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Jun 18, 2019, 08:35 AM
Registered User
Thread OP
Build Log

Restoring 80" clipped wing cub


Changed Thread Title to reflect that I am now posting the progress of this plane

Okay, I made a random purchase yesterday/ Paid 50$ for what looks to be about a 1/5 scale cub or some variant. 80" span, 56" long approx.

Anyway, it's basically just the airframe. Need to be recovered. Looks like it was wrecked and repaired at some point. I purchased this to see what it's like to work on a balsa plane before going down the path of building a kit.

So, here are the items I would love some assistance on.

1. Is there any great how to's on monokote? What brand is the best to work with? I am assuming I need to remove all the control surfaces so I can coat in there.

2. This plane has full-length ailerons. Since I have to remove them, would it be a good idea to split these and have flaps? I don't plan on any major aerobatics, and I do like STOL planes

3. There are many places the glue seems to have aged and cracked on the airframe. I may have made a mistake, but I been touching these joints up with gorilla glue, the kind that foams. it seems to do a good job of filling any gaps, but not sure this is recommended.

4. If you look at the pic from behind, you can see there is a curve to the back. This seems to be from the repair. I ran a string line down the center and everything looks lined up correctly. This could be from the original build. Will this affect anything?

5. The rudder seems to be plastic caps ver balsa. The top of the rudder plastic is broken off. I was planning on just carving the missing part from balsa and attaching it with pins or dowels. Will this work?

6. Electric conversion. I want this to be electric, as that is the route i am going with my planes. Looks like a 60 size motor should do. Does ANyone have any ideas on how to modify the motor mount to accept electric?

Sorry for all the questions. just not sure exactly where to start, but figured its a good place to start to learn about balsa planes
Last edited by nikbrewer; Aug 16, 2019 at 09:18 AM. Reason: changing threat
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Jun 18, 2019, 02:04 PM
B for Bruce
BMatthews's Avatar
Adding a new top to the rudder and keying it into place would be fine. But looking at the picture that is not a Cub rudder. Not sure why but some previous owner replaced the shape it should be with what is there now. Look at a bunch of Cub pictures online and do a new rudder that is more Cub like would be my suggestion.

The firewall on the nose that is supporting the beams is very likely plywood. So just cut away the beams to give yourself a nice clean nose to accept the electric motor. And reach in and remove the fuel tank if it's still in there.

You'll want/need to figure out some way to swap out battery packs before you start covering. Either leave the windows off one side of the cabine or find some way to make a hatch of some sort. Removing the wing each time would certainly get old REAL fast. There's no single best way. Really there will be lots of options and the best method will heavily rely on where the battery is best placed to help with the CG location.

The motor and battery you use will depend on the final flying weight of the model. For a plane of that size covered in Monokote or Ultra Cote I'd figure on adding about 12 oz worth of covering as a ball park amount by the time you apply the base and trim. Then there's the motor, battery, radio parts, wheels and anything else you can figure out. Do an estimate of all this and then look at motors, ESC's and packs. And trust me, you don't need a motor that says it has a .60 glow engine worth of power for this sort of model.

I'll assume that you want your Cub to fly like a Cub and not an F22. A good power level for that would be 60 watts per lb of model. It'll still let you climb at a good rate at a 40 angle of climb. So it's no slouch by any means. But it'll make it easier to fly in a scale like manner too.

That looks a lot like a clipped wing cub. Use web info for span and length for the full size Cub to figure out if the ratio of span to length is stock or more like a clipped wing version.

Anyway, there's not a whole lot of surface there to work with. So splitting them to make flaps and ailerons out of what you have even if you include the small infill pieces close to the fuselage as part of the flaps is going to result in very small ailerons that will have a slow response and small flaps that won't work all that well at doing what flaps do best. So without getting into a lot of work to cut away more of the wing and then make new surfaces for the ailerons and flaps I'd say it's just not worth the extra work.

What you could do to aid in shorter takeoffs and shorter landings is use a flap mix in with the ailerons. For takeoffs use about 15% lowered flap in the mix. Any more than that and the ailerons will start acting odd. This will alter the wing airfoil and allow a slower takeoff speed. For landings though I'd suggest you reflex the flaperons UP about 25 to 30 to act as spoilers and greatly steepen the glide angle so it drops in very predictably. And then play with settings between those two maximums. One thing for sure is that you do NOT want to lower the flaperons strongly with this mix. Must past 15 or maybe at most 20 and they start acting very oddly with lots of adverse yaw. And at around 40 of flap the aileron function starts not doing anything at all. So at most 20 down and maybe 30 of upward flap. And then play with how best to use these. Perhaps strongly reflexed to drop the model down from on high without a big build in speed and then go to neutral or 15 down flap to float it onto the ground near the end? That could be worth some trials up high at first and might do what you're after.
Jun 18, 2019, 02:31 PM
AndyKunz's Avatar
My hat's off to you! That much mildew would have me coughing and gagging on the floor in about 5 minutes.

Keep the pictures coming. I'm not the only one who will enjoy watching along as you resurrect this beauty.

Andy
Jun 18, 2019, 02:57 PM
B for Bruce
BMatthews's Avatar
Dang, I was thinking it was just old dust. If you find it bothering you like Andy mentions you might try giving it a damp spray (don't overly soak it) in a good dash of bleach in some water to kill the growing stuff.
Jun 18, 2019, 06:29 PM
Modeler from 60's, 70's, 80's
lee taylor's Avatar
Just my 2 cents worth

1. Is there any great how to's on monokote? What brand is the best to work with? I am assuming I need to remove all the control surfaces so I can coat in there.

Answer: Yes there were lots... back in the day. Most plastic coatings are very similar so most how-to's will likely work for you. I had Monokote fear when it first hit the market. I found out that it was pretty easy and self intuitive. The other day I picked up a Monokote iron for a dollar in an Ebay auction. Treat yourself to an iron. You will not regret it. Whether it is open frame of planking, stick the edges down and then use the heat to shrink the center.

2. This plane has full-length ailerons. Since I have to remove them, would it be a good idea to split these and have flaps? I don't plan on any major aerobatics, and i do like STOL planes

Answer: No experience with this

3. There are many places the glue seems to have aged and cracked on the airframe. I may have made a mistake, but I been touching these joints up with gorilla glue, the kind that foams. it seems to do a good job of filling any gaps, but not sure this is recommended.

Answer: Other than adding a little weight that can only help. GOOD idea


4. If you look at the pic from behind, you can see there is a curve to the back. This seems to be from the repair. I ran a string line down the center and everything looks lined up correctly. This could be from the original build. Will this affect anything?

Answer: The trim tabs on the transmitter can save you to a point. The items that effect the straightness of flight more than anything are the wings, horizontal and vertical stabilizers. If they are lined-up correctly, you have a good chance

5. The rudder seems to be plastic caps ver balsa. The top of the rudder plastic is broken off. I was planning on just carving the missing part from balsa and attaching it with pins or dowels. Will this work?

Answer: Yes

6. Electric conversion. I want this to be electric, as that is the route i am going with my planes. Looks like a 60 size motor should do. Does ANyone have any ideas on how to modify the motor mount to accept electric?

Answer: The motor mount looks like it is for a glow engine. Purchase your engine and THEN start looking at mounting it
Last edited by lee taylor; Jun 18, 2019 at 06:43 PM.
Jun 18, 2019, 06:32 PM
'Douglas' to his friends.
I have acquired two 1/6 Cubs to restore and complete, one of which is in a much worse state than yours..! It's an original, started but unfinished' Berkeley kit, with many broken parts. I'm currently doing the better of my two, which I'm hoping will help me when I get to the really bad one, and will be following this topic with interest, hoping to glean any crumbs of information that can advance my project, as well as yours. Good luck with it, and well done for taking on the task. Yes, it will be arduous, that's certain, but they're lovely 'planes when they're up and running..!
You won't get much real aid from my Build topic, but it may serve as light reading when you're in need of a respite from your labours...

Biting off more than one can chew ...

Jun 18, 2019, 06:44 PM
Registered User
JimboPilotFL's Avatar
I think that is a Citabria, a very aerobatic model.
Jun 18, 2019, 09:13 PM
Modeler from 60's, 70's, 80's
lee taylor's Avatar
I looked at the elevator and vertical stab again. You may want to consider cutting down the height of the elevator opposed to building up the vertical stab
Jun 19, 2019, 12:17 AM
B for Bruce
BMatthews's Avatar
Quote:
Originally Posted by JimboPilotFL View Post
I think that is a Citabria, a very aerobatic model.
The fin could be from a Citabria. But the horizontal tail and wing tips are very much Cub. I suspect some past liberties were committed on this model....

I forgot about the tutorial on covering with iron in films. Go onto You Tube and in the TY search line put in "covering model airplanes". More than 3/4's of the responses will be related to using iron on films. Watch a bunch of them as each has some ideas that the others do not have. You'll learn more by watching more.

On the curve to the rear fuselage. Since the lower side and if the lower side did not break or if it did break and was well aligned when repaired then most of your issue is with the upper corner longerons. You may need to replace or install diagonal braces to push things back into line.

In the grand scheme of things what I see is only a couple of trim clicks. But you and others will see the banana shape when on the ground. And I know for sure that my own brand of OCD'ism would NOT tolerate that. And clearly since you asked......
Jun 19, 2019, 08:13 AM
Registered User
Thread OP
Thank you guys so much for the help!. I think what may add confusion to the vertical fin is that the cap is missing in the pic. It was round and made the whole top of the rudder rounded.

I built it put with balsa and smoothed it out last night. Post pics tonight.

I removed the control surfaces so i can fix everything. I Have had no luck removing old hinges, but it seems like i can insert the new ones into the center of the old ones. Will this work? It looks like the old ones were that fussy material. The new ones i got were du-bro plastic ones with a hinge pin

What is on it does not appear to be mildew. It was in a welding shop and appears to be a gritty welding dust. It comes off with a very light sanding.

Everything is cleaning up pretty good. 1 area i need to address is the landing gear. Weighed it and it was 1.5 lbs just for the gear. That seems kinda heavy.

Next hurdle i have is it has a split elevator. Not sure how to handle it. I like the solution in this video
Split elevator Split fuse Servo set up (0 min 49 sec)
but no idea on where to get the hardware to do it.

I could also run 2 servos i guess. I have some 19g servos coming. I could run 2 of those verse 1 full-size servo.

This is definitely a clipped wing cub. After looking it up, they never came with flaps, so i am leaving that alone.

Battery access will be something i have to look at. I may have to do a hatch from the bottom which is not ideal but could be doable.
Jun 19, 2019, 11:22 AM
Pro Hoarder
turbonut's Avatar
It is a Cub for sure..The bend in the upper fuse aft of the wing is correct. The design of the kit is a bit add and to have solid tail parts is not a great idea. It will be tail heavy. The construction is close to the old Pilot kit but not the same
Latest blog entry: In flight
Jun 19, 2019, 11:30 AM
Registered User
Thread OP
The plane is definitely a Clipped wing cub. After doing research it looks like these never had flaps so I am going to just leave it as is.

I think what is confusing guys on the tail is the plastic cap is removed. it rounding out the top and extended over the vertical fin. I have not repaired it using balsa ( pics later today).

My issue today is it has a split elevator. Not sure how to address this. I like the hardware in this video
Split elevator Split fuse Servo set up (0 min 49 sec)
. No sure where to get it though

I could run dual servos. My receiver is 8 channel. I have some 19 G servos, so i could use 2 of those verse 1 26 g servo. pros, cons or each option?
Jun 20, 2019, 12:00 PM
Registered User
Thread OP
well, here are pics of my repaired rudder. THink it looks pretty decent. Will need a bit of filler but should look good when covered
Jun 20, 2019, 04:52 PM
Pro Hoarder
turbonut's Avatar
Nice work. You may want to put some holes in the tail parts before covering them. Its good to save weight back there
Latest blog entry: In flight
Jul 06, 2019, 09:24 PM
Ray
Just a note on polyurethane glues e.g. gorilla glue. They have very little strength as a gap filler. If you do need to fill gaps mix up some epoxy with fiber filler-not much-and that’s about the best you can do. Fine Woodworking did a test and in order of strength: PVA (yellow wood glue), then polyurethane then epoxy. Note that this is for wood to wood joints, clamped together.


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