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#11
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On Tue, 13 Oct 2009 15:11:07 -0700, Uncle Fuzzy wrote:
==== I wonder about painting the undersides of wings and tail black while leaving the rest of the glider white. That should stay cool while showing up well against anything except ice and snow. I like that idea, except that Black is boring. A nice rich RED is very close to black in grey scale value, and so much less boring. You've probably noted as much while looking up chasing runaway FF models. The best scheme for FF I've used is black undersides on the inner panels and dayglo orange top and bottom on the tips. The inner panel top colour doesn't matter much. I've used yellow, scarlet and white - all are equally good. However, the both the black inners and the orange tips show up really well against any sky and, as a bonus, the orange tips are highly visible on the ground as well. The pictures he http://www.gregorie.org/freeflight are a bit washed out, but do show why I like the scheme. I don't think the dayglo works as well on a sailplane because a lot of its visibility comes from light shining through the translucent wing covering and powering up the dayglo[*]. A friend uses purple inners and yellow/green dayglo. The yellow/green is pretty good but I don't think the purple is as visible in the air as black. [*] the reason that dayglo always looks so bright is that it absorbs ultraviolet and visible wavelengths of light and uses the energy to fluoresce, so it actually is brighter than other colours. Under more than a few feet of water almost all light is blue-green but even here orange dayglo fluoresces orange. Panels of it have been used to improve the colour balance of underwater photographs. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |
#12
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On Oct 14, 4:32*am, Martin Gregorie
wrote: On Tue, 13 Oct 2009 15:11:07 -0700, Uncle Fuzzy wrote: ==== I wonder about painting the undersides of wings and tail black while leaving the rest of the glider white. That should stay cool while showing up well against anything except ice and snow. I like that idea, except that Black is boring. *A nice rich RED is very close to black in grey scale value, and so much less boring. You've probably noted as much while looking up chasing runaway FF models. The best scheme for FF I've used is black undersides on the inner panels and dayglo orange top and bottom on the tips. The inner panel top colour doesn't matter much. I've used yellow, scarlet and white - all are equally good. However, the both the black inners and the orange tips show up really well against any sky and, as a bonus, the orange tips are highly visible on the ground as well. The pictures he http://www.gregorie.org/freeflight are a bit washed out, but do show why I like the scheme. I don't think the dayglo works as well on a sailplane because a lot of its visibility comes from light shining through the translucent wing covering and powering up the dayglo[*]. A friend uses purple inners and yellow/green dayglo. The yellow/green is pretty good but I don't think the purple is as visible in the air as black. [*] the reason that dayglo always looks so bright is that it absorbs ultraviolet and visible wavelengths of light and uses the energy to fluoresce, so it actually is brighter than other colours. Under more than a few feet of water almost all light is blue-green but even here orange dayglo fluoresces orange. Panels of it have been used to improve the colour balance of underwater photographs. -- martin@ * | Martin Gregorie gregorie. | Essex, UK org * * * | Actually, while ultraviolet works, most florescent (Trademark Dayglo) materials also absorb blue wavelengths and re-emit as a bright (but longer wavelength) color. As proof, use a blue LED to illuminate a florescent material and watch it light up. |
#13
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A couple of years back I was watching some local scale model glider
pilots flying (interesting winch launching mechanism) and noticed that they used reflective tape on their leading edges. This was also mentioned in the http://www.dg-flugzeugbau.de/Data/gl...uity-study.pdf article. I asked the scale model pilots about it and they said they often loose their gliders, especially during overcast days, so they circle and pick up the "flash" of the tape. The tape that they used is used for reflective fishing lures. See http://www.jannsnetcraft.com/reflect...es/309100.aspx for examples. So I bought some of the tape and used wing tape to attach about 3' on the leading edge near my wing tips. I communicated with Dick Johnson about it and he expressed interest in the concept. Unfortunately, life interfered and I never completed a reasonable study if I was more visible or not. I plan on being in a contest in 2010 which might be a good proving ground. The question is would it affect the aerodynamics of the wing? If so it might be a hard sell for competition pilots, which is a prime at- risk group. My $0.02. - John DeRosa |
#14
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On Oct 14, 9:35*am, ContestID67 wrote:
A couple of years back I was watching some local scale model glider pilots flying (interesting winch launching mechanism) and noticed that they used reflective tape on their leading edges. *This was also mentioned in thehttp://www.dg-flugzeugbau.de/Data/glider-conspicuity-study.pdf article. I asked the scale model pilots about it and they said they often loose their gliders, especially during overcast days, so they circle and pick up the "flash" of the tape. *The tape that they used is used for reflective fishing lures. *Seehttp://www.jannsnetcraft.com/reflector-tape-eyes/309100.aspx for examples. So I bought some of the tape and used wing tape to attach about 3' on the leading edge near my wing tips. *I communicated with Dick Johnson about it and he expressed interest in the concept. *Unfortunately, life interfered and I never completed a reasonable study if I was more visible or not. *I plan on being in a contest in 2010 which might be a good proving ground. The question is would it affect the aerodynamics of the wing? *If so it might be a hard sell for competition pilots, which is a prime at- risk group. My $0.02. - John DeRosa I have flown model XC soaring gliders for the past 22 years. It's not unusual for the model to be over 3000 above and up to 1 mile away from the pilot during the race. I have used several types of the reflecting tape and found for the models that the best result was with simple chrome film. The "swirly" patterns may be good to simulate motion to a fish, but the plain chrome gives a bigger brighter flash in the air. Top Flite (modeling company) sells an adhesive film, marketed as TrimCote, in a number of neon colors as well as the chrome. A 4"x30" sheet is about $4 at most hobby shops. You can buy a selection of colors and reflectivity and do your own evaluation. Checkerboard patterns in several colors are also available! Mike |
#15
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On Oct 14, 2:45*pm, Mike Bamberg wrote:
On Oct 14, 9:35*am, ContestID67 wrote: A couple of years back I was watching some local scale model glider pilots flying (interesting winch launching mechanism) and noticed that they used reflective tape on their leading edges. *This was also mentioned in thehttp://www.dg-flugzeugbau.de/Data/glider-conspicuity-study.pdf article. I asked the scale model pilots about it and they said they often loose their gliders, especially during overcast days, so they circle and pick up the "flash" of the tape. *The tape that they used is used for reflective fishing lures. *Seehttp://www.jannsnetcraft.com/reflector-tape-eyes/309100.aspx for examples. So I bought some of the tape and used wing tape to attach about 3' on the leading edge near my wing tips. *I communicated with Dick Johnson about it and he expressed interest in the concept. *Unfortunately, life interfered and I never completed a reasonable study if I was more visible or not. *I plan on being in a contest in 2010 which might be a good proving ground. The question is would it affect the aerodynamics of the wing? *If so it might be a hard sell for competition pilots, which is a prime at- risk group. My $0.02. - John DeRosa I have flown model XC soaring gliders for the past 22 years. *It's not unusual for the model to be over 3000 above and up to 1 mile away from the pilot during the race. I have used several types of the reflecting tape and found for the models that the best result was with simple chrome film. *The "swirly" patterns may be good to simulate motion to a fish, but the plain chrome gives a bigger brighter flash in the air. Top Flite (modeling company) sells an adhesive film, marketed as TrimCote, in a number of neon colors as well as the chrome. *A 4"x30" sheet is about $4 at most hobby shops. *You can buy a selection of colors and reflectivity and do your own evaluation. *Checkerboard patterns in several colors are also available! Mike A flash of reflected sunlight is by far the best way to see an aircraft at long range. Simple "Heliographs" with 6" mirrors were used by desert armies in the 19th century for "optical communication networks" spanning hundreds of miles. Survival packs are still equipped with signaling mirrors. I've wondered if this technology could be brought into the digital age. A simple 2" mirror driven by tiny stepper motors might direct flashes at a known target. Of course, you'd have to know where the observer was in 3D space, the sun angle as well as your own 3D position and attitude. Fortunately, devices like FLARM can determine that information. Even if I know the abstract location of another glider, actually seeing a flash is comforting. |
#16
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On Oct 17, 10:44*am, bildan wrote:
A flash of reflected sunlight is by far the best way to see an aircraft at long range. *. . . I've wondered if this technology could be brought into the digital age. *. . snip In a study done some years ago at the Cranfield Institute in the UK on conspicuity schemes, one of the best was to put some highly reflective foil - perhaps like that mentioned in an earlier post about RC models - on the control surfaces of a glider (rudder, elevator, ailerons). The movement of the control surfaces, far more frequent that movements of the airframe itself, was remarkably good at alerting others of the presence of the glider. Jim |
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