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6 Turning 4 Burning

A scratch built project,

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SR 7127/01/2020 20:43:46
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345 forum posts
90 photos

20200121_153802.jpg20200121_153743.jpgI have done a little more on the plug, its all about the right shape, some filling sanding, filling sanding to do, also the radome on the bottom of the fuselage plusone at the tail20200121_150408.jpg

SR 7127/01/2020 20:45:19
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345 forum posts
90 photos

I find this forum difficult posting pictures in the correct order,

SR 7101/02/2020 20:00:47
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345 forum posts
90 photos

20200125_124042.jpg20200127_142411.jpgThe plug is ready for glassing, i have cut the 4oz cloth for two layers, just waiting for the order for the resin to arrive20200124_152144.jpg

SR 7102/02/2020 21:41:33
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345 forum posts
90 photos

Well a disaster, got the resin kit and i have laid the two layets of cloth on the plug, but its not gone off, so on contacting the suppliets it appears that they have sent the wrong stuff, three small bottles of hardener and not resin but a large bottle of hardener, being the first time iv bought resin from them i did not know what it should be like, they are full of apologies and have sent me a new kit and some clothes and things to clean the plug, have spent a few hours on it but the hardener is to well soaked into the MDF to come out, the plastic pipe has come relatively clean , BUT20200129_123100.jpg

Dickw02/02/2020 23:03:29
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563 forum posts
79 photos

Is it worth trying to paint a thin coat of 'resin only' on to the MDF to see if it will react with the soaked in hardener and form a thin crust you can work on top of?

I know it's a desperate measure, but if all else fails what have you to lose.

Dick

SR 7102/02/2020 23:28:34
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345 forum posts
90 photos

Yes thats an idea Dick, but if i give it a coat of resin mixed as it should be then all the extra hardener soaked into the MDF should only make it go of quicker, ????? maybe LOL

Jon - Laser Engines03/02/2020 08:29:41
5104 forum posts
221 photos
Posted by Dickw on 02/02/2020 23:03:29:

Is it worth trying to paint a thin coat of 'resin only' on to the MDF to see if it will react with the soaked in hardener and form a thin crust you can work on top of?

I know it's a desperate measure, but if all else fails what have you to lose.

Dick

You could also mix the resin (assuming its epoxy) with some epoxy thinner or meths to thin it down. Its then more likely to mix with the hardener already soaked into the material. A quick blast with a hair dryer or heat gun will evaporate the thinner leaving you, in theory, with nicely mixed epoxy

Don Fry03/02/2020 09:40:48
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4412 forum posts
52 photos

West Systems recommend heat, and acetone/thinners to remove the material. I would not use epoxy on top of hardner. You will end up with uncured epoxy on the surface, then a layer of various thicknesses of resin in different cures, over the sealed in hardner.

Try heat, and acetone, then a normal mix, thinned, to seal the hardener in.

Life, and this hobby in particular is a bitch.

Erfolg03/02/2020 12:19:13
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11565 forum posts
1274 photos

I must admit straight away, I do not know with certainty what you are doing.

Are you laying the cloth on the plug, as a means of creating a plug, from which you will be making a female mould?

At first I thought you would be laying up on the mould to produce a shell, which would be cut from the plug.

Now I have come to the conclusion, that is not the intention, as with the materials you have used you would need to form a barrier, be it a sealed surface, waxing and possibly anther release agent, be it PVA (the moulding type) and waxing. So that approach appears to be a non starter.

So I await further developments.

As per the difficulties, they will be overcome, as in essence all of the suggestions, can be made to work. Dependent on your technique for the body actually is, one may be slightly better than another, luck as well as judgment etc., all play their part.

SR 7103/02/2020 20:52:06
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345 forum posts
90 photos

The acetone would not shift the gunk, so i have laid 4oz cloth on and brushed the new resin and hardener, in that they sent me, ill see what happens

Andy Stephenson03/02/2020 23:10:00
44 forum posts
1 photos

Acetone is a good solvent but it's ineffective on epoxy, cellulose thinners is what you need.

A.

SR 7103/02/2020 23:30:56
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345 forum posts
90 photos

Tried that first Andy it did not work either

PatMc03/02/2020 23:40:26
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4297 forum posts
524 photos

Isn't isopropyl alcohol (IPA) the correct solvent to use for uncured epoxy resin ? I assume it would also dissolve the hardener.
IIRC methylated spirits can also be used for cleaning up but not quite as effective as IPA

SR 7108/02/2020 10:01:50
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345 forum posts
90 photos

Last Monday i glassed it again having scraped as much of the gunk off as i could, just mixed a normal mixing of resin and applied with 4oz cloth, pleased to say it has gone hard, had it in the house all week

So today ill take it back out to the hanger and start sanding, iv also ordered a stack of ply and balsa from Slec so when that comes i can start that side of the build, been looking for engines / motors for it, surprised how little HK have got, one glow engine and all the electric motors that will do the job are out of stock

Erfolg08/02/2020 11:53:40
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11565 forum posts
1274 photos

Well done, there is always a way. Sometimes not as perfect or as straight forward as you want, yet as much as an achievement as something routine. Once again, WELL DONE!

SR 7109/02/2020 19:31:39
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345 forum posts
90 photos

I have been sanding for the last two days, getting it something like

Have not done a lot though as im dying

Of man flue20200129_123100.jpg

Erfolg12/02/2020 11:27:10
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11565 forum posts
1274 photos

You have not posted for a little while. Are yo actually ill at the moment? If so , then best wishes for a speedy recovery.

SR 7113/02/2020 19:46:31
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345 forum posts
90 photos

Yes sir i have been dying of a very bad case of man flue, anyhow i have managed to spend a little time on it, got the first coat of primer/filler brushed on, ( i like to brush it on as its thicker ) i then sprayed a light coat of black on top so that any low spots will show up dark

back to my death bedface 7

Don Fry13/02/2020 20:43:47
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4412 forum posts
52 photos

1 part honey. 1 part hot water. Three parts whiskey.

If posh, a twist of black pepper, course grinder.

Erfolg14/02/2020 16:07:24
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11565 forum posts
1274 photos

Don, do you really need the hot water? Or is it there to combine the honey into the Whisky, if so, best make it warm, to avoid evaporation of the Honey.

Recently I have been reading about the weight penalty of pusher drive shafts as discussed at a WW2 German conference considering the specification of a fighter invitation to tender. It was thought that the shaft assembly would add approx. 120 lb per engine.

When you consider the mass of the Wasp Major as used in the B36 of 3,400 lbs (I know weight).

3000 hp.jpg

You can see that whatever you do, either the engine on the wrong side of the CG, or an increase in weight, with a drive shaft, there is a penalty. Particularly when the improved aerodynamics from the arrangement were thought to be less than 10%, tractor arrangements become more attractive.

With a thickness of 21% (max) I guess the drag was high if you wanted to go fast, hence all the power. I assume the section was also chosen due to the high aspect ratio. Even with the YB60.

I wonder what the B52 used as an airfoil, could that why it was a bit faster.

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