Asymmetric wing DLG

Cuddles · Mar 02, 2004, 05:53 AM

Hi all
I’ve read about an “Asymmetric wing DLG” in the October number of Thermal talk and I think it’s a stunning solution.

“By far the most interesting poly at the event was the one flown by Bill Watson. Just when you thought you have seen everything something drastically different comes along. There are very few things in aviation that are asymmetrical but Bill has come up with another. If you look at the photos below, his plane just looks wrong or possibly that there is a distortion in the photo. I can assure you the photo is correct. The first instinct is to say that thing won't work. Well many can attest that it does, and it works quite well. One side of the wing has a wider chord and shorter span while the other side has exactly the opposite. The reason for this is that Bill has offset the fuselage towards the outside of the launch circle to gain more inertia. Unfortunately, I was unable to get the exact specs but I did speak with Bill and he said he made it just to test the idea and did not have plans to fly it in the contest. It flew so well that he managed to make the top ten fly off flying this oddity for the majority of the rounds.”

But in those 5 months I haven’t seed a thread in this forum in wich this solution has been even mentioned .Why?
Maybe it’s just me and Mr Watson that think this solution is good!
Since I would like to adopt this solution for my first scratchbuilt SAL I would like to have some feedback.
Thanx in advance and best regards to you all.
Cuddles

Cuddles · Mar 02, 2004, 11:33 AM

Maybe just because it's ugly?

Radian · Mar 02, 2004, 01:20 PM

Pictures and links to this plane would help us to comment.

Radian

John Gallagher · Mar 02, 2004, 09:07 PM

Bill Watson's plane is not the first Asymmetrical dlg flown in competition. Breck Baldwin is a very well known dlg pilot on the east coast. In 2001, he competed with what he affectionatly called the 'three legged dog', including the BASS event. Here's a link to a few photos of his dlg.

http://www.sjsf.org/hlg901.htm

Cuddles · Mar 03, 2004, 05:55 AM

Oh my gosh

This is a three legged bastard!!!
Simply wonderful

Thank you very very much John.Iwould like to know some specs and all the theory that is inside this system.
Best regards
Cuddles

Bill Mixon · Mar 03, 2004, 09:33 PM

So.. Where is the picture of the Bill Watson design?

Bill

jcstalls · Mar 04, 2004, 12:47 AM

Greetings,

Simple search, reveals much.

Jared

Bill Mixon · Mar 04, 2004, 09:48 AM

I've seen that picture and one other with one panel of the wing not totally in the picture. The picture above is from the side, and therefore doesn't show the planform very well. I thought he might have a better picture showing it from the top.
Notice he said look at the pictures below.. But he didn't put a picture...

A design like this will not fly the same at all speeds, so I can't see where the benifit in weight offset will make up for the difference.

Bill

John Gallagher · Mar 04, 2004, 10:18 AM

The three legged dog was heavy. Bill's rendition looks lighter.

There are two questions that need to be answered.
Does the design really give higher launches?
Does the design fly as well as conventional dlg's, including glide, penetration, and thermalling?

John

Cuddles · Mar 04, 2004, 11:35 AM

Good questions,John!
Who will answer?(certainly not me

)
But let's keep in mind that my model will be 1 meter span(for transportation).Weight offset had lured me into this solution:
Bill,why you say"A design like this will not fly the same at all speeds"?I can't understand this

.
Best regards
Cuddles

greg morrison · Mar 04, 2004, 12:20 PM

It won't ever fly as well as a flapped dlg with an airfoil optimized for the use of camber/reflex depending on flight conditions. These asymmetric models are the same as any other conventional poly ship in the sense that they have a fixed airfoil that is the designers best compromise for all flight conditions. I enjoy poly ships of all types but they are at a disadvantage to flapped models which can reflexed for launch and upwind penetration and cambered for minimum sink when working lift.

Greg

Bill Mixon · Mar 04, 2004, 03:33 PM

Quote:

Does the design really give higher launches?

I can see where the mass offset would give higher launches, but the offset on the Watson plane appears to be small. I'd guess a few more feet maybe in launch height. But as Greg mentioned it's not going to be very efficient in the air so the extra height wouldn't really matter.

Quote:

Bill,why you say"A design like this will not fly the same at all speeds"?I can't understand this

Look at the lift / drag properties of a low aspect ratio wing vs those of a high aspect ratio. The outer panel of the three legged dog would perform poorly compared to the inner high aspect ratio panel. You can do the calculations and come up with various airfoils and get it as close as possible for best glide, but it will never be "right".

Bill

Cuddles · Mar 05, 2004, 04:06 AM

Oh...

So this system is useless...

Thanks for the explanation.

ybanrab · Mar 05, 2004, 06:19 AM

Not that I think it would be worth doing, but just as an idea, could you make the mount between wing and fuse slide? For example, if you had forward and aft wing bolts and allow the mounts to slide on runners, but spring the mounts back to centre. On launch the fuse would slide out under centripetal force, giving you the extra inertia but as soon as the plane is released the spring would return the fuse to central. This would allow you to use a normal wing but possibly get the advantages of moving the fuselage mass outwards on launch. I've very little idea how badly the aerodynamics of an offset fuse would mess things up on launch and I suspect the system would be far too fiddly and heavy to implement at the sizes that DLG's operate at, but I thought I'd mention it...

Barny

greg morrison · Mar 05, 2004, 12:16 PM

Cuddles:

I don't think anyone here has said that the idea is useless. For my part I simply said that it won't outperform a flapped glider throughout a range of potential flying conditions. If you have the interest and inclination to build a hand launch with an asymmetric wing go right ahead. I'm sure that everyone will be interested in your results.

Greg

Mar 02, 2004, 05:53 AM	#1
Cuddles Be afraid! Join Date: Dec 2003 Location: Milano Posts: 345	Asymmetric wing DLG Hi all I’ve read about an “Asymmetric wing DLG” in the October number of Thermal talk and I think it’s a stunning solution. “By far the most interesting poly at the event was the one flown by Bill Watson. Just when you thought you have seen everything something drastically different comes along. There are very few things in aviation that are asymmetrical but Bill has come up with another. If you look at the photos below, his plane just looks wrong or possibly that there is a distortion in the photo. I can assure you the photo is correct. The first instinct is to say that thing won't work. Well many can attest that it does, and it works quite well. One side of the wing has a wider chord and shorter span while the other side has exactly the opposite. The reason for this is that Bill has offset the fuselage towards the outside of the launch circle to gain more inertia. Unfortunately, I was unable to get the exact specs but I did speak with Bill and he said he made it just to test the idea and did not have plans to fly it in the contest. It flew so well that he managed to make the top ten fly off flying this oddity for the majority of the rounds.” But in those 5 months I haven’t seed a thread in this forum in wich this solution has been even mentioned .Why? Maybe it’s just me and Mr Watson that think this solution is good! Since I would like to adopt this solution for my first scratchbuilt SAL I would like to have some feedback. Thanx in advance and best regards to you all. Cuddles

Mar 02, 2004, 01:20 PM	#3
Radian Pompano Hill Flyers Join Date: May 2002 Location: Coconut Creek FL Posts: 471	Need pics or links Pictures and links to this plane would help us to comment. Radian

Mar 02, 2004, 09:07 PM	#4
John Gallagher Registered User Join Date: Dec 2000 Location: Lindenwold, NJ, USA Posts: 2,485	Bill Watson's plane is not the first Asymmetrical dlg flown in competition. Breck Baldwin is a very well known dlg pilot on the east coast. In 2001, he competed with what he affectionatly called the 'three legged dog', including the BASS event. Here's a link to a few photos of his dlg. http://www.sjsf.org/hlg901.htm Last edited by John Gallagher; Mar 02, 2004 at 09:20 PM.

Mar 04, 2004, 12:47 AM	#7
jcstalls Dragons, Windmills. All Same. Join Date: May 2002 Location: Lawrence, IN Posts: 1,586	Greetings, Simple search, reveals much. Jared Attached Thumbnails 39.3 KB · Views: 802

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Mar 02, 2004, 11:33 AM	#2
Cuddles Be afraid! Join Date: Dec 2003 Location: Milano Posts: 345	Maybe just because it's ugly?

Mar 03, 2004, 05:55 AM	#5
Cuddles Be afraid! Join Date: Dec 2003 Location: Milano Posts: 345	Oh my gosh This is a three legged bastard!!! Simply wonderful Thank you very very much John.Iwould like to know some specs and all the theory that is inside this system. Best regards Cuddles

Mar 03, 2004, 09:33 PM	#6
Bill Mixon Registered User Join Date: Mar 2002 Location: Georgia Posts: 1,678	So.. Where is the picture of the Bill Watson design? Bill

Mar 04, 2004, 09:48 AM	#8
Bill Mixon Registered User Join Date: Mar 2002 Location: Georgia Posts: 1,678	I've seen that picture and one other with one panel of the wing not totally in the picture. The picture above is from the side, and therefore doesn't show the planform very well. I thought he might have a better picture showing it from the top. Notice he said look at the pictures below.. But he didn't put a picture... A design like this will not fly the same at all speeds, so I can't see where the benifit in weight offset will make up for the difference. Bill

Mar 04, 2004, 10:18 AM	#9
John Gallagher Registered User Join Date: Dec 2000 Location: Lindenwold, NJ, USA Posts: 2,485	The three legged dog was heavy. Bill's rendition looks lighter. There are two questions that need to be answered. Does the design really give higher launches? Does the design fly as well as conventional dlg's, including glide, penetration, and thermalling? John

Mar 04, 2004, 11:35 AM	#10
Cuddles Be afraid! Join Date: Dec 2003 Location: Milano Posts: 345	Good questions,John! Who will answer?(certainly not me ) But let's keep in mind that my model will be 1 meter span(for transportation).Weight offset had lured me into this solution: Bill,why you say"A design like this will not fly the same at all speeds"?I can't understand this . Best regards Cuddles

Mar 04, 2004, 12:20 PM	#11
greg morrison Registered User Join Date: Jul 2000 Location: San Francisco Posts: 980	It won't ever fly as well as a flapped dlg with an airfoil optimized for the use of camber/reflex depending on flight conditions. These asymmetric models are the same as any other conventional poly ship in the sense that they have a fixed airfoil that is the designers best compromise for all flight conditions. I enjoy poly ships of all types but they are at a disadvantage to flapped models which can reflexed for launch and upwind penetration and cambered for minimum sink when working lift. Greg

Mar 05, 2004, 04:06 AM	#13
Cuddles Be afraid! Join Date: Dec 2003 Location: Milano Posts: 345	Oh... So this system is useless... Thanks for the explanation.

Mar 05, 2004, 06:19 AM	#14
ybanrab Registered User Join Date: Dec 1996 Location: Teddington, UK Posts: 275	Not that I think it would be worth doing, but just as an idea, could you make the mount between wing and fuse slide? For example, if you had forward and aft wing bolts and allow the mounts to slide on runners, but spring the mounts back to centre. On launch the fuse would slide out under centripetal force, giving you the extra inertia but as soon as the plane is released the spring would return the fuse to central. This would allow you to use a normal wing but possibly get the advantages of moving the fuselage mass outwards on launch. I've very little idea how badly the aerodynamics of an offset fuse would mess things up on launch and I suspect the system would be far too fiddly and heavy to implement at the sizes that DLG's operate at, but I thought I'd mention it... Barny

Mar 05, 2004, 12:16 PM	#15
greg morrison Registered User Join Date: Jul 2000 Location: San Francisco Posts: 980	Cuddles: I don't think anyone here has said that the idea is useless. For my part I simply said that it won't outperform a flapped glider throughout a range of potential flying conditions. If you have the interest and inclination to build a hand launch with an asymmetric wing go right ahead. I'm sure that everyone will be interested in your results. Greg