[Moosehead]

I've just bought Sig's 1/4 scale J3 with every intention of modifying it up to a PA18 with flaps and fibreglass cowl, and eventually floats. I had every intention of putting the zenoah 26 under the hood but now I don't know. I've seen pics of a guy doing the same thing but it looks real tight. Would the 20 fit better and maybe provide a little more scale performance? I haven't even looked at other brand engines yet.

What has everyone else done?

[wingburner]

Here's what's going in mine.

http://www.syssaaircraft.com/sap.html

[DO335]

Depends on how much crap - carbs, mufflers, cylinder heads - hanging out the cowl and how much power you want.

Years ago, when the largest glow engine you could get was an OS 1.08 and there were no gasoline engines, I put the OS in my Sig 1/4 size clipped wing Cub.

With a Zinger 15-8 wood prop, even on floats, it was way, way overpowered. The engine would haul the plane off the water without a take off run if you put in full up elevator and instantly hit full throttle.

The engine and exhuast were totally enclosed within the cowl so I mounted the fake engine cylinders that came with the kit. Cooling was more than adequate.

If I were to do it again, I would use an OS 1.60 FX for mostly the same reasons as I chose the 1.08. The entire engine and exhaust will fit within the cowl and power would at least be adequate.

As far as converting it to a PA-18 goes, don't fall into the misbelief that a J-3 becomes a PA-18 by simply slapping on a cowl. There are many, many other differences, especially including the tail shape - stab, elevators, fin and rudder. The fuselage is different too. So are the braces behind the windscreen. And so on. A J-3 with a cowl more closely becomes a PA-11.

Conversion would be a major undertaking. But since the original Sig J-3 is already quite far from scale, the discrepancies may not be an issue for you. Cetainly most people looking at it would not have any clue that as either a J-3 or a PA-18 it's not accurate scale.

[Moosehead]

I guess I should have looked a little deeper into the forums. Then I would have seen Tech8's build thread. Sounds like he was going to do what I want to do.

Hey D0335, you posted a pic on his thread that showed the difference between the J3 and PA18. Was that from a tech manual or something? I would love to know all the various differences between the two. It sounds like a challenge!

[benchfitter]

hi got a 25cc weed eater in mine,flies scale,but not strong enough for floats,your zen26 should be perfect.

[Ken Currell]

One with a Super Tiger 2000 which previously had a an OS gemini 120 twin .

The twin sounded great and flew very scale like.
Haven't flown the Tiger yet but should have better performance.

Have a second cub but haven't decided what to use yet.

A gemini 160 would be cool but I think it will be a electric power this time. Lots of room for my A123 cells.

[MikeS]

I had a Balsa USA 1/4 scale Cub that I converted to a Super Cub. Started out with an Enya 120R GP Four stroke, which was more than plenty for scale flight. I'm sure that it would have hauled it on floats around easily as well. Fly at about 1/3 throttle. Eventually put an OS91 Surpass in, and ithat was absolutely perfect.
It was light though - just over 13 pounds.

Mike

[pipercub17]

i am puting a dle 20 on mine fits like a glove !
no holes on the sides of the cowl. but you do need to cut a hole in the firewall for the carb .

[russ]

eh piper, is yours a Sig or the B-USA?

[pipercub17]

mine is a sig
like i say the dle 20 is a great fit