Which Cub kit would be the best to modify to a 1/4 scale Supercub? And is it a possiblility to convert a kit to a supercub?

Either the Sig's or Balsa USA are easy to modify, Fiberglass Specialty sells cowling for the Supercub version, I've got the one for Balsa USA's, very well made, as a matter of fact it will be my next project after I finish painting a WWI biplane, aside from the nose area, the differences are in the shape of the stab and elevator and shape of the rudder, the addition of flaps will always improve your flight envelope and other visuals that you can gather from available photos on the web.

Hi Cub-fans,

I am just about to finish my 1/4 PA-18 Super Cub... it´s a conversion from Sig 1/4 J3 Cub kit. I have modified the tail feathers to make them look like Super´s, added flaps and re-designed the front end of the fuselage. I´m also building real cabin doors that I can open. I bought the Fiberglass Specialties "Super Cub cowl for Sig 1/4 Cub kit"... but I´m not going to use it and I don´t recommend it if you want to get even near the look of a real Super Cub. The cowl is a good quality item, but it doesn´t look like Super Cub. It is a way too narrow and the desing is... []

There is three things you should do to the fuselage is you like to convert your J3 kit to Super:

1. The fuselage of Sig J3 starts to get narrower ahead the windshield - the Super Cub´s fuse sides stay straight. So, I mean that the width of the firewall of Super Cub is same as is the width of the cabin area. The FS conv. cowl is designed for original Sig J3 fuselage, thát´s why it doesn´t look right.

2. The support steel wires are different between J3 and Super. Compare the pictures of J3 and PA-18... you can see what I mean.

3. The engine position in J3 is too high for Super Cub... the engine should be installed about half inch lower than the Sig J3 plan shows.

After these modifications, you must make your own cowling. But, what you get is very near the right thing.

I´ll post some pictures of my modifications very soon.

Regards, Hannu

OK, Sorry for the delay, here are the pictures of my Super Cub -conversion, based on Sig Piper J-3 Cub kit.

Modifications:

- Tail feathers redesigned
- Working flaps added
- Front section of the fuse redesigned
- Own fiberglass cowling

Specs:

Wingspan 104 inches, weight 16,5 lbs (7,5 kg)
Saito FA-120S, Master Airscrew K 18x6, Futaba servos (5 x S148 + 2 x S3010), Multiplex 12-ch. receiver, doubled NiCd receiver batteries (6,0V 1700 mAh)...


One of the pictures shows also our flying field´s radar antenna

Excellent HHjul
What did you do to get a Supercub windshield? Did you totally remake one from scratch or??

Thanks GarySS,

I used a 0,5 mm (0,02 inch) thick clear PETG plastic to all windows, the method I used is the very same Sig recommends when making a genuine J3 out of their kit. So, it was very easy indeed. I didn´t use the J3 kit´s balsa blocks in upper corners of the windshield, I just glued the plastic in place without those blocks, using only 1/4 inch thick hard balsa pieces which follow the wing LE profile exactly. PETG is a bit easier to bend than the original Sig window material, that´s why there was no need for vacuum forming etc.

Great job! Your SC looks very realistic, it must have been quite a feat to land in that spot, no?
What is and where do you get PETG plastic, first time I hear of it.

Thank you Walter D, the Sig kit is very simple and not-so-slow to build, but what really doubled the building time was those modifications. Well, I think it was worth the extra effort.

I even built a kind of "engine unit", I have a two-piece firewall and there is only 5 small hex bolts and after opening them I can remove the whole engine-tank-throttle servo unit for maintenance / bench testing / adjusting.

The trading brand of PETG sheet is "Vivak", it should be available in stores who sell plastics for industrial use etc.

More information about PETG "Vivak":

http://www.sheffieldplastics.com/product_vivak.cfm