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I am starting this new thread, in response to the XP-2 Rocket Glider thread:
https://www.rocketryforum.com/showthread.php?t=18078
The issue of Swing Wing pivots came up there.
I want to mention and show what I have done, but not have this info hidden inside of the XP-2 thread for those who might search the forum in the future.
I made lots and lost of Swing-wings in the 1970’s. From 1/4A thru F power. The ones with wingspans of 6 feet or more (one was 10.5 feet), I named Great Danes. I built at least 15 of them. The 15th one was one of the best, built for F Rocket Glide. It used an AVI E11.8 engine plug a B6 to nudge it into F class.
I learned the pitfalls and weaknesses of the original Swing-wings early on, and came up with better ways. Also, my first Great Dane suffered hinge problems due to the mass and deployment momentum of the wings. So I eventually came up with a much more robust (and easy) way to hinge them, using plywood “Pivoters” to take most of the hinge and deployment stress. The pivot pins were simply wood dowels, slid into place in the balsa plates on top and bottom of the pivoters. To keep the holes from being pried open or ovalized from deployment stress, I glued 1/64” or 1/32” plywood squares to reinforce the pivot pin holes. By being able to slide the pivot in and out, I could remove the wings for storage, even swap wings.
By the late 1970’s I moved on to Slide Wings for contest models.
In 1993, I made a B7 powered Rocket Glider for NARAM, due to the light weight of the 13mm B7 casing, compared to an 18mm Estes B4. The B7 thrust was so high that a normal wing would either shred or would need to be built be built too heavy (also draggy for high-speed boosts). So in that case a Swing Wing was the most practical way to use a B7 for a Rocket Glider. That one, I used either .015” or .020” Waferglass (G10) for the pivoters and for the top and bottom plates. , I do not recall which. I do not have any photos of that B7 model, or plans for the model itself. But I did make drawings for the Pivoters, which I have upgraded with color coding so they will make more sense.
In 1992, NARAM-34 had G Rocket Glide. I made a copy of Great Dane 15, including the Pop-Stab dethermalizer used for bringing it down early. I actually used R/C models for our team, that swing-wing was our #3 model (back-up for the back-up). But Mark Hamilton and Tom Beach did build and successfully fly their own copies of that model at NARAM-34 (used on F10 plus two 1/2A motors to nudge into G class.
Photo 1 - 1/16" Plywood Pivoters as used by 6 foot+ Span Great Dane models
Photo 2 - Waferglass pivoter drawings, parts as used for a B7 powered model.
Photo 3 - More B7 model Pivoter drawings, showing boost and glide configurations.
Photo 4 - Great Dane 1, in 1972. I am on the right.
Photo 5 - Myself holding the 1992 Great Dane model, which in 2007 was modified for rudder-only R/C (something I had wanted to do since the 1970’s).
More to come.
- George Gassaway
https://www.rocketryforum.com/showthread.php?t=18078
The issue of Swing Wing pivots came up there.
I want to mention and show what I have done, but not have this info hidden inside of the XP-2 thread for those who might search the forum in the future.
I made lots and lost of Swing-wings in the 1970’s. From 1/4A thru F power. The ones with wingspans of 6 feet or more (one was 10.5 feet), I named Great Danes. I built at least 15 of them. The 15th one was one of the best, built for F Rocket Glide. It used an AVI E11.8 engine plug a B6 to nudge it into F class.
I learned the pitfalls and weaknesses of the original Swing-wings early on, and came up with better ways. Also, my first Great Dane suffered hinge problems due to the mass and deployment momentum of the wings. So I eventually came up with a much more robust (and easy) way to hinge them, using plywood “Pivoters” to take most of the hinge and deployment stress. The pivot pins were simply wood dowels, slid into place in the balsa plates on top and bottom of the pivoters. To keep the holes from being pried open or ovalized from deployment stress, I glued 1/64” or 1/32” plywood squares to reinforce the pivot pin holes. By being able to slide the pivot in and out, I could remove the wings for storage, even swap wings.
By the late 1970’s I moved on to Slide Wings for contest models.
In 1993, I made a B7 powered Rocket Glider for NARAM, due to the light weight of the 13mm B7 casing, compared to an 18mm Estes B4. The B7 thrust was so high that a normal wing would either shred or would need to be built be built too heavy (also draggy for high-speed boosts). So in that case a Swing Wing was the most practical way to use a B7 for a Rocket Glider. That one, I used either .015” or .020” Waferglass (G10) for the pivoters and for the top and bottom plates. , I do not recall which. I do not have any photos of that B7 model, or plans for the model itself. But I did make drawings for the Pivoters, which I have upgraded with color coding so they will make more sense.
In 1992, NARAM-34 had G Rocket Glide. I made a copy of Great Dane 15, including the Pop-Stab dethermalizer used for bringing it down early. I actually used R/C models for our team, that swing-wing was our #3 model (back-up for the back-up). But Mark Hamilton and Tom Beach did build and successfully fly their own copies of that model at NARAM-34 (used on F10 plus two 1/2A motors to nudge into G class.
Photo 1 - 1/16" Plywood Pivoters as used by 6 foot+ Span Great Dane models
Photo 2 - Waferglass pivoter drawings, parts as used for a B7 powered model.
Photo 3 - More B7 model Pivoter drawings, showing boost and glide configurations.
Photo 4 - Great Dane 1, in 1972. I am on the right.
Photo 5 - Myself holding the 1992 Great Dane model, which in 2007 was modified for rudder-only R/C (something I had wanted to do since the 1970’s).
More to come.
- George Gassaway
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