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Old Jan 14, 2013, 04:35 AM
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Roodepoort, South Africa
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ASH30 Mi 1/3rd scaleish

Hi All,
Just before the December shut down I started carving the plug out of foam for this build, during the holidays I made some good progress on finishing the fuselage construction as well as the wings.
Part of the design was to build a big glider as light as possible, and with the longest component not greater than 2.6 mtr so it could fit inside my trailer.
The glider is not pure scale but rather practical scale, so the wing panels for example are made to fit the trailer, the fuselage has one or two changes, like bigger wing shoulders etc, but I will paint on a join line so it looks more accurate.

I did not have drawings so relied heavily on the photo's, the 3 view and also used a drawing of the ASH 25 to help with dimensioning.
Construction is well underway at this time, but I have also decided not to build this beast with any complex methods or equipment, even the wings are direct hand layed up, with out a vacumn machine, and bagging.

Here are some abbreviated build thread photo's, anybody want to see something specific I am sure I have some more detailed photo's .

regards
Mike
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Old Jan 14, 2013, 04:56 AM
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The fuselage

The Fuselage,
This is a lost foam ,one off , the pod is carved, fom real cheap(free) low desity Expaned Polystyrene, then screeded with wall crack filler(polyfilla brand), sanded and modelled to shape. The boom was made as a tube around a rolled up piece of mylar, the pod was taped with packagaing tape , waxed and then the pod glassed and eventually the boom mated and glassed to the pod.
The tailfin was made around a foam(blue foam) shape also taped and waxed and then released of the shape and boned to the fuselage.
The fuselage was made with 220gram UD aeroglass the boom with 2 x layers of glass and a layer of 200gram carbon. The entire outside got a layer of 106 finishing cloth after the first round of sanding.
Additional cloth around the wing shoulers, and also a layer of kevlar/arimid inside the cockpit area .
The fuselage weighs about 2.8kg with the ply formers glassed in , so for such a big glider, not too bad.
regards
Mike
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Old Jan 14, 2013, 08:19 AM
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Joined Oct 2004
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Very informative, thanks for sharing.
The 30 bumps the 25 for being the worlds best looking glider.
Too bad Schemp-Hirth designers didn't get a look at it before putting together the Arcus.

Regards Dean
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Old Jan 14, 2013, 02:51 PM
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Mike sorry I didn't find your build earlier I was sent a full set of drawings for the ash 30 including cross sections from the factory but too late now I guess.

Models looking great buy the way.
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Old Jan 15, 2013, 01:20 AM
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Roodepoort, South Africa
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wings

Hi there,
Just catching up with the build, here are the wings and how I went about making them.
Towards the end of last year I managed to get a hold of a few sheets of Dow blue foam , something very scarce in our part of the world, turned out to be Deckmate which has a nice density of about 26kg/cubic mtr, this was cut to panel block sizes and then all the cores cut .
The root on this glider is a HQ/13 2.5 the wing has this foil on the first 3 panels then it thins down at each panel break to HQ/12 2 then HQ/ 11 1.5 ETC the tip is HQ/10 1 AND HAS 1.5 degree washout and is 12cm wide.
Here are some pics of the cores the joiner tubes which are made around the carbon joiner(recycled from a previous project) they are made with carbon braid 200 gram 3 x layers and then bound with some Kevlar tow. The shear web is a spruce spar 8mm thick in the first panel, and 4mm spruce in the outer 1.6mtr panel.
The joiner boxes are fitted with an end grain balsa wedge to get the di-hedral , lots of flox/resin glues it all together.
The spars went into grooves that where cut out of the cores with a set of templates, I messed up a bit here and cut a tad to big which was easy to fix with filler but at a weight penalty of a few hundred grams.
The tows are layed up in batches of 4 and the final tally was 24 x 40k at the root and 4 at the very tip, also aiming to get some realistic wing flex on this sailplane.
hereunder some pics.
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Old Jan 15, 2013, 03:14 AM
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North Yorkshire UK, on a big hill facing the prevailing wind. Coincidence?
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Fantastic stuff Mike.

The only thing I don't quite get is that I was expecting to see the edge of the spruce webs visible, running down the centre of the spar channel before you started laying up the carbon spar caps. Did I miss something?

Also, did you cut the spruce webs to match the full depth of the core, so they actually protrude up into the thickness of the carbon cap, or just the thickness of the foam after rebating for the caps? Ugh - can't explain it in words. I'm pointing at the screen here but I guess you can't see that...

Rog
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Last edited by Sutton Bank; Jan 15, 2013 at 06:15 AM. Reason: the usual.
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Old Jan 15, 2013, 08:28 AM
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Quote:
Originally Posted by Sutton Bank View Post
Fantastic stuff Mike.

The only thing I don't quite get is that I was expecting to see the edge of the spruce webs visible, running down the centre of the spar channel before you started laying up the carbon spar caps. Did I miss something?

Also, did you cut the spruce webs to match the full depth of the core, so they actually protrude up into the thickness of the carbon cap, or just the thickness of the foam after rebating for the caps? Ugh - can't explain it in words. I'm pointing at the screen here but I guess you can't see that...

Rog
Hi Rog,
I know what you mean , I was going to use end grain balsa and carbon sock , but eventually decided to go for the spruce strip , so after the bottom carbon tow was laid up and cured I turned the wing over , and here is another lazy mans technique to high speed building, I heated a few pieces of different spring steel on a small gas camping cooker then on a test sample I cut a grove against a straight edge, found the right wire gauge , and managed to burn out my shear web groves real quick , down to the carbon spar, after fitting the spruce (note it has a join with ply support) it was marked and sanded to be just proud of the foam grove. Lots of flox mix beaded in and then I started laying up the top tows .
regards
Mike
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Old Jan 16, 2013, 05:50 AM
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Tailplane

Hi All,
Some more pics of the construction, the tailplane was cut with the SD8020
Aerofoil , the two halves joined and a piece of lite ply inset as the base for the fin attachment, this was all sanded too match the foil shape, then 3 x 12k carbon tows laid onto to leadting edge and 5 x 12k tows laid into a V grove which will act as a spar . The hinge is a strip of peel ply and will be on the top surface.
I ended up with a pre paint weight of 390 grams , now I know I can make a lighter one and save maybe 100 grams , but not having the stabiliser fail in flight is also nice, so I will go with this heavy but strong option for now.
I started assembling the pieces and cut out the fuselage so I can get the joiner through and check wing alignment.
The joiner will slide through the fuse in a re-inforced tube which will keep it aligned and prevent compression of the fuselage sides.
So Far things are fitting into place.
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Old Jan 16, 2013, 07:51 AM
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North Yorkshire UK, on a big hill facing the prevailing wind. Coincidence?
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Looking good Mike. Are you just glassing the cores straight on, or pressing them between the outside foam shells with a sheet of mylar to squeeze out excess epoxy and get a smoother finish?

Rog
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Last edited by Sutton Bank; Jan 16, 2013 at 08:39 AM.
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Old Jan 16, 2013, 07:53 AM
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Another question Mike. I looks like you cut the wing cores in fairly short (60cm?) sections. Why not cut them in complete sections between taper breaks?

Rog
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Old Jan 16, 2013, 08:10 AM
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Blimey Mike, you make it look so easy!
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Old Jan 16, 2013, 08:14 AM
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Multi taper wing

Hi Rog and all,
Good question on the wing panels , it is hard to cut long panels with a hot wire, you tend to get ripples, also the aerofoil changes several times along the length of the wing which looks curved with all the panel breaks.
I will post a pic hope you can see the curves.
cheers
Mike
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Old Jan 16, 2013, 08:55 AM
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Quote:
Originally Posted by Sutton Bank View Post
Looking good Mike. Are you just glassing the cores straight on, or pressing them between the outside foam shells with a sheet of mylar to squeeze out excess epoxy and get a smoother finish?

Rog
Hi Rog,
I like all your questions please keep them coming, lots of spectators dont ask, but also want to know about the answers.
I build a lot as you know and quite a few guys say , wish I could build stuff like that but I dont have a vacumn machine, so to see if it can be done this glider has been layed up directly onto the foam, the (lets call it porous glass the 220gr goes on first) it is onto the blue foam which was lightly sanded and carefully wiped and blasted with compressed . The outer 2 x layers of 106gr tight weave where rolled and left for 30 minutes, amazing how much resin blotted through, dry patches were wet out again and the last glass cloth also blotted through the resin.
The EPOLAM resin I used had a long cure time , roughly 24-36 hours so hopefully bonded well to the cores and especially the spars.

The wings look great and weigh 8kg in total with the joiners , lots of sanding and priming should see a glass finish, but I accept that finishing off a wing like this will require some extra work.
The wing flex also looks nice at this time.
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