Pylon mounted wings superior?

[J. Nieuwenhuize]

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?

[Craig Funston[_2_]]

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

[JS]

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

[Steve Leonard[_2_]]

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

[John Carlyle]

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

[Richard[_9_]]

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

[kirk.stant]

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

[Steve Leonard[_2_]]

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....

[[email protected]]

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..

[Martin Gregorie[_5_]]

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 here:
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
org |

[J. Nieuwenhuize]

Op dinsdag 4 februari 2014 22:53:33 UTC+1 schreef :
> 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.
I would expect the exact opposite. Looking at all the parts, easily a quarter of all the parts of a normal 15M sailplane are in the wing-fuselage intersection and the spar roots are a pretty beefy (and heavy) part since you have a joint at the highest loaded part of the whole structure. I don't have a weight breakdown at hand, but some earlier number-crunching yielded around 15 kg weight saved by carrying on the wing (and have 2 lighter joints outboard)
All those automatic connections add a lot of complexity and weight too and you can reduce their number by half. Not to mention spoilers (drag brakes) that can be in the middle of the wing since you're outside the fuselages "blocked zone" reducing the number of parts further.

> 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.

An excellent point. Yet, not certifying and having a homebuilt, development cost could be drastically less, though it'd still be wise to meet every requirement from CS22. Save France, to the best of my knowledge you can fly homebuilt sailplanes in most soaring-minded countries.

> 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 here:
>
> 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
> org |

A bit of number-crunching suggests something like 0.5-1 root chord, so 1-2 feet for a typical single-seater.

[Dan Marotta]

Why you bad mout' dat drag queen? Ever towed one?

I seem to recall Dean Carswell asking me to keep it over the airport and not
go above 50 mph. The old Bird Dog was shaking like a (pardon the
expression) wet dog throughout the tow. Dean's T21 is now in the musuem at
Moriarty.

"Steve Leonard" > wrote in message
...
> 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....
>

[Bob Kuykendall]

From the perspective of an inveterate pragmatist:

I think it comes down to operationality. Yes, the autoconnects add complexity. Yes, placing the wing panel separation at the station of maximum bending moment adds weight.

But what you get in return is a system of parts that allows for easy storage and transport, rapid assembly, and high reliability. That system has been proven to result in good soaring performance at the lowest possible cost in terms of operator fatigue. And that makes for a more enjoyable soaring experience. And when it comes down to it, quality of experience is what we should be trying to maximize here, not necessarily quality of performance.

It is easy to conceive of this or that adaptation that might result in greater performance for a no-holds-barred competition machine. However, all too often the result is a less robust machine that requires more work to assemble and prepare for operation. That's great if all you want to do is win prestigious contests and are prepared to either do or pay for the extra work required to campaign such an aircraft. It's less great for everyone else, and especially for those who buy such aircraft on the used market and find out what a pain it can be.

Thanks, Bob K.
https://www.facebook.com/pages/HP-24-Sailplane-Project/200931354951

On Wednesday, February 5, 2014 1:29:19 AM UTC-8, J. Nieuwenhuize wrote:
> Op dinsdag 4 februari 2014 22:53:33 UTC+1 schreef :
>
> > 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.
>
> I would expect the exact opposite. Looking at all the parts, easily a quarter of all the parts of a normal 15M sailplane are in the wing-fuselage intersection and the spar roots are a pretty beefy (and heavy) part since you have a joint at the highest loaded part of the whole structure. I don't have a weight breakdown at hand, but some earlier number-crunching yielded around 15 kg weight saved by carrying on the wing (and have 2 lighter joints outboard)
>
> All those automatic connections add a lot of complexity and weight too and you can reduce their number by half. Not to mention spoilers (drag brakes) that can be in the middle of the wing since you're outside the fuselages "blocked zone" reducing the number of parts further.
>
>
>
> > 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.
>
>
>
> An excellent point. Yet, not certifying and having a homebuilt, development cost could be drastically less, though it'd still be wise to meet every requirement from CS22. Save France, to the best of my knowledge you can fly homebuilt sailplanes in most soaring-minded countries.
>
>
>
> > 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 here:
>
> >
>
> > 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
>
> > org |
>
>
>
> A bit of number-crunching suggests something like 0.5-1 root chord, so 1-2 feet for a typical single-seater.

[Bob Kuykendall]

On Wednesday, February 5, 2014 1:29:19 AM UTC-8, J. Nieuwenhuize wrote:

>...Save France, to the best of my knowledge you can fly homebuilt
> sailplanes in most soaring-minded countries.

Jarno, are the regulations for such operations in the Netherlands very strict or complicated? I'd long thought that trying to sell sailplane kits in Europe was bringing coals to Newcastle, but it could be that I can offer a compelling value proposition. You might contact me off-line about this.

Thanks, Bob K.

[Martin Gregorie[_5_]]

On Wed, 05 Feb 2014 13:17:35 -0800, Bob Kuykendall wrote:

> From the perspective of an inveterate pragmatist:
>
> I think it comes down to operationality. Yes, the autoconnects add
> complexity. Yes, placing the wing panel separation at the station of
> maximum bending moment adds weight.
>
> But what you get in return is a system of parts that allows for easy
> storage and transport, rapid assembly, and high reliability. That system
> has been proven to result in good soaring performance at the lowest
> possible cost in terms of operator fatigue. And that makes for a more
> enjoyable soaring experience. And when it comes down to it, quality of
> experience is what we should be trying to maximize here, not necessarily
> quality of performance.
>
Good point.

I've helped rig one of the Slingsbys which had a three piece wing.
Getting the C/s on was quite a hassle. While it can be done by three
people, having five on the job makes it a lot easier. The problem is that
you have to lift the wing quite high to clear the fuselage and keep it up
while the odd-numbered man attaches the wing to the fuselage. Putting the
tips on is easy but that doen't matter compared with handling the c/s.

One of the local clubs where I fly gas an SZD Pirat, which has a 15m
three-piece wing. They consider attaching and removing the c/s is such a
hassle that its normally left on and just the tips are removed when the
Pirat is put in the hangar.


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

[Bob Gibbons[_2_]]

On Thu, 6 Feb 2014 02:08:38 +0000 (UTC), Martin Gregorie
> wrote:

.... text deleted

>Good point.
>
>I've helped rig one of the Slingsbys which had a three piece wing.
>Getting the C/s on was quite a hassle. While it can be done by three
>people, having five on the job makes it a lot easier. The problem is that
>you have to lift the wing quite high to clear the fuselage and keep it up
>while the odd-numbered man attaches the wing to the fuselage. Putting the
>tips on is easy but that doen't matter compared with handling the c/s.
>
>One of the local clubs where I fly gas an SZD Pirat, which has a 15m
>three-piece wing. They consider attaching and removing the c/s is such a
>hassle that its normally left on and just the tips are removed when the
>Pirat is put in the hangar.
>

On the difficulty of assembling 3-piece wings. Dick Johnson's 2-times
US Nationals winning (1963,1964) Skylark 4 has been flying in our area
(TSA) for the past 25 years with the same owner. The Skylark has a
3-piece wing with a 200+ lbs center section. Dick fabricated a slick
1-man fixturing assembly for the center section that allows 1-person
to handle the lifting while a 2nd person only has to guild a wheeled
assembly on the other end. Takes about 5 minutes to put the ship
together, with heavy lifting (~100 lbs) on the part of only 1 person.

Bob

[JS]

From the latest edition of "The Onion":

JP STEWART FLYING A BOWLUS BABY ALBATROSS WINS THE POLISH STANDARD NATIONALS

Jim

[J. Nieuwenhuize]

Giving up things like automatic connections would be down right stupid.

What I'm proposing is something like the V2/ASG29. Once you move the wing up to a pylon and join the inner halves, there's a large reduction in parts. 4 less half root ribs, 2 less shear web fillers, 4 less spar bolt inserts, 2 controls less (only one for flap, one for spoilers), one spoiler less, two push-pull tubes for the spoilers less, more room for a mixer and on and on.

One of the more interesting features of a pylon wing is in fact it's (potential for) practicality. Do away with the one-men rigging aids and put a spring-loaded joint on the pylon. Pull the middle wing from the trailer while the other tip is still in it's dolly, cant horizontal and put it on the spring-loaded receptor. No need to have a one-man rigging aid if your glider has it built-in. Vary required tip lifting by moving the wing dolly inboard a bit.

The interesting thing about the pylon-mounted wing is that nobody I discussed it with (including some involved in last-generation factory ships) actually disliked the idea that it had potential in the end. Especially for monocoque wings (like the Diana), there's a lot to be gained.

@ Bob,

Most countries around here have two regimes:
*Original design. Basically meet CS22/23/VLA/MLA, including ultimate load testing (SF 1.75-2) for every single major load case plus most of the load analysis/theoretical compliance.
*A design flying abroad. If built as it's flown abroad (same engine/plane combo, no extra winglets or structural/aero things), you can build and fly it with relatively little trouble. Given the nightmare that an STC for FES/jet sustainer for existing (certified to CS22) gliders can be, the HP24 might have a lot of potential there.

[SparrowHawk08]

My uber slick all carbon R/C sailplane has a nice pylon with 3 piece wing. With the new materials and a clean design you get a foot+ more wing for the same span. May only be important if you have limited span, remember 15 meters? I've wondered for years why no sailplanes had a pylon. With lighter materials and automatic hookups I don't see a problem.

[Steve Leonard[_2_]]

On Thursday, February 6, 2014 2:49:37 PM UTC-6, J. Nieuwenhuize wrote:
> Giving up things like automatic connections would be down right stupid. What > I'm proposing is something like the V2/ASG29.

So, how big a span on that center section are you proposing? Roughly the same as the inner sections on a V2C/ASG29 assembled? That would be one pretty heavy wing section!

> Once you move the wing up to a pylon and join the inner halves, there's a
> large reduction in parts. 4 less half root ribs, 2 less shear web fillers, 4 > less spar bolt inserts, 2 controls less (only one for flap, one for
> spoilers), one spoiler less, two push-pull tubes for the spoilers less, more > room for a mixer and on and on.

So, you are proposing a single spoiler panel that extends a couple of feet either side of centerline? Keep in mind that the flaps move as ailerons on those planes, so if you go to one flap pushrod going into the center section, you will force the aileron mixers into the wing. And since you are doing that, you might as well just go with one aileron input into the center wing. That is how many three piece wing ships do it. As to the reduction in number of parts, you will have the ability to use fewer pushrods, but I am not so sure you will be able to do away with all the ribs and things to attach the wing to the fuselage (pins in the root ribs and spar bolt inserts are now replaced with fittings to attach the center section to the pylon, ribs for control bellcranks, etc). And if I am understanding your location for the spoiler, you are going to lose a LOT of room where those connections are going on.


> One of the more interesting features of a pylon wing is in fact it's
> (potential for) practicality. Do away with the one-men rigging aids and put a > spring-loaded joint on the pylon. Pull the middle wing from the trailer while > the other tip is still in it's dolly, cant horizontal and put it on the
> spring-loaded receptor. No need to have a one-man rigging aid if your glider > has it built-in. Vary required tip lifting by moving the wing dolly inboard a > bit.

You lost me on the spring loaded joint on the pylon. Also, depending on how long the center wing panel is, you may have to roll the fuselage a LOT further back so that when you get the center section out so the far tip is at the back of the trailer, the middle of it is now along side the pylon. And, since you have a pylon sticking up above the fuselage, you will now have to lift that center wing panel 5-6 feet into the air to get it over the fuselage.

> The interesting thing about the pylon-mounted wing is that nobody I discussed > it with (including some involved in last-generation factory ships) actually
> disliked the idea that it had potential in the end. Especially for monocoque > wings (like the Diana), there's a lot to be gained.

There have been many advances in understanding aerodynamics since that experimental Std Cirrus with the pylon mounted wing. Maybe there is a performance benefit to be had? But with the biggest emphasis seeming to be reduction of the wetted area for whatever class is being worked, I am doubtful that adding the wetted area of a pylon of the required height to reduce the wing root interference drag is the road to performance improvements.

Just my thoughts.

Steve Leonard

[Mike the Strike]

Wouldn't it be simpler just to get rid of the fuselage and put the cockpit and pilot in the wing?

[Soartech]

On Friday, February 7, 2014 12:03:40 AM UTC-5, Mike the Strike wrote:
> Wouldn't it be simpler just to get rid of the fuselage and put the cockpit and pilot in the wing?

Now you're talking like the Horten Brothers. It works, but because of the washout required, it's not quite as efficient.

http://www.twitt.org/Hoiv-03.jpg

[J. Nieuwenhuize]

Op vrijdag 7 februari 2014 05:06:49 UTC+1 schreef Steve Leonard:
> On Thursday, February 6, 2014 2:49:37 PM UTC-6, J. Nieuwenhuize wrote:
>
> > Giving up things like automatic connections would be down right stupid. What > I'm proposing is something like the V2/ASG29.
>
>
>
> So, how big a span on that center section are you proposing? Roughly the same as the inner sections on a V2C/ASG29 assembled? That would be one pretty heavy wing section!

That'd probably too large. Not so much for weight I'd think, taking out the spar stubs and all the other parts at the joint saves a lot of weight, but for trailerability. Something around 8 meters would make it fit in any trailer and also be around the optimal span for the flaps, avoiding complexity further.

> > Once you move the wing up to a pylon and join the inner halves, there's a
>
> > large reduction in parts. 4 less half root ribs, 2 less shear web fillers, 4 > less spar bolt inserts, 2 controls less (only one for flap, one for
>
> > spoilers), one spoiler less, two push-pull tubes for the spoilers less, more > room for a mixer and on and on.
>
> So, you are proposing a single spoiler panel that extends a couple of feet either side of centerline? Keep in mind that the flaps move as ailerons on those planes, so if you go to one flap pushrod going into the center section, you will force the aileron mixers into the wing.

Yep, one spoiler. Or just do away with spoilers all together and have a "crow feet" approach (flaps down, ailerons up). That only works with very narrow chords though, due to the actuation forces and requires a mixer as complex as Waibel's latest achievement.
Not sure whether flaps moving with aileron function add much in roll moment, so we could just as well ditch that and bank the simplification.

> And since you are doing that, you might as well just go with one aileron input into the center wing. That is how many three piece wing ships do it. As to the reduction in number of parts, you will have the ability to use fewer pushrods, but I am not so sure you will be able to do away with all the ribs and things to attach the wing to the fuselage (pins in the root ribs and spar bolt inserts are now replaced with fittings to attach the center section to the pylon, ribs for control bellcranks, etc). And if I am understanding your location for the spoiler, you are going to lose a LOT of room where those connections are going on.

You can use the space below the wing for the automatic connections (buried in the pylon once assembled), but packaging would certainly be a challenge.

> > One of the more interesting features of a pylon wing is in fact it's
>
> > (potential for) practicality. Do away with the one-men rigging aids and put a > spring-loaded joint on the pylon. Pull the middle wing from the trailer while > the other tip is still in it's dolly, cant horizontal and put it on the
>
> > spring-loaded receptor. No need to have a one-man rigging aid if your glider > has it built-in. Vary required tip lifting by moving the wing dolly inboard a > bit.
>
> You lost me on the spring loaded joint on the pylon. Also, depending on how long the center wing panel is, you may have to roll the fuselage a LOT further back so that when you get the center section out so the far tip is at the back of the trailer, the middle of it is now along side the pylon. And, since you have a pylon sticking up above the fuselage, you will now have to lift that center wing panel 5-6 feet into the air to get it over the fuselage.

The mid-wing would have a vertical hole in the bottom and the pylon a small pin sticking upwards, which has 20 or so degrees freedom to cant fwd/aft. The pin is spring-loaded, such that when you put enough force on it, it'll sink in the pylon. Have the wing dolly on one side such that you can cant the chord from vertical to horizontal. Pull out the wing, cant it horizontal, position mid wing above the pylon and let it rest on the pin. Disconnect wing dolly, rotate wing to spanwise, pull down at the center and lock the lifting pins.

An alternative is to mount the outer panels like the S10 folding system and hang the 3 assembled panels from the roof of the trailer. Save a mechanical/electric roof lift and some reinforcements, it solves all the usual issues of assembling a sailplane and you have the potential to put the sailplane on a dolly and fold the wing without any external tools or help for an overnight in a hangar.

> > The interesting thing about the pylon-mounted wing is that nobody I discussed > it with (including some involved in last-generation factory ships) actually
>
> > disliked the idea that it had potential in the end. Especially for monocoque > wings (like the Diana), there's a lot to be gained.
>
> There have been many advances in understanding aerodynamics since that experimental Std Cirrus with the pylon mounted wing. Maybe there is a performance benefit to be had? But with the biggest emphasis seeming to be reduction of the wetted area for whatever class is being worked, I am doubtful that adding the wetted area of a pylon of the required height to reduce the wing root interference drag is the road to performance improvements.

It's mostly about improving the extent of laminar flow on both the wing and the fuselage. There's a huge area of turbulent flow there, which (at least in theory) could be turned laminar. Bosman spoke about sucking off the LE of the wing/fuselage section, but just taking wing and fuselage apart could yield 1-2 sqm of flow that's laminar instead of turbulent.

> Just my thoughts.
Thanks for sharing. Some interesting points.

[Steve Leonard[_2_]]

On Saturday, February 8, 2014 6:09:11 AM UTC-6, J. Nieuwenhuize wrote:
> It's mostly about improving the extent of laminar flow on both the wing and the > fuselage. There's a huge area of turbulent flow there, which (at least in
> theory) could be turned laminar. Bosman spoke about sucking off the LE of the
> wing/fuselage section, but just taking wing and fuselage apart could yield 1-2 > sqm of flow that's laminar instead of turbulent.
> Thanks for sharing. Some interesting points.

But, to get those "1-2 sqm" of turbulent flow converted to laminar, you added almost that much area exposed to the flow. Some of which is still turbulent. Roughly 5 square feet of wing that was "hidden" in the fuselage is now exposed to air flow (2 feet spanwise, 30 inch chord). And, you have added a pylon that is something on the order of 24 to 30 inches tall, and probably more than 30 inches in chord. So, at best, another 5 square feet of wetted area of pylon. Probably more, because aerodynamically, you don't want max pylon width at the same chordwise location as max thickness on the wing.

Even if you can do it with a shorter pylon, it is still going to be difficult to get lower total drag with greater wetted area.

Steve

K

[John Firth[_4_]]

A wing 3 ft above the CG will give excessive roll stability; to
get an acceptable roll rate there will have to be substantial
anhedral. It will be at least look peculiar but there may be
other detractions.
I do not remember if the Slingsby T 21 was too stable
but that might be an attraction in a trainer.

John F



At 21:17 05 February 2014, Bob Kuykendall wrote:
>From the perspective of an inveterate pragmatist:
>
>I think it comes down to operationality. Yes, the autoconnects add
>complexi=
>ty. Yes, placing the wing panel separation at the station of maximum
>bendin=
>g moment adds weight.=20
>
>But what you get in return is a system of parts that allows for easy
>storag=
>e and transport, rapid assembly, and high reliability. That system has
>been=
> proven to result in good soaring performance at the lowest possible cost
>i=
>n terms of operator fatigue. And that makes for a more enjoyable soaring
>ex=
>perience. And when it comes down to it, quality of experience is what we
>sh=
>ould be trying to maximize here, not necessarily quality of performance.
>
>It is easy to conceive of this or that adaptation that might result in
>grea=
>ter performance for a no-holds-barred competition machine. However, all
>too=
> often the result is a less robust machine that requires more work to
>assem=
>ble and prepare for operation. That's great if all you want to do is win
>pr=
>estigious contests and are prepared to either do or pay for the extra
work
>=
>required to campaign such an aircraft. It's less great for everyone else,
>a=
>nd especially for those who buy such aircraft on the used market and find
>o=
>ut what a pain it can be.
>
>Thanks, Bob K.
>https://www.facebook.com/pages/HP-24-Sailplane-Project/200931354951
>
>On Wednesday, February 5, 2014 1:29:19 AM UTC-8, J. Nieuwenhuize wrote:
>> Op dinsdag 4 februari 2014 22:53:33 UTC+1 schreef :
>>=20
>> > 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.
>>=20
>> I would expect the exact opposite. Looking at all the parts, easily a
>qua=
>rter of all the parts of a normal 15M sailplane are in the wing-fuselage
>in=
>tersection and the spar roots are a pretty beefy (and heavy) part since
>you=
> have a joint at the highest loaded part of the whole structure. I don't
>ha=
>ve a weight breakdown at hand, but some earlier number-crunching yielded
>ar=
>ound 15 kg weight saved by carrying on the wing (and have 2 lighter
joints
>=
>outboard)
>>=20
>> All those automatic connections add a lot of complexity and weight too
>an=
>d you can reduce their number by half. Not to mention spoilers (drag
>brakes=
>) that can be in the middle of the wing since you're outside the
fuselages
>=
>"blocked zone" reducing the number of parts further.
>>=20
>>=20
>>=20
>> > One of the interesting things about glider design is that, even for
>ope=
>n class, it's not really a free for all. The design has to comply with
>nati=
>onal 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
>in=
>to consideration even when you're trying to make a world championship
>conte=
>nder.
>>=20
>>=20
>>=20
>> An excellent point. Yet, not certifying and having a homebuilt,
>developme=
>nt cost could be drastically less, though it'd still be wise to meet
every
>=
>requirement from CS22. Save France, to the best of my knowledge you can
>fly=
> homebuilt sailplanes in most soaring-minded countries.
>>=20
>>=20
>>=20
>> > One. You need a fair pylon height to avoid interference drag in the
>gap=
>=20
>>=20
>> > between the top of the fuselage and the wing's lower surface. I'd
say=
>=20
>>=20
>> > interference drag is relatively high on the Sunseeker shown here:
>>=20
>> >=20
>>=20
>> > http://www.solar-flight.com/
>>=20
>> >=20
>>=20
>> > However I'm not an aerodynamics expert and have no idea what the
>optimu=
>m=20
>>=20
>> > height sound be except that its unlikely to be less than 10-15% of
the=
>=20
>>=20
>> > wing chord, think of the Wien for this pylon height, and that its
one=
>=20
>>=20
>> > problem the Ku-4 Austria didn't suffer from.
>>=20
>> >=20
>>=20
>> > martin@ | Martin Gregorie
>>=20
>> > gregorie. | Essex, UK
>>=20
>> > org |
>>=20
>>=20
>>=20
>> A bit of number-crunching suggests something like 0.5-1 root chord, so
>1-=
>2 feet for a typical single-seater.
>
>

[John Firth[_4_]]

Helpers add complexity and management problems; the minimum
number to handle the weight is usually optimum.

I was owner of 1/4 of a Skylark III for a year; not sure which piece
but it could have been the C.S. Midweek flying meant
being shorthanded but I managed to rig it without hassle
with a (strong) gilrfriend.
1. Remove the fuselage and support in a H steady.
2. remove the CS ( wheels at the inside end in the trailer.
3.lift one end onto a suitable support.
4. lift the other end high enough for the girl friend to wheel
the fuselage under the CS, and roll it a bit to align the
lift fittings with the holes. Insert the long pins.

At 28 I was fit but not especially strong, but 1/2 the CS was manageable,
briefly. We never broke anything, the glider or me.

John F



At 02:08 06 February 2014, Martin Gregorie wrote:
>On Wed, 05 Feb 2014 13:17:35 -0800, Bob Kuykendall wrote:
>
>> From the perspective of an inveterate pragmatist:
>>
>> I think it comes down to operationality. Yes, the autoconnects add
>> complexity. Yes, placing the wing panel separation at the station of
>> maximum bending moment adds weight.
>>
>> But what you get in return is a system of parts that allows for easy
>> storage and transport, rapid assembly, and high reliability. That
system
>> has been proven to result in good soaring performance at the lowest
>> possible cost in terms of operator fatigue. And that makes for a more
>> enjoyable soaring experience. And when it comes down to it, quality of
>> experience is what we should be trying to maximize here, not
necessarily
>> quality of performance.
>>
>Good point.
>
>I've helped rig one of the Slingsbys which had a three piece wing.
>Getting the C/s on was quite a hassle. While it can be done by three
>people, having five on the job makes it a lot easier. The problem is that

>you have to lift the wing quite high to clear the fuselage and keep it up

>while the odd-numbered man attaches the wing to the fuselage. Putting the

>tips on is easy but that doen't matter compared with handling the c/s.
>
>One of the local clubs where I fly gas an SZD Pirat, which has a 15m
>three-piece wing. They consider attaching and removing the c/s is such a
>hassle that its normally left on and just the tips are removed when the
>Pirat is put in the hangar.
>
>
>--
>martin@ | Martin Gregorie
>gregorie. | Essex, UK
>org |
>

[[email protected]]

Pat Beatty and Fritz Johl designed a number of sailplanes in South Africa in the 1960s-80s. They tried the pylon mounted wing with their BJ-5.

http://avcom.co.za/phpBB3/viewtopic.php?f=1&t=15852&start=15

There is a pic of the BJ-5 in the link. They reverted back to a high-shoulder mounted wing for later designs.

Clinton

[Soartech]

On Sunday, February 9, 2014 10:03:36 AM UTC-5, firsys wrote:
> A wing 3 ft above the CG will give excessive roll stability; to
>
> get an acceptable roll rate there will have to be substantial
>
> anhedral. It will be at least look peculiar but there may be
>
> other detractions.

Wings with anhedral have been shown to be more efficient (L/D) than straight wings. I can looks up the study if anyone needs to know more.
This may be the reason paragliders perform as well as they do despite large amounts of drag.

[[email protected]]

On Tuesday, February 11, 2014 12:56:19 PM UTC-5, Soartech wrote:
> On Sunday, February 9, 2014 10:03:36 AM UTC-5, firsys wrote: > A wing 3 ft above the CG will give excessive roll stability; to > > get an acceptable roll rate there will have to be substantial > > anhedral. It will be at least look peculiar but there may be > > other detractions. Wings with anhedral have been shown to be more efficient (L/D) than straight wings. I can looks up the study if anyone needs to know more. This may be the reason paragliders perform as well as they do despite large amounts of drag.

Given the trend in sailplanes toward multiple dihedral breaks toward the tip, and the associated benefit of spreading the flow field spanwise, it seems that your statement is based upon dated knowledge. Or possible it applies in some cases and not others.
UH

[J. Nieuwenhuize]

Op zondag 9 februari 2014 06:48:59 UTC+1 schreef Steve Leonard:
>
> But, to get those "1-2 sqm" of turbulent flow converted to laminar, you added almost that much area exposed to the flow. Some of which is still turbulent. Roughly 5 square feet of wing that was "hidden" in the fuselage is now exposed to air flow (2 feet spanwise, 30 inch chord). And, you have added a pylon that is something on the order of 24 to 30 inches tall, and probably more than 30 inches in chord. So, at best, another 5 square feet of wetted area of pylon. Probably more, because aerodynamically, you don't want max pylon width at the same chordwise location as max thickness on the wing.
>
> Even if you can do it with a shorter pylon, it is still going to be difficult to get lower total drag with greater wetted area.
>
> Steve
>
> K



It sure would be difficult, but the odds seem favorable. While you increase wetted area, the drag coefficient of that area (and the original area) goes down by a factor of something like 5 if you can get it laminar.
There are some other details at work; you gain lift, since now the wing is actually lifting (no dip in the spanwise lift distribution anymore), so you can actually shrink the wing area with a significant part of the wetted area increase. The pylon could be rather small, for a modern super-elliptic area distribution (winglets), we now need a root chord of something like 24".. Given the fairly low forces on the pylon (save yaw, groundloop), the pylon could be a lot smaller in chord and thickness.


I don't buy the point about anhedral. Many (ballasted) bigger ships have half of their weight in the wing, so we're talking about a 10" raise of the C of G or so. For many open-class ships, that's the difference between 1 and 1.5 G's (steep thermalling).

Bruce Carmichael seems to be the only one that has seriously pursued the idea of laminar-flow pylon wings. Time to win the lottery and start running a wind tunnel.

Thanks for the link to the BJ5 Clinton. Have been chasing pictures of that design for years.

[Steve Leonard[_2_]]

On Tuesday, February 11, 2014 11:56:19 AM UTC-6, Soartech wrote:
> Wings with anhedral have been shown to be more efficient (L/D) than straight
> wings. I can looks up the study if anyone needs to know more. This may be the
> reason paragliders perform as well as they do despite large amounts of drag.

Please do. Might be amusing.

On Tuesday, February 11, 2014 12:15:43 PM UTC-6, wrote:
>...Or possible it applies in some cases and not others.

Think you will find paragliders do have large drag, but such low speed as to make the horsepower consumed small. Think Paul MacCready and the Gossamer series of man powered planes. Most previous were cantilever, but he put wires out all over the place. Why? Lighter structure = lower flying speed = lower horsepower required. Horsepower is a cubic function of speed. Cut the flying speed in half, cut the horsepower to 1/8th. So you can afford a little higher drag if you knock the speed way down. Man powered flight is horespower limited. So is paraglider flight. They don't have to make much lift, and at low speed, all the risers don't make too much drag. Not much horsepower available from the low weight, either, so not much speed range.

On Tuesday, February 11, 2014 4:24:53 PM UTC-6, J. Nieuwenhuize wrote:
> There are some other details at work; you gain lift, since now the wing is
> actually lifting (no dip in the spanwise lift distribution anymore), so you
> can actually shrink the wing area with a significant part of the wetted area > increase.

Well, there is still a dip in the lift distribution. It is caused by the horizontal tail. If, of course, we are talking complete system, and not just wing. There is still a negative effect from the fuselage, but not NEARLY as big

On Tuesday, February 11, 2014 4:24:53 PM UTC-6, J. Nieuwenhuize wrote:
> The pylon could be rather small, for a modern super-elliptic area
> distribution (winglets), we now need a root chord of something like 24".
> Given the fairly low forces on the pylon (save yaw, groundloop), the pylon
> could be a lot smaller in chord and thickness.

The smaller you make the pylon and closer you get the load reacting points together, the higher the loads go. And, if you make the pylon too small, you lost all your volume for control connections. :-) Also, check the root chord on the AS-W27, V2, or even the Diana or Duckhawk. Think they are still 27 to 30 inches.

I also am not ready to buy into the need for anhedral for roll control if you have a pylon mounted wing. Weight of the wings, plus all the water carried in the wings, tends to make the fusleage and pilot a much smaller percentage of the mass of the flying machine. So, the center of mass is not starting as close to on the axis of the fuselage as you might think. What? The world doesn't revolve around the pilot? :-)

Good thoughts. Keep them coming.

Steve

[Dan Marotta]

Hey Steve,

The McDonnell XF-85 Goblin (
http://en.wikipedia.org/wiki/McDonnell_XF-85_Goblin ) had winglets *and*
anhedral (in the tail). Do you think it was much of a glider?

Coming to Moriarty this year?

"Steve Leonard" > wrote in message
...
On Tuesday, February 11, 2014 11:56:19 AM UTC-6, Soartech wrote:
> Wings with anhedral have been shown to be more efficient (L/D) than
> straight
> wings. I can looks up the study if anyone needs to know more. This may be
> the
> reason paragliders perform as well as they do despite large amounts of
> drag.

Please do. Might be amusing.

On Tuesday, February 11, 2014 12:15:43 PM UTC-6,
wrote:
>...Or possible it applies in some cases and not others.

Think you will find paragliders do have large drag, but such low speed as to
make the horsepower consumed small. Think Paul MacCready and the Gossamer
series of man powered planes. Most previous were cantilever, but he put
wires out all over the place. Why? Lighter structure = lower flying speed
= lower horsepower required. Horsepower is a cubic function of speed. Cut
the flying speed in half, cut the horsepower to 1/8th. So you can afford a
little higher drag if you knock the speed way down. Man powered flight is
horespower limited. So is paraglider flight. They don't have to make much
lift, and at low speed, all the risers don't make too much drag. Not much
horsepower available from the low weight, either, so not much speed range.

On Tuesday, February 11, 2014 4:24:53 PM UTC-6, J. Nieuwenhuize wrote:
> There are some other details at work; you gain lift, since now the wing is
> actually lifting (no dip in the spanwise lift distribution anymore), so
> you
> can actually shrink the wing area with a significant part of the wetted
> area > increase.

Well, there is still a dip in the lift distribution. It is caused by the
horizontal tail. If, of course, we are talking complete system, and not
just wing. There is still a negative effect from the fuselage, but not
NEARLY as big

On Tuesday, February 11, 2014 4:24:53 PM UTC-6, J. Nieuwenhuize wrote:
> The pylon could be rather small, for a modern super-elliptic area
> distribution (winglets), we now need a root chord of something like 24".
> Given the fairly low forces on the pylon (save yaw, groundloop), the pylon
> could be a lot smaller in chord and thickness.

The smaller you make the pylon and closer you get the load reacting points
together, the higher the loads go. And, if you make the pylon too small,
you lost all your volume for control connections. :-) Also, check the root
chord on the AS-W27, V2, or even the Diana or Duckhawk. Think they are
still 27 to 30 inches.

I also am not ready to buy into the need for anhedral for roll control if
you have a pylon mounted wing. Weight of the wings, plus all the water
carried in the wings, tends to make the fusleage and pilot a much smaller
percentage of the mass of the flying machine. So, the center of mass is not
starting as close to on the axis of the fuselage as you might think. What?
The world doesn't revolve around the pilot? :-)

Good thoughts. Keep them coming.

Steve

[J. Nieuwenhuize]

Op woensdag 12 februari 2014 01:12:40 UTC+1 schreef Steve Leonard:
> On Tuesday, February 11, 2014 4:24:53 PM UTC-6, J. Nieuwenhuize wrote:
> > The pylon could be rather small, for a modern super-elliptic area
> > distribution (winglets), we now need a root chord of something like 24"..
> > Given the fairly low forces on the pylon (save yaw, groundloop), the pylon
> > could be a lot smaller in chord and thickness.
>
> The smaller you make the pylon and closer you get the load reacting points together, the higher the loads go. And, if you make the pylon too small, you lost all your volume for control connections. :-) Also, check the root chord on the AS-W27, V2, or even the Diana or Duckhawk. Think they are still 27 to 30 inches.

I might have been too optimistic there with the root chord. Nevertheless I do expect the "next generation" to have narrower root chords, the modern super-elliptic planforms made possible by optimized winglets/polyhedral result in an almost untapered inner part of the wing.

I wouldn't worry too much about the loads on the pylon. Those are pretty small as compared to the wing. Packaging of the controls might be the major issue, though even there, there's some "unconquered terrain", see the Concordia control system. Having the flap/aileron mixer at the mid/outer wing joint could be a solution.


Here is some more in-depth discussion on pylon-mounted (sailplane) wings by the same author as your truly ;-)

http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/15371-reduction-interference-drag-laminar-airframe-pylon-wing.html

[John Firth[_4_]]

The kicker here is the torsional load on the pylon from a ground
loop or possibly a spin plus recovery. Even if a carbon fibre
tube could approach the torsional rigidity/strength of a standard
fore/aft pin attachment in the fuselage, the structure needed
to distribute the pylon loads into the wing may be compicated.
But I am willing to be proved wrong.
John F

At 00:12 12 February 2014, Steve Leonard wrote:
>On Tuesday, February 11, 2014 11:56:19 AM UTC-6, Soartech wrote:
>> Wings with anhedral have been shown to be more efficient (L/D) than
>strai=
>ght=20
>> wings. I can looks up the study if anyone needs to know more. This may
>be=
> the=20
>> reason paragliders perform as well as they do despite large amounts of
>dr=
>ag.
>
>Please do. Might be amusing.
>
>On Tuesday, February 11, 2014 12:15:43 PM UTC-6,
>wrot=
>e:
>>...Or possible it applies in some cases and not others.=20
>
>Think you will find paragliders do have large drag, but such low speed as
>t=
>o make the horsepower consumed small. Think Paul MacCready and the
>Gossame=
>r series of man powered planes. Most previous were cantilever, but he
put
>=
>wires out all over the place. Why? Lighter structure =3D lower flying
>spe=
>ed =3D lower horsepower required. Horsepower is a cubic function of
>speed.=
> Cut the flying speed in half, cut the horsepower to 1/8th. So you can
>af=
>ford a little higher drag if you knock the speed way down. Man powered
>fli=
>ght is horespower limited. So is paraglider flight. They don't have to
>ma=
>ke much lift, and at low speed, all the risers don't make too much drag.
>N=
>ot much horsepower available from the low weight, either, so not much
>speed=
> range.
>
>On Tuesday, February 11, 2014 4:24:53 PM UTC-6, J. Nieuwenhuize wrote:
>> There are some other details at work; you gain lift, since now the wing
>i=
>s=20
>> actually lifting (no dip in the spanwise lift distribution anymore), so
>y=
>ou=20
>> can actually shrink the wing area with a significant part of the wetted
>a=
>rea > increase.
>
>Well, there is still a dip in the lift distribution. It is caused by the
>h=
>orizontal tail. If, of course, we are talking complete system, and not
>jus=
>t wing. There is still a negative effect from the fuselage, but not
>NEARLY=
> as big
>
>On Tuesday, February 11, 2014 4:24:53 PM UTC-6, J. Nieuwenhuize wrote:
>> The pylon could be rather small, for a modern super-elliptic area=20
>> distribution (winglets), we now need a root chord of something like
24".
>> Given the fairly low forces on the pylon (save yaw, groundloop), the
>pylo=
>n
>> could be a lot smaller in chord and thickness.
>
>The smaller you make the pylon and closer you get the load reacting
points
>=
>together, the higher the loads go. And, if you make the pylon too small,
>y=
>ou lost all your volume for control connections. :-) Also, check the
>root=
> chord on the AS-W27, V2, or even the Diana or Duckhawk. Think they are
>st=
>ill 27 to 30 inches.
>
>I also am not ready to buy into the need for anhedral for roll control if
>y=
>ou have a pylon mounted wing. Weight of the wings, plus all the water
>carr=
>ied in the wings, tends to make the fusleage and pilot a much smaller
>perce=
>ntage of the mass of the flying machine. So, the center of mass is not
>sta=
>rting as close to on the axis of the fuselage as you might think. What?
>T=
>he world doesn't revolve around the pilot? :-)
>
>Good thoughts. Keep them coming.
>
>Steve
>

[J. Nieuwenhuize]

Op zondag 16 februari 2014 18:16:26 UTC+1 schreef firsys:

The kicker here is the torsional load on the pylon from a ground
loop or possibly a spin plus recovery. Even if a carbon fibre
tube could approach the torsional rigidity/strength of a standard
fore/aft pin attachment in the fuselage, the structure needed
to distribute the pylon loads into the wing may be compicated.
But I am willing to be proved wrong.
John F


I doubt that's nearly as much of a factor as many think.

Ground loop loads, at least from the regulatory point are not that high. 400N, so about 70 kgf (155 lbsf) ultimate load at the extremity of tip, balanced by an opposite load on the tail wheel. (CS22-5?? from memory). Same for spin recovery loads; those are nowhere near as high as rudder deflection @ Va, which is likely the limiting load case for the pylon.

As for the wing structure; mounting the pylon in yaw is pretty trivial. You're simply loading the skin in pure shear, which is about the easiest connection possible. The pylon load and mounting it to the fuselage skin are the biggie, but nothing a few layers of carbon won't solve. Less certain about flutter, but then most of the modes that involve yaw have much lower inertia (sideways boom bending/torsion), 2-3 orders of magnitude less inertia as a fully ballasted wing.

Kingfisher and plncraze came up with this thesis on http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/15371-reduction-interference-drag-laminar-airframe-pylon-wing.html

MANDATORY reading for anybody that thinks this is interesting. Not 1:1 applicable to full-scale sailplanes, but a most interesting read wrt pylon wings:
http://drum.lib.umd.edu/bitstream/1903/8141/1/umi-umd-5315.pdf

Also this article by Johan Bosman has some interesting remarks about moving the wing up (article on the end of the page):
http://www.glidinginternational.com/GlidingInternational.com/Special_Leading_Stories.html

[[email protected]]

At the worlds in 2010, Prof Boermans gave an interesting talk on wing-fuselage drag, suggesting that moving the wing to the top of the fuselage -- not shoulder, and not pylon -- could reduce drag. An article in gliding international followed up with some analysis from Jonkers suggesting they are going to implement the idea at some point soon. Not pylons, but higher mounted wings may be on their way.

john cochrane