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I've done upscales for 9 of my 24mm E-6 powered kits for the 29mm longburn H-13 motor which is a perfect setup for a lightweight constructed model at around 32 oz rtf yielding vertical boosts to around 900-1100' which is a good limit for visibility. One that I have not upscaled for that motor was my Shuttle. Since weight will be critical, and since I like the cleaner lines of the Buran a little better, I decided I'd take a crack at that one. The US shuttle oms pods at the rear even with ultra light construction would add two ounces to the overall weight which is too much. Turns out a 2x upscale of my 2.6" based Buran model yields a 36" span and 1:26 scale.
You have to be careful with weight for these types of designs to make them as big as possible for good glide, as the motor is 7.25 oz, and radio, battery and servos are around 1.9 oz, so that only leaves around 23 oz for the entire airframe painted and complete. CG shift is fairly large for this motor as the propellent lost is around 4 oz, so the larger you can make the model, the easier it is to compensate for the shift with simple elevon trim. All of my other versions have wound up in the 5-6' long, 30"-42" wingspan range and right at the 32 oz rtf target and fly really well. These are 1.5x upscales of my smaller versions that allowed me to use 3 or 4" lightweight tubing.
Since there is no lightweight tubing for a 6-7" diameter model I'll do a built up fuse with formers and 6mm skin on the sides and 3mm on the top to save a bit of weight. Vertical stab is two layers of 6mm depron with 3mm carbon spars glued in place inbetween them and laminated together with 3m-77 spray adhesive. Yields a nice stiff structure at 1 oz for a 12" tall fin.
The wing I went with a 9mm lower and 6mm upper laminated with 3mm spars top and bottom grooved, glued and taped in place. This yields a nearly unbendable spar unit sort of like an I beam that is lighter than a 5 or 6mm tubular single spar in the center. The top spar will be hidden by black trim anyway and the bottom is painted flat black. This was slightly lighter than a double 9mm wing. It will be a simple belly lander as weight of gear is too high and most of my flying sites for hpr launches are too rough for small gear anyway.
The entire wing with hinged surfaces weighs 9.25 oz.
The cockpit will be laminated from 17 pieces of 9mm with a hollow in the center for nose weight, battery and receiver, then carved to shape with a hatch at the bottom for access.
Servos will be mounted mid wing with a direct pushrod in the center of the surface.
You have to be careful with weight for these types of designs to make them as big as possible for good glide, as the motor is 7.25 oz, and radio, battery and servos are around 1.9 oz, so that only leaves around 23 oz for the entire airframe painted and complete. CG shift is fairly large for this motor as the propellent lost is around 4 oz, so the larger you can make the model, the easier it is to compensate for the shift with simple elevon trim. All of my other versions have wound up in the 5-6' long, 30"-42" wingspan range and right at the 32 oz rtf target and fly really well. These are 1.5x upscales of my smaller versions that allowed me to use 3 or 4" lightweight tubing.
Since there is no lightweight tubing for a 6-7" diameter model I'll do a built up fuse with formers and 6mm skin on the sides and 3mm on the top to save a bit of weight. Vertical stab is two layers of 6mm depron with 3mm carbon spars glued in place inbetween them and laminated together with 3m-77 spray adhesive. Yields a nice stiff structure at 1 oz for a 12" tall fin.
The wing I went with a 9mm lower and 6mm upper laminated with 3mm spars top and bottom grooved, glued and taped in place. This yields a nearly unbendable spar unit sort of like an I beam that is lighter than a 5 or 6mm tubular single spar in the center. The top spar will be hidden by black trim anyway and the bottom is painted flat black. This was slightly lighter than a double 9mm wing. It will be a simple belly lander as weight of gear is too high and most of my flying sites for hpr launches are too rough for small gear anyway.
The entire wing with hinged surfaces weighs 9.25 oz.
The cockpit will be laminated from 17 pieces of 9mm with a hollow in the center for nose weight, battery and receiver, then carved to shape with a hatch at the bottom for access.
Servos will be mounted mid wing with a direct pushrod in the center of the surface.
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