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1/4 Scale Cubs - Sig and Balsa USA, Rescue and Re-Build

Joker 53150

Mmmmmmm, balsa.
Mentor
I guess I'm addicted to Cubs... This morning I went to a guy's house to see a plane he was selling, and I made the mistake of asking if he's got anything else for sale. Lucky for me (I guess...) my truck was empty, as I bought the plane I went to see and ended up bringing home another Cub as well. This is a 1/4 scale Sig Clipped Wing Cub, covered with Solartex, riddled with patches, and in need of some serious TLC. But it was a decent deal and I couldn't pass it up. :)

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From what I've seen so far, it needs all covering stripped off and replaced. The wing needs a few small repairs, the wing struts are shot, the tail has some bad glue joints, the cowl is missing, the engine hasn't been run in a few years, landing gear is rusty and a bit tweaked, the windows and windshield are fogged, etc. But I've fixed far worse than this! :) He also has a 1/3 scale Cub that *MIGHT* be for sale, so I asked him to let me know if that happens. It too needs quite a bit of work, but it's a massive plane and would be a fun project.

That puts the total to three 1/4 scale Cubs in the hangar right now - the OD Green Balsa USA Cub, a Sig clipped wing Cub that has needed some work for a while, and now this Sig clipped Cub. I'm tentatively thinking about going electric with this one. Maybe 10 cell, which would let me use the 5 cell 5,000mAh packs I use on a few other larger planes. 10 cells would be a ton of power for this plane.... :)
 

Joker 53150

Mmmmmmm, balsa.
Mentor
A new idea presented itself for the "new" Cub's power-plant. Electric is probably off the table now, as I realized I have a .95 glow engine that needs a home. For the life of me I can't figure out where/when I got it, although it may have been bought from the same guy who sold me the Cub. :) Sig calls for up to a .90 for the Clipped Cub, so this should work out fine. Part of the rebuilding work will include adding the body mounts for a set of floats. A couple years ago I picked up another 1/4 scale Clipped Cub that came with floats, and it's a simple process to make them work on this plane.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
Speaking of Cubs.... :rolleyes: My buddy Mike picked this one up this past summer, and asked me to get the DLE 30 engine installed for him, along with a couple other tweaks so it's ready for Spring. It's a Sig 1/4 scale Cub, with a 1-piece wing, which is massive! It shouldn't take too much (hopefully) to make it ready, and as with the other Cubs I'll document it here for anybody interested in the topic.

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Joker 53150

Mmmmmmm, balsa.
Mentor
Upon further review, the DLE 30cc gasser may not be going into Mike's Cub. The rear-mounted carb would force me to cut a hole in the firewall and use shorter stand-offs so the carb would actually be inside the fuselage. Not a huge issue, it's been done plenty of times before, but it would keep us from using a Pitts-style muffler and it's a lot of weight far forward of the CoG. Option "B" is to use a different brand 26cc gasser. This one has a side-mounted carb which means the engine will be mounted right on the firewall (or a small mounting base). The carb would stick out the side of the cowl, which isn't a big deal. The muffler would also stick out the side of the cowl, but the muffler isn't huge so it's not a big concern.

He'll drop off the 26cc and order a bigger gas tank, as the one that came with the Cub is only 14 ounce and there is plenty of room for a 20-24 ounce tank. More to come! :)
 

Joker 53150

Mmmmmmm, balsa.
Mentor
So with Mike's Sig 1/4 scale Cub we were going to go with this engine, however I found it's got a rear-mounted carb which would require cutting a big hole in the firewall to recess it far enough for a proper fit in the cowl. Plus that would keep us from using a Pitts-style muffler meaning the current muffler would stick out the side of the cowl and be very noticeable. He's got a 26cc gasser with a side-mounted carb that'll work better so this engine will go on a different plane.

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The plane is in good shape, but there are some things that need fixing, such as the side windows. A little canopy glue and some Cub Yellow trim tape will take care of that pretty quickly. The covering is sagging a bit in a few spots as well which will be a quick fix.

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Switching over to my Balsa USA 1/4 scale Cub, I finished up the landing gear by adding the covering to complete the look. Last season it flew with just the wires and no fill, which looked a little odd.

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The interior also got a little detail. A new floor was added to covering the servos, receiver, and battery and the original pilot and seats I got it with were cleaned up and installed. The pilot in a Cub flies from the back seat, so that's where he's going! :)

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Last up is my Sig 1/4 scale Clipped Wing Cub, which is getting a new (to me) engine. It had a 26cc gasser, but after numerous tries I just couldn't get it running right. It's probably something simple that I'm missing, but the plane needs to fly and I've got a .95 OS glow engine that needs a home, so it's being swapped in.

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Joker 53150

Mmmmmmm, balsa.
Mentor
Time is finally starting to free up for me to get back to work on the planes. While I've flown a bunch this summer there really hasn't been much time in the shop. A few planes got some damage and were simply put off to the side to wait for repairs and other planes were rotated in. The yellow 1/4 scale Sig Cub shown in the previous post (belonging to my friend) is finally done. The engine and electronics are done and new windows are installed all around. All he has to do is install his own receiver, program it, and run a few tanks of gas through before the maiden flight. We went with a 26cc gasser that has a side-mounted carb, and it really seems to run well so far.

I also built a Tower Trainer .60 for him, complete with a .90 size 4 stroke glow engine. This was a pretty quick build since it's a balsa ARF. I don't know the history on the engine, but he got it from another friend who says it works great.

Then attention was turned to my Balsa USA 1/4 scale Cub. It's been my go-to big plane this year as it's just a joy to fly. Super stable and predictable, and it looks great in the sky. However, I've been neglecting a few things on it so time to change that! First up, it needed a cleaning. There were plenty of bug and grass stains on the prop and down the fuselage. The windows were also getting dingy and splattered. Weathering is good, bug guts are bad. :) An extra magnet was added to help hold the door closed in flight, meaning I won't have to add a piece of tape for security in the future. Last, the new suspension landing gear was sanded, painted, and installed. This should really help smooth out the ground handling. Under the bungee covers are, well, bungees. I ordered a couple different size bungee cords in 10' lengths and played around with size and amount needed to keep the plane from "squatting". It'll probably take a little more tweaking at the field, but will be easy to do. Eventually this plane will get a full make-over, with new covering, more details in the cabin, etc. For now its good enough for the next year or two.

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Joker 53150

Mmmmmmm, balsa.
Mentor
The Cub saga continues... I had it out to fly this past weekend and on the second flight the engine died, which is the first time it's ever done that on me. I wasn't going particularly fast and was only about 40' up and travelling away from me, so I put it into a shallow dive to try and keep airspeed up. Because it was far enough away and the ground at this sod farm slopes down as you head where the plane was going I had a hard time judging when to flare and ended up stalling it. It nosed in and I expected the worst... :( It was about 150 yards away so it was a loooooong walk to pick up the pieces. I could see the wings rip loose of the fuselage and flop forward when it hit, not a pretty sight.

When I got to the plane it had flipped over, and one of the suspension landing gear sides was flopped forward, both wings were indeed ripped from the fuselage.

And then I got a chance to really inspect it, and am happy with the limited damage! Indeed both wings took damage, but only the ribs that meet against the fuselage were torn out, and these can probably be saved and re-used. No other damage to the wings or wing struts, which amazes me. The front windscreen was broken, but I wanted to replace that anyway with a heavier plastic version so no big deal there either. The opening side window came off, but again that's something that needed work as well and it's not broken. The suspension gear took a bit of damage, but the guy who made the gear will repair the broken part. Heck, the "broken" part of the gear is just a simple tab that holds the bungee cord, the rest of the gear survived without damage. All covering is still good, although the wing ribs will need some pinking tape/covering to get it fixed up properly, which will be easy. The remaining fuel in the tank wouldn't siphon out so I think either the clunk came off and caused the dead-stick or it came off during the crash. Either way, it's 2 years old and time to service it.

Since the Cub is basically out of commission for the rest of the season I decided to get the parts to really fix it up properly. The muffler was hacked and welded by a previous owner, so I ordered a new aluminum muffler from B&B, new fuel tubing, new streamline aluminum tubes for the wing struts (going to make it more scale looking), new spark plug, etc. Basically a bunch of small projects so it's all pretty and ready to go in Spring! More to come...
 

Joker 53150

Mmmmmmm, balsa.
Mentor
Whew! Sounds like you came away in pretty good shape from that bump!
Far better shape than I could have hoped for. Normally it's "build big, fly big, CRASH BIG!" :) I just got word from Balsa USA that they will sell individual sheets for me to fix the wings, which is nice. It'll be a little more expensive than just repairing the broken ribs, but I want these pieces to be as strong and true as possible.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
Here's a shot of the main damage to the Cub after it's last "landing". This is the remainder of the inner-most rib from the wing still bolted to the fuselage (bolts are installed from inside the cabin). Replacement pieces were ordered from Balsa USA today as they're nice enough to sell individual sheets from their kits for repairs. I also ordered their dummy Continental engine kit for the cowl that will eventually go on to replace the original. I should have enough plastic sheet on-hand to replace the cracked windscreen and will go with a heavier gauge than original so it doesn't buckle so easily from prop wash.

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In the meantime, my order from B&B Specialties showed up today with the new muffler for the Cub. As mentioned previously, the original muffler on the Zenoah G23 was cut & welded to make it lower profile so it would fit inside the cowl. A good idea, but with poor execution as it leaks at the welds and makes a mess inside and outside of the cowl. Also pictured is new fuel line for inside the gas tank, as the regular gas line I used has gotten stiff with age (only 2 years old). This stuff was highly recommended as it stays soft and flexible quite a bit longer. A new spark plug is also in the mix for a quick tune up when the other work is done.

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Mentioned on my build thread for a Giant Stick, another plane recently followed me home - a Bud Nosen Trainer. Here's a size comparison, it's every bit as big as the Cub so I'll just assume this plane was meant to be 1/4 scale as well. It appears to be scratch-built from a few decades ago, and has aged very well.

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One of the more interesting things about this trainer is how much room it's got inside. This thing is MASSIVE, and you could almost fly a UMX inside it! :) I wish my other planes had as much room to work as this one does.

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rockyboy

Skill Collector
Mentor
Wow! You can put your transmitter inside the Nosen on the way to the field! And a gallon of fuel. Maybe lunch and a couple drinks too.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
Wow! You can put your transmitter inside the Nosen on the way to the field! And a gallon of fuel. Maybe lunch and a couple drinks too.
If the rudder and elevator servos were mounted on the same side of the fuselage my Taranis case would completely fit inside the fuselage with room to spare. Seriously, I checked. :cool:
 
This thread is getting yuge!! You should probably change the name to Joker’s 1/4 Scale Recovery and Repair Thread! Or Jokers 1/4 Scale Retirement Home! But this thread is invaluable there are Sooo many great examples of repair/modification processes!
 
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Joker 53150

Mmmmmmm, balsa.
Mentor
Giant scale Cubs are evidently as contagious as Skittles-Pox... I made the mistake of going to an RC estate sale today and this bird followed me home. For about $75 I couldn't pass it up! :) It's a Sig Clipped Wing Cub with an aftermarket fiberglass cowl. It was missing the rudder, wing struts, and tailwheel, but I still have the original plans from another Sig Cub so the rudder can be replaced easily. I've also got struts from a crashed Cub that may be re-purposed unless I decide to go with a more scale strut design. The builder did a very nice job with the construction, and judging by his other planes that were for sale he took a lot of pride in his craftsmanship. The wing and rear half of the fuselage is covered with what appears to be Solartex, and the ailerons and front half of the fuselage are fiberglassed with finishing epoxy. This plane was never finished, but some day...

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Although it's not a Cub, this is another plane that followed me home, a Taylorcraft. With a wingspan of about 82" that would put it close to 1/5 scale. It has quite a bit of scale detail, including opening doors, instrument panel, wing farings, etc. As with the Cub it was built very well and shouldn't require much work to get it airworthy.



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I may need an intervention...
 
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