Pylon mounted wings superior?

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

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.