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View Full Version : -18 upper structure on J3



D.A.
01-24-2022, 10:47 AM
I grew up flying J3's from the back seat and it just feels right. In fact, flying a J3 from the front just feels wrong. I often said I wanted my kids to solo from the back seat of a J3, after that they can fly whatever they want. All that being said, as I fly into my golden years I can no longer reach the controls (Carb Heat, Altimeter, etc.) that are all located up front. I don't like the feel of the J3 front seat but I DO like the feel of the Super Cub front seat. Is there an STC to put the Super Cub upper structure on a J3? I don't know about you guys but I've had really bad luck with 80 year old airframes so what I'd essentially like to do is buy a 90 (Preferable) or 100HP J3, have a new SC frame built and then swap it over. I still want to keep it light, yellow with a lightning bolt, exposed Continental and so on, but I'll have a fresh fuselage frame with a SC front seat and still LSA legal. Sounds like a great old man's airplane to me. As far as paperwork would be concerned, it would be an upper structure change, front seat change, removal of the tank in the boot cowl and some other structural improvements - - - In reality, it'll be a frame swap and at a lot less cost overall than buying a Sport Cub or a Legend.

Are there turnkey STC's to cover these mods?

Thanks.

Crash, Jr.
01-24-2022, 11:28 AM
I believe Atlee Dodge has all the STC's your looking for.

As for simply swapping an -18 fuselage into a J3 there's a whole lot more to it than that so I wouldn't expect a straight and easy swap. You'll be adding a decent amount of additional structure with an -18 fuselage so your empty weight will be a fair amount higher without the advantage of a higher gross weight. You would also have to rebuild and modify the wing spars to work with an -18 top deck. My advice would be to either enjoy the J3 as it is or consider getting into an experimental built J3 where you can do the mods you want and increase the gross weight but still retain the look of a J3. After all if you're doing a full fuselage swap and rebuilding wings you're not that far off of building an experimental cub.

bob turner
01-24-2022, 12:10 PM
Yeah - cost-wise a Legend would be cheaper. I believe PA-18-95s come up now and then at 50 grand. Maybe you could change the cowl?

I have never been able to reach the altimeter. Carb heat can be done with your foot, especially if you wear cowboy boots, but I have done it with sandals. My partner uses this ugly steel weapon made from a convertble top bow. It scares me, so I take it out and use my foot.

others tie a string to pull the knob, then push with their toesies.

Lots of ways to fly in back as we shrink. i was 6' 1" when I started - who knows now?

DENNY
01-24-2022, 12:49 PM
First off for the money you would spend to convert a J3 to what you want (Total rebuild with mods) you should just build an experimental. Second is I am not sure if it would still qualify as a LSA aircraft with all the mods. I have been told that to qualify as a LSA a certified aircraft cannot be changed form its original form. One of the smart paperwork guys can correct me if I am wrong. I don't think I have seen very few planes go in for a fabric and paint job that has not come out at double or triple the first bid because the owner got MOREBETTERDISEASE and started adding stuff while the fabric was off. Guide wings usually don't get changed but they want them back in a week to get the hunter out of the field.:lol: DENNY

RaisedByWolves
01-24-2022, 02:02 PM
Pretty sure the -18 top deck was field approval only, no stc. Atlee has j3 to -11 conversion and pa-18 front seat, fuel system, controls, trim, back seat and baggage stc’s


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Crash, Jr.
01-24-2022, 02:47 PM
Pretty sure the -18 top deck was field approval only, no stc. Atlee has j3 to -11 conversion and pa-18 front seat, fuel system, controls, trim, back seat and baggage stc’s

Just checked Atlee's website and you are correct. They do not have an STC for the top deck conversion. Looks like field approval is the only way to get that.

I'm just a short guy but the top deck changes would be the last on my list to do on my J3. The wing tanks, -18 fuel system, -18 elevator, -18 baggage and -18 front seat along with the PA-11 forward structure changes would be high on the list. The cowling is what makes a J3 look like a J3 so I'd keep that but if there was a way to use an -11 windshield for the better angle and less drag that would be a nice way to go.

mvivion
01-24-2022, 03:50 PM
Just checked Atlee's website and you are correct. They do not have an STC for the top deck conversion. Looks like field approval is the only way to get that.

I'm just a short guy but the top deck changes would be the last on my list to do on my J3. The wing tanks, -18 fuel system, -18 elevator, -18 baggage and -18 front seat along with the PA-11 forward structure changes would be high on the list. The cowling is what makes a J3 look like a J3 so I'd keep that but if there was a way to use an -11 windshield for the better angle and less drag that would be a nice way to go.

Back when, I owned a 90 hp J-3 and we were going to do some mods. I talked to Atlee, and he sold me all his J-3 STCs for, I think, $100. Most important were the conversion to wing tanks, and removal of the nose tank. That then permitted the conversion to a PA-11 windshield, which you can't do with nose tank....hard to reach tank filler inside on the glare shield...

I had a PA-18 seat in my 11, and I liked it better than the original seats for comfort, but it also sat me up to the point that my head was really close to that "headache structure" that ties the wings to the plane. If I were going to do what you suggest, I'd try to figure out how to modify the original seat to make it more comfortable.

I like the pressure cowl better than the exposed cylinders. A little less draggy. The big drag reduction, though, is the 11 windshield. I think Atlee told me that'd gain me 5 or 6 mph, and he was right on.....seriously. Hang a J-3 up in level flight attitude, and look at the windshield, it's almost vertical. When I had that J-3 before the conversion, water from rain would actually puddle in the middle of the windshield before running off.

MTV

Dan Gervae
01-24-2022, 04:57 PM
I think I just built the plane you speak of....sort of....lol. I built this experimental PA11 with O200, 2-18 gal tanks, electrics, PA20/22 elevators, extended baggage, aluminum lift struts, float fittings. folding/sliding front seat.
It's quite a step up from my J3 in many ways including cross country comfort.It's heavier for sure at nearly 850# but it really is nice to fly from the front seat without those tubes that support the J3 nose tank and being able to slide the seat all the way back is very nice....I dont seem to mind the the J3/PA11 style upper deck as I like to hold onto that tube with my left hand as I fly....I also put the flip up left window in.
59609

D.A.
01-24-2022, 07:01 PM
I think I just built the plane you speak of....

Dan, that's a good looking ship there and ideal. What prop is that?

D.A.
01-24-2022, 07:03 PM
...It's heavier for sure at nearly 850#...

Actually, that puts you right in there with the Legend and Sport Cubs.

D.A.
01-24-2022, 07:05 PM
...consider getting into an experimental built J3...you're not that far off of building an experimental cub.

I think you're spot on there!!!

Dan Gervae
01-24-2022, 07:18 PM
Catto 76-36 prop....I also have TK1 Shocks which are awesome

D.A.
01-24-2022, 07:46 PM
... I believe PA-18-95s come up now and then at 50 grand...

Unfortunately the PA18-95's aren't LSA...

Steve Pierce
01-25-2022, 07:53 AM
I got two field approvals years ago to swap the top deck of a J3 to Super Cub. An AL3 or AL11 would be cheaper and quicker I bet and you can start flying right now. None of us know how much time we have left.

TurboBeaver
01-25-2022, 08:39 AM
After flying a PA 11 for years and then getting into a family
friends non electric PA 18/95. In one 2 hrs flight I was amazed how much better I liked it than the old 11. Still think for just bombing around by yourself, an 850lb /18
is a lovely choice in many ways. J-3/90 and 11's are great performers for sure. But all around; all the stuff Piper did when they built the 18's are nice upgrades. Imho
Fly safe
E

Dan Gervae
01-25-2022, 09:41 AM
Unfortunately the PA18-95's aren't LSA...

If MOSAIC ever happens they will be.....I suppose it will happen the same day Acme and Catto get their STC's.
https://www.eaa.org/eaa/news-and-publications/eaa-news-and-aviation-news/news/08-08-2019-mosaic-rulemaking-package-detailed-by-faa-administrator

D.A.
01-25-2022, 11:33 AM
...J-3/90 and 11's are great performers...But...the stuff Piper did when they built the 18's are nice upgrades...

That's EXACTLY the conclusion I've come to. I grew up flying J3's and a 90HP J3 is a rocket ship but at this point in my life I'd like to combine (Or at least come close) the light weight J3 performance while sitting in an -18 configuration. I know - I know, an -18 will never match the light weight of a J3, but you can come close. Again, I just think that would make a great old man's Cub.

bob turner
01-25-2022, 07:47 PM
With BasicMed, the 18-95 still sounds like what you want. A J3 with starter, battery, and metal prop might approach the empty weight of the light 18, especially if you weigh it.