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Schleicher ASH31 4m

Posted: 11 Nov 2021, 09:40
by MartinE
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The Schleicher ASH31 is an elegant modern glider, one which I fancied making. There are no plans commercially available, so set about creating my own.

My workshop space is limited to a max wingspan of 4m, so plumped for the 18m variant at 1:4.5 scale.

Having drawn up all the fuselage formers, SLEC UK did a quick and quality job of CNN cutting them.

Wings will be bagged blue foam with carbon fibre spars.

Re: Schleicher ASH31 4m

Posted: 11 Nov 2021, 09:51
by MartinE
Here are the plans I'm working to....

Re: Schleicher ASH31 4m

Posted: 11 Nov 2021, 12:26
by MartinE
...here is a plan without having to download

Re: Schleicher ASH31 4m

Posted: 12 Nov 2021, 09:09
by Elliot Howells
ooh, watching! It's not often a glass glider is modelled like this, good for you.

Re: Schleicher ASH31 4m

Posted: 12 Nov 2021, 09:50
by MartinE
Thanks Elliot. I made an ASW15 like this ( from someone else's plan), I glasses the skin and painted which gave a smooth effective finish.

Here's my third attempt to post the plan drawing.
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Re: Schleicher ASH31 4m

Posted: 12 Nov 2021, 09:54
by MartinE
The first pictures were of the initial dry assembly. I've attached some glued pictures. Note the cheap laser level I used to line-up the main fuselage formers.
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Re: Schleicher ASH31 4m

Posted: 12 Nov 2021, 19:40
by B Sharp
I'm with Elliot on this one Martin. I will watch this build with interest.
Brian. :)

Re: Schleicher ASH31 4m

Posted: 13 Nov 2021, 15:00
by MartinE
Welcome Brian, I'm full of early build enthusiasm, so completed a bit more today, whilst ensuring still remaining straight.

I've used my block plane to trim the spruce stringers, before fitting. Certainly easier than widening former slots.

Central section, around the wing mount pretty strong now.

Re: Schleicher ASH31 4m

Posted: 13 Nov 2021, 15:49
by Peter Balcombe
Looking good Martin.
Following with interest :)

Re: Schleicher ASH31 4m

Posted: 13 Nov 2021, 16:12
by MartinE
Just noticed you're from Clevedon, Peter - i grew up in Congresbury - small world.

Re: Schleicher ASH31 4m

Posted: 13 Nov 2021, 16:30
by roo Hawkins
Hi l am following. Good look with the build. I built a 7.2 meter one I think it's one of the best builds I have done but not without it problems. The main issue was the 3 wing joiners and cg. So pleased with it it is now being re painted in 2k . Best of luck there is a thead .

Re: Schleicher ASH31 4m

Posted: 13 Nov 2021, 16:36
by roo Hawkins

Re: Schleicher ASH31 4m

Posted: 13 Nov 2021, 17:28
by MartinE
Thanks Roo.

I saw your build, with shaped fuselage - quite a task !

Re: Schleicher ASH31 4m

Posted: 14 Nov 2021, 09:56
by Kenneth Paine
Fantastic project! Just my cup of tea. I love the subject, love scratch building, love vacuum bagging and my workshop is 2x2 metres so I struggled to produce a 4 metre model.

Re: Schleicher ASH31 4m

Posted: 15 Nov 2021, 12:10
by Peter Balcombe
Martin,
Are you planning foam wings or a built-up structure?
Peter

Re: Schleicher ASH31 4m

Posted: 15 Nov 2021, 12:44
by Antonia
Nice project Martin, I notice on your first post you intend to vac bag blue foam wings, are you cutting them yourself or do you have a contact?
Can't wait 'til you start the wings, I have a little project rattling around in my head, will love to see how you tackle that part of the build :)
Antonia

Re: Schleicher ASH31 4m

Posted: 15 Nov 2021, 18:22
by MartinE
Wings will be bagged - 106gsm carbon onto XPS foam.

Homemade hot-wire boom and pulley system (blagged from Charlesriverrc.org)

Attached picture of my last model, with bagged wings.

Re: Schleicher ASH31 4m

Posted: 15 Nov 2021, 18:31
by MartinE
Rank amateur picture posting :D

Re: Schleicher ASH31 4m

Posted: 15 Nov 2021, 18:39
by Jolly Roger
Lovely curved leading edge on that red model. How did you achieve that with a hot wire bow? Did you hot wire cut in sections then blend the joins?
Looking forward to the rest of your thread.
Rog

Re: Schleicher ASH31 4m

Posted: 15 Nov 2021, 21:36
by MartinE
Yes Rog, 3 sections forming the shape, then smooth the leading edge (slightly) - bagged as one.

Re: Schleicher ASH31 4m

Posted: 16 Nov 2021, 16:57
by MartinE
The last of the stringers have been attached & and the nose formers.

The plan is to have a motor up front and use a 'scale spinner to maintain the nose shape.

Re: Schleicher ASH31 4m

Posted: 18 Nov 2021, 20:30
by MartinE
Fuselage skeleton pretty much done.

Also threaded through wiring for tail servos.

Re: Schleicher ASH31 4m

Posted: 18 Nov 2021, 20:33
by MartinE
Also hot-wired the tailfin, from EPS. then cut the obechi skins to size.

Note the aluminium tape on the edge of the hot-wire profiles (to give a nice smooth cutting motion).

Re: Schleicher ASH31 4m

Posted: 20 Nov 2021, 12:54
by MartinE
Next step for the tailfin is strengthening the skins and joining to foam core.

I've applied 1 layer of 106gsm bias carbon fibre (East Coast Fibreglass) and 3 lengths of 80gsm uni-direction carbon fibre (Easy Composites).

Foam core positioned on the skin and then weighted down in the foam negatives.

Re: Schleicher ASH31 4m

Posted: 21 Nov 2021, 11:36
by MartinE
Before all the sheeting is applied, I need to install the ballast tubes.

Made from a couple of layers of 180gsm carbon/Kevlar (over a Dowell rod), they are bonded into the pre - cut fuselage holes.

Some of brass slugs shown.

Re: Schleicher ASH31 4m

Posted: 28 Nov 2021, 19:08
by MartinE
Whilst still attached to the build base, the top and side skin sections are being glued on.

The skin is 1.5mm medium grade balsa - steamed (on the outside) to obtain the curvature.

Mini-spring clamps, pins and masking tape required to hold/glue the sections on.

Re: Schleicher ASH31 4m

Posted: 01 Dec 2021, 18:16
by MartinE
Last of the top sheeting applied. I've left the sections above the wings so that I can have access to epoxy in the wing location tubes.

The curvey lines are now evident.

Re: Schleicher ASH31 4m

Posted: 01 Dec 2021, 20:12
by MartinE
For the tailfin, I've made 4 reinforcements;
1. The spar, which is balsa with carbon fibre caps, with glass wrap
2. Top tailplane mount, with threaded insert
3. Bottom support plate
4. Rear spar, balsa strip with bias carbon fibre on one side

The servo wire slot is hot wired out

Re: Schleicher ASH31 4m

Posted: 02 Dec 2021, 14:47
by Andrew Ray
Beautiful work there Martin, you make it look so easy.

Re: Schleicher ASH31 4m

Posted: 02 Dec 2021, 15:07
by MartinE
Thanks Ray, as usual these things always take a bit of trial and error☺

The workshop is getting a bit chilli now (even with the heater on) so progression might slow done a bit - and my wife keeps reminding about some festive event coming up😁

Re: Schleicher ASH31 4m

Posted: 02 Dec 2021, 15:09
by MartinE
Apologies Andrew, I used your last name.

Re: Schleicher ASH31 4m

Posted: 02 Dec 2021, 17:24
by MartinE
The tailfin spar, having been bonded with resin, is now very stiff, offering good strength.

The foam was removed and spar placed in.

Re: Schleicher ASH31 4m

Posted: 02 Dec 2021, 17:25
by MartinE
Having finished the top sheeting, the support were sawn off and the formers rubbed down.

Bottom sheeting can now be glued on.

Re: Schleicher ASH31 4m

Posted: 02 Dec 2021, 21:58
by Andrew Ray
No worries Martin. I'll be keeping an eye on this thread now I've found it.

Re: Schleicher ASH31 4m

Posted: 04 Dec 2021, 11:57
by MartinE
More progress on the bottom sheeting - this was more tricky than the top, due to the compound curves.

I've also put together a fuselage stand (from the many ply offcuts I have in the workshop), with some foam edging.

Re: Schleicher ASH31 4m

Posted: 05 Dec 2021, 09:23
by MartinE
After an overnight cure, the tailfin has both sides and the spar bonded on. It weighs 116g and is very strong vertically & tortionally.

The leading edge was filled with a stiff expoxy/micro balloons mix and will be shaped to the correct profile.

Tail plane mounting screw at the top.

Re: Schleicher ASH31 4m

Posted: 06 Dec 2021, 20:39
by MartinE
Skin finished (bar sanding down) and the fuselage comes in at approx. 700g

Couldn't resist propping the tail on!

Re: Schleicher ASH31 4m

Posted: 06 Dec 2021, 20:43
by MartinE
As the front of the fuselage will potentially quite weak, I've lined the inner sheeting with 3mm, high compression, foam. (That will then be glassed on the inside.

Re: Schleicher ASH31 4m

Posted: 13 Dec 2021, 20:31
by MartinE
Where the wings will connect to the fuselage, it's important that the location pins are in line.

I created a jig from an oak offcut - drilled & reamed two 5mm holes, to give a snug fit to 2 carbon fibre rods. Then the brass tubes can bonded to the wing profiles perfectly aligned.

Re: Schleicher ASH31 4m

Posted: 16 Dec 2021, 16:40
by MartinE
Having bonded the foam onto the inside of the balsa skin, a layer 100gsm glass (on the bias) was applied.

Re: Schleicher ASH31 4m

Posted: 16 Dec 2021, 16:44
by MartinE
Meanwhile I'm putting together the wing-joiner.

This will have 2 carbon/Kevlar ballast tubes built-in (For steel rods, giving weight and strength) - photo.

These will be wrapped in a uni-direction carbon she'll.

Re: Schleicher ASH31 4m

Posted: 19 Dec 2021, 10:22
by MartinE
The tubes are bonded together, leaving a trough in between.
This is filled with several lengths of 12k carbon tow (infused thoroughly with epoxy resin) and lightly clamped onto the wing-joiner jig.

When that's cured this can be repeated on the other side.

Re: Schleicher ASH31 4m

Posted: 19 Dec 2021, 15:03
by MartinE
While the resin was curing, I made the tail-plane profiles ready for foam cutting.

3mm ply, profiles printed and then glued on with 3m 75, cut out on the fret saw.

Re: Schleicher ASH31 4m

Posted: 21 Dec 2021, 16:22
by MartinE
I got a bit side-tracked from the wing joiner, and cut the elevator foam cores.

These are cut from XPS foam (the old blue foam). I used this for a couple of reasons:
1. The higher compression vs EPS allows me to use a thinner skin (than the obechi) & so allows me to fit a thin wing servo inside the profile.
2. I can also then apply a live Kevlar hinge

It didn't go entirely to plan, with the hot-wire, so had to do some sanding afterwards.

Re: Schleicher ASH31 4m

Posted: 22 Dec 2021, 16:30
by MartinE
Still putting off the wing joiner!

This time it's the fuselage - sprayed on a light coat of 3m 75, then smoothed on the 100gsm twill glass fibre.

Re: Schleicher ASH31 4m

Posted: 22 Dec 2021, 18:48
by Jolly Roger
How exciting!

I'm really interested in how many layers of glass you'll add to the inside/outside, and which gsm values?

I asked around when I was making a lost-foam fuselage and the experienced builders suggested that for a 1/3 - 1/4 scale glider they'd use a total of around 800-1000gsm for the nose and 600-800gsm for the boom. With the balsa core approach you've used, I assume you're using a lot less glass?

Thanks for posting your build thread Mark. I've found it very informative.

Rog

Re: Schleicher ASH31 4m

Posted: 22 Dec 2021, 18:57
by Jolly Roger
Also...as an aside, I noticed what looks like a slim home-made carbon fibre fuselage on your workbench, and I wondered if you'd used carbon fibre braid to cover it? I moulded a tail boom this morning using carbon braid over a male plug, and it seems to have gone really well. I found that pulling the braid at each end made it tighten beautifully around the plug - like those Chinese finger traps.

Rog

P.S. I'm sure it's not just me that scrutinises photos of other people's workshops. Err. Is it? :oops:

Re: Schleicher ASH31 4m

Posted: 22 Dec 2021, 20:11
by MartinE
Hello Rog,

The ASH31 is still TBD, probably 1 more 100gsm up front & carbon fibre on the rear. That skinny bit by the fin will have some more added.

The fuselage in the background is another experiment - balsa rear with 110gsm carbon skin (not a tube, never used it), front in glass over shaped foam (to be removed later) - I digress😀

Re: Schleicher ASH31 4m

Posted: 22 Dec 2021, 21:23
by Jolly Roger
You have plenty going on in your workshop!

If I could make a suggestion about the narrow boom just in front of the fin (where most T-tail models snap). Carbon, although it has a very high Young Modulus and excellent strength to weight, is also very brittle and therefore prone to failing under the kind of shock-load experienced in a boom during a rough landing. For these stress-points, I've switched to aramid fabrics like Kevlar and Diolen. They have incredible tear-strength, so prevent the boom splitting, and allow a little flex so that the structure as a whole can absorb the stress as it bends.

I made a boom last week using two wraps of 200gsm Diolen plus 1 x 200gsm glass and I when I load-tested it in bending I could not break it, even at the 30mm diameter section. Out of curiosity, I took it out the test jig and tried to break it over my knee (and I'm a huge bloke) and I still couldn't break it! Also, Diolen is way cheaper than carbon and a much lower health hazard to work with.

Re: Schleicher ASH31 4m

Posted: 23 Dec 2021, 07:54
by MartinE
That's a very good point Rog, I recall reading they have a similar strategy for the cabin crash structure on full size gliders.

I have some 100gsm Kevlar so will use that. The fun will be avoiding sanding into it and getting fuzz. Perhaps a layer of glass on top - food for thought.

Re: Schleicher ASH31 4m

Posted: 23 Dec 2021, 09:23
by Jolly Roger
Yes Kevlar "fuzz" is a real pain! I've used thin CA to contain it, but a layer of glass over the top is better. And then there's the challenge of cutting Kevlar cloth...because I'm too mean to pay £40 for a pair of scissors. Mind you, it is bulletproof. :D

Re: Schleicher ASH31 4m

Posted: 23 Dec 2021, 13:10
by Barry_Cole
payer of scissors.

:shock: :shock: :shock: :shock:

BC

Re: Schleicher ASH31 4m

Posted: 23 Dec 2021, 14:21
by Jolly Roger
Jolly Roger wrote: 23 Dec 2021, 09:23
Ooops! I'm blaming auto-correct. ;)

Now edited.

Yes Kevlar "fuzz" is a real pain! I've used thin CA to contain it, but a layer of glass over the top is better. And then there's the challenge of cutting Kevlar cloth...because I'm too mean to pay £40 for a pair of scissors. Mind you, it is bulletproof. :D

Re: Schleicher ASH31 4m

Posted: 23 Dec 2021, 17:48
by MartinE
I keep meaning to find out what's special about Kevlar shears, I have some and they don't look any different to any others scissors.

They do the job. One thing that I found helped with cutting was using spray adhesive on the cloth, leaving to cure, then it seems to cut easier.

Re: Schleicher ASH31 4m

Posted: 24 Dec 2021, 15:31
by MartinE
Time to stop procrastinating - wing joiner construction;
2 lengths of pre-aligned carbon tow, 50mm wide (folded over double), the ballast tube construction and cut lengths of carbon tow.

I used way more than carbon tow than shown!

All assembled into the waxed & PVA'd mould. Now I'll have to wait till boxing day to see if it was a success (or not😥).

Merry Christmas all.

Re: Schleicher ASH31 4m

Posted: 26 Dec 2021, 09:18
by MartinE
Successfully came out of the mould, without any bother. Just needs to be cleaned up and cut down to size. Weighs approx. 130g.

Re: Schleicher ASH31 4m

Posted: 26 Dec 2021, 10:12
by NSWanderer
Fantastic work, Martin!

I'm sure there's been a fair amount of head-scratching, but you do make it look so easy - "Oh, I'll just design my own version of one of the latest glass super-ships. In rib-and-stick construction, to boot!"

I'm following your build with keen interest - may we use the plans that you shared?

Best wishes and a (belated) Merry Christmas!
Marian

Re: Schleicher ASH31 4m

Posted: 26 Dec 2021, 14:26
by MartinE
Hello Marian,

Yes lot's of thinking time for sure.

I shouldn't sing the praises just yet, not until it has successfully flown and landed. But you're welcome to use the plan (CAD also), but bear in mind it's no Chris Williams plan :D - lot's of mods & adjustments will be needed.

Re: Schleicher ASH31 4m

Posted: 26 Dec 2021, 19:09
by NSWanderer
Hi Martin,

Thanks for your prompt reply. Yes, with a fair bit of experience under my belt (OK, mostly a LONG time ago) I understand that a large chunk of any plan build is in the details and the bits that don't involve carving/cutting/gluing balsa or other material :twisted:

You mention CAD use of your plan - could I ask you for a DWG or DXF version of the plan file/s? I'd like to enlarge it to 1/4 scale and naturally will share it back with you.

Cheers
Marian

Re: Schleicher ASH31 4m

Posted: 26 Dec 2021, 21:31
by chris williams
but bear in mind it's no Chris Williams plan :D - lot's of mods & adjustments will be needed.

Ah, the innocence of youth...

Re: Schleicher ASH31 4m

Posted: 28 Dec 2021, 16:23
by MartinE
Youth :lol:

Cut down the wing joiner to length and sanded down to required thickness, then put another coat of resin on.

Re: Schleicher ASH31 4m

Posted: 28 Dec 2021, 16:27
by MartinE
The fuselage sheeting hasn't given me the nice shape I want, so having to fill (and will then sand down to a nice smooth finish).

This filler is really light/fine and sands easily.

With hindsight, some intermediate formers & stringers would have helped.

Re: Schleicher ASH31 4m

Posted: 29 Dec 2021, 06:19
by NSWanderer
Hi Martin,

Interesting how the distances between the formers and stringers look quite reasonable on your plan - I'm surprised.

Re: Schleicher ASH31 4m

Posted: 30 Dec 2021, 13:57
by MartinE
I sanded down the filler and the shape is much smoother, still some areas to be reshaped but will do those when the top has been glassed.

Before I do that, the wings roots need to be lined up & bonded in - i used the wing-joiner & the location pins to make sure it all aligned.

Re: Schleicher ASH31 4m

Posted: 30 Dec 2021, 14:00
by MartinE
The tailfin gets a bias skin of 25gsm glass on each side, before cutting & fitting to the fuselage.

To keep it light, I absorbed excess resin with a paper towel.

Re: Schleicher ASH31 4m

Posted: 30 Dec 2021, 15:07
by MartinE
As mentioned before, the elevator will have a live hinge - the Kevlar is 60gsm on the bias (I rolled the fabric to flatten it as much as possible).

Spray with adhesive & allow to cure before cutting the strip.

A 12mm wood chisel is used to make a depression in the foam, ready to accept the Kevlar, fixed in with 3m 75.

The spar cap is made up of multiple lengths of 80gsm uni-carbon, folded lengthways. Inserted into wing depression.

Re: Schleicher ASH31 4m

Posted: 30 Dec 2021, 19:03
by NSWanderer
Your progress is impressive - should be flying by the first weekend of 2022!
:lol:

Re: Schleicher ASH31 4m

Posted: 30 Dec 2021, 20:20
by MartinE
:lol:

Still lot's to do, but it's certainly taking shape nicely.

Re: Schleicher ASH31 4m

Posted: 31 Dec 2021, 13:47
by MartinE
Cut the rudder off the tailfin and trimmed for a trial fit to the fuselage.
Seems to line up nicely, vertically & lengthwise.

Re: Schleicher ASH31 4m

Posted: 31 Dec 2021, 13:48
by MartinE
Added the balsa sheeting above the wing roots and then glassed the top surfaces (100gsm bias).

Re: Schleicher ASH31 4m

Posted: 03 Jan 2022, 12:42
by MartinE
Final decision on the tail boom:

1 layer if 100gsm Kevlar at 45deg
4 lengths of 80gsm uni-carbon
Final layer of 50gsm glass, to lay down all the rogue Kevlar fibres

Re: Schleicher ASH31 4m

Posted: 04 Jan 2022, 13:20
by SedB
No idea, but guess that's well enough for belly landings!? :)
How easy/difficult was is to place the 100gr glass. All I uses so for was 50, and that I already found a bit of a pain in the corners..
Guess the fun job still has to come; sanding it all smooth? I'm curious what other treatments you'll for the fuselage covering (sanding, filling, priming).
Looks really nice so far!

Daniel

Re: Schleicher ASH31 4m

Posted: 04 Jan 2022, 16:16
by MartinE
Hi Daniel,

It feels pretty strong now. Now I need to remove some of the bumps and then fill and sand (as I did to the bottom).

The 100gsm glass is relatively easy to lay on a large fuselage like this. Spraying fuselage with a light coat of 3M 75, before laying, makes the resin application a lot easier, as the cloth does not move.

Re: Schleicher ASH31 4m

Posted: 06 Jan 2022, 22:03
by NSWanderer
MartinE wrote: 04 Jan 2022, 16:16 Spraying fuselage with a light coat of 3M 75, before laying, makes the resin application a lot easier, as the cloth does not move.
That's a great trick - thanks!

Re: Schleicher ASH31 4m

Posted: 08 Jan 2022, 13:50
by MartinE
In order to get the desired nose fit, I bought the GM spinner and 17x10 scale blades.

These are designed to fit the shape of the fuselage (and are already coloured white, obviously :D ).

Whilst not cheap (£60 for spinner & colet), they very well made, with the spinner in carbon fibre.

Re: Schleicher ASH31 4m

Posted: 09 Jan 2022, 16:05
by MartinE
To create the tail hinge, a carbon tube was glued into a slot in hard balsa, which was then glued to the fin, then shaped.

Re: Schleicher ASH31 4m

Posted: 09 Jan 2022, 16:07
by MartinE
2 fibre glass tabs were made (with a corresponding hole) then bonded into the tail.

Then the rod can be run down the tube, through the tabs to form the hinge.

Re: Schleicher ASH31 4m

Posted: 13 Jan 2022, 21:31
by NSWanderer
Very neat, Martin.

Re: Schleicher ASH31 4m

Posted: 14 Jan 2022, 09:15
by Barry_Cole
Please do not post on this Forum for the next 7 days (Approx).

The Forum is being moved to a new server, and your posts will be LOST forever

Thanks for your help.

BC

Re: Schleicher ASH31 4m

Posted: 26 Jan 2022, 17:28
by MartinE
Hope it's safe to post now.

Re: Schleicher ASH31 4m

Posted: 26 Jan 2022, 17:33
by MartinE
Some progress from the last week or so;

Filled and sanded top and bottom, front & mid section.

Filled the wing root fillets with balsa and ply rear curve.

Applied another glass layer to cockpit interior and removed the crossbar.
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Re: Schleicher ASH31 4m

Posted: 27 Jan 2022, 20:49
by MartinE
Cardboard mock up of the cockpit seat.

Re: Schleicher ASH31 4m

Posted: 27 Jan 2022, 20:50
by MartinE
Wing roots have an initial fill

Re: Schleicher ASH31 4m

Posted: 29 Jan 2022, 11:07
by MartinE
Rear fuselage section now filled and sanded.

The tail can now be bonded on, doing what I could with T-squares to get the angle set correctly.

The servo wires have been inserted before bonding.

Re: Schleicher ASH31 4m

Posted: 31 Jan 2022, 13:21
by MartinE
The open cockpit will be weaker than the general fuselage, so I've added 2 webs (one either side) from the main former to the cockpit sides.

3mm ply panels have been glassed, ready for radio gear and batteries.

Re: Schleicher ASH31 4m

Posted: 02 Feb 2022, 09:05
by MartinE
Having filled (with balsa) and blended the tail onto the fuselage, a layer of 60gsm Kevlar (ar 45deg) was applied to give the joint more strength.

A layer of 50gsm glass was then added to graduate the joint a provide a slightly smoother surface.

Re: Schleicher ASH31 4m

Posted: 11 Feb 2022, 07:47
by MartinE
I failed to source an off-the-shelf canopy, so will have to make my own.

The initial ply former had already been CNC cut, I just adjusted it to fit the opening.

Next step was to transfer it's shape onto some foam and fit.
Add the side blocks (shaping the underside to fit as close as possible). I used UHU foam safe glue to attach them.

Then rough-cut the outer shape.

Re: Schleicher ASH31 4m

Posted: 11 Feb 2022, 08:01
by MartinE
I reinforced the the tailfin joint (just at the leading edge) - it now feels pretty strong, as I've tried pulling & twisting it against the fuselage boom with very little movement and no cracking noises :D

Rudder could then be added. Starting to look like a glider now.

Re: Schleicher ASH31 4m

Posted: 11 Feb 2022, 16:53
by MartinE
To rough cut the canopy plug, I bought a Dunelm electric knife (£15 bargain!).

Next stage was with the course side of a Perma-grit sander.

Re: Schleicher ASH31 4m

Posted: 14 Feb 2022, 20:41
by MartinE
After the rough shaping, final shape was done with 120grit, smoothed with some well-used 120grit.

Re: Schleicher ASH31 4m

Posted: 14 Feb 2022, 20:42
by MartinE
To give me nice hard skin, the plug is covered in 200gsm glass, as well as 50gsm (for a smoother finish).

Re: Schleicher ASH31 4m

Posted: 14 Feb 2022, 22:31
by Jolly Roger
Looking good Martin!
Not sure how you will pull your canopy around that plug, but if you’re using a vacforming machine you will probably need at least 3 layers of 200gsm glass. Even that wasn’t enough to stop my canopy plug being crushed (although it was my first attempt with a vacforming machine so maybe I was clumsy).

In the end I just heated the plastic with a heat gun and pulled it down over the plug by hand. By the 3rd attempt I got a pretty good result.

Rog

Re: Schleicher ASH31 4m

Posted: 15 Feb 2022, 09:12
by MartinE
Rog, i was planning on doing it by hand; oven heat the PETG and with a vacuum box (just a vacuum cleaner).

I'll take your advice though, as an extra couple of layers are easy enough to add, and won't change the plug size significantly.

Here is the plug after overnight cure and trimming.

Re: Schleicher ASH31 4m

Posted: 15 Feb 2022, 12:48
by Barry_Cole
Martin,
What foam did you use??

BC

Re: Schleicher ASH31 4m

Posted: 15 Feb 2022, 14:06
by MartinE
Barry,

I used XPS foam (different colours but same density).

Re: Schleicher ASH31 4m

Posted: 15 Feb 2022, 18:14
by Jolly Roger
MartinE wrote: 15 Feb 2022, 09:12 Rog, i was planning on doing it by hand; oven heat the PETG and with a vacuum box (just a vacuum cleaner).

I'll take your advice though, as an extra couple of layers are easy enough to add, and won't change the plug size significantly.

Here is the plug after overnight cure and trimming.
That all sounds good Martin. Are you planning to extend the plug beyond the eventual cut-line, so you can cut off the distorted plastic where it has stretched around the edges of the plug? I made my plug in a similar way to you then added 15mm at the front and back, then extended the sides down to a flat base. Sorry if you already know all this!

Rog

Re: Schleicher ASH31 4m

Posted: 15 Feb 2022, 22:27
by MartinE
Yes indeed, that was the plan once I'm happy with the finished plug surface/shape (relative to the fuselage).

Re: Schleicher ASH31 4m

Posted: 19 Feb 2022, 17:34
by MartinE
2 more layers of 200gsm glass and some filler added to the plug, sanded smooth.

Now the extensions are being added, rough cut from foam.

Re: Schleicher ASH31 4m

Posted: 19 Feb 2022, 17:38
by MartinE
The tailfin has been filled in & sanded smooth.

The fake tailwheel (made from 3mm ply, hollow in the middle) was bonded on.
A strip of Kevlar applied to the circumference, then covered in glass.

Re: Schleicher ASH31 4m

Posted: 22 Feb 2022, 20:52
by MartinE
Tailwheel now blended in with lightweight filler.

Re: Schleicher ASH31 4m

Posted: 22 Feb 2022, 20:55
by MartinE
All the wing hot-wire profiles have been cut, smoothed and aluminium tape applied (this allows smooth running of the cutting wire).

I cut a sample to check the profile length & depth.

Re: Schleicher ASH31 4m

Posted: 05 Mar 2022, 12:09
by MartinE
Canopy plug has been extended all around, initially with foam followed by a couple of applications of P38 filler.

I've also put together a vacuum box from some bits of shelving I had lying around, the workshop. The top I got online, pre drilled and cut.

Hoover attachment pipe is 40mm waste pipe.

Re: Schleicher ASH31 4m

Posted: 06 Mar 2022, 16:02
by MartinE
Canopy plug sanded (250, 400, 600 all wet) & primed.

Smoothed with 600 then light coat of gloss.

Re: Schleicher ASH31 4m

Posted: 13 Mar 2022, 15:44
by MartinE
Elevator in the vacuum bag, for the top skin. I meant to take more photos but forgot!

Also in shot is the wing joiner with carbon fibre sleeves, to make the joiner boxes. The joiner was wrapped with polythene bag and waxed. Heat-skrink tape on the outside.

Re: Schleicher ASH31 4m

Posted: 13 Mar 2022, 15:46
by MartinE
Note that my vacuum pump is a fish-tank pump, with the internal seals reversed (to suck rather than blow).

Vacuum 0.3bar

Re: Schleicher ASH31 4m

Posted: 14 Mar 2022, 09:58
by MartinE
Elevator removed from the bag, with all the Mylar & kitchen paper removed (not fully trimmed).
Not bad - surface has quite a few pin holes, where I didn't get enough resin in, so more work will be needed to fill before painting.

Re: Schleicher ASH31 4m

Posted: 14 Mar 2022, 10:00
by MartinE
Wing joiner boxes come off pretty well, again some trimming needed.

Re: Schleicher ASH31 4m

Posted: 21 Mar 2022, 20:09
by MartinE
Elevator strengthening;
6mm ply piece for the central section, with holes for screw & dowel

Re: Schleicher ASH31 4m

Posted: 21 Mar 2022, 20:15
by MartinE
Now the shear webs;
Pre-cured 106gsm carbon fibre strips (45°), cut to size.

Knife used to cut full depth slots, wavy for the main spar & straight for the rear web. Reson injected into the slots, using a 16guage needle.

Re: Schleicher ASH31 4m

Posted: 23 Mar 2022, 20:36
by MartinE
Back to the wing joiner;

The location pins are 5mm carbon fibre, set into pre-drilled/reamed bass wood blocks.

Re: Schleicher ASH31 4m

Posted: 23 Mar 2022, 20:39
by MartinE
The key next step is getting everything aligned; boxes to wing joiner, end plates and location pins.

They were then all bonded together, whilst clamped to the fuselage.

Re: Schleicher ASH31 4m

Posted: 23 Mar 2022, 20:40
by MartinE
Not forgetting to wax the wing joiner, so nothing sticks to it :D

Re: Schleicher ASH31 4m

Posted: 27 Mar 2022, 11:59
by MartinE
The lower carbon skin has now been bagged onto the elevator.
Rough shaping done, but the leading edge needs filling and shaping correctly.

Re: Schleicher ASH31 4m

Posted: 27 Mar 2022, 12:02
by MartinE
Weighs in at 76g & is very stiff tortionally and along it's span.

Re: Schleicher ASH31 4m

Posted: 28 Mar 2022, 17:09
by Antonia
Looking really good Martin, what micron thickness of mylar are you using for the tailplane? Thanks.
Antonia

Re: Schleicher ASH31 4m

Posted: 28 Mar 2022, 18:42
by Jolly Roger
MartinE wrote: 27 Mar 2022, 12:02 Weighs in at 76g & is very stiff tortionally and along it's span.
76g is a REALLY impressively light construction. I’ve just made a very similarly sized tailplane sanded from 12mm balsa, glassed with 100gsm and with a living hinge and a carbon leading edge. It feels super strong, stiff and has a rock hard finish… but it’s 125g! Maybe I should have used 50gsm glass.

Loving your work. Please keep posting. 🙂

Re: Schleicher ASH31 4m

Posted: 28 Mar 2022, 22:27
by MartinE
Hello Antonia,

I used 250 micron Mylar (from Ideal Stencils, you can buy by the meter).

Re: Schleicher ASH31 4m

Posted: 28 Mar 2022, 22:32
by MartinE
Rog,

I was also pleased with 76g, I was expecting closer to 100g.
The foam is about 1/2 the density of balsa, with very good compression strength.

The carbon fibre shear webs are also very light.

Re: Schleicher ASH31 4m

Posted: 29 Mar 2022, 09:23
by Antonia
Thanks for the info Martin, picking your brains now…
With the tailplane tips, does the mylar comply with compound radius from leading edge profile to tip profile, or do you cut cleats in the mylar to go round the double compound curves then refinish the imperfections after curing? Thanks

Re: Schleicher ASH31 4m

Posted: 29 Mar 2022, 09:34
by MartinE
Hi Antonia,

I've never managed to get the mylar tips to fully conform (to foam), so I do put 1cm cuts into the curved sections. And even then I will have to fill & shape the tips.

Re: Schleicher ASH31 4m

Posted: 29 Mar 2022, 11:07
by Antonia
Hi Martin, thanks for that, thought that might have to happen.
Really looking forward to the wing build when you get there, great project, thanks for posting your progress.

Re: Schleicher ASH31 4m

Posted: 30 Mar 2022, 09:11
by Kenneth Paine
Hi All,

Great build Martin.

I have always used 0.35mm (0.014") Mylar and never had issues with getting it to wrap around compound curves at the tip. My secrets are:
  • Block-sand a thickness taper to the outside of the first 15mm to 20mm of the Mylar's LE and tip. Sand it down to say half its thickness or whatever feels right to you flicking the edge with your finger. Yes, this is laborious for Mylar is tough, yet you must be careful not to cut through it.
  • Cover the sanded surfaces with clear adhesive tape to prevent epoxy sticking to them.
  • Set the Mylars 5 to 6mm back from the core's LE and tip. Nothing will conform to such tight radiuses except the bag.
I trim my wet cloth flush with the root and trailing edges of the Mylar and let it overhang the LE and tip by 10mm so that the top and bottom skins meet in front of the LE and tip ribbon forming a lip which is trimmed after curing.

Below are some samples. Unfortunately this forum resizes images so you cannot pixel-peep the detail, but if anyone is interested I can place them on the Cloud and provide a link.

Discus 1/5 wing tip
Discus 1/5 wing tip
Discus 1/5 stab
Discus 1/5 stab
Rotor wings
Rotor wings
Rotor stabs
Rotor stabs

Re: Schleicher ASH31 4m

Posted: 31 Mar 2022, 08:56
by MartinE
Hello Kenneth,

Thanks for that info, I will try that on the wings. I have (on previous wings) tried scraping the LE of the Mylar, without much success - probably didn't remove enough thickness.

Your surfaces look very smooth, would you say the 350 vs 250micron has a significant influence on that?

Re: Schleicher ASH31 4m

Posted: 31 Mar 2022, 10:02
by Kenneth Paine
Hello Martin,
MartinE wrote: 31 Mar 2022, 08:56 Thanks for that info, I will try that on the wings.
I am glad to be of help.
MartinE wrote: 31 Mar 2022, 08:56 I have (on previous wings) tried scraping the LE of the Mylar, without much success - probably didn't remove enough thickness.
I agree with your thinking that you did not remove enough thickness. It is hard work. I use a combination of Dremel with coarse disk sander followed by a 15cm sanding bars with 80 and 180 grits. Careful though, if you get carried away with vigorous shoe polishing you may damage your Mylars.
MartinE wrote: 31 Mar 2022, 08:56 Your surfaces look very smooth, would you say the 350 vs 250micron has a significant influence on that?
I think 350 micron will do a better job at concealing cloth weave print-through and span-wise hot wire ridges on your foam core than 250 micron, but it will not conceal a uni carbon ribbon laid on the core as a spar.

Kenneth

Re: Schleicher ASH31 4m

Posted: 31 Mar 2022, 10:09
by Kenneth Paine
Another super secret :mrgreen:

The surfaces in the last two photos were riddled with pinholes which allowed primer through the skins causing localised dissolution of the cores leading to lots of remedial work.. The surfaces in the first two photos had no such problems.

The difference? Having learned my lesson first time round I started my layup with tissue against the Mylars before any cloth. Voila! Also, the tissue becomes invisible in epoxy so if you want to show off a natural carbon skin your panels will look fabulous.

Re: Schleicher ASH31 4m

Posted: 31 Mar 2022, 10:58
by Kenneth Paine
MartinE wrote: 31 Mar 2022, 08:56 Your surfaces look very smooth, would you say the 350 vs 250micron has a significant influence on that?
Yes, smooth but not wave-free. Mylar is shiny but still has waves and ripples in it which are fine for a slope soarer but, together with core imperfections, not good enough straight out of the bag on a scale model in my opinion. Sure, you can take the wings out of the bag, spray them and have a nice glossy model, but glossy in a FlyFly sense, not wave free in a European mouldy sense which is the standard I aspire to.

Even though my wings looked beautiful out of the bag, my sanding block quickly revealed how far the surfaces were from wave free. For nauseating detail have a look here: Wing contouring starting at post #158.

The long and short of it is that, given the amount of contouring work my Mylar bagged surfaces still needed before painting, why bother with Mylar at all? I have made a decision that for my next scale model I will lay the cloth straight onto perforated release film, kitchen towel on the outside to absorb excess epoxy and spread the vacuum, and straight into the bag the assembly will go. The post bagging work remains the same but the cost and faff of Mylars are avoided.

My 2p for what it is worth.

Kenneth

Re: Schleicher ASH31 4m

Posted: 31 Mar 2022, 16:13
by MartinE
I think if a 'moulded finish is desired then there is no escaping the graft! I'll have a look through your RCgroups thread. Thanks.

Your last point may well be very wise - let us know if you try it.

Re: Schleicher ASH31 4m

Posted: 03 Apr 2022, 17:31
by MartinE
I've hot-wire cut the inner wing sections. My cutting board consists of smooth piece of MDF, with a pulley rail attached and a weighted, pivoted lever to pull the boom through the foam.

This way the cut sections do not end up dished in the middle. This wing section is quite long at 820mm.

The spar cap slot was then sanded in, with 12mm wide 100grit, glued to the edge of some plywood. Meter rule to keep is straight.

Re: Schleicher ASH31 4m

Posted: 03 Apr 2022, 17:35
by MartinE
Lengths of carbon fibre tow cut ready to fill the spare cap slot.

Re: Schleicher ASH31 4m

Posted: 03 Apr 2022, 21:20
by Kenneth Paine
How are you going to tackle the shear web Martin?

Re: Schleicher ASH31 4m

Posted: 03 Apr 2022, 22:02
by MartinE
Once I've layed the top spar cap in, I'll then bond in a shear web as I did with the elevator, then bond the bottom spar cap to it.

Re: Schleicher ASH31 4m

Posted: 04 Apr 2022, 22:57
by Jolly Roger
Hi Martin,

I wondered if you'd considered using pultruded carbon strip rather than laying up your own using tows? Something like this...

https://www.hyperflight.co.uk/products. ... rbon-strip

or here..

https://carbonfibreprofiles.com/index.p ... cts_id=629

The benefit would be that the strips would be stronger and more uniform than hand-laid tows, due to a higher fibre/resin content and most importantly that the fibres are much straighter and more aligned.

I think the main drawback of hand laid tows is that the vast majority of them are twisted or wavy (even if only slightly) with the result that they do not evenly share the tensile stress. When the spar is loaded, the tiny minority of straight strands find themselves having to accommodate a stress that was designed to be taken by all the fibres in the spar - so they fail and pass the stress onto the next wavier strands...which fail etc and then whole spar fails. A pultruded spar on the other hand contains very accurately aligned fibres due to the pultrusion process, so that when it's loaded they are much more likely to share the stress across the whole crossection of the spar.

Added to this, hand-laid tows will probably include imperfections like air bubbles and specks of foam etc which will act as stress concentrators and further points of failure.

I hope this doesn't sound negative Martin, I'm just offering it as a suggestion.... :)

Rog

Re: Schleicher ASH31 4m

Posted: 05 Apr 2022, 10:36
by MartinE
Hello Rog,

Your suggestion is very welcome. I have & do use those pull-truded strips, particularly on shorter lengths, like tails.

My reasoning for using tows on wings is the ability to achieve tapered spar width and depth. Granted the layup and bond won't be as good, however, I tend to over engineer the amount of tow.
I will also cure under vacuum which should reduce the risk of voids, etc.

So far I've never had a spar cap failure (kiss of death :D ), de-lamination/buckling of the skin seams to occur first (& never in flight), although I don't fly my models in the alps!

Re: Schleicher ASH31 4m

Posted: 07 Apr 2022, 11:42
by MartinE
Here is the first inner wing section after spar cap has been bonded in (under vacuum). For this stage I used perforated film and kitchen roll, to absorb excess resin (& distribute vacuum).

I've added a 48gsm leading edge strip & an 80gsm bias D box.
The spar cap top is below the wing profile so I will now fill and shape, before adding the final carbon skin.

Note the added foam end blocks to stop the tows wrapping over at the ends.

Re: Schleicher ASH31 4m

Posted: 12 Apr 2022, 20:32
by MartinE
Left hand inner wing section now in the bag, to cure the upper spar cap and d-box.

Weighted down using the profile negative and my old gym weights (long since used to improve muscle tone :lol: )

Re: Schleicher ASH31 4m

Posted: 12 Apr 2022, 20:33
by MartinE
Elevator at the back with filler skim, to fill pin holes

Re: Schleicher ASH31 4m

Posted: 12 Apr 2022, 20:37
by MartinE
The mid section wing joiner are assembled and bonded (with spots of 5min epoxy).

10mm carbon rod, joiner tube previously formed over it then cut into 4.

5mm carbon location pins into brass tubes

Re: Schleicher ASH31 4m

Posted: 13 Apr 2022, 08:48
by Kenneth Paine
MartinE wrote: 12 Apr 2022, 20:32 Left hand inner wing section now in the bag, to cure the upper spar cap and d-box.
Good progress Martin. Just perforated film and kitchen towel is the way I want to go in future; no more Mylar nonsense.
MartinE wrote: 12 Apr 2022, 20:32Weighted down using the profile negative and my old gym weights (long since used to improve muscle tone :lol: )
When you get to applying the full skins I suggest you weigh down the trailing edges with a straight bar to prevent them curling. I make an MDF board for - and the shape of - each of my cores to put between them and the weights to spread the load evenly.

Re: Schleicher ASH31 4m

Posted: 13 Apr 2022, 19:22
by MartinE
For the outer skin, I think I'll try a test bagging with perf-film (on a sample profile), not Mylar. I'm a little worried about that trailing edge.

1 piece of MDF makes sense Kenneth - i have tended to use some flat pieces of oak, of various sizes, to spread the load, but just for bagging the outer skin.

Re: Schleicher ASH31 4m

Posted: 15 Apr 2022, 10:41
by MartinE
Top side of the elevator has been filled and sanded, then 3m putty applied & sanded again (it's good stuff, fills small imperfections really well - BE WARNED, it melts foam).

A light coat of primer was sprayed on, still small areas needing attention.

Countersunk fixing hole also added.

Re: Schleicher ASH31 4m

Posted: 15 Apr 2022, 13:13
by MartinE
Elevator now ready for top coat.

Couldn't resist installing it onto the fuselage. :D

Re: Schleicher ASH31 4m

Posted: 18 Apr 2022, 17:24
by MartinE
Further steps on the right-hand inner wing section;

Spar cap filler sanded to the correct profile.
160gsm reinforcements added to each end and left to cure.
(annoyingly, pictures won't post!)

Then the foam is cut out where the joiner boxes will go (no going back Now!!)

Wing joiner/end cap bonded in.

Re: Schleicher ASH31 4m

Posted: 18 Apr 2022, 17:25
by MartinE
Oh and servo wire slot cut (with hot wire)

Re: Schleicher ASH31 4m

Posted: 18 Apr 2022, 21:40
by Kenneth Paine
MartinE wrote: 18 Apr 2022, 17:25 Oh and servo wire slot cut (with hot wire)
Excellent progress Martin.

Regarding the servo wire slot, I recommend you put a sturdy tube there and fill any cavities around it, other the vacuum will collapse the core around it.

Kind regards,

Kenneth

Re: Schleicher ASH31 4m

Posted: 19 Apr 2022, 07:21
by MartinE
Hello Kenneth,

Yes the wire channel is something needing some thought. I have got away with it on previous wings, but this one is bigger & nearer the surface.

It does bring us back to the Mylar discussion, as this would bridge the gap to a degree, with just a dip in the skin likely to be left, after bagging.

Regards

Martin

Re: Schleicher ASH31 4m

Posted: 19 Apr 2022, 09:02
by Kenneth Paine
MartinE wrote: 19 Apr 2022, 07:21 ...It does bring us back to the Mylar discussion, as this would bridge the gap to a degree, with just a dip in the skin likely to be left, after bagging.
The Mylar will not remove the dip entirely and you have the cost and inconvenience of having to use Mylar. I routed out my servo wire channel with a radiused bit, lay down a plastic tube, applied splooge to fill the gaps around the tube and capped the channel with foam sanded flush. See here starting post #92: https://www.rcgroups.com/forums/showthr ... st43908949

Re: Schleicher ASH31 4m

Posted: 20 Apr 2022, 16:55
by MartinE
Good suggestion Kenneth, I mulled over using carbon tubes, but have ordered some styrene ones, as recommended.

I've now applied the LHD inner wing reinforcements and then bagged.

Re: Schleicher ASH31 4m

Posted: 22 Apr 2022, 09:10
by Kenneth Paine
Very nice Martin, however, it is important that you know that you cannot get a good structural bond onto a cured epoxy laminate unless:
  • You have used peel ply which you tear off the surface just before bonding to it or,
  • You sand the surface to a dull finish before bonding
You don't want to be sanding carbon because it is toxic and extra work so in future I suggest:
  • You lay up all your layers together in one session or,
  • You use peel ply between layers if you want to do one layer at a time.
My 2p for what it is worth.

Kenneth

Re: Schleicher ASH31 4m

Posted: 22 Apr 2022, 09:36
by MartinE
I sand the surfaces between applications, using a 3m mask & dust extractor.

I don't believe the dust is toxic, but can get deep in yours lungs, so continued exposure is certainly not good for your long-term health.

Re: Schleicher ASH31 4m

Posted: 22 Apr 2022, 09:40
by MartinE
Both inner wing-joiners are attached and the inner wing sections slide nicely onto the wing joiner & into the fuselage.

I had already applied a single coat of 'build' primer, to the fuselage, to identify any areas needed filling. It's not bad, just a couple of small areas.

The area around the wing will need to be blended (into the wings) before that is painted.

Re: Schleicher ASH31 4m

Posted: 24 Apr 2022, 10:01
by MartinE
Outer wing wing joiners bonded into the inner wing sections - all the pins line-up and move smoothly (phew, no faffing around to be done).

You can just see the white wire conduits, in their slots (Thanks for that suggestion Kenneth). I think I'll fill the gap with some balsa, then sand smooth.

Re: Schleicher ASH31 4m

Posted: 24 Apr 2022, 10:02
by MartinE
Note that all the wing joiners are mounted in between the upper & lower spar caps.

Re: Schleicher ASH31 4m

Posted: 01 May 2022, 09:27
by MartinE
Wing top surface bagging:

I decided in the end to use Mylar (as I already had it).

First photo shows pre-primed Mylar (rolled up), tissue paper, breather fabric & 106gsm carbon fibre (bias).

I used a roller to apply the resin, this gives even distribution and does not move the cloth.
Using the tissue paper, instead of 25gsm glass was much easier (Thanks again Kenneth).

And the into the bag for 18hours.

Re: Schleicher ASH31 4m

Posted: 01 May 2022, 09:33
by MartinE
What I didn't show was the wing foam negatives top and bottom, fully weighted down.

The wings came out of the bag this morning and (as expected) they're certainly not moulded wing smooth, but definitely my best bagged wings. Still some slight dips and ripples.

The tissue paper has eliminated any pin holes, which is great.

On to the underside shear webs, spar caps, etc.

Re: Schleicher ASH31 4m

Posted: 07 May 2022, 15:25
by MartinE
On to the undersides;

2 slots are cut, down to the top spar cap - 1 straight & 1 wavy. Resin is then injected into the slots and then pre-cured/trimmed lengths of bias carbon fibre are slotted in.

The wave should give compression and shear strength.

The spar caps, from carbon tow (and resin), are then laid on top.
The wings are then bagged.

Re: Schleicher ASH31 4m

Posted: 08 May 2022, 17:37
by MartinE
While the wings cured, i started on the tail servos. Both tucked inside the vertical tail.

Holes cut either side of the rudder mount and the foam dig out. Then 2 mounts made that allow me to install servos from the rear.

Re: Schleicher ASH31 4m

Posted: 09 May 2022, 09:49
by Kenneth Paine
MartinE wrote: 07 May 2022, 15:25 On to the undersides;

2 slots are cut, down to the top spar cap - 1 straight & 1 wavy. Resin is then injected into the slots and then pre-cured/trimmed lengths of bias carbon fibre are slotted in.

The wave should give compression and shear strength.

The spar caps, from carbon tow (and resin), are then laid on top.
The wings are then bagged.
Good progress Martin; I am glad my tissue paper idea worked for you.

Interesting shear web set-up. Did you borrow the wavy shear web idea from James Hammond who includes it in his designs? I am not convinced yet; if forced to cut two shear web slots I would choose straight cuts at the front and back of the spar cap to make a (torsion) box spar.

How did you cut the slots to the top spar? Any interesting jigs and tooling or just by hand?

Kenneth

Re: Schleicher ASH31 4m

Posted: 19 May 2022, 19:03
by MartinE
Test

Re: Schleicher ASH31 4m

Posted: 19 May 2022, 19:06
by MartinE
Hello Kenneth,

Sorry for late response, been having issues posting & now away on holiday.

Yes the idea was from Mr Hammond. Works very well.

Martin

Re: Schleicher ASH31 4m

Posted: 19 May 2022, 19:08
by MartinE
Yes I did think about a way to cut since wave slot, but to be honest, just did it by eye.
Not sure how much difference an accurate done wave cut would make.

Re: Schleicher ASH31 4m

Posted: 12 Jun 2022, 20:11
by MartinE
Back to it, after having been away.

Foam for the outer wings sections has been cut. A similar process will then be followed as for the inner wing sections.

Re: Schleicher ASH31 4m

Posted: 13 Jun 2022, 12:37
by Kenneth Paine
Great! I was missing my weekly fix of this thread :mrgreen:

Re: Schleicher ASH31 4m

Posted: 10 Nov 2023, 12:19
by MartinE
Hopfully my previous login issues are now sorted.
Here is the finished glider, on the South Downs

Re: Schleicher ASH31 4m

Posted: 10 Nov 2023, 12:36
by MartinE
Wow, I've been able to post something!!!
Here are some more pictures (fingers crossed).

The ASH has been flying for just over a year. Final weight is approx 4kg.
Flys really well both flat field thermalling & slope. No nasty tip-stall, all very gentle and predictable.
Very happy with it!

BTW the seagul is my wifes idea of a joke :D

Re: Schleicher ASH31 4m

Posted: 10 Nov 2023, 17:13
by Kenneth Paine
Congratulations! It looks Fantastic!

Re: Schleicher ASH31 4m

Posted: 11 Nov 2023, 11:21
by MartinE
Thanks Kenneth

Re: Schleicher ASH31 4m

Posted: 30 Nov 2023, 11:35
by roo Hawkins
Very nice. I have had log in problems fo the last year but seems OK now. Your ash 31 looks fantastic. Have just sold my 7m ash last month plus my 6 m dg 800. I think smaller models is the way to go for me now. Your ash looks a nice size

Re: Schleicher ASH31 4m

Posted: 04 Dec 2023, 08:29
by MartinE
hello Roo,

I've never owned, or flown, anything larger than 4m.
I can launch the ASH myself, on slope, but have been doing a bungee launch on flat-field (then run the motor when airbourne) as I'm not confortable to hand-launch with motor running.

I have no intention to go bigger, just because launching will become more 'entertaining' (I assume)!