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:
![IMG_2919.JPG IMG_2919.JPG](https://cdn.imagearchive.com/rocketryforum/data/attachments/179/179682-32af0c2be429a3e0275b68fabe0a2bc7.jpg)
Then, all the basic parts were gathered up:
![IMG_2905.JPG IMG_2905.JPG](https://cdn.imagearchive.com/rocketryforum/data/attachments/179/179683-2d1c3e8c4bfbccbb3e8fe0400dd2b806.jpg)
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...
![IMG_2919.JPG IMG_2919.JPG](https://cdn.imagearchive.com/rocketryforum/data/attachments/179/179682-32af0c2be429a3e0275b68fabe0a2bc7.jpg)
Then, all the basic parts were gathered up:
![IMG_2905.JPG IMG_2905.JPG](https://cdn.imagearchive.com/rocketryforum/data/attachments/179/179683-2d1c3e8c4bfbccbb3e8fe0400dd2b806.jpg)
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...