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The Janowski Project - Rethinking the J1B/J2/J3

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Vigilant1

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While I admire the look of all the composite tadpole like designs these are not very accessible for the homebuilder on a budget. The faceted flat panel composite build up is a little more achievable but there are lots of corners dependent on good bonds to achieve strength.

I'm wondering at this point if its easier, simpler and less expensive to build the fuselage pod with ply skins on the inside of the framework whch carries the load paths, infill the sides of the structure with foam and add some compressive areas in the nose and under the seat. You could then carve to a pleasing shape and wrap with kevlar/carbon for a strong pod structure ala 21st Century KR1/2 and vari eze. Just thinking out loud as to how I could do this in my garage.
I don't think homebuilders would find it hard to make strong edge bonds when joining flat composite panels. It's a good spot to introduce some internal reinforcement, too. But, if desired, another approach is to make the corners using the "Foldaplane' method used by the Vision. Vacuum bag the foam core and external skin against a flat smooth surface. When cured, cut kerfs in the foam to allow it to be folded at the edges where desired, drop it into exterior bucks of the right shape, then install the bulkheads and interior skin to lock everything in place. Yes, the cut lines still require exterior glassing, but the vast majority of the exterior skin is smooth and almost ready for paint.
 

Hephaestus

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Yup manufacturability is pretty much driving force for me. But that may include the need to possibly cnc hotwire (Not that the cnc hotwire is a huge cost/challenge to build/use).

What I've been thinking - is to build very much like the original. Longerons using an XPS core wrapped in wet layup been debating how to actually make that work though. Top would be flat and could be vacuum bagged but it's a long piece. Lower's got more curves - would have to be in a core.

Kind of been wondering if stretch wrap (the 3" wide tape they use to secure construction material/pallet loads Mini-Wrap Stretch Wrap, Mini Stretch Wrap Rolls in Stock - ULINE.ca - Uline ) over a wet layup in somewhat a hybrid prepreg method might work.


Since DIY'ing a 16' long oven/autoclave isn't really feasible for 4 parts.

The filler panels/webs could then be vacuum bagged down on a glass table, so flat and almost finished... Install with micro rutan style, one last layup over top. Inside and outside to consolidate into one.

Maybe totally impractical, maybe not. Haven't decided yet.
 
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patrickrio

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I have been thinking of cheap ways to do a temp controlled autoclave that is long enough to do wing sections.

I think you could take a piece of sonotube concrete form and insulate it. then you put plugs in the ends created with a plunge router circle jig. Then create a PID controlled convection oven air circulation fan path inside it at the bottom.

to hold higher pressure at the plug ends, you could thread tension wires holding the end caps together. The sonotube can hold a few atmospheres in its diameter no problem.

for those that need a visual, basically a long one of this but a few feet in diameter and 15 feet long or so:

sonotube subwoofer.jpg
 

Hephaestus

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I have been thinking of cheap ways to do a temp controlled autoclave that is long enough to do wing sections.
Interesting idea. I know there's ways to do it, just hesitant about switching processes. And prepregs needing to be transported frozen and having a best before date - doesn't give me warm and fuzzies.

Andy's J2 v3 red.png

not in love with the rhino rudder look, but it is simple to build, could add a bit more rudder authority on final - I seem to recall some discussions in the pusher threads about rudder effectiveness when the engines idled...

Definitely looks faster in red :)
 

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Mohawk750

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not in love with the rhino rudder look, but it is simple to build, could add a bit more rudder authority on final
Love the red, not loving the look of the nose wheel and it's worse with that fairing. I would gladly add an inch oer two to the rudder for more authority if needed but would REALY like to see this in taildragger configuration....Pleeease 😁
 

Hephaestus

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Love the red, not loving the look of the nose wheel and it's worse with that fairing. I would gladly add an inch oer two to the rudder for more authority if needed but would REALY like to see this in taildragger configuration....Pleeease 😁
lol yeah there will be 2 places for the gear, pretty sure I can't force anyone to install a piece of plastic :)

So that's ballpark conceptual design.

Trying to figure out how to model those fuselage angles in VSP, see what it says. Still a very long way from plans.
 

James Gyore

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I once visited a builder over near Akron Ohio. He used to be a member here (Carribeanbound????) and was building a glass/foam sandwich J-1B. Never heard if he finished or not. Last I heard is that he moved back to Florida.

Anyway, he told me that he had an engineer look at the original design and was told that it was over built. Probably because 1970s Communist Poland did not have a Aircraft Spruce outlet, and he had to use what was available.

So there is certainly room for improvement with modern materials.
Oh, you’re referring to Jerry. I don‘t think he ever finished it. He’s getting about in Hawk Arrow these days.
 

Mohawk750

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By pure coincidence I stumbled across the missing link in the J Series. I had asked myself for years "what ever happened to the Janowski J4?" The obvious gap in the series led me to believe there was a missing aircraft and sure enough I found it on a Polish website tonight and have translated the entry below.

Enjoy,

Project of the J-4 "Solidarity" amateur sports plane.
(Source: [1] ”Stanisław Gradolewski's website”).

1612930928445.png

In 1977 (other sources give an incorrect date - 1980) Jarosław Janowski started to design a small two-seater J-4 "Solidarity" plane for training in aero clubs. It was to be a low-wing side-by-side, powered by a 50 kW Limbach engine, used to drive the SZD-45 "Ogar" motor glider, of which aero clubs had a supply. The aerodynamic model of the aircraft was tested at the Warsaw University of Technology. The aircraft's layout was related to the American Rand KR-02. It was to have a 19.6% Wortmann profile, a gap-free flap and spoilers instead of ailerons.

The construction of the aircraft began in 1979. In the workshop of the Aero Club of Łódź, J. Janowski together with W. Kalita, W. Stefański and M. Luziński made 50% of the fuselage and began building the wings. The plane was to be built in sets at the Aero Club of Łódź and assembled at flying clubs. The fuselage of the aircraft was presented at the 1st National Rally of Aviation Amateurs Constructors in Łódź (13-19.07.1981). After the imposition of martial law in December 1981, the Aero Club of the Polish People's Republic stopped its interest in the plane and the Limbach engines were transferred to the GDR. The Security Service blocked construction and the plane was not completed. The name was also provocative for the authorities at the time.

Construction:

Two-seater medium wing of a mixed structure (wood-laminate). The wing was to be constructed of Conticell foam and laminate. It was to consist of six identical segments with a span of 90 cm each, and endings on the outer edges. There were supposed to be spoilers instead of ailerons. Over the entire span, gap-free flaps. Hull made of plywood and laminate. Crew seats next to each other (two). Classic tail. Classic fixed chassis. Laminate spring legs, wheels from the "Stork" glider.

Technical data J-4 "Solidarity" (according to [1]):
Equipment - basic on-board instruments, radio.
Engine - Limbach with a power of 50 kW (68 HP).
Span - 7.0 m, length - 4.8 m,
height - (according to [2] - 1.25) m,
bearing area - 6.8 (according to [2] - 6.0) m2.
Own weight - (in [2] - 250) kg,
payload - (in [2] - 230) kg,
take-off weight - (in [2] - 480) kg.
Max speed (probably) - 290 km / h,
cruising speed (probably) - 240 km / h, range - 2000 km.

Source:

[1] "Stanisław Gradolewski's website".
[2] Glass A. "Planes of Jarosław Janowski". Polish Aviation Technology. Historical Materials No. 65 (10/2010).
[3] Glass A. "Polish amateur planes and motor gliders". Aviation and Astronautics Technology No. 1/1984.
[4] "From the Country". Aviation and Astronautics Technique No. 10/1981.
[5] "From the Country". Aviation and Astronautical Technique No. 12/1978.
 

Vigilant1

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By pure coincidence I stumbled across the missing link in the J Series. I had asked myself for years "what ever happened to the Janowski J4?" The obvious gap in the series led me to believe there was a missing aircraft and sure enough I found it on a Polish website tonight and have translated the entry below.

Enjoy,

Project of the J-4 "Solidarity" amateur sports plane.
(Source: [1] ”Stanisław Gradolewski's website”).

View attachment 107319

In 1977 (other sources give an incorrect date - 1980) Jarosław Janowski started to design a small two-seater J-4 "Solidarity" plane for training in aero clubs. It was to be a low-wing side-by-side, powered by a 50 kW Limbach engine, used to drive the SZD-45 "Ogar" motor glider, of which aero clubs had a supply. The aerodynamic model of the aircraft was tested at the Warsaw University of Technology. The aircraft's layout was related to the American Rand KR-02. It was to have a 19.6% Wortmann profile, a gap-free flap and spoilers instead of ailerons.

The construction of the aircraft began in 1979. In the workshop of the Aero Club of Łódź, J. Janowski together with W. Kalita, W. Stefański and M. Luziński made 50% of the fuselage and began building the wings. The plane was to be built in sets at the Aero Club of Łódź and assembled at flying clubs. The fuselage of the aircraft was presented at the 1st National Rally of Aviation Amateurs Constructors in Łódź (13-19.07.1981). After the imposition of martial law in December 1981, the Aero Club of the Polish People's Republic stopped its interest in the plane and the Limbach engines were transferred to the GDR. The Security Service blocked construction and the plane was not completed. The name was also provocative for the authorities at the time.

Construction:

Two-seater medium wing of a mixed structure (wood-laminate). The wing was to be constructed of Conticell foam and laminate. It was to consist of six identical segments with a span of 90 cm each, and endings on the outer edges. There were supposed to be spoilers instead of ailerons. Over the entire span, gap-free flaps. Hull made of plywood and laminate. Crew seats next to each other (two). Classic tail. Classic fixed chassis. Laminate spring legs, wheels from the "Stork" glider.

Technical data J-4 "Solidarity" (according to [1]):
Equipment - basic on-board instruments, radio.
Engine - Limbach with a power of 50 kW (68 HP).
Span - 7.0 m, length - 4.8 m,
height - (according to [2] - 1.25) m,
bearing area - 6.8 (according to [2] - 6.0) m2.
Own weight - (in [2] - 250) kg,
payload - (in [2] - 230) kg,
take-off weight - (in [2] - 480) kg.
Max speed (probably) - 290 km / h,
cruising speed (probably) - 240 km / h, range - 2000 km.

Source:

[1] "Stanisław Gradolewski's website".
[2] Glass A. "Planes of Jarosław Janowski". Polish Aviation Technology. Historical Materials No. 65 (10/2010).
[3] Glass A. "Polish amateur planes and motor gliders". Aviation and Astronautics Technology No. 1/1984.
[4] "From the Country". Aviation and Astronautics Technique No. 10/1981.
[5] "From the Country". Aviation and Astronautical Technique No. 12/1978.
Thanks, very interesting. Really different from his other designs, maybe he reasoned that a more conventional design would have more popular appeal.
Dimensions, engine choice, weights, and projected performance were pretty close to a Sonex (which came 20 years later, and is all metal). Well, except for that 2000 km range, which might be a misprint or it had a really big fuel tank to allow a lot of fuel to be carried when flown solo. And, I think he probably would have changed the spoliers to ailerons during the development.
Thanks again.
 
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Hephaestus

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While autodesk is screwing up my plans to work on this... Started looking at the tail more. Fusion's refusing to open the file the past few days.

Curious - think the icon a5's higher Hstab mounting is aerodynamic choice or wing fold choice? Comparing against other pushers - above centerline of engine thrust by a good foot.

Pondering how to do a decent printed rc model for this one - method I used for the lazybee isn't going to work (I just kicked out solids, effective, too heavy for this wing area) more reading required.
 
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Mohawk750

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While autodesk is screwing up my plans to work on this... Started looking at the tail more. Fusion's refusing to open the file the past few days.
Man, I hope that gets worked out, hate to see you loose all that work.

I'm not a designer but I would think that the Icon A5 has had a more thorough engineering development than most any other recent experimental amateur built aircraft. I bet they tried dozens of iterations but my gut tells me that the high position of the tail is an aerodynamic compromise to facilitate the wing folding.

While not quite as elegant as the A5 the Seamax has been around much longer and has some interesting features including a folding cruciform all flying stabilizer.


Perhaps some of the aero engineers on this board could help us understand the advantages/dis-advantages of positioning the horizontal stab above or below the thrustline and what might prove to be optimal.
 

Vigilant1

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Curious - think the icon a5's higher Hstab mounting is aerodynamic choice or wing fold choice? Comparing against other pushers - above centerline of engine thrust by a good foot.
Other possible reasons:
1) Aesthetics/marketing. Same reason the V-stab and rudder are swept despite having mild adverse aerodynamic consequences and no benefits. If you spend this much for a Jetski of the skies, it had better look sporty and modern.
2) Maybe to keep the H-stab out of the water/water spray and eliminate the chances of dragging the H-stab through a small wavetop, etc. on an overrotated takeoff.

Like most of these configuration decisions, there were surely pros and cons for each option. I think your wing-fold hypothesis (esp not having the tail in the way while the wings are secured) was probably a major factor.
 
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Hephaestus

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Icon's high wing T-Tail, so could be it's just getting it that extra foot+ up to get it out of the wing wake too

download (1).jpg

hstab and vstab have an interesting shape - slightly more visual appeal than what I'd roughed out. I figured since it's had a lot of CFD and aero invested in it, probably a good layout to consider strongly as I steal ideas.

Pretty sure autodesk will resolve the issue, think it's a bug from the last update... Quick check on the fusion boards says yup not the only one having the issue.
 

Yellowhammer

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J2 to J3 differences -
Conventional landing gear, wortman laminar airfoil, and added spoilers.

Cockpit lines seem a little smoother.

I don't suppose anyone archived the Yahoo group before it died? I don't see any reference to it being moved to groups.io or anything.

I have a friend who archived a ton of aircraft. I will check and see if he has this information.
 

Mohawk750

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hstab and vstab have an interesting shape - slightly more visual appeal than what I'd roughed out. I figured since it's had a lot of CFD and aero invested in it, probably a good layout to consider strongly as I steal ideas.
I think the "back slant on the upper portion of the A5 rudder is there simply to get the trailing edge ahead of the elevator hinge line. That way they the rudder can fill the gap to the stab and not have to be relieved to allow elevator down travel. Most T-tails trim the top of the rudder to clear the elevator. On the J2/J3 full flying stabilator angular travel is just a few degrees and it appears providing clearance for the rudder was not an issue.

FWIW, with a constant chord wing I think a constant chord stabilator looks about right. It also fits with the estetic of the flat square boom and flat faceted fuselage pod. You could spruce up the stabilator to match your wings with the addition of the "Wittman" tips if you like, ;)
 

Hephaestus

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Yeah been wading through the naca/nasa/glider tail flutter articles trying to wrap my mind around all of it.

At closer to part 103 speeds/low hp not a big deal, but when I want to throw a 80hp+ yamaha at it...

Kind of thinking it'll have to go to more normal hstab/elevator. May be able to keep the trim as angle of the stab though. Then that bulbous bullet fairing can go away (originally wanted to hide the counter weight & mechanism)
 

Ried

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Yeah been wading through the naca/nasa/glider tail flutter articles trying to wrap my mind around all of it.

At closer to part 103 speeds/low hp not a big deal, but when I want to throw a 80hp+ yamaha at it...

Kind of thinking it'll have to go to more normal hstab/elevator. May be able to keep the trim as angle of the stab though. Then that bulbous bullet fairing can go away (originally wanted to hide the counter weight & mechanism)
You don't like the look of a chunk of lead hanging in the breeze???

Seriously though, the thought rattling around between my ears is to stretch a J1 out into a wood Sky Arrow, tandem seated aircraft. I need to sharpen up a bunch of No. 2 pencils and get to work.

Thanks for this thread of inspiration.
 

Hephaestus

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You don't like the look of a chunk of lead hanging in the breeze???

Seriously though, the thought rattling around between my ears is to stretch a J1 out into a wood Sky Arrow, tandem seated aircraft. I need to sharpen up a bunch of No. 2 pencils and get to work.

Thanks for this thread of inspiration.
Where's that picture of a toddler hanging off the blackhawks pitot tube? :) It was posted on hba in the last few weeks again.

I have an issue with things that protrude that can easily be damaged incidentally or because they make perfect hand holds. That and I'll put my eye out kid - wouldn't be the first protrusion I've walked/turned/stood up into and damaged.
 

Vigilant1

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I have an issue with things that protrude that can easily be damaged incidentally or because they make perfect hand holds.
There was an incident/ story from several decades ago of a certain country which had received their first squadron of F-16s. It was an important prestige item regionally, and this was far more important than any tactical significance of the jets.
Of course there were 24/7 sentries around the lined up aircraft. Well, it's pretty boring out there at night, and one of the gaurds did some pullups on the pitot tube of one of the aircraft. To his horror, he noticed that pitot then angled noticably downward compared to the other F-16s, and he knew what this would mean for him, and probably his family. You can guess what he did next...pullups on the pitot of every jet to make them all match.
I don't think it worked out well for him.
 

Mohawk750

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Well you guys are thinking opposite to me on this. And that's the great thing about this thread, it gets the creative juices flowing. Everyone says the J1/J2 is overbuilt but nobody has figured out where all that extra weight is yet. That would be the first step to figuring out what has to stay and what can go.

I would want either a folding wing J1 with T-tail or a removable wing J2 in taildragger configuration. Build in wood because it cheap and available and there are species substitutions that can preserve strength if not the weight when the optimum is not available. Use foam ribs with plywood cap strips and leading edge d-cell in the wing, fin and stabilator, no flaps just ailerons, constant chord so all the ribs are the same and fabric covered. The foam and ply sandwich fuselage pod could be caged by with a rollover structure for a windshield frame and a side door instead of canopy and reinforced with carbon if needed.

Power with a half VW or industrial four stroke. It might not make Part 103 weights but would be inexpencive to build own and operate.
 
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