#21
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It wasn't exactly no rules: 3. If a model rocket engine is constructed by an authorized Section of the NAR as a result of a program conducted and directly supervised by an adult instructor who has (a) satisfactorily received and completed credit for 15 semester hours of college chemistry or its equivalent at a recognized, established, and competent university, and (b) has registered his name and address and has presented his credentials to NAR Headquarters for approval, said model rocket engine shall be allowed to be operated at NAR test centers and in competition. However, full data on the motor shall be presented. This data shall included (a) thrust, (b) duration, (c) specific impulse, (d) composition of propellant, (e) method of preparation and loading, (f) combustion pressure, and (g) burst pressure of the motor casing. It will cost you $1.00 to read the whole thing .
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Bill Spadafora http://www.billsplumbing.com billspad@comcast.net bill@billsplumbing.com |
#22
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
#23
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If the NAR *said* that they are B14s (by way of certifying them as such), then they *are* B14s, no matter what an instrumented static test firing's data would indicate...just like the BATFE was able to say (until a NAR [and TRA, too, if memory serves] lawsuit forced them to accept chemical data over what they claimed was true) that ammonium perchlorate, an oxidizer, is an explosive. Isn't it wonderful to be a self-proclaimed authority of power? :-)
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
#24
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Safety equipment and arrangements (eye protection, heavy-duty gloves, having water handy, etc.) would be easy for users to set up. The drill bit could be made of plastic or (for better durability combined with greater safety, especially regarding static buildup) non-ferrous metal. A "Deluxe model" could even use a hand crank and gears, so that the motor (in its vented holder sleeve or frame) would have its nozzle facing sideways, displaced completely off the line of sight, so that if it did somehow ignite, the results would just be embarrassing. In addition: A spring-loaded drill chuck assembly (*or* having the motor spring-restricted at its front end [an aircraft-type drill bit with the set-able "depth collar" would stop the bit's forward progress at the prescribed drill depth]) would enable the exhaust gases from any accidental ignition to be vented to the atmosphere. But when used as recommended (drilling slowly on non-dry days, to avoid frictional heat and static buildup), such occurrences would be virtually unknown.
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
#25
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Follow the link. The dollar doesn't go to me it goes to the Heinlein archives.
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Bill Spadafora http://www.billsplumbing.com billspad@comcast.net bill@billsplumbing.com |
#26
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That's because they *were* still calling them B14 for awhile, the eventual shortening of the pintle notwithstanding. Though, from what I heard, the shortening wasn't entirely intentional; i.e. the pintle kept breaking off, and they would press a few hundred or thousand units before noticing. So they eventually decided that that was as deep as it needed to go, and made future pintles at the shorter length. I wonder what happened to the motors that the pintle broke off in. Sounds good, but still doesn't explain why the C5 came out from Centuri before the B8 (the same geometry). I should ask Ed Brown, but I'm lazy.
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Roy nar12605 |
#27
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It's easy to ask Ed. He logs in here regularly.
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Scott D. Hansen Ye Olde Rocket Shoppe - Your One Stop BAR Shoppe! Ye Olde Rocket Plans - OOP Rocket Plans From 38 Companies! Ye Olde Rocket Forum WOOSH NAR Section #558 |
#28
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I know. He's also a facebook friend. Surprising to some, I know, but modroc trivia is actually a low priority for me.
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Roy nar12605 |
#29
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Thanks for splitting this discussion into it's own thread.
kj |
#30
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Blackshire (and others), I am glad you are excited about pintle drills. I am offering to manufacture one who's design has already been engineered and validated. It is possible to verify the core depth and diameter and throat diameter with cylindrical drills then fab the special tool as a properly tapered and spark free material. Then anyone with the tool could mod a commercial motor into a special purpose FX motor.
As for EX numbers, that applies to shipping, and the shape of the core is not a factor in those approvals at all. Therefore even a modified motor can be reshipped presuming you have the approvals to either mail or ship rocket motors from that vendor. Motor modification rules are club rules not shipping rules. Before you mention NFPA, nobody enforces that until after an incident. Totally ineffective regulatory regime thank goodness. As you know, the entire club HPR universe is a mere 4500 people worldwide. MR only a few more than that. Tech Jerry Last edited by Jerry Irvine : 04-29-2015 at 09:53 AM. |
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