RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

SunDevilPilot Love the tires in the photo above. I need a set of them that are about 8 to 9 inches.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

There is a thread on that. About the only available source is from Bill Hempel. He has them for his big 50% Cubs. Kinda spendy though.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

I have looked at them but the rims are too large. I'm building a 1/3 scale and need bush tires on it. wish I could over inflate the dubro but then it would bounce like crazy on landing

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

We need everyone to email DuBro with our wishes for an 8" bush wheel. I too am building a 1/3 and am looking for the same.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Me too.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Turns out that I recently needed a set of giant "tundra tires" too on a low budget.

In my case, I used the inner tubes from hand truck tires with rims from laminated balsa and lite ply on the ends. The suggestion was to use a piece of PVC tubing for the wheels which would also work.

These came from the design of a Mud Duck, which you can find on RCU or at the Mud Duck web site.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Oppps wrong scale I need 1\4 scale.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Finished a minor detail on the fuselage which I had been putting off. I was a little apprehensive about carving a recess into the lower rear of the fuselage for the tailwheel mount but it went off without a hitch. I changed the mount to a blind nut that I cut the barbs off and mounted inverted on the plywood plate. I just didn't like the square nuts that Sig gave for the mount. The fuselage cutout was done with a double flute straight cut bit on my route table. I just set the depth and mounted a stop to give me the proper cutout. Then, reluctantly, I ran the fuselage across the bit. The router made quick work of the job and the results were great. I was afraid of what the router may do the balsa (splinter it) but I found it cut it clean and smooth with no splintering. A recess was made for the blind on the fuselage.

I made my own ply plate out of a little better grade ply than stock.

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

I received the 22X12E Mejzlik prop from Desert Aircraft and it looked a little large. Fortunately, with the 6" tires there is plenty of clearance between the prop and the ground when the plane is level. I'll just need to be careful with hard landings. I'm really happy with how the cub is looking to this point...

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

That prop is huge for a Cub, considering my 108" Super Cub flys great on a 16". Can you go down a bit in size like 18 or 20" and run a lesser battery? I'm not into electrics and don't profess to know anything about them. Just seems like you will be spending a bunch of money on broken props.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

The prop is quite large, I agree. However, if I went down in battery I would need to go up in propeller. The motor will spin the prop in the neighborhood of 5700 RPM. So, a large prop spinning at low rpm. This should be super efficient and allow for a long flight time. It will have quite a bit more power than scale but that is what the throttle is for.

Reference prop strikes. Hopefully three inches clearance is enough. I have a large gasser with a similar clearance and I have never had a prop strike (Except for when the landing gear failed during taxi). If needed I could go three bladed to reduce the diameter. For now we'll see what it does.

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Speaking of those batteries, how are you planning on doing battery changes? I saw a 1/4 scale cub that was converted to electric only to be later converted to gas because of the pain of taking the wing off to change batteries.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Your right on with the prop. Swing the biggest prop ground clearance will allow.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

The batteries will easily fit through the side door. The wing can stay on the plane during battery changes.

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Okay,like I said, I know nothing about electrics. Just seems to me that if you have less power with a smaller battery, you wouldn't load down the engine more with a bigger prop. Smaller motor? Anyway, you guys know what your doing so I'll just watch.
Battery changes should be no problem with the side door option that SDP already has built in.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

It is a little confusing but in short. Electric motors are rated in kilovolts. At a given voltage the motor wants to spin at a given speed. The more volts (bigger battery) the faster it spins, a thus the smaller prop.

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

I won't deny the prop looks big.... However, I was looking at the previous photos and for some reason it looked really big. May have been the perspective of the photo. I am attaching a few with the cowl on and the tail feathers in place. A better sense of scale can be seen with those parts installed. Once the wings are built I think it will look really good.

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

http://www.youtube.com/watch?v=wbHSRrcxzq8

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

I came across this video. Seem to be one, likely expensive, solution.

http://www.youtube.com/watch?v=F8lVdUhdJVE&sns=em

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

No, I wont be adding two of those to MY cart.

http://www.akbushwheel.com/

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Wow! Those are expensive. I would be quite unable to take a razor blade to them after spending nearly $1000.00 for a pair.

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Work has started on the wings. I moved my building table into the house due to the heat in the garage. I'll tell you, the wife loves the new addition to the living room!

The photo shows the ribs dry fit to the bottom spars. Once it was together I decided I will duplicate rib W2 and place it about midway between the stock W2 and W1. This will allow me to have a rib in the area of the sheeting right at the location I plan on ending the inner edge of the flap. The inner sheeting will be modified to allow for the flap. I also adjusted the main spar slot on W2 rib to allow the wing to have no dihedral. From all the photos I have seen a Cub, and a Super Cub, have little to no dihedral. For some reason the Sig Cub calls for quite a bit. I may put a tiny amount but with the larger slot that can be done when the wings are fitted to the fuselage. The slot is more of a pass through than a structural element.

The wing design appears to be quite simple, time will tell.

(Keep in mind reference the photo. This was only a dry fit. The spar and ribs will be pinned tight to the board when I glue them in place. I will also protect the plans with some wax paper.)

SunDevilPilot

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

It looks a though you plan on building each wing panel over its own drawing. I did that with my Sig 1/4 clipped wing Cub. Much to my surprise, the result was that one panel was about 1/4" longer than the other.

I've heard of paper shrinking and expanding depending on humidity. However, when I actually measured the plan panels under identical weather conditions, they were different spans.

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Yeah no kidding. I was thinking like $100 each. I can't imagine the most expensive item on my plane being the tires. Seriously though $1000 for tires for a RC model plane and they are not even the right scale!

RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)
 

Push you/Pull me speaks the truth on this one. Measure those wings out.