Scale 50cc Scratch Build From My Own Design Revisited

[Jetpainter]

I glassed and painted a lot back in the day on jets, early pattern and other things and I wasn't one of those guys that could do a super light job. I did do a small pylon racer back then with glass cloth and dope instead of resin. It's pretty light, but it didn't take long for the dope to shrink and the weave of the cloth to show through and make me very unhappy.

This time I want to try a few new things when I glass. I know Terry and a lot of guys like to use hairspray on their sheeting before resin when they're bagging wings. It keeps resin from soaking in as bad when your spreading it, so you use less and get a lighter job. I don't see why that wouldn't work when your glassing. You may end up with less pin holes as well. I also want to experiment on light weight ways to deal with pinholes before I prime.

No matter what I do, this airplane is not going to be light, well maybe compared to an anvil. It's the first large plane I've designed and I built it like a tank, but I learned a lot. I mostly just wanted to see if I could do it, and it beats the hell out of sitting around watch reality TV and killing whatever brain cells I may have left.

Doug

 

[Terryscustom]

Absolutely, 2-3 coats of cheap-n-nasty 80's spray will keep that resin up on top. There is a guy here locally that does some warbird stuff and he has used water based polyurethane as well. I may have to do some tests..... I'm going to be sheeting some canopy decks in a couple weeks that will need to be sheeted. Funny.....I have never sprayed the outside with hairspray before sheeting

 

[Jetpainter]

I've watched some videos on the water based polyurethane on YouTube. It looks easy, but it also looks like it takes a bunch of coats so I wonder about weight and how well it fills the weave. Another thought, since it's not catalyzed is it going to shrink like the dope did on mine years ago? With a flat finish like on a lot of warbirds you wouldn't see it, but when it's shinny that stuff shows.

 

[Jetpainter]

I finally started planking the turtledeck and stab area. I did the very top edge first by gluing a narrow strip of balsa right down the center spine. After that I added another strip to each side of the center one.

After the top edge I sheeted the last flat spots in the rear. The main sheet down the sides in the back is 1/16". I used 3/32" on the last upper flat pieces because I wanted to make sure I had plenty of meat to make the transition into the curved turtledeck sheeting. It's easier to sand it off than add more on.

Next, I spent several evenings staring at the transition between the vertical stab and the turtledeck trying to figure out what to do with it. I had decided earlier that I hated the way I had it laid out, but didn't know what I wanted it to look like. There was a sharp 90 degree corner where the stab came out of the turtledeck and it didn't fit the look of the airplane at all. I made a couple of balsa formers to glue to the lite ply ones that were already there so I could change the shape into something more pleasing to the eye. I used some fishing line to make sure my line was straight from front to back when viewed from the side and sanded the new formers till I came up with a more flowing look. If you look closely you can see the difference between the ply and balsa formers.

 

[Wacobipe]

'll be watch in' this because I'm planning to 'glas the wings and tail.on my Delro Raven that I'm starting...so tips on best methods will be great!

 

[Jetpainter]

I've got several to do myself. USPS and FedEx both delivered classic pattern airplane kits this week. The big one is an original Dr Jekyll kit and the smaller one is a new Tiporare 750. The Dr. Jekyll is massive! I can't believe they pulled that thing around with a 1.20 four stroke.

 

[Terryscustom]

We so need one of those with a 60cc or 70cc twin on the nose!!!!!!!!!!!!!!!!!!!!!!!

 

[BalsaDust]

Looking awesome.

 

[Wacobipe]

I've got several to do myself. USPS and FedEx both delivered classic pattern airplane kits this week. The big one is an original Dr Jekyll kit and the smaller one is a new Tiporare 750. The Dr. Jekyll is massive! I can't believe they pulled that thing around with a 1.20 four stroke.View attachment 704

I think we've all become drunk on cheap power . If you look at any of the older plane designs the power recommendations are always ridiculously small compared to today ...and they weren't underpowered aircraft! Extreme 3D might need today's power recommendations...but IMAC, scale, and sport flying would do well in my opinion to learn more about how to fly on the wing instead of the prop.

I'm about to start building. 2.5M Raven made by Delro in Germany...when they built the plane they used an MVVS 85cc...DA (where I bought the plane) says you need a 100cc-120cc engine... I am very tempted to put a DA 70 twin in it, at 22-24 pounds I don't think it needs any more than that to fly scale. My 26% Pitts is 25 pounds and flies great on a DA60, unlimited vertical, and a hell of a lot more drag than a Raven is going to have...

 

[Jetpainter]

My 2.3 meter Extra weighs 21.75 pounds and has plenty of power with a GP61. I've flown it as heavy as 22.5 pounds on a DA50. It lacked vertical performance with that setup to say the least.