Sig 1/4 Scale Clipped Wing Cub, Bringing it Back to Life!

[Joker 53150]

Since I'm new to gassers and don't have easy access for somebody to show me in person how to tune the engines, I'm turning my gaze to the mighty Interwebs. I found a method that appears to work pretty well, and many swear by it as a fast & easy method to get the high & low needles set properly. Some have expanded the flowchart to try and get it even better, but for now I'll stick with the basics.

Weather was warm enough to spend some time outside testing it out, and so far I'm impressed with the results. The idle is smoother and I have very little 4-stroking now. The engine is far from broken in, so I expect this to be a "work in progress". The engine is currently running a tiny bit rich at idle, but after more tanks of gas are burned I'll lean it out slightly so it runs better across all RPM ranges. Too rich isn't ideal, but it's better than too lean, and until I know more I'll err to the rich side.

 

[Joker 53150]

Snow and ice across the state yesterday, 40 degree temps today, and 50's over the weekend. Gotta love Wisconsin weather... The plan is to take the Cub out again this weekend to see how the new engine tuning works. Before it goes up again it got a full nut & bolt inspection, and there were a couple things that needed to be addressed.

First, although I like the metal housing on the power switches for the ignition and receiver, the fuel port that is built into it just doesn't work well for me. It's designed for a much larger hose so it stretches out the hose I'm using, plus the bung doesn't stay in securely enough. For now I simply installed a new fuel port like I'm using on the other Cub. The original port will just be left open. When I eventually re-cover this Cub I'll change the switch assembly out to one that doesn't have a fuel port.

Second, the elevator servo was acting a little strange so it was replaced. It's operation just wasn't smooth, and was a little jittery, not quite what you'd want for an elevator. It is an older servo and larger than what is used now so I added some extra material to the servo tray to fill the gaps. The new servo operates as it should with no jittering.

With that done it should be set to fly again, hopefully without any dead-stick landings!

 

[Joker 53150]

Flying season is fast approaching, and I recently found a place to fly with access to water. It's almost perfect - a man made rectangular pond at a state park, as large as a regular RC runway and only a few feet deep with clean, clear water. Currently my only float plane is a Hobby Zone Super Cub, but the Clipped Wing Cub came with a set of Sig floats. However, they needed repairs to make them usable (see my other 1/4 scale Cub thread). I think they were covered with some kind of fabric covering and painted silver, but the material didn't stick very well to the balsa as it peeled of with little effort. They certainly weren't waterproof in the condition I got them in. To re-do them I'm starting off with fiberglass, and will eventually paint them. A heavier cloth is being used on the bottom and lighter will be used on the tops and sides.

 

[BobK]

Awesome job on this plane as well. I can't wait for the float flying, I am lucky enough to have a six acre clean spring fed pond on my property and a 12' boat for plane rescues..and even a rescue dog lol.

 

[Joker 53150]

Nice!

Here's the area I'm planning to spend time at this year, Bong Recreation Area, named after Richard Bong who was America's top ace of WWII. It's not apparent until you look at a full satellite picture of the area, but this was originally going to be a runway capable of handling B-52 bombers. In true government fashion, construction was well underway and then the plug was pulled. Now it's a state park and recreation area. The squiggly lines in the pic are ATV trails around what was once the runway. The RC field is in the same area, at the right end of the runway and you can just make out the paved runway areas. The dark spots at the bottom left are the ponds for RC planes and boats. The park offers areas for hunting, horseback riding, model rocketry, hiking, camping, etc.

 

[BobK]

That looks great, at least they did something with the property that people can use, sometimes areas like that are fenced off and forgotten.

 

[BobK]

I was going to mention on the floats, a technique I thought worked quite well was drilling a few small holes in the top then using lightweight expanding spray foam to fill the cavities. After the foam sets fill and cover over the holes. Even if the float is heavily damaged it won't take on water and still float.

 

[Joker 53150]

Not a bad idea. Weight would be minimal, and I've got some expanding foam in the shop.

 

[BobK]

Speaking of floats, I thought this was an interesting combination. I might go check it out it's for sale not too far from my location.

AT-6 Texan

 

[Joker 53150]

That's a crazy looking setup!

 

[BobK]

Yes it is, I have never seen a Texan on floats, I wonder how it would perform..or even if it is worth checking out. Not trying to take away from your thread, but I was curious what you thought about it.

 

[Joker 53150]

Interesting plane, but seems a little expensive compared to what I've seen at swap meets. I also wonder how well it would slow down when using the floats. My Texan doesn't want to fly slow, even with flaps it wants to keep moving quickly.

 

[BobK]

Pretty much my thoughts. I would probably use the floats on something else, but yeah the price is a bit steep.

It doesn't look badly built from the pictures, but pictures can hide a lot. Doesn't hurt to look though.

 

[Joker 53150]

I'm with you in that, but I tend to "accidentally" buy anyway!

So the float bottoms are glassed. Once it cures I'll sand them and do the sides and tops. More sanding and fill coats of epoxy resin to follow.

 

[Joker 53150]

The clipped Cub has been sitting collecting dust for a few months now. It flies great, but there has been a problem with keeping the engine running. The first flight would last about 3-4 minutes until the engine would start to sputter, so I'd bring it in for a quick landing. Everything looked good, so I'd take off again and the flight would end with the engine quitting less than a minute after take-off. I got pretty good at emergency landing a 1/4 scale dead-stick! After a few short flights like this it wouldn't even start until it sat for a while.

Other projects got in the way and I never really got into why I was having problems. The problem could be an air leak in the fuel line, a collapsing fuel line, weak battery, bad ignition module, bad carb gaskets, or a few other items.

I really want to get it back into the air again ASAP so I ordered some parts to give it a full going over. New carb gaskets, new Tygon fuel line, and LiPo batteries w/regulators to replace the NiMh. The only thing I'm not replacing (yet) is the ignition module. Since the other 1/4 scale Cub is sidelined due to it's battle with gravity, I'll grab the ignition module from it and try it IF the above items don't fix the problem.