Monday, March 2, 2009

Launching Model Rockets

My oldest son is doing a science fair project on model rockets. He's done an enormous amount of research on the history of rocketry, the founders of the space program, and rocket design; and we felt it was appropriate to give him the experience of actually launching a model rocket. Coincidentally, the boy scouts have been hosting me to teach the boys things in preparation to receive their Space Exploration Merit Badge. Part of that is to launch a model rocket, and I managed to secure one for use by my son.

Last Thursday he started assembling the rocket. With his science fair project due the next Wednesday, we didn't have much time to do this, so he started gluing the rocket together Thursday, finished on Friday, and we went to launch it on Saturday. We also borrowed a launch pad from our very good home teacher.

We went to a local park that had a big fenced in area that will be having some construction done in it. There were signs posted "No Trespassing" but there was a gate that was open and it was clear that people go in there all the time. The day was windy and partly cloudy, which would be grounds to cancel any real rocket launch, but we needed to do it then or not at all.

We proceeded to set up about 2/3rds the way upwind of the length of the open space. We slowly and deliberately set up the pad and prepared the rocket for launching. I had found some instructions for constructing a device that could be used to calculate the altitude that the rocket reached, and took some time to remind all three of my children how they work. They stood off to the side and looked through the devices as I got set to launch the rocket. They looked pretty silly, and by their sober mannerisms, you'd've thought we were launching the space shuttle with seven live astronauts on board.

The countdown from 10 began, progressed, and completed and the rocket went skyward ... out of sight! We couldn't see it, let alone track how high it actually went. The kids were stunned, my oldest son in particular, who had estimated the rocket would only fly about 30 or 40 feet high (clearly his depth of experience was extremely shallow). We eventually found it on its way down, just outside the big open space into somebody's back yard. I was afraid that it was going to fall on top of their house, but it landed literally feet park-side from the house. We were lucky.

I told the kids to let it lie where it was, as I needed to pick it up and count the paces for how far away it had flown. 215 paces! At roughly 34 inches per pace, it had flown over 600 feet from where we were. The winds were indeed very strong. Our attempts to estimate the altitude went badly, and at best we calculated it went up just under 200 feet. I think it actually went much higher -- probably 300 or 400 feet, but we couldn't tell for sure.

The parachute had actually melted a little on that first launch. Apparently we hadn't added enough "recovery wadding" (we had used 3 of the toilet paper-like squares, crumpled up and stuffed in the tube between the rocket motor and the parachute). The parachute had melted enough that it couldn't fully inflate, but it seemed serviceable so we proceeded to the launch again. For the second launch, we added 5 squares of the wadding, moved the launch pad to the most upwind part of the empty space in the park, and then my son, himself, pushed the button to make it fly.

He absolutely loved being the one in charge. He counted down and skyward it went! My wife and I were off to the side; she was taking pictures, and I was attempting to get some video, while measuring the altitude (which again went badly, but returned nearly identical results). I paced it off again, and it was about the same distance away when it landed. The trajectory clearly went nearly straight up, though, then the wind took it and pushed it down-range as it floated down.

The third launch didn't go so well. The shock cord that attaches the parachute to the body of the rocket came apart, and the body and the nose-cone (still attached to the parachute) came down at different places, much nearer to the launch site and at a different angle from the launch pad. Either the wind shifted, or the launch just went radically off course.

Even though the parachute had melted and we had a "launch failure" on the third try, the kids had a great time. It was a very positive experience. I think I learned a few things, too, such as: don't try to figure out how high it flies while holding a camcorder while the rocket races downwind (and into the sun) right after pushing the launch button. Next time, I'll try to get video OR take an altitude reading (while standing much further away), and, of course, the kids can push the button every time.

It was so much fun. I remember as a kid not being able to participate in the rocket launches my science group was doing when I was in the third or fourth grade because we didn't have the money to buy the rockets. I remember that it was just one of many "expensive hobbies" that we couldn't afford, and I was so disappointed about it. Even at that young age I had a thing for the space program. Well, now I do the real thing (I even gave a "Go!" for launch a few years back!) and, well, I can afford it. My kids don't know how lucky they are ...

1 comment:

Doug & Laurel said...

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