Wednesday, August 01, 2012

SpaceX Falcon 9/Dragon build post

This was a pretty simple build and will only warrant one post. If you get one of these kits, you should read Chris' series of posts. They are all applicable except for the ones regarding the body wrap. Where I deviated from the instructions, I have highlighted the text in red.
  1. I decided to go with the stock motor mount.  Once I peered at the bottom of the molded tail section, it was clear the water bottle retainer wouldn't fit.  The motor mount is typical build - tube, clip, block and ring.  Except the ring location is marked, the slot for the spring clip is laser cut, and only one ring is needed (the plastic unit incorporates a lower ring). I used wood glue to assemble the mount.
  2. Installation of the nose cone wrap was unremarkable.  Chris has a tip on this step.
  3. The launch lug position is marked on the body. I removed a strip of the wrap where the lug attaches.
  4. The 12" plastic parachutes are old school. You have to cut them out, cut the lines to length, and tie knots. I built them both but may not use them. I added small swivels to each. 
  5. The nose is intended to come down base first on its own 'chute. A thin string is attached through a hole near the nose. When mounted, it nestles in a slot molded into the nose. I ditched the string in favor of a piece of thin Kevlar.  The instructions have you tie several knots on the string to keep it from coming out of the slot. A couple of knots on the thicker Kevlar would have sufficed but  I tied the it to a small washer anyway. (Chris used the stock string and has his own tip.)
  6. The kit provides a fiber baffle, which keeps the 'chutes near the top.  This won't protect the 'chutes so wadding is still required. The provided Kevlar shock leader is looped through holes in the baffle prior to installation.  To mount the baffle, you are supposed to form an 'installation tool' from scrap paper. I opted to use a AeroTech 38mm case instead and marked the proper depth with a piece of masking tape.
  7. The motor mount is attached to the plastic tail using epoxy and the finished assembly is also epoxied into the body.
  8. The last step is to attach the plastic fins.  Three of the four slots has some flashing but other than that they snapped right in place.  Once they are installed, you run a twist tie through the exposed tabs. I found this fairly difficult. If I hadn't had a hemostat, I don't think I would have gotten them in. I assume you could remove the tie to replace a broken fin. However, it would be tough to cut a replacement!
  9. Even though the tube is thick, I added a duct tape zipper protector where the Kevlar meets cardboard.
  10. I finally read the flight prep instructions and they mentioned the option of attaching the nose cone to the main 'chute. That's what I'll do whether I use the stock 'chute or not.
  11. The nose cone is hollow and I saw a comment on TRF about the parachute blowing up into the cone and staying there. So, I went to the trash and pulled out an ad, crumpled it up, and plugged the hole.
  12. And, that's that!