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  #1  
Old 05-19-2018, 03:23 AM
DavidQ DavidQ is offline
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Join Date: Aug 2011
Location: Washougal Washington
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Default An eggsiting build

In my rocketry class for 4th and 5th graders this year, one of the topics I wanted to cover was payloads. The planned launch part of that topic was to launch some egg lofters.


I had a few egg lofters that I build from scratch with my own designs. But, they used D engines, and for a school yard, that was a bit too much. I'm also a bit paranoid at the school, and prefer to launch kits, or clones of kits, since those designs are more proven. I just want to avoid finger pointing should an egg land in the wrong place.


So, I dug up one of my old kits, the old Estes Eggspress, kit #1996. Its of an old design with die cut balsa fins, being circa 1988 to 1991. It's been sitting around in mine, and like one or more ebay seller's, build piles for quite a while. One thing I liked about it is that the egg compartment is already yellow, and is large enough for padding and at least a medium egg.
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  #2  
Old 05-19-2018, 03:31 AM
DavidQ DavidQ is offline
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It's really not much of a challenge of a kit.

First, get the fins in place. I'm not using this rocket for competition, and am kind of concerned about launching it too high at a school yard, so I left the fins with blocky square edges. I did round the leading edge, because it just seems sacrilegious to skip that step.

Also, I've recently decided to give epoxy a try instead of white glue. I did still tack the fins in place with a dab of white glue at the front and back of the fin. This I let dry in place with a fin alignment guide.

After the fins were secure, I removed the guide, and applied a layer of epoxy squished under the fin and as a fillet. I've used epoxy for the fins long ago, and was unhappy with the finger ridges left behind around the fillet. So this time, I feathered the epoxy up the fin and onto the tube for a clean joint.

I also used 15min epoxy, because I've had unhappy experiences with 5min epoxy in the past. It just sets up too fast for a patient build.

At this stage in the build I discovered a surprise. That yellow nose cone was leaving yellow all over my hands, and all over parts of the kit. In the photo you can see yellow smudges on the parachute. I have no idea what was going on with the nose cone - maybe it was trying to set an example for all of that plastic floating in the Pacific gyre, by spontaneously disintegrating. Nonetheless, I did find that I could wash the nose with soap and water, and the yellow stuff would disappear down the drain, leaving a yellow nose cone that didn't shed. Any ideas what that was about?
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  #3  
Old 05-19-2018, 12:37 PM
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naslrogues naslrogues is offline
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Where did you get the fin alignment guide? I have been looking for those?
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  #4  
Old 05-19-2018, 01:09 PM
DavidQ DavidQ is offline
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I'm tooting my own horn a bit, because they are parts I make. They are here
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Old 05-19-2018, 01:11 PM
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naslrogues naslrogues is offline
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Great! I just ordered them!
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  #6  
Old 05-19-2018, 01:54 PM
DavidQ DavidQ is offline
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The motor mount is just a motor mount.

But, I tweaked the launch lugs a bit. The plans call for two risers, so the launch rod will clear the wider diameter of the nose cone. Atop those two risers would be placed two launch lugs.

I've found that 4th and 5th graders (or, as some may say aboot now, kids in grade 4 or grade 5), can have a tendency to break one lug when trying to lace the launch rod through two lugs. It's like they've never done this before and haven't yet developed the fine dexterity of lowering cardboard tubes onto long rigid wires.

So, I used some of my launch lug stock from BMS, IIRC, and put on one long launch lug straddling the two risers. Just get it started, and the launch rod can't miss.
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Old 05-19-2018, 01:57 PM
DavidQ DavidQ is offline
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At this point in construction, I finished the rocket. Close your eyes and imagine me filleting the fins and launch lug risers with epoxy, waiting, sanding, spraying filler primer over the body, waiting, sanding, painting the thing white. I didn't paint the nose cone, because that yellow was good enough, being all yolk colored (or coloured for some readers), and all.

That was a lot of waiting, and I don't have a temporal camera, so I didn't take pictures of the finishing.


But, I did take pictures of the finished rocket.
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