canardlover

Howdy SPADders, I have been SPADding a bit myself some years ago but discontinued because of two major drawbacks imo: 1) glueing is very tricky and 2) planes do become rather flimsy and/or heavy.
However, I now do plan to make a comeback, this time using "coroplast" made of polycarbonate(Makrolon, Lexan) which is available in several thicknesses here in Europe (4, 6, 10, 16...mm, see attachment) typically used for greenhouses and terrace roofs. As you all know polycarbonate is extremely tough and durable and much stiffer than the usual polypropylene coro. Weight per area unit is only slightly higher than the usual PP coro and I guess glueing canardly be worse than PP. To my surprise I have so far not seen polycarbonate coro being used in the RC-SPAD community, either here in Sweden or elsewhere...why..? Have I missed some relevant thread please show me..THANKS...or is there a problem I´m unaware of..?? Please enlighten me...Thank you.

aspeed

I bought a piece about 9 years ago for $60. Now the price has doubled here. For that reason I am out, except maybe for stiffening a fuselage or wing. It is nice stuff though, it would not curve like for most wings, but might be good for a profile fuselage. It could be stiffer, and paint or cover it all except the canopy..I have never seen Daffy Duck and Winnie the Pooh together before.

aspeed

Just stumbled across this one. Kind of looks nice in the clear. https://www.rcgroups.com/forums/show...-Polycarbonate Still pretty spendy compared to regular coroplast, at least in the store I checked.

canardlover

Thanks a lot aspeed for the link to rcgroups..I missed that in my search. This is encouraging since glueing with hot glue seems to work. My main reason for using polycarbonate is outlined here:
http://www.rcuniverse.com/forum/scra...b-trainer.html
No response yet, where are all SPADders..?..flying ARTF..?!

aspeed

I think the regular coro is pretty tough too, maybe more? IDK. We used polycarbonate in the model car rug racers, and it was plenty tough. I like your trainer design with the motor protected in the back, but I always had trouble with trike gear on trainers. It bends back and won't steer any more and you have to take it home to fix...A regular gear seems to work better for me, maybe not so much for taxiing. I try to get some type of torsion in the gear so it comes back to normal and doesn't snap. Like a big U somewhere. Where are the Spadders? IDK, I want to fly my old .40 combat again soon, it did some cartwheels last flight last year. Seems OK. I got four on the go. One is a B combat Battle Axe and the other two are downspout fuselages. One with a thick wing like the SPAD edge base, and the other one with an ASP .15 on a little combat job. Oh, and a Gnat. Might get one of the four projects going.

canardlover

Thanks for input aspeed, will consider your thoughts but imo a taildragger is not my favourite for students. It will inevitably nose over for them both during both start and landing. If you bend the gear forwards to eliminate noseovers the plane will instead bounce on landing. So I will stick to trike gear for the UBBCT. Will soon buy the Makrolon sheets and have a try at it.
Battle Ax..!.is that the FSW canard plane..?!?!..got pics..?!....Cheers/

aspeed

Treneff RC - R/C Combat Home! Foam wing combat that was fairly popular in the US.Pretty tough. The guys liked them better than the coro wings I think because they are lighter.

spaceworm

One significant issue with polycarbonate is it's vulnerability to attack by aromatic hydrocarbons, such as lacquer thinner, acetone, xylol, MEK, dope thinner and all paints thinned or reduced with the same. It will be destroyed by those. Aliphatic solvents such as naptha, mineral spirits, turpentine, do not seem to affect polycarbonates. nor will alcohol. Nitromethane is an aromatic solvent so it will attack polycarbonate. Polypropylene is resistant to almost everything.

canardlover

Valid point spaceworm and also very good news. It shows that Polycarbonate(PC) is not nearly as inert as PP and lends itself to glueing. Attacks by acetone and nitromethane does not bother me, I have used Makrolon for years in various places on my planes and glow fuel with up to 10% nitro is no problem. BTW, which airplane canopy can withstand acetone or concentrated nitromethane..?!?

canardlover

Too bad the Battle Axes are not available today..! They remind me of the SPAD Draco design which I like a lot. Should be good and tough trainers.

abachiwing

Hi there Canardlover,
I dug up two old 1 mm sheets of plastic, intended for my canopies, and tested them with undiluted acetone and nitromethane.
Acetone is chemically a ketone and nitromethane is chemically an acid.

One sheet is Lexan which was used for model car bodies many years ago when I bought it. This is polycarbonate. I never managed to pull a canopy from it because it requires pre-drying and too high temperature. It resists nitromethane but not acetone.

The other sheet is Quinn PET-G which is a copolyester. I have used with success to form canopies in recent years. It has a low max. operating temperature of 70^C (160^Fahrenheit) and does not resist nitromethane nor acetone. I have also been recommended to use the copolyester Vivak which has very similar properties although "PET-G" is not mentioned in the product leaflet.

Today, I also tested two corners of a canopy bought from Vintage RC Plans. They produce nice canopies but do not specify the material. It reacts like copolyester. There may be other materials available but finding one that resists nitromethane and is easy to pull over a plug may be difficult. Search among the instruction movies on Youtube!

Lars

canardlover

Lars, thanks for comments. I do not think solvent attack will be an issue with PC. Glueing of Makrolon works fine with 5´ epoxy, that I know for sure. Canardly wait to receive my 4, 6 and 10mm polycarbonate "coro" sheets I ordered recently...cheers/

aspeed

The 10mm might make a good profile fuselage for up to a .46 maybe. If you are worried about fuel dissolving it, you could paint it or maybe put a coat of wax on and wipe the fuel quickly/

canardlover

OK, thanks aspeed, what kind of paint would you suggest for "pc coro"..?

aspeed

Not sure what would react with it. For nitro fuels, a two part automotive paint is good, but I would test it on a scrap first, as thinners would likely craze it. We used acrylic latex on the carpet racer cars, but they were electric. I think it was water based artist stuff way back when. Some new water based two part automotive paints may work. A clear over the old acrylic latex may fuel proof it and not go through the paint into the plastic. I read somewhere about the old Future floor wax being used for a clearcoat, you could read up on that too.

canardlover

Yes, I think too that acrylic latex would be a good starting point....will keep you posted....Cheers/