New to R/C aviation - lots of questions (& pictures) - New to me 1/4 Scale Piper Cub


New member
New to R/C aviation - lots of questions (& pictures) - New to me 1/4 Scale Piper Cub

About a year ago I purchased (and saved) a 1/4 scale Piper Cub with a massive gas motor. The previous owner had intended to use it as a revenue builder for his R/C club where people could shoot paint balls at it until it crashed. The builder looks like they had some interesting skills working with what was available. As you might see in the pics their work, especially soldering, was not the best. The wings are not covered in fabric unlike the fuselage.

I'm very new into the R/C world so I have a lot of questions. I used to fly as a private pilot and I’m mechanically inclined. I’d like to think these skills will help me to be successful with R/C aircraft. When I bought this cub I decided I would try to get it back into the air on a minimal budget. Then the following week I bought the Phoenix Simulator with an included DX6i Transmitter.

The Aircraft:

The Motor:

Known Issues/concerns - Engine:

1 - only the two upper motor mounts were attached (lowers will be secured during reinstall)
2 - fuel tank needs to be installed
3 - need/want to identify the motor (who made it, specs, mixture required, idle RPM, max RPMs, fuel consumption, displacement) It seems comparable to a Zenoah G38 but I believe the seller said it was a 45 or 50+; I can likely measure the cylinder bore to ID this - I have a ZEN manual I will begin to review
4 - custom made exhaust has holes and is corroded. Made of aluminum, I'm gong to clean and repair with JB Weld
5 - this might be a re
6 - Ignition system - most important - the builder installed a switch that in the labeled "off" position closes the circuit between the green wire and the red wire. Would it make sense to install an electric switch/relay component I can switch with the flap switch on the transmitter to brake the circuit and shut down the motor?

Known Issues/concerns - Air-frame:

A - Left wing - balsa wood support for aileron separated from internal structure, skin damaged (glue and tape)
B - Rudder support - separated (JB Weld - initially)
C - Rudder hinge pins - not fully installed (further evaluation required)
D - I'm a little disturbed by the minor amount of up elevator I will have. The protractor was zeroed the the plane of the horizontal stabilizer. The servo was rotated full up elevator and the extent of travel was 13.5°, down was substantially higher, nearly 40°. Does this seem reasonable? Too me, this would indicate the plane was setup to fly with down elevator.
P6100094.JPG P6100095.JPG

More to follow, too late to continue tonight. Thank you.


Skill Collector
Welcome to the forums!!

That's a great project that looks like it only needs a light restoration touch - if you poke around in the Mad Balsa Builders subforum you'll find some other restoration project threads that might be interesting and offer some techniques and ideas.

As a new to RC person, I'd highly recommend getting a BNF (Bind and Fly) foamy model to learn on - starting on the simulator is a perfect first step, but learning to fly with something that is both very damage resistant and that you don't have a lot of emotional attachment / work hours put into will be very important to have a good experience with that beautiful Cub.

For that foamy model selection, the Apprentice, Parkzone Cub, or pretty much any other high wing plane with AS3X stabilization (since you already have the DX6i) will be a great place to get into the air.

After all, we want you to have a great time flying that 1/4 scale Cub, and not a pile of sticks to put back together after a rough maiden flight :)


New member
Thanks for your feedback. Unfortunately I don't have the means to buy a lot of items. I was considering building a wheeled FT Guinea Pig for practice. Even buying everything needed at the sale price is a bit of a stretch this month.

PS - wish we had met each other years ago. I was actually deployed to the DC area and lived in Alexandria each time. It was a wonderful home away from home.
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Well-known member
I'm guessing that you are going to want to fly that monster at a club or something. The club near me offers free flight training for members using the Apprentice. I'd recommend going that route as well as becoming an AMA member for the insurance alone. Just in case you accidentally drill a hole through someones new Cadillac CTS.

EDIT: I wanted to mention that I am also a Private Pilot. It's great knowledge for stuff like energy management and so on....but it does not help when you get dumb thumbs. Stuff happens fast with RC and then next thing you know you have created your very own crash site to investigate.
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Skill Collector
Guinea Pig would be good or this new Tubby Cubby that's going to be released shortly - it'll be much cheaper than the As3X ready to fly stuff and you'll get to have all the fun of building it too!

And definitely look into the local club suggestion - the one I'm a member at does free training on a club plane too.

Next time you are back in Alexandria give me a shout :)


New member
Thanks again Rockyboy!

I have an electric only filed about a mile away and an everything place about 15 minutes away. I'll be sure to check into both soon.
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Joker 53150

Mmmmmmm, balsa.
That's a nice plane, it appears to be the Balsa USA 1/4 scale Cub, based on the wing design. I've got the Balsa USA and Sig 1/4 scale Cubs and love the way the Balsa USA one flies, but hate the way the wings get installed. Your pictures don't show it, but I assume the door & window on the right side of the fuselage open up to give you access to the wing bolts and electronics?

You mentioned that the builder didn't do a great job with the soldering, so one thing you'll want to really look at is the landing gear to make sure it doesn't break. I had the lower brace break on mine, but luckily it didn't cause any further damage.

You've probably figured out that the wing struts are absolutely required. One thing I don't see on yours are the braces that go about half-way between the fuselage and the ends of the struts. If I remember correctly, they aren't 100% required on the Balsa USA version and they simply slide in to the wing without fasteners, however, the guy who built my Cub years ago made them functional with screws holding them in place for additional strength to the wing.

Depending on the age and general condition of the plane, you might want to consider tearing off all of the covering and checking the airframe thoroughly. You never know what kind of damage or bad glue joints are hidden!

For the engine size, it doesn't look big enough to be in the 45+ range to me - my guess is more in the 26cc range which is plenty for a plane like this unless you want unlimited vertical climb! My Balsa USA Cub uses a 23cc Zenoah, which works perfectly. I had a Sig 1/4 scale Cub that used a 20cc, which was a bit under-powered. My clipped-wing 1/4 scale has a 26cc which gives me the extra power I need for floats and aerobatic flight. Either way, if you post your engine pics on one of the main RC plane forums on FaceBook you'll get an answer quickly, and I may be wrong on my assessment.

I'm also wondering if that engine was purpose-made for RC, or if it's a former chainsaw or weed-eater motor converted to RC. That mounting plate and the extra blocked-off hose from the crankcase are throwing me off a bit. Check your throttle linkages for slop and to make sure those ends are secure! It looks like the builder just did some simple bends in the wire, which could be a big problem if it jams or breaks during flight!

The switch you mention grounds the magneto to the case, which kills the engine. That is handy when the plane is on the ground, but in the air it does no good. Electronic ignition engines can be killed remotely, but the magneto setup requires a little extra work to let you kill the engine from the transmitter. With my 23cc Zenoah I purchased a small reed-style switch and attached a servo to it. The servo arm moves over and presses the reed on the switch, completing the circuit and killing the engine. My fail-safe programming on lost signal will run the throttle down as low as it goes AND also closes that switch to kill the engine. If the engine had a servo-operated choke I'd also choke the engine.

Oh, and you'll want to install all new gas lines, a new bung for the gas tank, and probably a new gas tank since they're cheap.

For your elevator UP limit, is that limited because it binds or is that physically as much as the elevator servo has for throw? Since you've got WAY more down than you'll ever need, maybe the solution is simply removing the servo control horn and re-installing it a few notches over?

As was mentioned before, check out the balsa forum on here, I've got a couple threads for the 1/4 scale Cubs (and other planes) that I've been rescuing over the past few years, and the info may come in handy.


New member
Thank you Joker. I rushed though your thread last week and it was amazing! Sorry about your Sig, I can't imagine what that would feel like, it was a gorgeous aircraft.

I'm not at all sure where the motor came from, had a coworker look at the pics and he wondered if perhaps the tank was somehow being presurised by the motor case.

I'm in a tight spot at the moment financially, I'd almost be more interested in selling the Cub than buying anything. It's time I start to liquid some assets from another hobby I'm afraid.

Joker 53150

Mmmmmmm, balsa.
Thanks, it was hard watching it crash, but it's part of the hobby. My dad took it much worse than I did, for some reason. Planes fly, planes crash, you move on. :)

The more I look at it, the more I think that engine is from a weed wacker, chainsaw, or some other gas device. It was pretty common to re-purpose them years ago, before companies started making gassers for planes. That port could have been a drain or to pressurize something.

I shouldn't ask, since I've already got enough 1/4 scale planes, but where are you located? I hope it's way too far from Wisconsin for me to even consider making an offer on it.


New member
Well, lol.... I'm in Mankato, Mn, grew up near La Crosse, WI, and my parents live near Kiel. I could probably get close to deliver the bird. :black_eyed:

Joker 53150

Mmmmmmm, balsa.
That's WAY too far away, from what my wife tells me! :) The problem with big planes like this is that they're extremely hard to hide.


New member
Subwofer2, if you still thinking about getting rid of the Cub, in the late spring, I will be up near Tomah, if my accountant (Wife) lets me and it is still in need of a home, maybe we can work something out. If not take it slow and rebuild it as the funds come in. I can help out with advice.