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#1
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Will be refinishing and profiling a LS3A this winter. Need the wing profile
data which manufacture will not share. Does anyone out there have tha data they would be willing to share with me? Bob Fidler |
#2
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This site, compiled by Dave Lednicer, lists the LS-3 as using the
Wortmann "FX 67-K-170" at the root and a "FX 67-K-150 mod" at the tip. http://www.ae.uiuc.edu/m-selig/ads/aircraft.html This agrees with the data in the Thomas book as well as the directories by Martin Simmons. It was a very popular airfoil on a lot of gliders from that era. If you go to this site, you'll find a data file that lists the coordinates in non-dimensional values. http://www.ae.uiuc.edu/m-selig/ads/coord_database.html Now the tricky part.... It may or may not be 17% thick at the root, and typically the airfoils were scaled in thickness to allow for more uniform spar height tapering. As a result, you'll probably need to measure the thickness vs chord ratio at a number of stations and scale appropriately to match. Also, the tip airfoil is different, and who knows where the designer started to "blend" into this airfoil along the span... Now the cool part...and I'm sure I'll get flamed from people who disagree.... Can't wait.... ![]() It really doesn't matter that you get the shape just right for the full length of the airfoil. The underlying structure is by itself fairly accurate. You're not going to be sanding away fiberglass. What does matter is that the profile itself is relatively free of waves and that the underlying surface quality is quite smooth. Waviness will do more damage than a slightly in-accurate profile. Hence, you could get by with just stripping down the gel-coat to the glass, spraying up a nice uniform thickness of new gel-coat and then spending all of your time getting rid of chord wise waves. Once that is done, polish up the final result to a mirror smooth surface and you're done. Technically you don't even have to polish to mirror smooth, 600 grit sand paper would yield a smooth enough surface, but your gel coat will last a lot longer if you go higher. No templates necessary. -Kevin |
#3
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On Oct 21, 6:45*pm, Robert Fidler
wrote: Will be refinishing and profiling a LS3A this winter. Need the wing profile data which manufacture will not share. Does anyone out there have tha data they would be willing to share with me? Bob Fidler Careful about free advice! It ain't just about waves. The 67 series is very sensitive to correct profile on the leading edge. A few measurements should show linear taper root to tip with airfoil doing the same thing. The bad news is that to make templates , you have to plot the airfoil at each station interpolating between the 67-170 and 67-150. You don't really want to know how I know this. It's painful. Look up the series Dick Johnson wrote on improving the PIK-20 which uses the same series airfoils. There is much to learn in these articles. Good luck UH |
#4
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You know, I've been flying FX 67-150 and -170 airfoils for years. I've
smashed thousands of bugs, flown through many rain showers and even collected substantial ice on occasion yet I've not seen any unusual performance degradation when analyzing flights with SeeYou nor did I feel any in flight. In fact, those glides with crappy wings often show a height/distance ratio well above the published L/D. I know Bob Faris gets great results with his LS-3a in the same conditions. I wonder if these airfoils are getting a bad rap. There are PC software programs that will interpolate airfoils and generate intermediate templates. Just save the results as a .dxf file and email it to a laser cutting shop so they can make a complete set of templates. I've had them made out of Plexiglass with laser alignment holes. A complete wing set should cost no more than a couple of hundred bucks. In fact, if you just like airfoil shapes as wall hangings, your local plastic/sign shop can burn them on its laser cutter from .dxf files. wrote in message ... On Oct 21, 6:45 pm, Robert Fidler wrote: Will be refinishing and profiling a LS3A this winter. Need the wing profile data which manufacture will not share. Does anyone out there have tha data they would be willing to share with me? Bob Fidler Careful about free advice! It ain't just about waves. The 67 series is very sensitive to correct profile on the leading edge. A few measurements should show linear taper root to tip with airfoil doing the same thing. The bad news is that to make templates , you have to plot the airfoil at each station interpolating between the 67-170 and 67-150. You don't really want to know how I know this. It's painful. Look up the series Dick Johnson wrote on improving the PIK-20 which uses the same series airfoils. There is much to learn in these articles. Good luck UH |
#5
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"Bill Daniels" bildan@comcast-dot-net wrote
There are PC software programs that will interpolate airfoils and generate intermediate templates. Just save the results as a .dxf file and email it to a laser cutting shop www.profili2.com would be my first choice: inexpensive, powerful and easy to learn and use. Once you know chord length and t/c ratio of your wing creating a DXF for the templates takes less than one hour. IIRC there were different versions of the FX67 leading edge, see http://www.gliderforum.com/thread-vi...?threadid=2128 for a start. Michael |
#6
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On Oct 21, 11:26*pm, "Bill Daniels" bildan@comcast-dot-net wrote:
You know, I've been flying FX 67-150 and -170 airfoils for years. *I've smashed thousands of bugs, flown through many rain showers and even collected substantial ice on occasion yet I've not seen any unusual performance degradation when analyzing flights with SeeYou nor did I feel any in flight. * That's astounding... I owned an HP-18 for years that made an honest 40:1 clean... and about 7:1 in light rain. I'd feel the ship get draggy with the first tiny spots on the canopy. In a light rain shower the entire ship hummed audibly and one had to push the stick forward to maintain 55 kts. The stall speed went up rather a lot too, but I don't recall any specifics. More recently, I watched a Glasflugel (or HPH or whatever they are) 304 -- which has a very similar looking airfoil the root if not precisely the same airfoil -- get "washed" off a ridge in rain showers that had little effect on my ASW-20. He might as well have flown into a net. I wonder if you have a different leading edge section on your ship, by happenstance or design. It would be very interesting to discover what the difference is. -T8 |
#7
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Been-there-done-that and guess what? Only the first 4 inches are
important. I make up templates before starting, every 24 inches and then keep everything aft of that dead smooth both cord-wise and span- wise. Quick and dirty templates can be made from cardboard that is cut close then crammed over a strip of bondo which is gooped over aluminum foil every 24" with wing leading edge vertical. Both Dick Johnson and Allen Bickle made up full scale templates, worked forever and the bird didn't perform any better than advertised, except it was a lot heavier because of all that bondo!. Bickle's bird had a trailing edge that was a good 5mm thick, because that's what the templates dictated. Save your time and bondo, concentrate on the first 4". JJ When I say bondo, I'm talking about Evercoat Rage Gold, good stuff, works easy and sticks like mad! wrote: On Oct 21, 11:26�pm, "Bill Daniels" bildan@comcast-dot-net wrote: You know, I've been flying FX 67-150 and -170 airfoils for years. �I've smashed thousands of bugs, flown through many rain showers and even collected substantial ice on occasion yet I've not seen any unusual performance degradation when analyzing flights with SeeYou nor did I feel any in flight. � That's astounding... I owned an HP-18 for years that made an honest 40:1 clean... and about 7:1 in light rain. I'd feel the ship get draggy with the first tiny spots on the canopy. In a light rain shower the entire ship hummed audibly and one had to push the stick forward to maintain 55 kts. The stall speed went up rather a lot too, but I don't recall any specifics. More recently, I watched a Glasflugel (or HPH or whatever they are) 304 -- which has a very similar looking airfoil the root if not precisely the same airfoil -- get "washed" off a ridge in rain showers that had little effect on my ASW-20. He might as well have flown into a net. I wonder if you have a different leading edge section on your ship, by happenstance or design. It would be very interesting to discover what the difference is. -T8 |
#8
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Some thoughts to "muddy" the discussion.
Many years ago, we made leading edge templates of a wing of an undamaged and relatively new LS sailplane. The templates were made with bondo and cardboard in the JJ manner. We all know the root is bigger/fatter than the tip. We would slide the root template from the root to the tip and observe the changing shape as it neared the tip. We then took the root template to the other wing and did the same. They were not same. Not even very close and we found the middle of the other wing was actually fatter than the root. This particular LS went we very, very well. It was a winner in many competitions. Conclusion? Bob "Careful about free advice! It ain't just about waves". (previous message) |
#9
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On Oct 21, 9:26*pm, "Bill Daniels" bildan@comcast-dot-net wrote:
You know, I've been flying FX 67-150 and -170 airfoils for years. *I've smashed thousands of bugs, flown through many rain showers and even collected substantial ice on occasion yet I've not seen any unusual performance degradation when analyzing flights with SeeYou nor did I feel any in flight. *In fact, those glides with crappy wings often show a height/distance ratio well above the published L/D. *I know Bob Faris gets great results with his LS-3a in the same conditions. *I wonder if these airfoils are getting a bad rap. Bob Faris flies an LS-3, which is rather different than an LS-3a in the flap/aileron vs flaperon and wing weight areas. Read something in the past year that suggested that the FX67/170 and 150 did not degrade on long spans where the thickness was 15%, but can't find it at the moment. Frank Whiteley |
#10
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The LS-3 measured higher in L/D than the 3a according to Dick Johnson's
tests. I actually have a letter from Wolf Lemke that was with papers that came with my LS-3a assuring owners that there is no difference in performace from follow-up factory tests of the 3a after Dick's flight tests?? I also noticed the following quote on wikipedia for the LS-3: "In spite of its weight the LS3 is a nimble climber. It is also less sensitive to rain or dirt than other types with the same profile." I'm not sure who posted this to the Wiki or if this applies only to the 3 or 3a? Was there any change in profile for the 3a? Matt LS3-a "RX" At 15:44 22 October 2008, Frank Whiteley wrote: On Oct 21, 9:26=A0pm, "Bill Daniels" wrote: You know, I've been flying FX 67-150 and -170 airfoils for years. =A0I've smashed thousands of bugs, flown through many rain showers and even collected substantial ice on occasion yet I've not seen any unusual performance degradation when analyzing flights with SeeYou nor did I feel any in flight. =A0In fact, those glides with crappy wings often show a height/distance ratio well above the published L/D. =A0I know Bob Faris g= ets great results with his LS-3a in the same conditions. =A0I wonder if these airfoils are getting a bad rap. Bob Faris flies an LS-3, which is rather different than an LS-3a in the flap/aileron vs flaperon and wing weight areas. Read something in the past year that suggested that the FX67/170 and 150 did not degrade on long spans where the thickness was 15%, but can't find it at the moment. Frank Whiteley |
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