RT (Reaction Tester) Builds - Page 5 - RC Groups
Thread Tools
Oct 30, 2012, 02:42 AM
Remember... Fly for fun!
Well starting the long process of repetitive waxing for a new mold.

Wing mold needs re-doing. Should have Durateched and then sanded the wing plug beforehand as mold has a really bad cloth imprint in it. May be able to use it as a test/experimental mold.

Hopefully will pull a fuse out sometime this week, most likely next week. Will start it this week
Sign up now
to remove ads between posts
Oct 30, 2012, 03:00 AM
Registered User
Fuse mold looks great, bet it will be great to take the first fuse out.
Oct 30, 2012, 04:58 AM
Remember... Fly for fun!
I'm getting super excited! Really looking forward to popping out the first one!

What are people using to inflate a bladder inside fuse? How do you regulate to around 10psi? Do I need to buy some nice pump to regulate it at that? Can I use something I already have?
Oct 30, 2012, 06:00 PM
Registered User
I haven't done it but I would have thought if you fitted the valve off a bike inner tube and used a car tire/bike pump with a dial you would be good enough.
Oct 30, 2012, 06:01 PM
Registered User
Double post
Last edited by ReaperRob; Oct 30, 2012 at 06:02 PM. Reason: Double post
Oct 30, 2012, 10:33 PM
608 km/h!
josh18's Avatar
Looking great Alex, bad luck on the wing mould- Will the print polish out?
I use my compressor with the regulator set to zero, connect everything up and then slowly turn it up to ten psi. If you can support your bladder all round you can go heaps higher. Anyway I reckon one of those cheap comressors would do the job- better than a pump because the bladders always seem to leak down a bit and a regulator will keep up the pressure, even if the bladder pops you can keep ten psi, it just cycles pretty often.
Cant wait to see the first one!
Oct 30, 2012, 11:53 PM
Remember... Fly for fun!
I need a regulator. My compressor doesn't regulate, just has a relief valve
Oct 30, 2012, 11:54 PM
Remember... Fly for fun!
Put the 8th wax on this morning and then painted it up. Need to sort the bladder before laying it up. Will hunt around work for an old regulator
Oct 31, 2012, 04:14 PM
608 km/h!
josh18's Avatar
Nice one, reg will be well worth it.
Nov 01, 2012, 04:10 AM
Where is the inspiration
wdeighton's Avatar
I have a accumulator (Old Fire extinguisher) and a pressure switch on mine.
I like the way it works.
Vacuum regs are too expensive

Or are you talking compressed pressure
Nov 01, 2012, 04:47 AM
608 km/h!
josh18's Avatar
Compressor, for the bladder
Nov 01, 2012, 05:12 AM
Remember... Fly for fun!
I have a regulator now. No problems. Will set it up next week when have time
Nov 01, 2012, 05:19 AM
Dave Pope Manawatu NZ
pope's Avatar
Have not tried the bladder method yet, it will be good to see it comes out out.
Nov 01, 2012, 05:36 PM
608 km/h!
josh18's Avatar
Alex, make sure you pump up your bladder with the mould flanges ever so slightly apart, then clamp them up tight after 20 minutes or so. I skipped this step last time and got voids in the seam. I can only think trapped air could have caused this. Next time Ill run a bead of splooge right round the seam before closing too.
Good luck mate
Nov 06, 2012, 08:06 PM
Wind, hill, ... I'm keen ...
AvB's Avatar
I've done a lot of bladder infusions. If your mould is an absolutely perfect flush closure then you can get trapped air pockets. There are some good pics of this in a Zone V2 DLG thread - fuse mould got air pockets. But you really have to have an absolutely schmicko gloss perfect clean mould flange for that to happen. Mine are not that good. Any paint overspray, a few carbon fibres or crap on the flange will allow a minute gap which is all you need to get the air out. So unless your moulds are "Wyowindworks" quality, don't worry. If they are, you can slip a few small strips of very thin plastic, or thread in between and inflate at say 5psi for about 10 mins then remove the threads and pump up higher.

More frequent problem with basic moulds like mine is the bag popping out at the mould join. You absolutely must make sure that you have cloth overlapping at the joins or the bag can have an aneurysm and blow/pop into the gap. Even one layer of fine cloth is enough to prevent it. I don't think splooge prevents it. Common place to pop is the nose tip because it's hard to get the overlap right there. So a good tip is: cut a circle of floppy cloth (eg satin) and wrap it over the tip of the bladder, like a small parachute, so that as you inflate it, it pushes the cloth into the nose tip and seals off any gaps.

It's definitely a bit of an art, but once you work out the basics it's easy and you don't any fancy stuff. I made an open nose cone mould recently, and the first one I made was too tight on the fuz ... I'd designed it all originally from a cone made by inflation, and when I made it using the open mould and rolled seam it was thicker and rougher compared to the cones made with a nice flat tight seam from my old inflation mould. So I just worked out a way to screw a flat plate onto the end of the new open mould and converted it into an inflation mould! Lay it up and close the mould open-ended fashion, and then put the bladder in and screw the plate on the open end (bladder stylet pokes thru hole drilled in the ply plate). I used a piece of that soft closed-cell foam (like roll camping mattresses are made of) as a squishy seal between the mould and the plate, and I pumped it to 25psi and it's the best nose cone I've made yet!

Another big tip is make sure your bladder is slightly oversize. I tended to whittle my template down and it took me a few blown bladders to realize I'd started making them too small.

You can make lighter thinner layups with the bladder, and you can use the pressure to push the cloth into sharp corners with very little use of splooge ... particularly if the cloth sections overlap just either side of the corner and can slide over each other as they press tightly into the corner. Don't lay a big section of cloth over a corner because the pressure won't be enough to press it right in there. You need to either splooge the corner or cut the cloths either side of the corner to let them press in.

Oh, and another thing ... I've had a few where I've got a leak and let it keep going. As Josh said, for most leaks, usually the compressor can keep running enough to keep enough pressure in there. But the results aren't good. Each of those has had areas of really porous cloth and it seems that the air tracks around the place, taking resin with it. If it's an important one, and it leaks early, it may be best to dismantle the whole thing and put another bladder in (very messy). I like to heat the thing up fast once the bladder is in so that it gels sooner and I can stop worrying about leaks!
Last edited by AvB; Nov 06, 2012 at 08:30 PM.

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion 10 in1 servo tester (professional servo tester) flydreamrc Radios 22 Dec 12, 2016 02:22 AM
Alert RT Models Beaver Pre-release build St. Martin Scale Kit/Scratch Built 86 Jun 29, 2008 05:01 PM
Build Log kin'Brilliant Build Pics (PU-RT) wdeighton Slope 30 Mar 18, 2008 03:38 AM
Discussion RT Models MIG-15 Build AeroDude Electric Ducted Fan Jet Talk 34 Mar 02, 2008 05:49 PM
Discussion RT Mig 15 Build nut Electric Ducted Fan Jet Talk 8 Jul 30, 2007 01:17 PM