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Shoulder wing unpopularity

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cluttonfred

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Weighing in late on a subject near and dear to my heart, please take a look at this earlier thread Swept-forward, shoulder-wing configuration and especially the article on Bjorn Andreasson's original simple homebuilt BA-7 attached to this post. The shoulder-wing blend of high-wing ground clearance/downward visibility and low-wing upward visibility is very appealing. A Volksplane-simple wood-and-fabric design or a Skyranger-style bolted-tube-and-dacron design along these lines could, I think, have broad appeal.
 

stanislavz

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Weighing in late on a subject near and dear to my heart, please take a look at this earlier thread Swept-forward, shoulder-wing configuration and especially the article on Bjorn Andreasson's original simple homebuilt BA-7 attached to this post. The shoulder-wing blend of high-wing ground clearance/downward visibility and low-wing upward visibility is very appealing. A Volksplane-simple wood-and-fabric design or a Skyranger-style bolted-tube-and-dacron design along these lines could, I think, have broad appeal.
Shal we join both threads ?

To my knowledge, the only other design gone from homebuild to certified aircraft, was pazmany pl-2.

Anyway - shoulder wing do looks to feel well with thinner tailand happensvto have more compact and shorter front area. In a high wing you have an classical problem triangle. You have to make cabin high enought, to have view above motor, place motor as low as possible, and still have normal height of landing gear.

Shoulder wing solves it, just by putting pilot head above wing.

Lets design it !
 

BJC

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To my knowledge, the only other design gone from homebuild to certified aircraft, was pazmany pl-2.
The Glasair Aviation GlaStar was, with modifications, TCed as the Symphony.
The Pitts S-1S morphed from homebuilt (and many commercially built Experimental versions) into the TCed S-1S.
The Glasair Aviation Sportsman is currently being evaluated for TC.

Ther are others.


BJC
 

stanislavz

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Forward swept wing with taper looks nice.










And it did flight :



Sad story - it was designed only for production, and before final testings - investors do ran out of money.. But have very nice and roomy cabin :)
 

Aerowerx

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Janowski J-1B.

Although it would be a bit better if the wing is a couple inches lower. In this view the wing is right at eye level. Would be better if the pilot could look over the top of the wing, IMHO.

 

cluttonfred

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stanizlavz, that little microlight is pretty close to a "Skyranger-style bolted-tube-and-dacron design" but better looking than what I had in mind. I am not sure that the a tapered planform is really that useful in this application and I can see some areas for simplification to make for an easier build. I have to ask, what in the world is going on with that wing spar? I have never seen anything like it.

Aerowerx, that J-1B is neat, and I agree that the wing could be a little lower. Another option would to use a transparent leading edge/root rib forward of the spar to give a little window.
 

cluttonfred

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Very interesting, it's like a traditional strut-braced, ladder-frame ultralight wing that has had the struts integrated into the wing by flipping them upside-down to make compression struts. It's beyond my limited engineering knowledge to say how efficient it is, but it certainly looks easy to build and worth the complication in terms of the wing ribs, etc.

Found some better photos
 

Riggerrob

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Stemme has one solution to straighten the wing spar. They install the engine under the wing. Side-by-side seats are both forward of the wing. A drive shaft transmits power to a tiny gearbox in the nose. That gearbox turns the propeller.
In the near future, electric motors will be light enough to install in the extreme nose with batteries or generator behind the cockpit. That would allow cockpit windows almost as large as helicopters.
 

Riggerrob

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You know, you can solve the problem by using a twin boom pusher midwing configuration . The spar can then be just behind the seat for a side-by-side or single, or between the seats for a tandem. Adjust engine position and/or seats to get the CG in the right place.
Sadly, most single-engined pushers suffer balance problems that can only be solved by installing the prop hub well forward of the trailing edge, or installing seats way farther forward than is structurally sound. Look at the original Republic Seabee. It had a brilliant airframe, but the weak (barely 200 horsepower) Franklin engine needed an 18-ish inch drive shaft to balance. Only a few Seabees have been retrofitted with more powerful engines because of balance hassles. The best up-engine program involves installing a 300 hp, automotive V-8 engine stolen from a Corvette car with a 20-ish inch extension shaft.
Drive shafts are problematic in the hands of all but the very best engineers.

Single-engined pushers also suffer airflow separation problems as the cockpit pod tapers rapidly from the cockpit to the trailing edge. Remember that the prop has to be close to the trailing edge for balance. look at all the vortex generators retro-fitted to Glass Geese seaplanes.
 

Topaz

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I din't realise it was a Rutan design, i thought it was Australian.
You were right the first time. The Eagle X was conceived by an Australian company as an inexpensive two-seat airplane for private use and flight training. Another "modern Cub" concept. The particular "bright idea" of this one was that the wing and canard were supposed to be pultruded shapes, including, I believe, the spar caps and webs. There would be one pultrusion die, and you'd simply cut off a shorter piece for a canard panel, and a longer piece for a wing panel. You'll notice that the flap (on the canard and wing) and the aileron are about the same chord, so they're another "cut to length" piece.

Burt Rutan didn't design the Eagle X. The "connection" to Rutan is that the airfoils, and some of the aerodynamic design, were done independently by John Roncz, who was Rutan's aerodynamicist at the time. The actual airplane was designed by the Australian company.

Unfortunately, it turned out that the "cut to length" gimmick resulted in very heavy flying surfaces. The fact that the airflow over the canard influences that over the wing (and vice versa) meant that simply cutting off lengths of identical flying surfaces prohibited them from being given twist to compensate for the flow interaction. This turned into horrific near-stall characteristics and, to "save" the gimmick construction technique, the Eagle X sprouted the densest forest of aerodynamic "fixes" you'll see on any light plane, ever. There are cuffs, there are dog-teeth, stall strips, fences, and vortex generators. The flaps and aileron sizes needed to be adjusted, so that they were no longer able to be pultruded from a common die, and had to be made as custom components. It was determined during the design process that the horizontal tail couldn't be drawn from the same die and inverted (the original goal), so that turned into another custom part.

All in all, the airplane ended up flying "okay", but was never a "joy" to fly. It wasn't any less expensive than anything else in the category, and then there's the "wisdom" of a primary trainer that cannot be stalled at all, because of the three-surface configuration. The project was pretty much a disaster, and while the rights to the design traded hands a few times, eventually coming to rest in Malaysia.

The most extensive online information on the project is here, I believe: http://stargazer2006.online.fr/derivatives/pages/eagle-x.htm
 
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cheapracer

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Australian company as an inexpensive
You put Australia and cheap into the same sentence, bahahaha!


Found some better photos :

Better photos of what please? What brand, model is it?

I would love to make a truss wing, there is a very real acceptance problem in light aviation though, that's why I'm not mentioning what I am doing now, snigger snigger ....
 

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stanislavz

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Can someone explain forward swept tapered wing stall behavior ? un-swept do have not very nice - not gentle, and may stall at all span at once .
 

stanislavz

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Better photos of what please? What brand, model is it?
Sadly, but nope. This one was taken from webarchive itself. Just an sad story, when an good idea have to be forgotten. And this one still lack two members, as per x ray photo of airplane. As i can see. But it is only simple truss..

Just curious, how it would look on paper in comparison with composite wing, rigid nose, and same construction in situ formed longerons/reinforcements, using composite..

It could be just easier to calculate in comparison with stressed skin.
 

cheapracer

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un-swept do have not very nice - not gentle, and may stall at all span at once .
That's the designer/builder, not the design per say. Look up wing twist, and wing cuffs. Some designs even use different wing profiles from root to tip. Plenty of straight wing planes stall gently.


Sadly, but nope.
I wasn't asking for photos, I was asking what brand or who built it please?
 

stanislavz

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I wasn't asking for photos, I was asking what brand or who built it please?
Its called Voron. Was build in Russia. I think, therea are some video on youtube with testing.

And taadam. skyciv online truss modeling..



Which tube shall i use ?
 

stanislavz

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Its called Voron. Was build in Russia. I think, therea are some video on youtube with testing.

And taadam. skyciv online truss modeling..



Which tube shall i use ?
Crap - mine free account, only allow 5 members, so will left, just an curious experience...
 
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