J-3 Eagle

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BJC

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I’ve always liked those designs. Was in a Tee hangar with a J-5 back in the 1990’s.


BJC
 

Mohawk750

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I have the plans for the J1B and the J2 Polenez (in Polish) and have been comparing the two. A little internet search will reveal that only a single J3 Eagle was produced and I am still unclear on the differences between the J2 and J3.

Others on this forum are building variants of this design and at least one is combining the J1B which s slightly larger with the T tail of the J2 with a lengthened fuselage. I cant recall the name at the moment, perhaps they will chime in here.

At least one builder in Russia converted the J1B to aluminum which would be of interest to learn more about. There are a few reported issues with the J1B plans and design which have been reported and are fixable. The angle of incidence of the wing is one and poor horizontal tail authority due to its low position is another that can be rectified with the T-tail.

How about a hybrid J1B in aluminum with J2 T tail built using angle longerons and aluminum skins? The higher strut braced wing would allow for folding aft like early kit fox designs.
 

Flyguyeddy

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I have the plans for the J1B and the J2 Polenez (in Polish) and have been comparing the two. A little internet search will reveal that only a single J3 Eagle was produced and I am still unclear on the differences between the J2 and J3.

Others on this forum are building variants of this design and at least one is combining the J1B which s slightly larger with the T tail of the J2 with a lengthened fuselage. I cant recall the name at the moment, perhaps they will chime in here.

At least one builder in Russia converted the J1B to aluminum which would be of interest to learn more about. There are a few reported issues with the J1B plans and design which have been reported and are fixable. The angle of incidence of the wing is one and poor horizontal tail authority due to its low position is another that can be rectified with the T-tail.

How about a hybrid J1B in aluminum with J2 T tail built using angle longerons and aluminum skins? The higher strut braced wing would allow for folding aft like early kit fox designs.
I like the idea of a J1T with a kaw440
 

Mohawk750

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I've studied the plans quite a bit, it's not a quick build. I think there is quite a few opportunists for simplification. The J1 is a bit deeper and wider than the J2 so if you had a J1 with the J2 tail and legnthtn the boom about 6 inches and add the tail it would look great!
 

David L. Downey

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I have the plans for the J1B and the J2 Polenez (in Polish) and have been comparing the two. A little internet search will reveal that only a single J3 Eagle was produced and I am still unclear on the differences between the J2 and J3.

Others on this forum are building variants of this design and at least one is combining the J1B which s slightly larger with the T tail of the J2 with a lengthened fuselage. I cant recall the name at the moment, perhaps they will chime in here.

At least one builder in Russia converted the J1B to aluminum which would be of interest to learn more about. There are a few reported issues with the J1B plans and design which have been reported and are fixable. The angle of incidence of the wing is one and poor horizontal tail authority due to its low position is another that can be rectified with the T-tail.

How about a hybrid J1B in aluminum with J2 T tail built using angle longerons and aluminum skins? The higher strut braced wing would allow for folding aft like early kit fox designs.
Wondering if you know where plans for the J2 can be acquired...with Google(or other) translate available it should be no problem to work out the critical issues? I like the cantilever wings a lot.
 

Aerowerx

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Others on this forum are building variants of this design and at least one is combining the J1B which s slightly larger with the T tail of the J2 with a lengthened fuselage. I cant recall the name at the moment, perhaps they will chime in here.
That was me. But I gave up on the project. I will not go into why, but it is buried in the archives somewhere.

The reason for lengthening the fuselage is that the J-1B is slightly short coupled for the size of the rudder. Then the T-tail gets the elevator up in the prop blast. The original J-1B IIRC had a problem with elevator authority.
 

Mohawk750

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Wondering if you know where plans for the J2 can be acquired...with Google(or other) translate available it should be no problem to work out the critical issues? I like the cantilever wings a lot.
I found them on the old Yahoo Janowski group but I recon some searching would turn them up again. I messed around a little with the translation but didn't save my work. It would be a valid project to translate the note and materials keys for each of the plans sheets and then post them along with the plans somewhere for discussion and study if nothing else. I printed copies for study but I need to find my back-up thumb drive to find the pdf. files again. I had a computer crash and lock up my old hard drive.
 

Hephaestus

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Wondering if you know where plans for the J2 can be acquired...with Google(or other) translate available it should be no problem to work out the critical issues? I like the cantilever wings a lot.
J2 plans are here in another janowski discussion - hit search, janowski - under a J1B discussion - J-1B 'DON QUIXOTE' ULTRALIGHT AIRCRAFT?

This is one that could really work if it's construction method was tweaked to more modern CNC / cad based construction, throw a Yamaha 2cyl on it to get some HP on it, 3cyl it would scream...

Needs a nose gear variant for the current generation of pilots.
 

Mohawk750

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I like the J2 shoulder wing too but it's short coupled and smaller than the J1 and the wings demount rather than fold. The whole J1B/J2 could be the springboard for a new design (as it was for a whole generation of rag and tube ultralights). If you were to "right size" the cabin for today's pilots and build with foam and wood wings stressed for a little heavier 4stroke engine and the J1B/J2 hybrid with folding wings would be very attractive.

I still prefer the little wheel be located at the "proper" end of the aircraft;)
 

Vigilant1

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One approach is to keep the overlapping spar carrythroughs of removable wings (which is structurally efficient and minimizes point loads) and use a simple removable separate fixture to hold the root end of the spar as it is pulled out and swivelled. It can also hold that end of the wing while it is being stored flat against the fuselage. This allows quick one-person folding and unfolding of the wing, but avoids the weight and fussiness that can result when the folding mechanism also must take the spar's flight loads.
Dave Thatcher made a fitting like this for the CX4.
 
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Mohawk750

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Yes, I did see the CX4 fixture. The J2 wing panels would not be very heavy. The trick I suppose is a reliable system that can be done by one person. You don't want your wing falling on the leading edge and being damaged!

I spent some time around the sailplane community and am familiar with "pinned" wing systems. There always seemed to be two or three people involved in getting the aircraft out of the trailer and put together.

The use of fixtures seems appropriate

img-0354.jpg
 

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Mohawk750

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I hadn't noticed it before but the short coupling may have been addressed with the J3 Eagle. Hard to get true profile pics. Sadly no plans were ever drawn for the J3.
J2 Polenez.JPGJ3_Oshkosh.jpgJ3 eagle.JPG
 

Victor Bravo

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I realize this thread is about the J-3, but I have to say that the wing assembly and disassembly ideas and spar arrangements were included in the big list of improvements that resulted in the J-5.

What are the advantages or worthwhile reasons to build the J-3 as opposed to the J-5?
 

Mohawk750

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For one you can't build a J5. It was a kit only design and is long out of production. I think there were only ever eight J5's imported to North America and I believe two have been destroyed. If you could find a derelict project maybe you would have a chance but you still wouldn't have the latest model.

The J6 Fregata is the latest in the series but sadly no one responds to email on that sight anymore, at least not to me. I did a search and there have been three J6 Fregata's imported to Canada and all have mid 2000's registrations. It's unclear if any were sport versions with fixed gear and short wings. And they are bound to be expensive.

 

BJC

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For one you can't build a J5. It was a kit only design and is long out of production. I think there were only ever eight J5's imported to North America and I believe two have been destroyed.
I love the J-5. There was one being modified with a larger engine, but the last that I saw - several years ago - the project was at a standstill. My hangar mate died in one in Clearwater, FL.
The J6 Fregata is the latest in the series but sadly no one responds to email on that sight anymore, at least not to me. I did a search and there have been three J6 Fregata's imported to Canada and all have mid 2000's registrations. It's unclear if any were sport versions with fixed gear and short wings.
Do you know if they had the Honda marine engine?


BJC
 

Victor Bravo

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BJC I am sorry to hear that someone you knew passed away in that airplane. What happened... structural issue or not aircraft-related?

The one being modified with a different engine is Doug Crane, "Crane's Planes", and I believe he was a Navy flyboy of some type. He was halfway through the concept of burying an engine in the wing root and running a belt drive up to the pylon, and then everything stopped.

To me, the J-5 with a single retractable main gear, assuming that one of the newer paramotor engines can be made to work reliably... would be the cat's meow for a fuel-efficient sporty little runabout.
 

Mohawk750

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I love the J-5. There was one being modified with a larger engine, but the last that I saw - several years ago - the project was at a standstill. My hangar mate died in one in Clearwater, FL.
Sorry to hear that, was it a failure of the aircraft in any way?

Do you know if they had the Honda marine engine?
According to the Canadian registry all listed the Honda as the engine installed.
 

Mohawk750

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The one being modified with a different engine is Doug Crane, "Crane's Planes", and I believe he was a Navy flyboy of some type. He was halfway through the concept of burying an engine in the wing root and running a belt drive up to the pylon, and then everything stopped.
VB, I corresponded with Doug this morning. I first met him on the Yahoo groups. He has the J5 on hold and is halfway through the rebuild of a Kis Cruiser he bought. When the Kis is done he'll go back to the J5. Will be interesting to see how the redrive holds up with that long belt though some of the trike guys do it that way to keep the CG low. The installation has come a long way since this pic was taken. I believe he added a slack side idler pulley and ran the set up on a test stand. He's foamed in som upper wing root cooling ducts and is building a plug of the fuselage for a cowling mold.


J5DC.jpg


To me, the J-5 with a single retractable main gear, assuming that one of the newer paramotor engines can be made to work reliably... would be the cat's meow for a fuel-efficient sporty little runabout.
I would agree , but also would like a bit more airplane in front of my feet for protection though none of the J series were generous in this area.
View.JPG
 
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