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Build session report, Troop 232, Lino Lakes (10/16/2010)

On Monday I attended the weekly troop meeting of Boy Scout Troop 232 at the Living Waters church in Lino Lakes. I helped 9 scouts built various Level 1 kits from a Custom Rockets Variety Bulk pack. It contained various SL 1 kits based around BT-50 (24mm) size body tube, 18mm motor mount, 4 fins and 12 inch chute. They are all similar to size and shape of an Estes Alpha (with an extra fin!).

I did not pick the kits. The Scout Master had ordered them. While the kits from Custom are great SL 1 rockets, they are tough to finish in a 60-90 minute build window. The following problems arise in trying to get these done that quickly:

1. Custom still has die-crunched fins. This means the kids have to finish cutting them out.
2. Die-crunch fins require more sanding than laser cut fins
3. It takes time to build the 18mm motor mount for a BT-50 rocket. These mounts use 2 centering rings, motor clip and motor block. You have to build it and then let it dry long enough to slide it into the main body tube w/o moving the centering rings on the motor tube.
4. Custom has you assemble the 12 inch chute in the same manner as traditional Estes parachutes (cut out the plastic, cut and attach the shroud lines)
5. These are 4FNC vs 3FNC models. Takes time to attach that 4th fin
6. You have to cut out body tube marking guide and shock cord mount (Estes type paper mount glued to inside of body tube)

I knew what the kits were going to be ahead of time so I did the following to try and speed things up a little bit:

1. I pre-cut 12" lengths of Kevlar shock line. I had the scouts attach the sock line to their motor mounts and the supplied elastic shock cord a-la Quest. This avoided the need to cut out the shock cord mount and glue it in.
2. I brought along several of the yellow plastic tube marking guides from the Estes tube marking and cutting kit. I had 3 to bring. This was faster than cutting out the paper tube marking guide, wrapping and taping it to the body tube and marking from that.
3. I got a 36 inch length of 3/8" Plastistrut V-channel and cut it into 4" lengths. These are great to use to mark the fin alignment lines on small body tubes. They are self-aligning. I didn't have enough of the Estes tube cutter/markers to go around so this was quick and easy.
4. I used VCP (it was handy) to print out fin alignment guides for BT-50 based, 4FNC rockets with 3/32 fins. I glued these to pieces of cardboard. I cut a couple of the guides out myself and got some of the adults at the troop meeting to finish cutting them prior to the start of the meeting. These are great bot both holding the fins on the rocket and keeping then perpendicular to the body tube.
5. I use fast drying yellow glue and kept reminding the boys to apply THIN layers of glue to let then set faster. I also had then pre-glue both the fin roots and body tubes right after the tube marking was done. Then when they applied the fins they reglued the fin roots, waited for a minute or so, attached and held for 30 seconds, and the fins were tacked into place.

Even with the above, I think only one of the boys building 4FNC kits finished. All told we only have about 65 minutes of build time during the troop meeting. However, I let all the boys take home the plastistrut tube markers and the cardboard fin alignment guides. My attempts to 'save time' helped overall but there are things I realize I could have done differently that would have saved even more time:

1. I saved time by the boys not cutting out paper shock cord mounts. I lost time diverging from the instructions to explain the alternate process of attaching the Kevlar line to the motor mount and elastic shock cord. Next time, I will just print and cut out a bunch of paper shock cord mounts and bring those. Saves the cutting time, the boys don't cut out parts of the instructions and I don't have to worry about Kelar line.
2. I saved cutting time using the Estes fin marking tools but lost time because the boys had to sharer a couple of them. Plus, I was again diverging from the instructions. Next time, I will just print out fin marking guides using VCP. Between #1 and #2 all of the paper cutting time gets eliminated and we can just follow the instructions all the way thru.
3. Attaching 4 fins takes more time than 3 fins. I would print out both 3-fin and 4-fin marking and alignment guides and suggest they build the rockets as 3FNC.

Despite not quite finishing, the boys all seemed to have a great time building. It was obvious this was the first glue-together model of any type (would, plastic, ...) that some of them had ever tried to assemble. We plan to fly the rockets on Nov 6.

[Buzz McDermott]

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