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Old Oct 27, 2012, 08:56 PM
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mintie's Avatar
Kaiapoi , New Zealand
Joined Jun 2007
596 Posts
HI Mike...nice build here following along with the rest.

I will share a wee tip with you all here that I have found very helpfull with my Full size aircraft composite work..
I use the green PVA release and spray it on with a small touch up gun.One or two coats on small parts and three on larger parts.
Now releasing the the part from the mold,once I have a few gaps that are starting to open I run a small stream of water into the gap.As the release agent is water based it starts to soften and releases a lot quicker and easier.
Very handy on larger parts which sometimes take for ever to seperate.
Keep up the good work ..Graeme
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Old Oct 29, 2012, 10:24 AM
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mikegbogh's Avatar
Roodepoort, South Africa
Joined Aug 2007
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The first fuselage comes together.

Hi All,
Friday I masked the mold and gave it a coat of 2k white. First a dusting coat sprayed from some distance , once this flashed off I did a few more wet coats.
Saterday, I started early as the fuselage layup had to be completed before sundown, sunday was a flying day not a building day.
First it really pays to have a project plan, so I precut the layers of glass fabric and lay them in order of layup on two seperate piles, no good having 4 layers in one side and two in the other. I also make up a small chart which I tick off as each batch of 50 grams of resin is used , although not an issue in the fuse, resin weight difference in the wings is important to control.
The first step is to mix some flox and resin and fill the sharp edges , basically the fin and wing roots.
Then first layer of glass cloth goes into the mold and is wet out , carefull checking to ensure an even wet out, not so easy against, the white paint background, 1st layer fin, and boom only 104gr, The I wet out several small pieces and contour in around the nose, canopy lip, wing roots and tailplane to fin platform.
Next a complete layer of 163gr cloth the entire mold, followed by a 200gr carbon piece in the Fin and thin boon areas.
The rest of the fuselage gets 3 more layers of 163gr right down to the tailfin part of the boom, the verticle part of the tailfin gets another 106gr fine layer as does the cockpit area.

It is important to now get the timing right , I was using an Epolam epoxy which at 20 degrees should start gelling at 3hrs, it took about 5hrs, to gel,at this time the resin is no longer sticky but still soft and rubbery, now is the time to slice off the overlaps on the mold, it cuts off shear in a few minutes if you pick the right window, leave it overnite and it is impossible to cut.

With the two sides now semi-cured and cut clean to the mold edge, I remove all the masking tape and carefully re-wax the mold upto the edge but not the actual fibreglass .
Switching to a smaller brush the top edge of the one side mold it lightly painted with resin and the bottom edge of the other mold, a thin glass tape is cut and wet out on the top of side A and the bottow of side B, one all wet out it is carefully worked back up with the brush so it stands about 1cm above the mold. I used a faster cure epoxy here with a cure time of 2hrs. Time for supper

You need to constantly check the joining tape, the moment it gels and starts going rubbery , its time to mix up about 30grams resin to harderner and add about 30 percent micro balloons and 60 percent Flox, the mix must not be too dry and look wet.

I place this in a syringe and run a bead against the glass tape on both molds, as well as a bead at the nose and up the fin leading edge where tape is not used, because of the fine angles.

The two molds are slowly brought together slighty offset so the proud wet tape fits into the hollow of the opposite mold, then you slide them together until the keys locate, and bolt and clamp,and stand upright so the epoxy pools and does not run out, mission accomplished .
Sunday time to go flying

regards
Mike
Ops nearly forgot Shed I especially made big flanges on the molds and with blocks of foam it is steady to work on , I learnt that from my last molds which rocked.

Mintie, thanks for the PVA tip and the use of water, someone here also said compressed air helps release things , I think I will just stick with a crowbar. lol
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Old Oct 29, 2012, 10:36 AM
Hunting for Goat Lifters
Titus ZA's Avatar
South Africa, GP, Randburg
Joined Jul 2012
109 Posts
Another update and another awesome detailed post. love it! What i find interestnig is the amount of different materials used to make the glider. ie. various types / weaves /weights of glass, carbon, and also different resins and epoxies. However, the result speak for themselves, awesome!

I suppose if you going to do it, you must do it properly and build light and strong. Also, be smart about the building, as you have done.

Cant weight to see the first fuzz come out. holding thumbs

cheers
T
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Old Oct 29, 2012, 10:44 PM
registered weapon
IHAVAWDY's Avatar
United States, MT
Joined Mar 2008
3,279 Posts
Mike, thanks for taking the time to photograph and post your work.... fantastic!
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Old Oct 30, 2012, 03:20 AM
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mikegbogh's Avatar
Roodepoort, South Africa
Joined Aug 2007
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First Fuselage Fantastic

Hi All,

Last posts left off with the mold upright and hopefully everything curing inside.
My mold is a fairly light affair and when it comes to releasing I literally stand on the flanges and you can hear the pops as the surfaces release,I know some molds like wings , need to be very thick and strong to prevent warps etc , but I prefer a slightly flexable fuselage mold.

The tail area released first and with a bit of flexing both sides came free, the area around the wing roots holds on more tightly, after inserting, some soft wooden mixing sticks and a a soft flexable shatterproof ruler the final grip released and one side just popped of. The inspection revealed an excellent result especially as this is the first fuselage and I half expected a bit of paint to stick but no major issues.

Now it was time to get the second mold off , and it just would not let go,
I ran my soft plastic ruler around all the edge but no go even tried pulling a soft string from the tail forward to release things, The ruler trick eventually worked amazing that such a tiny bit of paint and resin could be so stubborn.

The first JS1 fuselage is excellent , it is very strong , especially the tail section with the carbon, the join seam is great also, both sides alignment is good but I generally will waterpaper with 600 grit and then respray with a finish coat to hide the join line. She weighs 1kg exactly which is in the target weight , I am sure I could reduce that a bit, but for robust slope flying the extra strength is great.
This comming weekend I will layup no 2 as well as a rudder and joiner mold, also start thinking about the multi taper Schuman planform stabiliser, which I will also make a mold for.
regards
Mike
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Old Oct 30, 2012, 03:47 AM
Hunting for Goat Lifters
Titus ZA's Avatar
South Africa, GP, Randburg
Joined Jul 2012
109 Posts
Man that looks good! Your time and effort has really paid off. Really keen to see how you address the wings and the other bits.

Cheers
T
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Old Oct 30, 2012, 04:22 AM
scratch build everything
DudleyLeRoux's Avatar
South Africa, KwaZulu-Natal, Botha's Hill
Joined Aug 2009
1,219 Posts
looks awesome Mike, as with all your builds.
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Old Oct 30, 2012, 06:19 AM
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Joined Nov 2008
189 Posts
I am literally in awe Mike. I can't wait for your wing masterclass so I can copy it for my ASG29 - but you make it look easy and I know from personal attempts that it is your vast experience that makes it look so.

Simon
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Old Oct 30, 2012, 07:20 AM
Deniable plausibility
Shedofdread's Avatar
Derbyshire, UK
Joined Aug 2008
2,323 Posts
Good to see the first fuselage out OK. It's always a somewhat tense process, eh?
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Old Oct 30, 2012, 08:02 AM
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North Yorkshire UK, on a big hill facing the prevailing wind. Coincidence?
Joined Oct 2007
915 Posts
That is Wow.com! Must be your best fuselage yet? Looks real quality Mike.

Rog
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Old Oct 30, 2012, 08:36 AM
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mikegbogh's Avatar
Roodepoort, South Africa
Joined Aug 2007
1,038 Posts
Hi Guys,
I am really happy with this one , I remember my first big glider 6 years ago and while it flew and was composite, by todays standard it was really rather rough, now many mistakes later I build something that really looks good and a guy on one of the other threads posts pics of his JS1 and I feel like a beginner again.
But then my glider is homebrew , handmade, no fancy CAD/CAM machines or molds in my house, and hopefully built with methods that the average handy modeler can achieve..
Lets hope it also flies great, just opened my HK parcel so now I have enough flat wing servo's to equip 2 sailplanes.
Saterday I will layup no 2 and maybe use kevlar/Aramid cloth rather than carbon
I have a roll of it, any comments?? I am not sure if it will add stiffness to the boom.
Thanks for watching, should be onto the wings in a few weeks.
cheers
Mike
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Old Oct 30, 2012, 08:51 AM
Deniable plausibility
Shedofdread's Avatar
Derbyshire, UK
Joined Aug 2008
2,323 Posts
I've used Kevlar tow for years to reinforce fuselages (with good effect) but as for the cloth, it's a royal pain in the **** so I'd only use it on a job that I'm being paid to do! IF you can work out a way of using it such that you don't have to 'green trim' it, then you'd be OK but really it belongs in the nose and carbon for the boom.

If you want to add strength and stiff ness to the boom, try adding some foam stringers down the length and laminate over them.
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Old Oct 30, 2012, 10:37 AM
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Roodepoort, South Africa
Joined Aug 2007
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Quote:
Originally Posted by Shedofdread View Post
I've used Kevlar tow for years to reinforce fuselages (with good effect) but as for the cloth, it's a royal pain in the **** so I'd only use it on a job that I'm being paid to do! IF you can work out a way of using it such that you don't have to 'green trim' it, then you'd be OK but really it belongs in the nose and carbon for the boom.

If you want to add strength and stiff ness to the boom, try adding some foam stringers down the length and laminate over them.
Hi Shed,
Thanks for the reply, kind of my thoughts, but I have a roll of 100gr Kevlar cloth and another small roll of carbon/kevlar hybrid cloth and have always avoided using it because its a pain to work with ,thought now might be a good time, but then again maybe stick with the current layups.
Cheers
Mike
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Old Oct 30, 2012, 03:34 PM
scratch build everything
DudleyLeRoux's Avatar
South Africa, KwaZulu-Natal, Botha's Hill
Joined Aug 2009
1,219 Posts
HI Mike,

My understanding is that Aramid is better for the boom/tail area than carbon. Carbon snaps when reaches it's limits, aramid bends. You may find you tail boom will be more resistant to breakage with Aramid.

Incidently my Grob G103C fuselage is entirely aramid. It's a factory produced model.

An accurate template is the answer to working with Aramid.

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Old Oct 30, 2012, 07:28 PM
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North Yorkshire UK, on a big hill facing the prevailing wind. Coincidence?
Joined Oct 2007
915 Posts
On my semi-scale ASH25 I sandwiched a layer of Kevlar cloth between some glass and carbon cloth, the idea being that I'd avoid that dreaded fluffing up thing it does whenever you so much as show it a piece of sandpaper. Well it worked well except at the edges of the moulding e.g. the canopy frame where suddenly it was golden fuzz everywhere. What worked quite well was to wick thin CA into it which made it stiff and relatively trimmable.

Probably wouldn't bother using Kevlar again, and I only used it because my sister was about to bin all these big offcuts after making herself a transatlantic rowing boat. Mind you, makes your plane bullet-proof. Literally.

Rog
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