D40 Flying Wing - by me not Joe Manors

[Peter Garsden]

About 3 months ago my D40, which is only for the mad, insane, and requires barbiturates upon landing to calm down, crashed. Something had gone wrong with it - don't know what, and it had become uncontrollable. I think there were stress cracks which had affected its stability. I am not sure.

I never found the fuselage front which was buried somewhere in the field. I thus lost the 4 cell AAA battery but retrieved everything else. The fuselage was a write off.

Johnnie Vaughan saw the damage and said , "Why don't you make it into a flying wing?" - there grew the germ of an idea.

The wing is slightly damaged and needs some filling etc.

I took out the lead from the wing tips as this will not be for Dynamic Soaring.

I bought some very thick lining paper to draw up the plans for a fuselage.

Edited By Peter Garsden on 07/03/2019 17:55:42

[Peter Garsden]

The original fuselage is built like a brick s**t house using kevlar and carbon, so will my replacement fuselage. I am going to do a lost foam version using blue foam then dissolve the middle with acetone.

I am going to make the fin out of 1.5mm carbon sheet which should be light and thin.

The fuselage will be a mixture of kevlar for the nose and fibreglass behind the wing with reinforcements of carbon.

Don't know if you can see the fuselage shape

This is a 4 cell AA battery but I am going to use a 4 Cell AAA battery, just making sure there will be enough room.

Edited By Peter Garsden on 07/03/2019 18:00:24

[Andy Meade]

What wing section was the D40 Pete? Looks interesting, always good to re-use and re-purpose

[Peter Garsden]

Posted by Andy Meade on 08/03/2019 09:35:05:

What wing section was the D40 Pete? Looks interesting, always good to re-use and re-purpose

Don't know Andy. It is made by Joe Manors and I can't find any information on it. Thin and very strong is all I can say.

I have shortened the length of the fuselage behind the trailing edge because it didn't look right. I have also slimmed it down a bit, but may do more.

1.5mm carbon sheet was a. Expensive and b. Far too heavy, so I have returned it and re-ordered 0.5mm sheet which is still strong enough but much lighter.

More soon.

[Peter Garsden]

Well I have now amended the plan to make it look more proportionate. I have shortened the fuselage both in front of, and behind the wing. I also narrowed the fuselage in top view. Hopefully it will now do as I have cut out the side, top and bottom templates.

I have cut a piece of blue foam with my serrated Japanese Saw, marked centre lines on all 4 faces, end lines, and carbon copied the top and bottom cardboard template ready for cutting. I have marked lines every 30mm so as to call the cutting progress top and bottom, when I go for it with the hotwire

Obviously I have the wing from the D40, which I have programmed as a flying wing with coupled flaps and ailerons, and both moving as elevons. Took a while to figure out the programming but we got there in the end.

[Peter Garsden]

Made a bit of progress yesterday with another pair of hands to cut out the blue foam blank for the fuselage plug. I used my trusty smaller hot wire cutter turned up to quite a high setting.

As you can see I marked off the templates with numbers each side to make sure Keith and I were cutting at the same speed. We called out the numbers as we cut.

We then had to turn the template over and somehow keep it together for the other plane cut. I did this by taking the other set of pins out (they would have bound the cutting wire in the other plane, and held the block together with masking tape.

Turned out pretty well. Now have to sand it round to shape then cover in parcel tape.

[cymaz]

Look forward to the dissolving with acetone. Moulds have always intrigued me but never had the patience to make one.

[Peter Garsden]

Don't remind me of the acetone dissolve it is the most dreadful thing imaginable.

[Peter Garsden]

One has to be careful sanding down the blue foam so as to avoid parting the foam with the sanding strokes. I tried to sand the end of the fuselage with the sanding disc but it was too brutal so I patched it and it is fine. Now for the wrapping of it with parcel tape.

[fly boy3]

I have also read that care must be taken when sanding blue foam. A mask would help. Cheers

[Alan Gorham_]

I've enjoyed watching you put this fuselage together Pete. You might have seen on another thread that I'm on a quest to find blue foam: it seems to be out of production. Where did you get yours from?

[Peter Garsden]

Posted by Alan Gorham_ on 29/03/2019 08:43:44:

I've enjoyed watching you put this fuselage together Pete. You might have seen on another thread that I'm on a quest to find blue foam: it seems to be out of production. Where did you get yours from?

Blue Foam - oh I bought this job lot about 5 years ago as a job lot. There was seller on Ebay selling in bulk, and I bought loads of it. Still got a lot left. Sorry.

[Peter Garsden]

Yes indeed a mask - didn't think of that but that would be prudent indeed so. Still alive and not coughing though.

Anyway, I have assembled my trusty cradle and attached it to the bench to support the fuselage.

First layer will be 150gram Kevlar - super strong. Didn't show this but first I ironed on some brown parcel tape to stop the epoxy damaging the foam.

I then wiped it in wax.

I then used some 3M spray adhesive to attached the kevlar to the mould and when covered hung it on the cradle. I applied some resin and covered it in peel ply to dry.

[Alan Gorham_]

Thanks Pete, was worth asking. I think I'm going to try some of the new grey foam that is replacing blue.

Are you sure you needed to put brown tape over the foam? I used blue foam for the nose, spinner, wingtips and radiator on my Hurricane and glassed straight onto the foam. It's polyester resin that eats foam.

[Peter Garsden]

Good question Alan - if you use brown tape covered in wax it makes the inside easier to get out when you pour in the acetone. Otherwise the epoxy would eat into the foam and it would be a bigger mess with a very serated fuselage inside. The tape just pulls out with the rest of the gunge giving you a smooth finish to glue to. In fact it ends up a shinier surface than the outside.

Incidentally the peel ply has worked really well giving a nice smooth surface for the next layer of fibreglass which will also be 150 gram, then a final layer of 80 gram. The peel ply also absorbs some of the excess resin which otherwise you would dab off with kitchen roll.

I think I am going to glue the next layer of cloth with spray adhesive as well to stop it sagging whilst it dries.

Edited By Peter Garsden on 02/04/2019 08:20:26

Edited By Peter Garsden on 02/04/2019 08:44:01

[Alan Gorham_]

That makes sense Pete, I can imagine anything that makes getting the foam out is easier and less messy is worth doing.

I have used PeelPly three times now when glassing balsa sheeted models and I agree it's very worthwhile using.

[Peter Garsden]

Well I have finished all the layers of cloth and resin

1. 150gram Kevlar
2. 150gram Fibreglass
3. A carbon ribbon down each side avoiding the frontal area where the receiver should be.
4. Final layers of 80 gram Fibreglass
5. Thick coat of Epoxy Resin and Microballoons which you can see in the photo. This I will sand down to a thin smooth coat with a horn shaped sander,

Then its goo and acetone time - not looking forward to that one.

[Peter Garsden]

After a pause spent repairing some ARTF Power Models I fly at the Caravan. The problem is it is on the beach and the salt destroys everything. Servos pack up and motors go rusty. Pain.

So have now sanded down the filler above using a domestic shoe sander and my hand Proxxon model shoe sander which is amazing.

The worst part was the acetone and trying to get the foam out of such a small space. Acetone, poking with sticks and mess. I made the mistake of sealing the nose which I shouldn't have done. There is still a bit of tape in there but it will be fine as if anything it will take a slug of lead.

The biggest difficulty was sanding the Kevlar because it doesn't cut. Stops bullets but doesn't sand. You have to cut it, and it blunts blades very fast.

You can see that most of the filler has been sanded away and made for a smooth surface.

You can see the ragged edges of the kevlar here. This is where the acetone went in. Although I used latex gloves, acetone dissolves latex - problemo!

Bit of fiddling and the wing is in position with the existing tongue under the front of the canopy as per the original. The beauty is that as it is a flying wing the incidence doesn't matter - as long as the fin is in line. I still don't believe it will actually fly, but we will see!

Still a bit of filling then paint and finishing off, and how to cut the carbon fibre fin first time accurately because there will be no sanding it. Dremmel done very carefully over a shape marked out on masking tape with a carbon template is the plan.

[Peter Garsden]

I cut out a piece of 6mm ply and installed a T Nut. I then dipped the bolt in Vaseline and let it set. Unfortunately I think it is at the wrong angle. I should have lined up the wing.

[Peter Garsden]

Next painting the wing with rattle cans - I was planning to make a pretend carbon effect with floor liner but it didn't work.

Black first after, of course, some coats of grey undercoat.

This is the shelf liner which you lay over the top and spray through - at least that is the theory.

This shows the silver sprayed over the liner before the reveal

I don't know what went wrong - maybe too much paint but it didn't work. I am going to just use black instead. Not to worry but worth a try.

[Peter Garsden]

Have reverted to plain black with fluorescent wing tips. Will also put the same decoration on top of the fin. I am still doubtful whether this will ever fly after all this effort. Fingers crossed.

[Peter Garsden]

Stages since the last photo

1. I cut out the fin from .5mm carbon sheet using masking tape and a cardboard template. I keep changing the shape of the fin.
2. I cut a slot down the middle of the fuselage with my dremmel.
3. I put the fin in position, and the model just didn't look right. They say "if it looks right it will fly right", so I still have the old tailplane so decided to make it into a conventional model.
4. I was up Rushup Edge talking to the boys up there who make and design their own mouldies! So they should know? Jonathan Wells has his own design flying wing which goes like stink. They were saying that to avoid it being twitchy, the root chord has to be thick. When I looked at my flying wings they are all designed that way. The D40 is twitchy enough as it is, so I thought, hmm......
5. I cut a slot in the fuselage at the rear to take the tailplane. I went for 0 degrees incidence. I hope that is right ie lined up with the wing. Any thoughts?

I think the carbon sheet looks really good. I have repainted the tailplane black (it was white with blue and yellow trim, which I could never see against the sky anyway.)

The slot was a bit hit and miss, and I am going to have to fill the gaps.

I think one of the problems with the old D40 was that the horn had previously broken and had been ground down so the attachment was really close to the surface. I think it put too much strain on the tailplane and moved it in flight, so I have made a new horn which will be better, I hope.

As my fuselage is intentionally slightly deeper than the D40 there is space for a 12g servo - Emax - very cheap and metal geared. Hopefully it will work OK.

I have installed a 1.5mm carbon rod and sleeve left over from a previous smash with the Willow, and I think it will work well. Metal Clevis on one end and a bent over wire at the tailplane.

[conrad taggart]

Peter enjoying this thread a lot. Looking really good - love the "carbon Fiber" tail !

[Peter Garsden]

Thanks Conrad.

I have changed my mind over the elevator connection and gone for a small ball and socket attachment which will slide over the 2mm carbon rod and be neater. I have put some thread lock on the nut to keep in situ on the horn.

[Peter Garsden]

Just thought I would show you the elevator connection. After some coats of paint and varnish it needed freeing up as it was binding. In the process I wrote off a servo. I hope it will be strong enough. We will see.