Just a quickie post about the next three weeks' camp...
Tomorrow, I start teaching the first week of the Ivy Tech College for Kids model rocketry camp. Unlike last year, when I was actually living here in Bloomington, I had to make sure I brought or shipped myself anything I might need from home, which means I can't decide one morning to take a special tool or larger rocket to show off. I'll have fewer toys and props to play with, but I think I can still make a pretty good camp out of the minimum of tools.
One activity I tried last year was to do with altitude tracking. It can be hard to tell, from close to the launch pad on the ground, how high your rocket flew, especially if you are new or inexperienced. The kids are always surprised by how high the rockets actually fly (one girl said she thought it would only go about as high as the top of a street lamp). When you ask "How high do you think that went?" the kids will guess anywhere between 100 and 1,000 feet.
So, the package I sent to myself included an Estes Altitrak altitude tracking device, a Jolly Logic 2 altimeter, and a rocket with a payload section - the Estes Reflector.
Everything arrived more or less intact, except the Reflector.
Despite being well-packed, in the middle of the package, something crushed the body tube, causing a kink in the airframe and tearing the decal. It'll still fly, and I brought this particular rocket because it didn't exactly turn out as I'd hoped, so I was anticipating some damage. I just thought the damage would be from flight and landing, not shipping.
Week one is overbooked. The class was supposed to be capped at 10 kids. I'll have 14 the first week. I think it's great we have such interest this year, but 14 kids can be a lot to handle! On top of which, not everything on my shopping list was purchased, and we're going to run out of rockets.
Last year, I tried to get the Estes Alpha. It's a long story as to why that didn't happen, but I discovered that some kids had already built this rocket the previous year. The Alpha is a great educational first rocket, but I decided to go with something kids are less likely to have built - the Avion, from Apogee Components.
The Avion is also a great first rocket for classroom use, but there were a few things I hadn't realized. The first is that the nose cone comes in two parts and must be glued together with plastic cement, so I went out and bought a tube of that.
The shock cord - made of Kevlar rather than the typical Estes rubber shock cord - is a bit short.
|The display model. I'll lengthen this|
shock cord with an elastic leader.
Because Kevlar is less flexible than rubber, a short shock cord made of Kevlar can cause a jagged tear or zipper down the body tube of the rocket. This can happen when the delay of the motor is a little too long or two short, so that when ejection happens, the rocket is traveling too fast. The force of the parachute opening can cause the shock cord to rip down the body tube.
This shock cord is also attached to the motor mount. One of last year's rockets, the Quest Astra, had the same construction. Some kids had a hard time with this. So we'll be building this rocket using a paper mount. With the shock cord mounted near the top, the Kevlar will be much longer, and even if there's a zipper, it won't go any further than the paper mount. If you use elastic instead of Kevlar, you lessen the risk of a zipper even more.
Some people don't like the paper mount, and hate using sewing elastic. But a paper mount is easy for kids to construct, and most first rockets don't last long enough for it to be a problem.
Construction in class will be simple - bare balsa fins, paint but no primer. Still, I wanted to make a nice-looking display model.
And because I'm so fussy, I shaped the fins into airfoil shapes.
I did them quickly, so they're not perfect, but they're pretty good. The fins are 1/8 inch thick, pretty clunky for a rocket this size, so I figured it would be worth it. A simple rounding of the leading and trailing edges would have been easier and quicker. For most first model rocket camps, people avoid any fin shaping. But I've got these kids for a whole week, so we have lots of time to fill. Last year's kids liked rounding the fins "for higher altitudes." It used to be pretty standard practice in kit instructions to streamline fins, so it's not too hard for first-time builders to give it a go.
I tried finding some sanding sealer, but the local hobby shop didn't have any, and hardware stores only sell huge cans of the stuff. I tried using filler primer to fill in the wood grain, but with no sealer, the primer seems to have simply soaked in. So, my fins won't be as smooth as I like them. I used a whole can of Dupli-Color filler primer on this rocket, and I've still got wood grain.
I try to make this class inspiring. I want the kids to get something more than just launching a few rockets out of it.
Fortunately, this year's TARC winners were in about the age group of my kids. A $20,000 prize is pretty inspiring! The message is Do your math and science homework, and you may never have to pay for college!
I'm staying in an empty apartment this week, far from campus. Class starts at 8:30 tomorrow morning, and I have over a one-hour bus commute to get there. Lots left to prepare, so I'm going to leave it here for now.
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