Building a scale 1/4 scale Super Cub from Balsa J3 kit
 

I am not the first one to do this I'm sure but we all have our different ways. Making this as scale as reasonable is possible with the Piper Mfg. drawings and a slew of pictures to aid in it's construction. First I had to redraw the tail components and the cowl and engine location. This super cub is a wide body variant from the PA-14 which is also 2" longer than the standard full size plane so I'm adding 1/2" to the nose, (likely because of the bigger 165 HP engine) that will make the fuselage 68.5" long, it's 7.5" wide at the strut mounts.

I'm starting the elevator, stabilizer and rudder first, fin also because they are being scratch built, the rudder and fin along with the stabilizer and elevator have been contoured to the Piper drawings, while not dead on they will be close and will be tube mounted like the real one with elevator control inside the fuselage ahead of tail post. It will have a dummy jack shaft for trim control just to fool the judges and on lookers. Perimeters of elevator and rudder are 1/4" X 1/16" laminated 6 ply while the stabilizer leading edge will be 3/8" of the same, the elevator does have tapered ribs like the real one. Fin and rudder are 1/4" through out and I will use Du-Bro hinge points on all surfaces.

This will not be a real fast build as there are a lot of things to work out as I go, part of the fun of building in this manner and my mind has been working over time every since I got the kit.

Some of the parts I have to build the plane.

#1 Balsa 1/4 scale J3 kit
#2 DLE 30 cc gas engine
#3 Robart 1/4 scale main gear for the wide body cub
#4 Ohio Superstar tail wheel
#5 H9 1/4 scale J3 Struts
#6 Hitec HS-645MG High torque servos
#7 DLE Engines On-Board Digital tachometer, (will go on instrument panel)
#8 Du-Bro 5.5 tundra tires

And the usual small parts, I still have to get the wing tube.( it will take some of the strain off the struts)

I hope some of you will join my build, there has been many of these built and I'm always interested in what others have done, I will try to keep mine interesting and build a real "Super" cub.

Meet the builder in the picture, Leroy Gardner

Leroy

I am along for the ride.

Alright Leroy,
So glad you've begun. Will be a great ride. :cool:
Yippie.............

Kevin

Be nice to have you along Robert, you have done a lot of this.

I never mentioned that I have never laminated before, I got that from some of you that have. The upper first pict is strips being formed, not sure how long to let them dry before putting another set on the form. I made a tube to soak the strips in which is water and some ammonia, wasn't sure of the amount but the strips were no problem doing the radius on the form. I did seal the edges of the form before I started.

I plan to glue them up with Tightbond 11, with 6 of them I wonder if they all can be done at the same time without the glue setting too fast, some pointers would be helpful. I will use the same form so both sides will be exact. These should be a lot stronger than the kit way of making these which is bad from the start with all the small parts.

I have back to back building tables, tail on one and fuse on the other, makes it easy to work on both while glue is setting up, will start the fuselage just as soon as I get the strips all formed up.

Leroy

Leroy, incase you didn't think to. Wax your form also. If just a little glue gets between balsa and form. Balsa chunks will tear out.
Ask me how I know :rolleyes:

Kevin

If you have ever noticed on any of my builds the magnetic uprights, that is what they are for, laying up duplicates. Use pieces of wax paper between lay-ups (at the joint) and they won't stick to each other. There are two ways I like to glue, first is the regularl way of dabbing some glue on the joints and assembling. The other being dabbing the glue at the points of contact on all the parts on all the lay-ups and allowing it to dry to a tack free surface, then assemble in jig (still with wax paper in between the assemblies at the joints), and then heat with the covering heat gun. The Titebond II will instantly reset under heat making for a permanently glued joint. And of course one could always use ca after each is assembled in the jig. But, I would cover the entire lay-up with plastic (such as painters plastic) before the next lay-up to prevent any ca from reaching the lower lay-up.

Waxed paper works good for wood glue and epoxy but ca will eat right through it hence the painter plastic for ca. Of course the plastic works great for all adhesives and is all I use. The painters plastic is about twenty bucks for a roll that is big enough to last for a number of years.

Thank you Robert & Kevin, some good tips there. I did not know heat would activate the tightbond and the wax sounds like a good idea also.. I will have some scraps to test with and get a feel for bonding. After it's all glued up and sanded with edges rounded the CA could be used for hardening and taking care of any marginal bonding not to mention the added strength in the whole structure of the laminated parts.

I removed the first batch of strips and put them on the plan and put the second batch on the former, I left the heat on and they should be dry enough to glue up tomorrow. I like this way of making these parts, it's going well.

I posted my building lay out for all the snoopers, some of that getting to know you was going on with the SW if I recall. I'm blessed to have a nice shop to work in, don't mind sharing it with you guys. It's also great to be building again, it will be a good winter regardless the weather.

That PVC tube is my soaker tube with kit and parts table behind it, the two station build boards, some building equipment, all the things needed to build planes.

Leroy

Count me in !!

http://s8.postimg.org/yxq0hmvgh/MG_272.gif


John M,

I'll be lurking. Have fun

I'm here as well!!!

Hi Leroy thanks for alert us to this build and thanks to Robert for posting the link over in the Spacewalker thread! Good looking float plane keeping you company!

The problem with waxed paper is they modified it for use in microwave ovens so it is slightly porous that is why CA leaks through but a heavy viscosity glue like Titebond or other PVA types don't.

I have done laminatingon this level before myself but the more times I try something new in the hobby the more fun it seems to be!

I will be watching.........:cool:

Subscribed !!!

I have signed on for your build, you will love this airplane. I have always had a Cub, I am flying a 1/4 scale Cub.

Rich

Hi Leroy

I would like tag along as I have this kit and most of the bits, but due to a bad flying season for my birds, The cub is on the back burner at the moment, I have also done some of the lay out for the fuse with what looks like about the same dimensional results, and confirmed my fire wall shape by getting a cowl from "Fiberglass Specialties" but I have not done any thing with the tail feathers as yet except take a bunch of pic's of a full size and measurements, So would you be willing to share your out line dwg,s ?

Cheers Bob T
AMA13377

Leroy, good luck with the build will be following along.

Roger

I will be watching intently also. Thanks for posting your project.

Richard, Sig 1/4 J3, Zenoah G23; H9 1/4 J3 (gen 1), YS F120; GB Anniv Cub (NIB), Saito 130T (?)

I would add some carbon fiber tow to the horizonta stab. Have seen several fail resulting in complete loss. I added a carbon rod about one inch forward of the hinge line on mine. I broke the leading edge in a minor handling mistake. The balsa isn't as good as it used to be.. If i was doing a another it would get a layer of cf in laminated there... And on the rudder too. Have you thought about using the hanger 9. Super cub cowl? It takes some reshaping up front but is much nicer shaped than the fiberglass specialties busa cowl.. Have fun!

First I would like to thank all of you having interest in this build, John M., Oldflyer 2< Flyer in OKC, Vincent, Kieth, jwRich, Bob T, Roger, Richard the spaceworm,Richard the Ace, Kevin and 2walla. Don't be afraid to comment or add to this, lets make it interesting for all to enjoy, the cub is a very popular plane as I'm finding out.

Leroy

Hi Bob and yes I will share whatever I have with others. I have drawn the tail parts about 3 times and then had the real drawings scaled to 1/4 and transferred to 1" graph paper to be my plan. You should be able to reproduce the drawing by counting the squares in the picture, The green high lite on the rudder is the new outline, most of it is from the scaled Piper drawings. I could chart out what I have for the fire wall and take a picture of that if you"d like, my cowl is from F.S. also.

Glad to have along and hope the picts help.

Leroy

After digesting Richard's and Kevin's advice I decided to give my method a try, no wax or wax paper involved but did use plastic film under the former. I also did not use clamps but did drill the holes for them, part of the reason is that clamps rarely have square faces and cause depressions in the soft balsa. I was able to laminate 3 strips at one time on the former by running a small bead up the center of the strips, securing one end on a reference mark on former and the same for the strips guaranteed the same location as the forming had. By running a square block around the strip spreading the glue (tightbond 11) I pinned the other end and then went back and using the block with a pin between it and the strips pushed them in all the way around, I also made sure they were all flush to the board. After 30 min. I did the other 3, total time 1 hr. per side, they came out great. When I removed them they went right on the building board to dry and were pinned in place. Reason for that is the glue wets the wood and they could change shape some causing tension during the final assembly and I don't want that. Turns out this is very easy to do with great results, strong too.

Leading edge of stabilizer went well also, I glued and stacked 6 of them ( they are 3/8" wide) and using the same method as above pinned them to the board, one to go and I can start with the other parts and assembly. Strips are on the former for the rudder drying and will glue them up tomorrow. I have a small step to put in the oak dowels so they will fit the brass tubes, they will get some silver soldering for mounting and a horn for the elevator, more on that later.

I said it before but it sure feels good building again and I love the chat at night on what I'm doing, great to have your company.

Leroy

2walla all those issues you mentioned are being addressed, the tail is not being built anything like the plans show, they will be a total remake. To late, I have the F.S. cowl and it too will get some up grades. Thanks for the advice on the tail and your right, it needs a lot of improving which I'm doing. You and others may not know the cowling is made for this kit which is wider than all the other ones, I don't think the H9 would even come close to fifing this one.

Thanks for joining me,

Leroy

Leroy,

Off to a great start :)

I love the look of a laminated curve. It is just so elegant.
I dont think i'll ever do a curved tail any other way.
Strong as all get out this way too.

So glad your horse (cub) is out of the barn and on it's way.
Cool.....

Kevin

I'm in.

Flyer the cub in the picture was at a EAA fly-in I went to and it really is a beauty, it's made in Yakima Washington. Their planes are certified replicas of the wide body Super Cubs with metal flaps and ailerons, it is impressive on floats.

Leroy