EXPjawa
Well-Known Member
After building my clone of the Estes Advanced Target Drone and then finding that Excelsior prints decals for a BT70 upscale version, I decided to add that to my list of projects. That's now cycled round to the top of the list. So, first things first, I made an upscale design using RockSim (View attachment ATD70-1.pdf) to get the bugs worked out, make sure CP/CG was suitable, etc. The regular ATD uses cardstock that's about .040" thick for the bodywork, but for this I elected to use 1/16" aircraft plywood. My intent is to make seperate panels for the horizontal and vertical surfaces, then glue them together. Fin templates were made from the RockSim patterns:
Then, all the basic parts were gathered up:
The parts list as such is as follows:
The BNC70G isn't quite the right shape; ideally it would be more parabolic rather than ogive, but its pretty close. The dorsal & ventral fins will be made of balsa, the wings themselves will be plywood. Note that I said motor mounts - the design I came up with uses triple 24mm mounts in a linear cluster. There is an E-sized mount in the main tube and will have a D-length mount in each body pod. From the RockSim simulations, it should fly well enough on 3 D12s, or combinations of an E9/12 with 2 C11s or D12s. The RockSim file is attached. One catch for the short term is regarding the decals - as long as Excelsior's printer is down, I'll have to hold off on finishing. But that's down the road, I'm not going to worry about it right now...
Then, all the basic parts were gathered up:
The parts list as such is as follows:
- 2 18" BT70 tubes
- 1 segment of BT50 to make the motor mounts from (a scrap that I had)
- 1 BNC70G nose cone
- 3 CR5070W centering rings
- 1 BT70 baffle kit to serve as tube coupler
- 1 30" Top Flite parachute
- a sheet of 1/8" balsa
- a sheet of 1/16" light ply
- a partial sheet of 1/8" light ply
- 1/4" launch lug
- 3/8" dowel for the nose cone
- there will also be some misc hardware that hasn't been gathered up yet
The BNC70G isn't quite the right shape; ideally it would be more parabolic rather than ogive, but its pretty close. The dorsal & ventral fins will be made of balsa, the wings themselves will be plywood. Note that I said motor mounts - the design I came up with uses triple 24mm mounts in a linear cluster. There is an E-sized mount in the main tube and will have a D-length mount in each body pod. From the RockSim simulations, it should fly well enough on 3 D12s, or combinations of an E9/12 with 2 C11s or D12s. The RockSim file is attached. One catch for the short term is regarding the decals - as long as Excelsior's printer is down, I'll have to hold off on finishing. But that's down the road, I'm not going to worry about it right now...