Pylon mounted wings superior?

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.

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

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

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

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.

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

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 |