MIRO 2

[CSpaced]

I love what you guys are doing (nice article on your Raven Barrie), its very inspiring! But man are you guys in a league of your own!

[Rod]

Still playing around with the fuse stiffeners. I found rolling the foam in the mold with a hard roller really got the foam to conform to the fuse shape. It looks like I might be able to do without the vacuum bag for the fuse. With means I can join the halves wet in the mold which is lighter and stronger. Will probably apply epoxy and microballoons as I roll the foam just before I layup the fuse so it is nice and sticky when I put it in.

[Rod]

Time to layup a fuselage. Here I am marking the 76gm cloth with a disappearing ink pen. The layup will be 76gm glass/reinforcements/120gm S glass/foam/50gm glass.

[Rod]

I managed to take some photos in glove changes. This is how I do the microfibre filler in the sharp corners.

[Rod]

Here I have the 76gm cloth in the mold and have reinforced the hatch openings with some 120 gm S Glass. Have also put in some 200gm carbon cloth in the nose and around the UC area also reinforced the wing tube area (I hope).

[Rod]

To cut a long story short here are the halves ready to join. The resin is still uncured. You should be able to see how the lap joint method works from this shot. Actually it was a bit of a fiddle getting it together but its all done now. I used a narrow ribbed roller on a stick to lay down the seams once the halves were joined.

[Imac Kiwi]

Here is a couple of pictures of Barries Raven powered by DA 85

[Rod]

That's awesome.
Thanks Alan

[CSpaced]

The part that I always wondered about was the joining of the two fuse halves. How do you insure that you are getting a good overlapped seam? It seems that once they are joined together that there isnt a lot of room to get in there and make sure its all seated correctly?

[brusty]

Thats a great post Rod, thanx for the pics Alan. Hey do you guys ever sleep, I can't wait to get down here in the morning to see what you've been up to !!

Very interested in your layup Rod, esp joining in the mould wet. I have spoken to Ewan, but to date not been game to try it, must save quite a bit of that dreaded weight as the model gets bigger. A definite for next time. I note you are using S-Glass, whereas Ewan spoke of I think 3oz Kevlar in his later Matrix layups, do you have a comment there ?? I like the idea of a piping bag, I was brushing in a bit of M/Bal thickened epoxy and running a few strands of carbon uni around the corners. It was a bit hit and miss, your system looks better.

You ask about weight saving on the Raven. I read overseas they are flying the DA85 at arround 26/27lbs (I'm too old to convert totally to metric!) the Raven came out at 30.5, and okay, I put a bit much emphasis on "scale", and although appears to fly great, does suffer a bit at the top of the uplines . It will be great for my limited ability, but does need to shed some weight. The old story, like your Miro, better the second time around. Where would I lose it. I could most likeley lighten or lose a layer of cloth right thru, wings and Fuz. I put a lot of reinforcement from the wing root right thru to the nose which on hindsight was totally unnecessary from and inch in front of the firwall forward, plus i think I overdid the reinforcing carbon Cloth. I would lighten the layup of all the "extras", spats, wingtips, exhaust stacks and the rudder and tailwheel. minimal cockpit detail (my pilot and cockpit would account for over a pound) and i would do away with the carbon canopy frame and just used the masked canopy without reinforcement, as I only access the rudder servos thru there so it seldom comes off (I hope). Maybe also need to lighten up on the remedial fibreglass work, gear mounting with a bit more thought, and the final amount of paint. There's the challenge, like you I will do another, an IMAC only one, that DA 85 is an awesome motor and frankly is as big as I want to go, so it deserves a lighter ship !!

Regarding the manifold header pipe, the plate is from 5mm SS with a hole bored to receive the first bend, which is half a 90 stainless 28mm inside diam 1.8mm th. The rest of the bends and pipe are 28mm Outside dia 0.6mm stainless Mike supplied, it comes as a pack of fittings from DA, tho I think from MTW, they have them on their website. The flexipipe is stainless 33mm O/D, and I know you can get that from 436, I have had some for a few years. I just cut and taped and trial fitted it all, then brazed it with easyflow. If you are interested, I still have the MTW header for the DA85 that I bought for the motor with the MTW tuned muffler, but it wouldn't fit the Raven, and i don't think will fit the Mustang either. It could be suitable for your Sukhoi tho as the cowl is so volumous.

At the moment, for a bit of light relief after thirteen months of concentrated effort, I am doing a 2 meter Sukhoi SU-31 for an OS 160 I have lying in a box. Quick build, plug /mold composite Fuz, and foam and brown paper wings and stabs, target weight UNDER twelve pounds !! wish me luck, the wings are done, tho may now do a second set as these are a few ounces over budget, tho acceptable but I can aleady see where to save as there is plenty of rigidity and strength. Isn't life a challenge ??

Carry on the good work, I'm watching with interest.

Regards, Barrie.

[Rod]

Here is the seam roller. There is tons of room in this mold to get in there. Once you get used to the wet join system you will find it is the easiest lightest and strongest way to join. It also eliminates seam cracking einafter painting. The down side is not being able to vacuum bag the molding. Although the glider guys sometimes use a pressurised bag inside the mold which means you have to seal any holes in the mold.

Barrie I have used Kevlar quite a bit. At the moment Kevlar is not available here in these light weights. Kevlar is UV sensitive (it goes a brownish colour and looses strength. Kevlars main strength is in tension not compression which we mostly need. Although it is light it soaks up more resin because of its bulk. S glass is 25% stronger than standard E glass and is easier to work with too. I had to get 25 yards from CST but it is only 27" wide so freight isnt too bad.

[Rod]

BTW I tried using a micro balloon mix on the foam reinforcements. This didnt work very well so I ended up just using straight resin and towelling off the excess. Gave the foam a good rolling with a solid roller once in the mold. This squashed the foam from 2.2mm down to about 1.5mm.