AboutJames Bell Expertise I am a member of Tripoli Rocketry Association, and am certified to fly hi power rockets. I can answer questions anyone may have about design, materials selection, stability calculations, motor selection, altitude and performance predictions, and parachute and recovery options.
Experience I make my rockets from existing kits or parts readily made through commercial channels. I do NOT make my own motor propellants (they are challenging enough even for the companies that do this for a living), and I do not advocate making rockets using "typical household item" such as paper towel rolls.
Question QUESTION: Hi James. I did some more searching last night and finally came across my answers about how to set up the black powder ejection charge. I don't recall what I finally used as search terms in "Google", but I got to Info-central.org and Rocketry Planet and learned about how to make the charge and how to wire it to be triggered.
There were basic ideas like making a cup out of plastic wrap (with an electric match taped and taped really tight), PVC cups with tape on top, to reuseable items like the "No Match ejection system".
I read that the black powder comes in different qualities (3Fs - 4Fs, etc), and that it's better to make a charge a little too strong than not enough (damage to the former can be mitigated by a longer shock strap... to a degree).
So, I think I got enough basics that I can go from here on my own: purchase BP at a gun store or something, figure out a containment device, ignition method attached to the containment device, timer/altimiter connected to ignition method...
If I'm off target with this stuff, let me know.
Thanks. --Glenn
ANSWER: Glenn -
You are pretty close on your solution. I prefer FFFg (3Fg) powder, but 4Fg works well also. I used an altimeter that charged a capacitor, releasing all its energy at once. I used a large flash bulb with long leads. I take the charge of black powder and wrap it in a small piece of plastic cling wrap. Just enoug to hold it, but not too thick. I wrap and tape the powder package around the flash bulb. I would imagine an electric match would also work. All you need is to have the black powder contained so the match can ignite all of it at once. I've never experimented with reusable plastic PVC cups. The match/bulb goes off, the powder burns and expands through the plastic wrap and the expanding gases blow off the nose cone.
If you don't have any electronics for your altimeter, I would suggest you look at one of the Adept systems (http://www.adeptrocketry.com/).
Sincerely,
James Bell
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QUESTION: Just writing to say thanks. I'm asking for a Level I cert rocket for x-mas: a LOC Weasel or Legacy, or something similar that's not expensive and RocketReviews.com suggests a fairly straightforward assembly... so the dreaming begins! The dual recovery issue is a dream I'd like to realize later next season, but am starting planning now.
(what are your thoughts of the LOC as a L-I Cert rocket? Price, assembly, durability are all factors)
I've read the Adept website, and like the website and products. I also like the looks of the Perfectflite altimeter because it's a recording altimeter that's also dual event. I like the idea of the recording altimeter, Adept doesn't seem to have one that's also dual event. I've read a ton of reviews of both, and Adept/Perfectflite seem like the most reliable ones in that price range. Same with their timers/stagers if I ever need one.
Anyway, thanks again for your time. Maybe someday I'll be experienced enough to help others answer questions. Keep up the great work. --Glenn
Answer Greetings again, Glenn -
You seem to have your path well plotted. I flew a LOC IV for my Level I cert flight. I didn't have any electronics in that rocket, it was very basic. I have an Adept ALTS2-50K altimeter. It records maximum altitude and can fire two deployment charges ... one at apogee and one at 750 feet. It works great and I have a rig set up where I can quickly move it from one rocket to another, so I don't have to get multiple electronics.
