Pylon mounted wings superior?

After some back and forth discussion, it seems pylon-mounted wings could have a lot of potential for sailplanes.
WRT aerodynamics, they make a laminar upper wing and much more extensive laminar flow on the fuselage possible.
Structurally, notably yaw forces might be problematic (ground-loop), but nothing impossibly difficult. With the possibility of a mid-wing one can remove the heavy spar stubs and control connections and also reduce complexity a lot, notably for drag brakes and flaps.

A few designs from the past come to mind. SH had a pylon-wing on an experimental Cirrus and it reportedly flew well. The Streifeneder Albatross and the Akaflieg München Mü31 are heading in that direction, but are only halfway to the advantages of a full pylon wing.

So why don't we see pylon-mounted wings on modern sailplanes? I can see why not in production ships from the established factories; any radical change demands a steep and risky learning curve. But for new factories and/or experimental ships, at first glance there seems a lot of potential.

Any major issues with pylon wings that we've overlooked?

On Tuesday, February 4, 2014 7:28:31 AM UTC-8, J. Nieuwenhuize wrote:
After some back and forth discussion, it seems pylon-mounted wings could have a lot of potential for sailplanes.

WRT aerodynamics, they make a laminar upper wing and much more extensive laminar flow on the fuselage possible.

Structurally, notably yaw forces might be problematic (ground-loop), but nothing impossibly difficult. With the possibility of a mid-wing one can remove the heavy spar stubs and control connections and also reduce complexity a lot, notably for drag brakes and flaps.



A few designs from the past come to mind. SH had a pylon-wing on an experimental Cirrus and it reportedly flew well. The Streifeneder Albatross and the Akaflieg München Mü31 are heading in that direction, but are only halfway to the advantages of a full pylon wing.



So why don't we see pylon-mounted wings on modern sailplanes? I can see why not in production ships from the established factories; any radical change demands a steep and risky learning curve. But for new factories and/or experimental ships, at first glance there seems a lot of potential.



Any major issues with pylon wings that we've overlooked?

Eric Raymond has been taking advantage of this for years. Both of the Sunseeker aircraft have pylon mounted wings. http://www.solar-flight.com/

Craig
7Q

Ah, finally the value of the sleek Slingsby T21 "Rhone-Moose" will go up.
Jim

On Tuesday, February 4, 2014 11:11:33 AM UTC-6, JS wrote:
Ah, finally the value of the sleek Slingsby T21 "Rhone-Moose" will go up. Jim

Only if you also install winglets, Jim!

Steve

Or we could remove the engines from a PBY-5a Catalina and turn the pontoons up to get (nearly) the same effect.

-John, Q3


On Tuesday, February 4, 2014 12:11:33 PM UTC-5, JS wrote:
Ah, finally the value of the sleek Slingsby T21 "Rhone-Moose" will go up.

Jim

On Tuesday, February 4, 2014 8:41:07 AM UTC-8, Craig Funston wrote:
On Tuesday, February 4, 2014 7:28:31 AM UTC-8, J. Nieuwenhuize wrote:

After some back and forth discussion, it seems pylon-mounted wings could have a lot of potential for sailplanes.



WRT aerodynamics, they make a laminar upper wing and much more extensive laminar flow on the fuselage possible.



Structurally, notably yaw forces might be problematic (ground-loop), but nothing impossibly difficult. With the possibility of a mid-wing one can remove the heavy spar stubs and control connections and also reduce complexity a lot, notably for drag brakes and flaps.







A few designs from the past come to mind. SH had a pylon-wing on an experimental Cirrus and it reportedly flew well. The Streifeneder Albatross and the Akaflieg München Mü31 are heading in that direction, but are only halfway to the advantages of a full pylon wing.







So why don't we see pylon-mounted wings on modern sailplanes? I can see why not in production ships from the established factories; any radical change demands a steep and risky learning curve. But for new factories and/or experimental ships, at first glance there seems a lot of potential.







Any major issues with pylon wings that we've overlooked?



Eric Raymond has been taking advantage of this for years. Both of the Sunseeker aircraft have pylon mounted wings. http://www.solar-flight.com/



Craig

7Q

The main reason Eric has pylon mounted wings and a T tail is that the solar cells can not be partially shaded it causes problems.

Richard
Craggy Aero

On Tuesday, February 4, 2014 11:15:50 AM UTC-6, Steve Leonard wrote:
On Tuesday, February 4, 2014 11:11:33 AM UTC-6, JS wrote:

Ah, finally the value of the sleek Slingsby T21 "Rhone-Moose" will go up. Jim



Only if you also install winglets, Jim!



Steve

And a couple of air extractors...

Kirk

On Tuesday, February 4, 2014 12:04:03 PM UTC-6, kirk.stant wrote:
And a couple of air extractors...
Kirk

Maybe some de-turbulators....

It seems it would make the structure more complex and heavier. I would guess it also would cost more to build a pylon wing glider. Shoulder wings with smooth integral wing root fillets (ASW-15 for example) should also be more efficient than simply mating the wing end on to the side of the fuselage but Schleicher seemed to give this up as not worth the effort when they moved to the ASW-19 (mid mounted wing with a more vestigial fillet).

One of the interesting things about glider design is that, even for open class, it's not really a free for all. The design has to comply with national airworthiness requirements and have acceptable flying characteristics for the average pilot. Compare this to an Unlimited Reno racer for example. I remember what Gerhard Waibel said about the ASW-12 in hindsight. It was something about learning how all new, hot gliders will become older gliders flown by less than top rank pilots eventually and you have to take that into consideration even when you're trying to make a world championship contender..

On Tue, 04 Feb 2014 07:28:31 -0800, J. Nieuwenhuize wrote:

After some back and forth discussion, it seems pylon-mounted wings could
have a lot of potential for sailplanes.
WRT aerodynamics, they make a laminar upper wing and much more extensive
laminar flow on the fuselage possible.
Structurally, notably yaw forces might be problematic (ground-loop), but
nothing impossibly difficult. With the possibility of a mid-wing one can
remove the heavy spar stubs and control connections and also reduce
complexity a lot, notably for drag brakes and flaps.

A few designs from the past come to mind. SH had a pylon-wing on an
experimental Cirrus and it reportedly flew well. The Streifeneder
Albatross and the Akaflieg München Mü31 are heading in that direction,
but are only halfway to the advantages of a full pylon wing.

So why don't we see pylon-mounted wings on modern sailplanes? I can see
why not in production ships from the established factories; any radical
change demands a steep and risky learning curve. But for new factories
and/or experimental ships, at first glance there seems a lot of
potential.

Any major issues with pylon wings that we've overlooked?

One. You need a fair pylon height to avoid interference drag in the gap
between the top of the fuselage and the wing's lower surface. I'd say
interference drag is relatively high on the Sunseeker shown he
http://www.solar-flight.com/

However I'm not an aerodynamics expert and have no idea what the optimum
height sound be except that its unlikely to be less than 10-15% of the
wing chord, think of the Wien for this pylon height, and that its one
problem the Ku-4 Austria didn't suffer from.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
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