I am now learning the art of making my own electric matches. The point being that you dip the electric match into pyrogen* to create an igniter. The igniter is slipped into the core of a pyrodex pellet which is then placed into the heart of the rocket motor. When the pyrodex pellet is ignited it simultaneously builds the pressure in the combustion chamber, preheats the fuel grain, and burns the fill hose away from the injector which allows the nitrous oxide to make its contribution to the magic of thrust-producing science.

Very. Loud. Science.

*From the Rocketflight Products website comes this description of their Magnelite Igniter pyrogen:

Once ignited the pyrogen burns for approximately one second at a temperature around 5,400 degrees Fahrenheit! Amperage requirement for successful ignition is 5 to 6 amps at 12 volts DC per igniter.

Science, baby!!!

Posted by: Ted at 05:38 AM | category: Rocketry
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Yesterday was our regularly scheduled rocket club launch out at Great Meadow. Besides the usual sport launching (for fun), there was a regional contest event scheduled and the sky was full of rocket gliders, helicopter recovery rockets and more.

I almost didn't go because I'd worked for most of the week on converting one of my high power rockets for hybrid-engine flight. On Friday night about 10pm I ran into "one more problem" and got frustrated. Rather than try to force things, I just decided to not take anything but small model rockets to the launch. Even then, the weather forecast called for pretty stiff winds and I'd heard that there were several cub scout packs due to attend. Not conducive to improving my mood.

What the heck, I went anyway. The winds were brisk, but not insurmountable, the hordes of cub scouts didn't materialize (or they were the smallest horde on the planet), and I had a good time.

Two other rocket-bloggers were there. Dick Stafford flew his usual assortment of unusual rockets, including his legendary "hat of death", his too-new-to-be-legendary-yet "Yamikazi" and a couple of models made completely out of folded paper. Rich (of Vertical Force Rocketry) was there with his family. Hopefully he'll make it out to the launches a little more often this year. It was good to see them again.

There were several high-power flights made, and towards the end of the afternoon a wedding was taking place up the hill at the Summer House. We all got a chuckle after one particularly roaring flight, when we could hear the wedding guests do a collective "holy shit!" Someone imagined that the Bride's mother was probably having a conniption over our activities, and I impersonated the Groom at the alter: "Whoa... huh? Oh yeah, I do."

I remembered the sunblock, stayed hydrated, flew streamers for recovery because of the wind (and still had long walks to recover most everything), and worked a couple of hours as safety check-in dude. As usual, it was big fun.

Here's what I flew:

1. Vampyre - A10-3T - Original design ringfin. Perfection.

2. YJ-113 - A10-3T - This little beastie is a downscale of the Estes Yellow Jacket, and it's about 7" tall. My Level 2 certification rocket is an upscaled version of this same rocket, about 7' tall. Like all Yellow Jackets, there is a tendency to severely over-engine the rocket and this time was no exception. I didn't have a 1/2A engine so I went for the full A and almost lost it due to extreme speed and altitude. I love this design.

3. Groove Tube - C6-5 - Centuri classic tubefin design from the 70's. Big motor, recovered on twin streamers because of the wind, but still had a long walk because of the drift. With all those tube fins, she gets her nose into the wind and acts like a glider.

4. Zen Doggie - B6-4 x3 - I haven't flown this rocket a whole lot over the years because it is sometimes marginally stable. The fins are rather small, and there is a gap between the front fins and rear fins. It looks cool, but I suspect that the gap is causing the air to be too turbulent over the rear fins to be useful, which makes the rocket squirrelly and not too safe. Couple that to the fact that it's a three-engine cluster, and there's a whole lot of weight at the back end, which is exactly where you don't want it. I've added nose-weight and tweaked the design some, and today I decided to try something different. I put a layer of masking tape between the two sets of fins, effectively turning them into one fin surface, thinking that it might solve the stability problem. Oh yeah. The flight was perfectly straight, so I'll be making this a permanent mod. Rich had a great idea about using clear plastic packing tape, so the fins still look split, but behave like a single fin.

5. Sparrow - A10-3T - This was my original "born-again rocketeer" rocket, and I fly it once a year just for old time's sake. It's a tiny Estes kit and it's battered and worn, but she made yet another flight without falling to pieces.

6. DTR-1 - B6-6 - Great flight from this original six-fin design.

7. Dynamic Carrier - B4-4 - I've done this cool Custom Rockets kit up as an alien space ship. She looks great and flies great too. Perfect recovery.

8. Saturn III - A10-3T x4 - four-engined original design, it looks Saturn-ish. All four motors lit, and at ejection it sounds like popcorn as all the ejection charges go off within a split second of each other. Great flight, long drift again.

That was it for me. No damaged rockets, no lost rockets, no sunburn. Good day.

Posted by: Ted at 07:30 AM | category: Rocketry
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1 I couldn't stay long cause the kids get restless. Plus, other than the 1 reload I had for the Mustang I forgot a whole box of stuff that I needed

Posted by: Maelstrom at June 11, 2007 12:38 PM (V0o94)

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