If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
|
Thread Tools | Display Modes |
|
#1
|
|||
|
|||
Wing root fairings
I have noticed that several articles on glider performance refer to
adding/modifying the wing root to get better performance. Can anyone refer me to further info on wing root fairing design and or mods to improve performance. Cheers, Don |
#2
|
|||
|
|||
What type of glider?
At 15:18 27 October 2003, D.A.L wrote: I have noticed that several articles on glider performance refer to adding/modifying the wing root to get better performance. Can anyone refer me to further info on wing root fairing design and or mods to improve performance. Cheers, Don |
#3
|
|||
|
|||
Earlier, D.A.L wrote:
I have noticed that several articles on glider performance refer to adding/modifying the wing root to get better performance. Can anyone refer me to further info on wing root fairing design and or mods to improve performance. Wing fuselage junction fillets are often a pretty troublesome aspect of glider design. The way I understand it, they are usually developed either empirically, using tuft testing, or using lots of CFD computing horsepower. On the other hand, it seems to be one of those aspects where you get some points just for trying. Dick Schreder developed the HP-18 side-of-body junction by eye, and seemed to have gotten it pretty close on the first try. The only thing I would have done differently would be to adjust the fillet trailing edge slightly so that it lines up at the -5 flap setting instead of 0. There are some references in Thomas' _Fundamentals of Sailplane Design_, but the book itself is pretty skimpy regarding developing junction fillets for existing sailplanes. Small radii near the leading edge, big radius at the bac, that sort of thing. One of the cites in Thomas is to a study by Mark Maughmer at Penn State. If you can get in touch with him, he might be able to give you some reasonable guidelines. Another cite is to Dick Johnson's 1979 compendium of flight test articles; you can get most of those off of the SSA Web server. Bob K. http://www.hpaircraft.com/hp-24 |
#4
|
|||
|
|||
Bob Kuykendall wrote in message ...
Earlier, D.A.L wrote: I have noticed that several articles on glider performance refer to adding/modifying the wing root to get better performance. Can anyone refer me to further info on wing root fairing design and or mods to improve performance. Wing fuselage junction fillets are often a pretty troublesome aspect of glider design. The way I understand it, they are usually developed either empirically, using tuft testing, or using lots of CFD computing horsepower. On the other hand, it seems to be one of those aspects where you get some points just for trying. Dick Schreder developed the HP-18 side-of-body junction by eye, and seemed to have gotten it pretty close on the first try. The only thing I would have done differently would be to adjust the fillet trailing edge slightly so that it lines up at the -5 flap setting instead of 0. There are some references in Thomas' _Fundamentals of Sailplane Design_, but the book itself is pretty skimpy regarding developing junction fillets for existing sailplanes. Small radii near the leading edge, big radius at the bac, that sort of thing. One of the cites in Thomas is to a study by Mark Maughmer at Penn State. If you can get in touch with him, he might be able to give you some reasonable guidelines. Another cite is to Dick Johnson's 1979 compendium of flight test articles; you can get most of those off of the SSA Web server. Bob K. http://www.hpaircraft.com/hp-24 ************************************************** ****************************** For the sake of the discussion, why have an upper wing root fillet at all? The Caproni A 21 wing blends into the top of the fuselage. What are the advantages/disadvantages to this type of design? |
#5
|
|||
|
|||
The Calif A21 has a pretty elaborate wing root fairing (I own one, so I
should know). -- Bert Willing ASW20 "TW" "Slingsby" a écrit dans le message de om... For the sake of the discussion, why have an upper wing root fillet at all? The Caproni A 21 wing blends into the top of the fuselage. What are the advantages/disadvantages to this type of design? |
#6
|
|||
|
|||
Bert Willing wrote:
The Calif A21 has a pretty elaborate wing root fairing (I own one, so I should know). -- Bert Willing ASW20 "TW" "Slingsby" a écrit dans le message de om... For the sake of the discussion, why have an upper wing root fillet at all? The Caproni A 21 wing blends into the top of the fuselage. What are the advantages/disadvantages to this type of design? A better example of a wing root without fillet is the LS1f. But the manufacturer added them to the LS4. Another example is the Janus B (just had a look on our Janus now disassembeld in the workshop). |
#7
|
|||
|
|||
Several of us have added Vortex Generators (VG's) to the upper wing / fuselage
juncture area on the Genesis 2 and found very good results. As I understand it, the VG's, placed near the high camber location, cause the local flow to become turbulent, but the "turbulent" flow reattaches and prevents complete separation. Anyway, I am able to thermal 5 knots slower and no longer feel and hear flow separation. The VG's are 1" long X .25" high and .25" wide (base only) the vertical web is about 1/16" wide. We place them in pairs that are angled in about 30 degrees to each other. The hot set-up seems to be 3 sets on each side with 2 on the wing and 1 on the fuselage. I have seen similar things on a Nimbus 3 and wondered if they worked. I could play a tune on my Nimbus, by just moving the flaps up and down, so something bad was going on back there. The VG's work on the Genesis 2. JJ Sinclair |
#8
|
|||
|
|||
"Robert Ehrlich" wrote in message ... Bert Willing wrote: The Calif A21 has a pretty elaborate wing root fairing (I own one, so I should know). -- Bert Willing ASW20 "TW" "Slingsby" a écrit dans le message de om... For the sake of the discussion, why have an upper wing root fillet at all? The Caproni A 21 wing blends into the top of the fuselage. What are the advantages/disadvantages to this type of design? A better example of a wing root without fillet is the LS1f. But the manufacturer added them to the LS4. Another example is the Janus B (just had a look on our Janus now disassembeld in the workshop). Most common Grob models have no fillet and fly like it. Peter Masak had a small publication a few years ago on performance enhancements, including photos of ASW-20 fillets and mods and tufts in action. No clue if it's still available. Frank Whiteley |
#9
|
|||
|
|||
Robert Ehrlich wrote in message ...
Bert Willing wrote: The Calif A21 has a pretty elaborate wing root fairing (I own one, so I should know). -- Bert Willing ASW20 "TW" "Slingsby" a écrit dans le message de om... For the sake of the discussion, why have an upper wing root fillet at all? The Caproni A 21 wing blends into the top of the fuselage. What are the advantages/disadvantages to this type of design? A better example of a wing root without fillet is the LS1f. But the manufacturer added them to the LS4. Another example is the Janus B (just had a look on our Janus now disassembeld in the workshop). I have done extensive dye flow testing on the wing root area of my Janus C. The Janus has no fairing--the wing just butts into the fuselage. Where the leading edge of the wing meets the fuselage, the fuselage boundary layer is rolled up by the wing boundary later, forming a horshoe vortex that trails back over and under the wing root. This is caused by the velocity gradient in the fuselage boundary layer. The flow just above the surface overruns the flow below, but when it runs into the stagnation at wing leading edge, it doubles back along the surface. At hight angles of attack, the dye tests show a clear stagnation point on the fuselage in front of the leading edge (about 10cm), and reversed flow from the leading edge forward to the stagnation point. They also show the vortex is attached to the fuselage above the wing, where any dye that enters the vortex is scrubbed out at an upward tilted angle relative to the flow. A thick line of dye marks the upper edge of the attached vortex. The vortex separates from the fuselage near the point of maximum wing thickess (where the fuselage also begins to taper sharply), briefly attaches to the wing upper surface, and then trails off into the flow. If you imagine bending one of those pool toy "noodles" in half over the leading edge of the wing root, then straight back on both sides, you would get a pretty good picture of what is going on. BTW, the interesting finding from the Maughmer wing root study was that a concave fairing was actually worse than no fairing at all. He got the best results from a straight 45 degree angle fairing. Perhaps the concave fairing supports the vortex while the 45 degree fairing does not? |
#10
|
|||
|
|||
Bob Kuykendall wrote in message ...
Earlier, D.A.L wrote: I have noticed that several articles on glider performance refer to adding/modifying the wing root to get better performance. Can anyone refer me to further info on wing root fairing design and or mods to improve performance. Wing fuselage junction fillets are often a pretty troublesome aspect of glider design. The way I understand it, they are usually developed either empirically, using tuft testing, or using lots of CFD computing horsepower. On the other hand, it seems to be one of those aspects where you get some points just for trying. Dick Schreder developed the HP-18 side-of-body junction by eye, and seemed to have gotten it pretty close on the first try. The only thing I would have done differently would be to adjust the fillet trailing edge slightly so that it lines up at the -5 flap setting instead of 0. There are some references in Thomas' _Fundamentals of Sailplane Design_, but the book itself is pretty skimpy regarding developing junction fillets for existing sailplanes. Small radii near the leading edge, big radius at the bac, that sort of thing. One of the cites in Thomas is to a study by Mark Maughmer at Penn State. If you can get in touch with him, he might be able to give you some reasonable guidelines. Another cite is to Dick Johnson's 1979 compendium of flight test articles; you can get most of those off of the SSA Web server. Bob K. http://www.hpaircraft.com/hp-24 Thanks for the info and references Bob! Don. |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Looking for Cessna Caravan pilots | [email protected] | Owning | 9 | April 1st 04 02:54 AM |
ANG Woman Wing Commander Doesn't See Herself as Pioneer, By Master Sgt. Bob Haskell | Otis Willie | Military Aviation | 0 | March 18th 04 08:40 PM |
wing root strakes (not canard A/C) | Wallace Berry | Home Built | 0 | October 2nd 03 08:47 PM |
Props and Wing Warping... was soaring vs. flaping | Wright1902Glider | Home Built | 0 | September 29th 03 03:40 PM |
An Affordable Homebrue 60 in DS machine | Grant | Soaring | 0 | August 8th 03 03:52 AM |