Pylon mounted wings superior?

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 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
org |

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

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....

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...t/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 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

org |



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

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.

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 |

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

From the latest edition of "The Onion":

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

Jim

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.

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.

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