60" sloper build thread

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[thermaled]

 Just started a new build with the help of Robbieuk. He has donated a bit of his shooting star fuselage and his roughed out block of wood for the new nose.
  While he wasn`t looking I stuck a new block of wood in and got busy with a nice sharp block plane and some sandpaper. 
  A good smear of filler round the wing saddle area to fill in some previous remodeling work, more sanding and a coat of grey g4 pond paint, workshop was a bit  so thought it wise to get out of there for an hour, but should get another coat on later tonight.
  What do you think Rob?

[thermaled]

Well thats the second coat on. G4 is great stuff for plug finishing, no catalyst, goes on with a brush, recoats every 2 -4 hours, but if you leave it you have to wait at least 2 days for it to fully harden. I find doing two coats at a time works best, leave it a few days then give it a good sanding with wet and dry before doing it all again. It releases every time with epoxy or polyester resin as long as you use a pva release agent and 10 coats of wax, just pulled my Backdraft2 molds, they released great with no pva, and got a mirror finish without any sanding, dont try that with polyester though. 
  So what are we doing with the wings Rob? I have a set of cores cut already, Dynamite/Nitro shape, already have the mylars sanding jigs ect, for this planform, just as well use them for our first ones I reckon. My set are hn1038, what are yours going to be?
  If we keep the wing bolts standard we can swap wings easily and try out a few different sections, almost anything with max thickness less than 8.2% is going to fit.

M

[RobbieUK]

Well thats the second coat on. G4 is great stuff for plug finishing, no catalyst, goes on with a brush, recoats every 2 -4 hours, but if you leave it you have to wait at least 2 days for it to fully harden. I find doing two coats at a time works best, leave it a few days then give it a good sanding with wet and dry before doing it all again. It releases every time with epoxy or polyester resin as long as you use a pva release agent and 10 coats of wax, just pulled my Backdraft2 molds, they released great with no pva, and got a mirror finish without any sanding, dont try that with polyester though. 
  So what are we doing with the wings Rob? I have a set of cores cut already, Dynamite/Nitro shape, already have the mylars sanding jigs ect, for this planform, just as well use them for our first ones I reckon. My set are hn1038, what are yours going to be?
  If we keep the wing bolts standard we can swap wings easily and try out a few different sections, almost anything with max thickness less than 8.2% is going to fit.

M

 STREWTH MATE   you just move too fast for me! i'm still sat here thinking about it all, and you've nearly finished. Nice looking job on the fuse. Yeah, go with your wings you have then i'd love to try some "Erwin" section.  I'll dig out my glass/resin contribution  and come over at some point.

Rob.

[thermaled]

STREWTH MATE   you just move too fast for me! i'm still sat here thinking about it all, and you've nearly finished.Rob.

Not really Rob, cut the wing cores back in August ready for the October 60" race at the Bwlch. Im a bit behind really.
   Fuse will take a while too I expect.

[thermaled]

Got a nice build up of grey G4 on the plug now, its looking good. Time to start with the black, once I have a few coats on can give it a good sanding with wet and dry, then farcella polishing compound, safe in the knowledge that if the plug turns a bit grey I still have some paint thickness left. Might have some molds by the end of the year.
 What shall we call it?

[Andy_B]

Call it bobs bitsa ..........he'll haver it re kitted soon enough  ....

[Zim]

Well seeing as you're using that pond sealant... how about Pondlife?

Watching this one with great interest mate - please carry on with max detail!

Thanks

Zim

[RobbieUK]

Call it bobs bitsa ..........he'll haver it re kitted soon enough  ....

  Mark's made me in charge of the switches!!! could be interesting

[southern soarer uk]

mark only give him switches that are permanantly on

[thermaled]

Have been quietly building up some black g4 thickness on the plug. Got a bit experimental with the airbrush too. Was concerned it would gum it up as the g4 has a quick initial cure, so first time was a fast spray and a good clean out. It needs a good thinning with its own type of thinners but works very well, found I can get a light coat on every 10+ minutes, airbrush just needing a blast through with thinners each time. After about an hour the g4 seperates from the thinners so it pays to mix up small batches for 2 or 3 coats at a time. More hassle than getting a brush out, but leaves a nice flat surface that needs much less sanding, means that the details in the plug remain intact....more or less. Anyway I like it, more paint going on faster has got to be good. Its been left for a few days to cure hard before the final sanding and polishing. Intend to make up the parting board first to avoid scratching the plug, then polish it out over the weekend.
     Meanwhile another couple of derivatives are underway.
     See what happens when you leave me unsupervised Rob. It gets worse, I`ve called it Burp!  Its a 45" wing, straight leading edge, 170mm root 100mm tip thinned PW51. So far the foam cutting templates and plan board are done, it only takes a few minutes really, I print out the wing profiles onto thin cardboard from Profilli wing program, glue them onto 1/64 ply, then cut them out with a scalpel using several light cuts, the blade tends to follow the first light cut so pays to take your time and cut it right. With practice they just need a light rub with sandpaper and they`re good to go. If a lot of cores are going to be cut then it would be worth making them out of metal or formica, lot more work though.
    I end up with a bottom cut and top cut profiles, so for a single taper wing thats 4 templates. The plan-board is just my way of storing information fot building the wing, its a piece of hardboard cut out to the plan shape of half the wing,1 piece for each taper. I simply draw round this to give me the foam block shape to rough out before attatching the templates and cutting the aerofoil profile, I also cut out the servo position, draw the wing mounting blocks, ailerons, servo wire route, anything relevant to the wing really. Its my one piece of wood reference sheet, well I am a chippy.
     The Burp wing will fit onto any of my broken 60 inch fuses, (very useful for you Rob), so including it as part of this thread. Just cut off the tail boom and glue in a vertical fin, bolt the Burp wings on and its a whole new plane.
     Mylars are cut and sprayed up ready, just need to cut some cores now.
    At the same time I cut out some templates for the Nitro/Dynamite planform, my own tweaked section that I want to try out, should fit nicely on this plane so you have choice Rob. First wing will go on  a light all carbon Nitro fuse to see how it goes, yep another build....Nitro-lite.
     Perhaps you had better pop over during the Hols Rob, will need some help with the nose boat shape, + bring a couple of cans plasticote paint to paint up your wing mylars, i can get on and bag them then. You had better give this bird a name too, before I come up with another.

Mark

[Zim]

Thanks for sharing all this mate! By the way - is Plasticote our equivalent of this Krylon that the Americans frequently talk about?

When you do a lay-up on the back of this Plasticote stuff, does the epoxy seem to sort of fuse into it and make the paint a lot harder than it would be if you applied it to the wing in the normal way? i.e. after it came out the mylar... I figure it's easier to do it on the mylar and looks better, but just also interested if the paint seems to be toughened up by doing it this way too...

Thanks in advance for your response - looking forward to seeing the completed slopers!

Zim

[thermaled]

I think its the uk equivalent Zim, but not entirely sure. It works anyhow, readily available in a range of colours from most diy stores, best of all, comes in spray cans and in 55ml bottles, thined down with white spirit works great in an airbrush for small areas, just need to learn how to use my airbrush better, but for painting mylars the cans work best. Mike Y gave me a good tip about masking off areas on the mylars, use packing tape, so am giving it a try on the Burp wing with metalic purple and white strips underneath, plain white on top, then will mask off and paint areas later.
    It forms a tough finish, its an enamel so is fairly tough anyway, but after leaving it on the mylars for a few days to cure, then bagging your wings, the paint is stuck to the wing with epoxy, so very scratch and peel resistant. The ultimate is probably a two pack paint of some kind, not tried that yet though.
   The downside is that it only goes where the mylars go, so leading edges and wintips stay paint free, saves lots of filling and priming though.

M

[thermaled]

The paint on the plug is now nice and hard, so started the sanding and polishing process this afternoon. Started off with 400 grit, sanding lightly and checking regularly, keep going until its all a dull matt black with no shinney bits.
   Give it a wash in clean water and move on to 600 grit, then 800.
  Thats as far as I have got, the grey g4 is showing through in places, should have spent another week painting it maybe, few little ripples around the wing saddle too, the price to pay for using a well knackered Robieuk fuse. Its probably easier to start from scratch. Could start spraying again at this stage, and repeat the whole process but I`ve run out of patience, gotta build it.
    Will work on the splitter board now before the final sanding and polishing.

[billscottuk]

I think its the uk equivalent Zim, but not entirely sure. It works anyhow, readily available in a range of colours from most diy stores, best of all, comes in spray cans and in 55ml bottles, thined down with white spirit works great in an airbrush for small areas, just need to learn how to use my airbrush better, but for painting mylars the cans work best. Mike Y gave me a good tip about masking off areas on the mylars, use packing tape, so am giving it a try on the Burp wing with metalic purple and white strips underneath, plain white on top, then will mask off and paint areas later.
    It forms a tough finish, its an enamel so is fairly tough anyway, but after leaving it on the mylars for a few days to cure, then bagging your wings, the paint is stuck to the wing with epoxy, so very scratch and peel resistant. The ultimate is probably a two pack paint of some kind, not tried that yet though.
   The downside is that it only goes where the mylars go, so leading edges and wintips stay paint free, saves lots of filling and priming though.

M

Interested in how and with what you thin Plasticote. My experiences of trying this were never very successful with the paint separating out from the thinner very quickly

[BridlingtonFlyer]

Pictures aren't very big.  Are you treating us mean keeping us keen

[thermaled]

Interested in how and with what you thin Plasticote. My experiences of trying this were never very successful with the paint separating out from the thinner very quickly

Works fine with plain old white spirit, not had any seperating issues with it either, I just mix up enough for immediate use though.

M

[thermaled]

Pictures aren't very big.  Are you treating us mean keeping us keen

Sorry about that, found my phone camera has better quality but smaller pictures, just getting used to the amount of editing they need, will see if I can alter the existing ones.

M

[billscottuk]

Works fine with plain old white spirit, not had any seperating issues with it either, I just mix up enough for immediate use though.

M

That could be the problem, I think I used turpentine substitute.
Will try next time with white spirit!

[thermaled]

Have done some work on the splitter board. I start off with some expanded polystyrene, and scoop out a divot in it deep enough to lower the centre line of the fuselage plug level with the top edge of some melamine chipboard. ( will scribe and glue on the melamine afterwards). I am going for a horizontal split with this mold, or else with the v-tail mount I will end up with a three piece mold, the good news is that by remolding just one piece, the top rear part, can adjust v-tail mount, decalage, wing seat ect. There is a down side, nose of the plug droops down from the centreline, so for a clean release I will have to make the splitter plate on two planes, pictures explain it really. Once i have a nice flat slope sanded into the front end of the foam I mix up a bit of plaster and place a few dabs under the fuse plug, then squash it down until the centre of the fuse is level with the melamine, leave it to harden for a day or two then scribe the pieces of melamine into the plug.
   Scribing, whats that?  Its a tecnique to mark out irregular surfaces, like skirting to a bumpy floor or architrave to a bumpy wall, worktops ect. You can use anything really, but lets say for example you use a steel washer, push the melamine up against the plug, then put the washer at one end, place a sharp pencil inside the hole then roll it down the side of the plug, keeping the pencil pushing into the plug. This will give you a very accurate line a constant distance from the plug, as long as you cut it out accurately, it will be a perfect fit.  I have found that doing it this way is much more exact than cutting out a hole in the middle of the melamine to perfectly fit the plug, it never happens, leaving some holes to fill with plasticine or filler which has always ended up compromizing the seam line, at least on my molds.

M

[thermaled]

Got the melamine fitting reasonably well, needed something to fill up a few hairline gaps so used some softened wax, not tried this before so see how it goes but should find its way into those little imperfections better that plasticine, which I have always struggled with. Another first is that for registration indents I will be trying out glass screws with those srew in chrome caps, should make some very neat indents.
    10 coats of mold release wax, then sprayed on several thin coats of pva release. Mixed up some epoxy tooling resin and painted this onto the plug and splitter plate, keeping the brush strokes all going the same way to avoid any air bubbles I built up about 1mm of thickness and then left it to cure for about 7 hours, well to be exact, I went to bed. Next morning it was still  tacky, just right, so mixed up  laminating epoxy and sprinkled 3mm chopped strand glass around the edges of the plug, wetting it out with a  brush until there was enough of a fillet for 6oz glass to wrap around. Used up lots of my scrap pieces of 6oz glass as the first reinforcement layer next, then left it alone for a few hours to get tacky. 2 layers of 10 oz rovings next, again mainly scrap pieces, let it get tacky then a final session putting on another 2 layers of 10oz rovings. Probably with all the overlaps I have 5 layers of 10 oz and 1 layer of 6 oz all over now, should be enough thickness I reckon.
     Laying up my molds in epoxy first Rob, then will do yours in polyester, we can get on with the nose boat plug then.

M

[thermaled]

I forgot to mention that the burp wing is in the vacuum bag as well, it was quite a drama though. I have had one or two wings break lately so decided they needed some extra strength in the centre. I remembered a layup spreadsheet that I downloaded ages ago and couldn`t understand, so gave it another go, still baffled about the use of carbon with it but for a glass stressed skin layup its very interesting, I am not reinforcing the centre of my wings nearly enough.
    Back to the burp, layed up the mylars using 6 oz glass with two pieces top and bottom so there is a centre overlap of around 200mm, also put two more layers on the top mylar, one at 350mm  the other at 500mm as the spreadsheet shows that more strength is acquired by thickening the top skin. So all this glass is on the mylars and wetted out with epoxy, laid the foam cores onto the botom mylar and it was 50 mm short 
    What the ?s going on, turns out my mylars are perfect at 45" but the core is 43", I had incorrectly marked out my hardboard wing layout board at 21 1/2" which was then used to mark out the foam block before hot wire cutting it to shape, doh.
     Nevermind, it has a straight leading edge so no problems there, just let the mylars hang over an inch at each tip then trim the tips and trailing edges when it comes out of the bag, just a shorter wing than I planned.

[thermaled]

The epoxy is getting nice and hard now on the first mold half, soon be time to lay up the other side. Meanwhile, done a little more work on the Burp, wings are out of the bag and look nice, so slitted the back of the fuselage to accommodate the fin and fixed it with ca, then put several strands of glass tow around the base, as well a glass tow fillet on the outside. Layed up a couple of layers 6oz cloth on some acetate sheet, smeared some thickened epoxy over it, then laid the lot on the wing seat and squished the wing down into it. Acetate sheet stopped it from all sticking together, lift the wing off and leave it for a day to cure. Tidyed it up this morning before going flying with a dremel like tool and a bit of sand paper, its all ready for some cosmetic filler now, then spray it to match the wing, white and purple. The fuselage is from my Dynamite mold, three years ago I made this one for a mate, which he flew for at least 18 months all the time until it got broken, so I swapped it for a new one, planing to build this sort of thing one day. Wing seat was for an ag series wing, thin discus launch section with lots of camber, in case you are wondering why the Burp wing doesn't fit it without some cosmetic surgery.

M

[thermaled]

Re: 60" sloper build thread