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  #1  
Old 01-03-2019, 11:16 PM
DavidQ DavidQ is offline
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Join Date: Aug 2011
Location: Washougal Washington
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Default Building a BMS School Rocket

It's getting that time for me to plan on the rocketry class this year. (Assuming we can have the class, as the school is undergoing construction and the yard is mostly filled with heavy equipment. I'll proceed for now as though we can have the class.)

I just placed an order with BMS - gotta love them - and decided to test out their School Rocket Kit as a contender for the class. I want to see how it compares to the Apogee Avion (which we built last year), the Alpha (the year before), the Alpha III (before, before), Estes Generic (before even that), etc.

As a summary, I really like the BMS School Rocket's design for the class.


Like most rockets, the first part to build is the motor mount. Or the engine mount.


Unlike many rockets, the BMS rocket uses wooden centering rings. Only the thrust ring is a cardboard ring. (I think even that could be a wooden ring, if it simplified construction, since it's what I would do with my equipment at home. Heck, for the paranoid, two wooden rings could be used as the thrust ring.)

The cool thing is that the engine tube is pre-marked and pre-cut, unlike the Estes parts. The hole for the engine clip is already there, and one doesn't need to cut the slits the night before class so as to avoid having the 4th and 5th graders use knives. The markings for where the centering rings are there too, laser etched.

A feature that I liked is that the shock cord is just a long piece of Kevlar, like Quest does, that connects to the motor mount. If you notice my build, this is where I made a bit of a mistake at first, because I hadn't built this specific technique before. The instructions show to slide the centering rings on first, between the marked rings. But, it doesn't say to glue them. I glued them. Then, the shock cord is mounted, and finally the centering rings are to be glued at the markings. So, I glued the centering rings twice.

In class, I'll have the students put the shock cord on first, and then put on the centering rings.
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  #2  
Old 01-03-2019, 11:26 PM
DavidQ DavidQ is offline
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The fins are pretty cool too, since they are through-wall. I also used one of the classroom fin alignment guides that I make (BT50432) to keep the fins perpendicular to the tube. The slots cut into the tube will keep them aligned lengthwise, even easier than an Estes Alpha.


Another thing of note is that the launch lug is not a small 1/8" lug. It looks like a 3/16" lug. I've had students get globs of glue over the end, thus demonstrating the effect of lots of friction on the launch rod. Or, sometimes, they get shown quick field repairs like slicing off the back or front end of their lugs to remove that glob of glue.

In fact, the body tube has a small rectangle laser etched as to where the lug should be placed.

(Another in-a-rush oops of mine - I didn't push one of the fins in all the way when the photo was taken. I have since done so, and will check that my class does too. That, or I intentionally left it out a bit to show the through-wall feature. Take your pick.)
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  #3  
Old 01-03-2019, 11:38 PM
DavidQ DavidQ is offline
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The nose cone is balsa. Not just balsa where the eye screw can be tightened and stripped loose in the soft balsa. Instead, the nose cone comes with a hole drilled in, which accepts a hardwood dowel. This dowel has a small hole drilled into it which accepts an eye screw.


So, if glue is put into the hole in the nose cone, then the dowel can be pressed into the nose cone. If one paid attention and left the hole in the dowel sticking out, they have a perfect strong attachment point for the eye screw.


I almost made the mistake of putting the hole in the dowel into the nose. I think I'll have the students start twisting the eye screw onto the dowel so they see how it goes together. Then, when they are still attached, I'll have them start gluing the dowel into the nose. This will prevent the wrong end of the dowel from going into the nose. (If both ends of the dowel had a hole, this would be moot.)

The recovery is a streamer. It's a heavier mylar than I typically use on my scratch builds, so I like it.
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Old 01-03-2019, 11:44 PM
DavidQ DavidQ is offline
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Since no trifold is used to attach the shock cord, there is no glue on the inside just behind the nose cone. So, it's safe to assemble immediately, without the shock cord or streamer getting glued into the rocket. Which, kids like to do in their rush to see their assembled rocket.

No decals or paint, however. I'm fine with that, since I can bring in old stickers and let them decorate their rockets how they see fit. Felt pens work well too. It's amazing how 4th and 5th graders will gussy up their rockets.

I'll get the kids rocket stands too, since I also make those. When we built the Avion, which won't stand up, I was asked by kids for some of my stands that were on my rockets. We didn't encounter that with the Alpha rockets.
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  #5  
Old 01-04-2019, 12:28 AM
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BEC BEC is offline
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The BMS School Rocket is one of my favorites for kids as well....it teaches many skills you don’t get building a Generic or Alpha III.

In my experience the Kevlar shock cord will burn through in around 20 flights (I’ve flown the heck out of several of these).

They also handle breezy days well - with a straight boost as well as with the streamer recovery.

It is a 3/16 inch launch lug. I asked Bill about that and he said it makes it easier for young ones to get ‘em on the launch rod. In practice it works fine.

Also ask Bill about the optional payload section for another $1. It’s about 2 1/2 inches of BT-50, a coupler and ply disk. Great for carrying altimeters or other small payloads.
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Old 01-04-2019, 07:13 AM
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GuyNoir GuyNoir is offline
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The Fox Valley Rocketeers LOVE using the BMS School Rocket. Even with the pre-measured / pre-marked stuff, it's better for teaching actual craft skills than other kits.

Our only problem is getting the class sponsor to buy them. The kit's a bit more $$$ than others, and that usually stops them from trying it.
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Old 01-04-2019, 07:20 AM
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tbzep tbzep is offline
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It's also light, which means it needs an A8-5 instead of the bulk A8-3. I tried to get Bill to kit a 13mm motor version a long time ago. It would fly great on an A3-4T and those motors would be cheaper than a bulk pack of A8-3's (-$.26 each at ACSupply), which would help offset the higher kit cost.
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