Antonov AN 124 Rusian

This is getting very tedious.

Super wobbly so the initial planks will have to be very narrow.

Printed parts have a serious drawback. You cannot sand them 'to fit' like you can in balsa or Depron. It just has to be modified in CAD and reprinted even for just 1 mm so nearly half the formers needed to be reprinted. Of course it just had to be the big and complex ones!

Just as well it is going to pour for the next few days.

why can't they be sanded? looking good though

paul
Even PLA is pretty hard, harder than hard wood, so sanding is very slow assuming the structure is rigid enough to stand it. Go too fast or hard and the temperature generated causes it to locally soften (at just 50 C) which completely gums up the sand paper.

ps Thanks to Addlestone Models I now have 5 sheets of white 3 mm Depron.

oh ok, didn't realise that!
glad you got your depron..

The result of almost a day slowly planking the nose.
It is temporarily fixed to the fuselage to ensure it matches. Once the planking is complete it will be cut free.

As I feared the initial planks had to be narrow and highly tapered to stand any chance of keeping the nose to shape.
The nose is now much less delicate so the planks can be bigger but each has to accurately fitted and hand formed to shape as much as possible so progress remains slow.

At last the planking is complete and the nose itself cut clear.

That nose has 33 individual planks all different.
Still needs some pegs adding so it locates accurately. It will be held on with magnets.

As white will not cover the grey Depron well the colour scheme will have to change a bit.
Silver covers almost anything easily so much of the new nose will be silver!

The yellow circles show the two nose retaining pegs.
The underside of the whole fuselage will be ultramarine blue as before.

Started thinking seriously about retaining the 'plug in' wing panels.
The wing tubes do not pass into 'fixed' tubes but simply passes through 3 specially reinforced ribs. In the course of measuring I discovered that one of the tubes is ominously short and only just enters the 3rd rib. It of course on the side that failed.
That 'short' tube needs to be extended by 10 mm so its retention will be much less critical. I do have a potential way of doing this so I might as well do both sides.

After much deliberation and testing I have finally come up with a wing retaining solution using a 10BA bolt and some small printed parts that required the least structural modification.

A clamp body is glued on the inside of the centre section wing rib which only requires a small hole to be cut in the wing skin. The 10 BA bolt 'pinches' on the existing outer wing panel front locating pin once the wing is in place.

When complete the only external feature is a small hole in the leading edge to give screwdriver access to the bolt head. The bolt has a long thread (20 turns!) and as it only has to be 'tightened' on the pin it should never need to be completely removed. A loose10BA bolt is not field friendly!

On the principle that drag would be most likely to cause the wing to move securing the front pin should securely retain the wing but of course the wing spar tube can still simply fail under 'g' loading.

Now I have just got to do the other side.

Well done! a lovely neat solution Simon, can't wait to see it fly again.

paul d wrote: Well done! a lovely neat solution Simon, can't wait to see it fly again.

Ditto that. Necessity is the mother of all invention, as they say.

Thanks for the kind words.
The problem with those really close up shots (that bolt hole is just 3.5 mm diameter) is it make you realise just how 'rough' the Depron surface actually is.
Some work with a fine sandpaper required.

With the other wing retained much of the primary structural work is done so painting can start.
The removable nose is virtually complete.

Just the magnets but thinking about it a "10BA bolt clamp" as on the wing but gripping the upper nose peg would do just as well.

I have started to think what to do with the white 3mm Depron.
I rather fancy building a new fuselage for the V-1 but using printed formers (easy as they are all circular and all the remaining parts are usable) as it would mean the Depron would only be used for the skin. Lots of big formers actually use up nearly as much sheet as the skin!

Q. Why don't you save the depron & build it in balsa. You know that pulse jet you just happen to have laying around !

crash happy wrote: Q. Why don't you save the depron & build it in balsa. You know that pulse jet you just happen to have laying around !

I Agree!