build videos, so it seems everywhere. But I test fitted a hinge to a spare bit of balsa using CA, and it instantly stuck - in the wrong place. So I'm a bit hesitant about using it for that reason and ruining the build.

I have a bottle of the white Gorilla Glue, and some Zap 5 minute epoxy. I've also seen the brown Gorilla Glue in the local shop, but I think that's an expanding one good for filling gaps.

The white one is the one to use. Don't forget to cover your plan with clingflim !

As said, CA is brittle, and only bonds the very outer skin of the surfaces, so tears off again easily. I use it on hinges, but I drill through the wood and the hinge plastic from underneath , and dribble thin slow ca into the hole, so it can spread out in the slot.
As previously said, a drop of oil on the hinge pivots before you glue can stop the ca from sticking it solid, but it is best to keep wiggling the hinge until the glue has cured, as insurance!

Gap-filler foaming glue provides no structural strength - it just fills gaps!

Extra ribs in the centre won't do any good, unless you are strapping the tailplane on with elastic bands (for crush-resistance) - it is the bending/twisting force you need to consider.
Tailplane tearing off the fuz - use thicker wood? I assume the sheeting is 1/16 or whatever that is in these silly modern foreign measurements - which is pretty weak for tearing strength, use 1/8 or even 3/16, and maybe even a small sub-spar across the centre, extending out a couple of ribs either side to spread the load. (remember what I put about repeating the designer's mistakes?)
As Simon put, the rib only provides the curved shape, a curve is slightly stiffer across the span than a flat plate.

Epoxy glue is heavy, and you don't want extra weight at the back end of the model.

I've got tracing paper under it

I'm back to square one with the ribs.

I knew something didn't seem right, as at the TE spar, the ribs were a lot thinner than the old tail. Then I realised I'd made the rib profile of the ones nearest the root, where they're fully covered(so those 4 are usable). I need to make a new template for the partially covered ones.

I suppose this is why you mock it up and check before glueing.

CA is used because it is quick. 10 seconds and you can move on safe in the knowledge that the joint is at full strength.
Useful if you are 'assembling' a laser cut kit of parts but if you are 'building' something with parts you have made to normal human abilities having a bit of wiggle room as well a glue that provides a bit of gap filling is important. Then there is also the panic ability to undo a joint when you realise you made a mistake!
Having to leave a joint alone for glue to dry enforces the time for the next step to be carefully thought out first, in other words traditional balsa building.

What some people do is intersperse CA with Aliphatic, the CA holds it while the Aliphatic sets and gives the strength.

Take 2. Looking better this time. I'd forgot about the bottom sheet last time anyway. Everyday's a learning day as they say :lol:

I put a spar across the centre section between the ribs. I might add some thin ones along the sides of the ribs too, but I'll see how it is once it's all glued.

What some people forget to do, when they use cyano on a laser-cut frame - is to sand the edges first, to remove any charring and ash! :S