Aeromaster

[FlyinBrian]

If the GF bandage you use has a thick edge cut this off before using, I prefer to cut sections from a piece of 4oz cloth than to use bandage.

If you need to blend in a GF wing bandage put sellotape or similar about 1 - 1 1/2 inches outboard from the edge of the bandage then use lightweight filler between tape and bandage. Once the filler is hard you can sand it back to a really nice finish so long as you don't sand past the sellotape.

Having said that, PVA works well too.

[Nigel R]

I was too young and impatient to think of such a simple answer as "cut the thick bit off" I'm afraid!

[FlyinBrian]

This is my current AM, the fuz is about ten years old, the bottom wing is older and the top wing was replaced due to a warp in the original

 

Last year I managed to aquire a Giant Aeromaster which I have not yet done anything with, It needs a motor and I can't decide whether to go Electric or IC, the GP original used a 40cc petrol.

 

Edited By FlyinBrian on 14/05/2020 20:30:53

[Nigel R]

I do likes a good sunburst scheme especially on a bipe.

Small step forward for my build last night, the next layer of thin glass:

[Nigel R]

[FlyinBrian]

Nigel, such a colour scheme makes orientation easier for my aged peepers. BTW those checkers underneath are not patterned film, the base colour is yellow and all the red squares were individually cut and applied.

Once you have glassed the wings please load test them, I have a vague 40 year old+ memory of a club-mate who used glass tissue having the wing fold in flight right at the join.

I look forward to seeing yours finished.

[FlyinBrian]

Just one more photo.

[FlyinBrian]

Posted by Nigel R on 07/05/2020 14:32:41:

Love the black and white pictures tosh. Could be a r real homebuilt buzzing the strip.

I'll be very happy if mine comes in under 6-1/2lbs.

You'd probably need about 900w to equal an older crossflow sixty.

I recall and engine test of an Enya 60, one of the last X flow two strokes, its bhp was 1.0 about 700 - 750 watts so 900 should equal a good schnurle engine from the early 70''s. My first had a HP61F which was plenty.

[FlyinBrian]

Sorry double post

Edited By FlyinBrian on 15/05/2020 09:13:03

[Bob Cotsford]

Posted by Nigel R on 15/05/2020 08:34:01:

I do likes a good sunburst scheme especially on a bipe.

Small step forward for my build last night, the next layer of thin glass:

I too use multiple layers of thin glass though I usually use epoxy finishing resin. I'm ready to add the reinforcing glass in the centres of my Panic wings but I'm out of resin, I do have plenty of cheap PVA though. Do you let each layer of glass dry before adding the next or do you whack them all on in one go? I'm planning on using three layers of 1oz cloth on the Panic, it's as much there to prevent the wing bands and seats digging in as to join the panels structurally.

[Nigel R]

Bob I wait until one is dry before doing the next. I would imagine the pva softens up when more goes on though so it probably makes little difference. I do a couple of coats of just pva when all the layers are complete, to fill the weave.

It's worth putting the wing somewhere warm when you're doing this with pva. It is a lot of pva going on, and I had one wing - left in the shed which was near freezing that night - where some sheeting absorbed moisture from the glue and lifted up from the structure where the wood had swelled and warped. Needed a fair amount of replacement sheet to repair it... shouldn't be an issue this time of year though.

Brian I have done a number of wings like this. I don't spare the horses in the air and no failures yet.

1hp sounds on the money. Time that 900w electric system is measured at the shaft it will have lost a bit in various inefficiencies and be down to a very similar output.

[Martin McIntosh]

Whilst awaiting the wood I have been hard at it producing the cowl and spats.

The second left side being waxed prior to making the final mould.

The cowl female mould which I expected to need to hammer and bang at to part from the plug but it almost fell off.

This was the plug it came from.

I normally mix up my own epoxy gel coat but since I was running out of resin I ordered some more along with better cloth and their gel coat . This has just arrived as I am polishing the final two moulds but is polyester resin, not epoxy, so I called them to ensure compatibility and am assured that it is fine. Been caught out before so this had better work.

[FlyinBrian]

Impressed with the moulds

[SR 71]

How did you get the mould off the cowl plug in one piece Martin

[Martin McIntosh]

Well, I have produced many moulds over the years and in fact make most of my cowls like that but this one was a bit daunting. Despite being very careful the spats seemed to stick at one edge when removing from either the wood or the female mould so I expected to be bashing away with my rubber hammer, metal hammer, bits of wood etc but luckily the ply base came away easily. I hit the whole thing with gusto and suddenly realised that it was popping out. Phew, I was expecting to have to cut the thing in half.

I have put the new to me gel coat on these last two moulds and really should be applying glass now that they are tacky but have had enough for one day.

[Nigel R]

Looking forward to seeing the end results of your glass work Martin. The moulds look great from here.

[Martin McIntosh]

Me too. Although the supplier says that the new to me gel coat is compatible with my resin I am always a little suspicious so am only doing the last spat half with it for now to see how it turns out before committing to the cowl.

The other spat is currently being joined, not an easy task although I have done it before a few times.

[Nigel R]

Ok, another layer of thin stuff on:

You can see how wide this layer is...

[Nigel R]

... and how it just covers up the patch I made in the sheeting...

[Nigel R]

That piece is 16" wide. I'd usually use one about 12" so I didn't have to add very much to hide (or is it reinforce? Reinforce sounds better!) the surgery in the sheeting.

[Martin McIntosh]

I would have thought that the PVA would end up as an unsandable surface to cover. Why not Poly-C or similar if you don`t like epoxy resin?

The first foam wing I bought came with a thick bandage and a pack of polyester resin. Some of the hardener must have leaked out of the bottle during transit because the stuff took ages to set, leaked through the veneer and dissolved the wing core!

Polyester would be an alternative to glue though because you do not have to wait long for it to set and is easily sanded. The Halfrauds stuff is fine for this. Epoxy is more fool proof.

[Nigel R]

The short answer there is that I don't try sanding it. I've not tried using poly c but I guess it should work as well or better for this job.

Did a bit of trimming of the tissue and then a dry fit of the servo:

[Nigel R]

[FlyinBrian]

Nigel - I am impressed by that wing joint

Re: the aileron servo, its a bit late to suggest this but I have found it useful to use two servos in separate rx channels to allow mixing of flaps with elevator, this tightens the looping radius, only needs about c15% mix.on my JR DSX9

I have used two servos on models with torque rods such as you are using simply by installing two servos in the centre of the wing and using each separately to drive a single aileron.

I have used diluted PVA to cover a model with glass fibre, I think it was Resin W and it was fine to sand, I shirked the painting though and finished off with Profilm, I used a quite low heat while covering and it went on well

[Nigel R]

Brian,

Thank you. Up close it still looks and feels a little rough, after just the single coat of PVA - there are some loose 'hairs' from the tissue, but when the 'filler' coats of PVA have gone on it is quite smooth, and a few swipes with some 80 grit take the stray hairs off. At that stage I have found film attaches quite well. The 'sticking' part of attaching film needs to be done a bit slower than for normal balsa, but by going slowly it works perfectly well (just like sticking it to ply or hardwood).

Resin W is quite a posh choice

I can always retrofit another servo in the wing centre as you say - I have had this setup in the past.