Blue or Pink?

[cagey]

I have a winter project on the go, namely a 1:12 F6 Lightning using the edf set up out of my old Squal EP, and am considering foam for most of the airframe.

Which is the best suited out of the blue or pink types of EPP available to us ? Assuming I can get hold of some, up to now I've drawn a blank there, so if anybody knows of a supplier of these materials, I'd be grateful for a nod.

If I do use foam, is there an approved method of covering and finishing that'll add minimum weight, a bit of strength and protection.

Finally (phew) what are the main differences between these foams and what is the correct names for them ?

Much obliged for any info peeps.

[riverlandgirl.]

Hi there cagey, I've built a couple of EPP slope soarers, and must say that I think polystyrene is better. EPP is quite hard to work with and lacks stiffness. As for the colour difference and suppliers I don't know, maybe the UK gents will have a better idea. It is hard to get here in NZ, at least when I was looking for it. Coloured packing tape for covering is standard on the slope soaring side of things, though I've known people who have had good results with solar film. Check out the planes in my albums, they are all polystyrene and packing tape. None are edf, but might give you an idea of what to expect. Good luck and let us know how you get on!

[Chuck Plains]

Hi Cagey. I've heard that Depro Aero is very nice but currently only available in 3mm x1250x800mm @ £14.75 per pack of 4 . The only thing I can personally recommend at this time is, pale green, Kilma underfloor insulation from Screwfix. 6mm only x1000x750mm @ £27.50 per pack of 8. Both are EXP (expanded polystyrene) Kilma seems to strongly resemble what I've read about standard Depron , it's 6mm thick x. You can bend it cold with packing tape on the outside for sharp folds, or induce permanent shape with careful heating. Actually, short pieces will cold form with the shiny side inside. But making a non taped fuselage is giving me problems with cracking etc. Boiling water might be my next step. Kilma is pretty durable if taped, and moderately rigid after folding or shaping. Put it this way, I broke my trainer wooden stick style fuselage twice, but the fully taped up wings were fine.

Bent with heat and taped.

Same piece held to shape in glueing position.

Up to a certain width, it can be cold formed. But the experimental fuselage cracked, so I cut off that end.

The remaining long piece has gone to approx 45% but is now showing some tiny cracks. Indicating that either taping will be necessary, or I will be forced to try boiling water.

Yes, and what you can also see in the pics is my new trainer fuselage, made from the most bendy of all EPE, and my Cub under camber style wings,. Soon to be running a pusher prop for increased public sfety!

Cub style.

[cagey]

Thanks for that riverlandgirl and Chuck. Very interesting info there folks and maybe helpful later, but at the moment I'm aiming at using EPP or EPO for their bounceability, my Art Tech EDF has bounced all over the patch many times and survived with the aid of epoxy and cyano to just keeping on, tho' it looks like road kill now LOL. It's made from EPO,nice, not like my (EX) Squall, made from polystyrene which just explodes into confetti with a ground interface.

Big problem is supply here, the nearest I got was a mininmum of ten blocks blue or pink 50gltr at £126 a bunch, too dense, needs to be around 30 gltr to be workable, no bending Chuck, all done with a bread knife Hah ! I've redrawn the wings to be built up now , at only 29" span with 1/16 ribs and 1/32 sheeting shouldn't be that much heavier than foam skinned with glass.

You've sliced a few bits of EXP there riverlandgirl, don't it drive you bananas all them little bits sticking every where.

Cheers peeps, Ken.

Edited By Biggles' Elder Brother - Moderator on 03/12/2012 17:17:31

[10 lover/clive]

hi there cagey the blue foam is dow chemicals and is ok to hot wire cut . ibelieve the pink gives off nasty fumes when hot wired,sheffield insulations sell it

[cagey]

Cheers Clive. Any idea of what the stuff is called, the've got an incredible amount of various types etc. It's a mine field in their site. Be obliged for a clue here buddy.

Edited By cagey on 03/12/2012 17:34:32

[10 lover/clive]

dow floormate thats what i used on mine see my 2cnd photo

[Erfolg]

As has been stated "Blue Foam" is actually a Dow product for use as under floor insulation, or for cavity wall insulation. I think from memory that the most common is the floormate X200, for flooring.

I understand that many of these products including the pink is actually extruded polystyrene, available in several densities. So you take your choice, dependant on availability and requirements.

I buy my own from Sheffield Insulation I was told it ws only us modellers who buy a single sheet @ about £12., which is 8' * 4' available in a number of thicknesses, I buy 75mm.

Edited By Erfolg on 03/12/2012 18:24:15

Edited By Erfolg on 03/12/2012 18:24:40

[10 lover/clive]

just looked on travis perkins they do cellecta yellow eps foam not a bad price but dont know what its like

[Erfolg]

Hmhhmmmmmm.

The product sounds more like Celotex or Kingspan type insulation. which unfortunately is not generally suitable for our purposes. Again from memory they are a polyurethane foam. Rather soft, pretty good insulator, but structurally poor.

I would suggest you be careful

[cagey]

Clive, that's the bunny my friend. Ain't going to be a VC10 though as my workshop is the kitchen or living room if allowed by HM. Grateful thanks for the info.

Can you advise on the best adhesives and finishing products for Floormate ?

[Erfolg]

Flootmate can be joined by PVA, if the surface is first roughen. But takes a day ort two to set.

I suspect that most use UHU Por.

Evostick is not good if solvent based as it melts the polymer,

Polyurethane again works, but needs the surface roughening and is heavy.

Of course Epoxy will work, best roughened, yet again heavy.

For finishing, I have used PVA with tissue and glass cloth with WVP. WVP is better

[cagey]

Hi Erfolg, PVA ? Hard to sand that stuff, how about alephatic fast grab resin ? Doesn't take overlong to dry and can be worked easier than PVA. I've used epoxy and as you say, heavy, not so easily worked either without taking out the foam each side of the joint.

WVP is better , good. What's WVP ? Don't think I've heard of that.

[Erfolg]

Alphatic glue is apparently a slightly differing formulation of PVA, being harder, but more brittle than PVA. In this case they both dry by evaporation. or being absorbed into the material being glued. With a polymer this is a long business, at least a day.

My technique is to cut all the blocks, glue and then scotch tape together, and forget for a few days.

If this is to long winded, UHU Por is probably the best solution.

Polyurethane needs one surface dampening, then binding tightly and preferably weighted down for a good few hours, until the glue has cured, as it tries to expanded, particularly when unrestrained..

The above is made from a number of peices.

Then sawn, carved and sanded using templates to get the profile acceptable form.

[Chuck Plains]

I've used both PVA and polyurethane (Gorilla) glue, and would use PVA for larger areas. But if a fair sized area of material to be joined is nice and flat, I've squeegeed out the Gorilla to an absolute minimum, to save some weight, before clamping it to the other 'wetted' piece for a coule of hours.. And it's excellent, even retaining some of the foam's flex, while giving a perfect bond. Personally, I don't like UHU POR that much. I stuck some EPS with it, and taped over the join temporarily. But on removing the tape after the glue had set, most of the POR pulled out of the join attached to the tape. Plus, it's not available, as far as I can tell, in anything but small tubes.

[10 lover/clive]

i like polyurethane myself stuck the skins to the foam cores on my wings .got the foam from wickes 1200x450x50 slabs of white foam hot wire cut them and save the outer cuts,cut balsa/obechi skin larger than needed .note what cut came off i.e under side, top side. put bottom off cut on bench put bottom skin on it dampen both sides of wing core,turn top skin upside down now pour gorilla glue on skins and run it all over with a old plastic card like with evostik. next put wing core on top of glued bottom skin then put top skin on then the top off cut then a piece of 18mm flat mdf then weigh it down with lots of weight .with some gorilla glues you only need about 1 hour 1wing done                                                                               ps DONT be slow about it

Edited By 10 lover/clive on 05/12/2012 18:42:40

[cagey]

Thanks to you fellas, I've got a good idea how to do some serious damage to the Floormate when I get it. Never used Gorilla and always thought it to be a form of UHU, Evosticky type of adhesive but'll give it a go.

Busy scaling up my draft plans to give me a 29" span with 38.5" length for 1:12 th of the big beast, so it isn't going to equal your VC10 Clive, now that's a real work of art buddy, most impressive. How did the flying go may I ask ? Be interested to know a bit more about the development and final weights etc.

Much obliged everyone , Cagey.

[Erfolg]

You do not need to use Gorilla, there are many polyurethane glues out there. They may not sound that macho, but are all very similar. I have used a number now, from Woodmate, ELK (Henkel), No Nonsense (Screwfix), including Gorilla.

The basic trouble with polyurethane glue is that it comes in industrial sizes, normally a small will be 500ml. Unlike PVA, storage is a issue. You need to keep all air out, or use it fast. Just atmospheric vapour cures the stuff. It is not cheap, in the quartiles a typical modeller will use, if you can actually use it before it goes off, then that changes everything.

Other than sticking Blue type foam or the expanded polystyrene I have not found a modelling use for it. For general joinery, particularly when moisture will be encountered, where it is great.

[10 lover/clive]

sorry erfolg imeant to say any of the gorilla type glues i.e polyurethene

[10 lover/clive]

cagey ididn't take it up fist time a good friend of mine maidend it good job really ,cos i was a bit emotional if you no what i mean . it all started as a dream brought abook post war jets , 3 view drawings and seemed to spend hours and hours on the plan .then away we go it took years to build start it change it you if you no wat i mean.change things as you build ,and go to work 12 hours a day .. here we go its 2.5m span 2.4m long 6kg weight ,4x 68mm ducted fans 11servos and retracts

[cagey]

Thanks Clive. All fits in with what I'd guessed it to be, except I thought 4 X 90mm fan units for 13 pounds AUW. Must have been a real heart stopper that maiden huh ? So is it still around and flying ? Great job my friend. Wish I could get started on my 1/12 F6 Lightning, but can't get hold of any of that Floormate stuff local and UK suppliers only sell it in packs of 4, 6 or 8 sheets depending on thickness and at nigh on £100 a pop. As I only want one square meter of 60mm looks like I may have to use EPS instead, bummer but maybe covered with a layer of medium weight tissue and a light spray of acrylic it'll pass muster eh ?

Thanks again, regards Cagey.

[road king97]

Finishing foam **LINK** Hope this helps. joe

[Colin Leighfield]

Erfolg, is that a Bachem Natter I see in your photo? Have you flown it?

I've got a huge block of blue foam in the loft and I recently got myself a hot wire cutter. Must give it a try.

[Erfolg]

It stands in my work room, needing a power plant.

I am considering using a flexible drive, as used on boats, to position the motor so that an acceptable CG can be obtained.

[Colin Leighfield]

Erfolg, that's a really enterprising project. I assume that means you intend to use a pusher propeller, I can see that a ducted fan would be a struggle with this design. You could combine it with some Estes rocket motors to get it off vertically! You have my greatest respect, I've never seen a model of this one before.