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A/V UFies: want to help make a rocket video? | by wwill | 2014-05-16 03:23:24 |
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how soon do you need it? | by radiowave911 | 2014-05-16 09:11:51 |
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A week, ten days, something like that. | by wwill | 2014-05-16 13:24:14 |
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Maybe just to instill a bit of respect... | by mtempsch | 2014-05-16 22:49:07 |
| I understand and even agree. And it will be |
by wwill |
2014-05-16 23:41:22 |
covered during the week. But not in the opening intro.
We're using "A" engines, low impulse 18mm x 70mm size, A8-3 rating (8 second burn, 3 second delay before ejection charge initiation).
With an A engine, that gives you 2.5 Newton-seconds of impulse, in this case for that 8 seconds. These are "Black Powder" engines, Potassium Nitrate/Sulfur/Carbon based fuel. That means that they accelerate FAST when coupled with a vehicle sized to make sense with that engine. The small rockets the kids will be building are made with this engine in mind, and I am expecting most of them to hit right at about 275 meters at apogee. Maybe as much as 300 meters.
Worst-case failure mode being an unbalanced rocket looping and flying at high speed close to the ground in an erratic and unpredictable fashion exposes the kids to a sub-100-gram projectile moving at a fairly high rate of speed for no more than eight seconds.
On the good side, the erratic flight path means it will be going much more slowly than if it was in flight trim and moving directly up. The weight, the size of the projectile (cross-sectional area), and the velocity make the most likely injury nothing worse than a bad bruise.
If the exhaust impinges on them, it might cause a 1st degree burn. It would have to -stick- to them for a fairly long time, a second or more. That isn't a likely outcome for this kind of thing, it's moving too fast and will likely not stop moving, making the contact time very short.
So, a scare, a bruise, and a small scorch. Not pleasant, but quite survivable. And EXTREMELY unlikely.
They'll be in a shallow depression area, outside the perimeter of the usual "looper" trajectory. I know that perimeter size pretty well, because I've had these things go bad before and I know just about how far one of these little piddly rockets will go when they're falling off their tails and going in circles instead of up.
Also, there is no, "You'll shoot your eye out!" issue, as ALL of them will be wearing safety glasses - as do I. (My normal prescription every-day glasses have snap-on side-shields to turn them into full safety-glasses. The lenses are up to that standard as well.)
There is one pair for each kid already available in the classroom. They came with a science kit which was used for several years when they still had a decent science program, before the "No Millionaire Left Behind" idiocy made testing the be-all and end-all of the academic world.
Since my wife is retiring, and we're LONG past the foolishness of needing to keep the fools on the school board happy, she decided that her last two years were going to be a protest against the idiocy. She is TEACHING the kids, not teaching the TEST. And lo, and Behold!! Her kids scored VERY highly on the standardized tests ANYWAY. It's why we're doing literature-based reading ("Charlie and the Chocolate Factory" currently) instead of those boring "leveled readers." They're making a big bulletin board display, with life-size paper cut-outs of all of the book characters. The kids are loving it. Scissors, glue, markers, messes to make, what could be better? (Oh, and they also get chocolate...)
And this is why she has me in doing science, as often as possible, HANDS-ON, instead of just the drudgery and pablum spooned out from the approved science text. It's no -wonder- why as a nation we're behind in science, if you've ever looked at the crap they're making MANDATORY for these stupid standardized tests. It's the most boring crap possible. Teaching science should rile kids up, it should be exciting and fun, it should show how the world around them is put together and how to make it MOVE when you need it to, and they should want more of it when you're finished with the lesson.
If you only go along with their text book, you'll have a hard time keeping them awake! Forget excited, they'll be snoring!
It doesn't all have to be smoke and bangs, either. I keep my bigger microscope in her classroom these days, and every year I go there and let the kids use it to look at things. Random stuff, like their shirt cloth, or a drop of water from the drainage ditch out back, some grass, a flower petal, some cheek cells scraped from inside my mouth. Whatever they can think of. They get more out of that short time than any number of pages of that groaner of a text ever could give them.
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