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View Poll Results: Which motor do we need most ? | |||
B14-x (18mm) | 36 | 32.73% | |
D30-x (24mm) | 15 | 13.64% | |
D8-x (18mm like the old Cox D's, not some 20mm oddball diameter) | 14 | 12.73% | |
A8-0 (18mm) | 21 | 19.09% | |
1/2A3-0T (13mm) | 11 | 10.00% | |
C5-x (18mm) | 13 | 11.82% | |
Voters: 110. You may not vote on this poll |
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#21
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How did you ignite them? If you lit the BASE of the core instead of the top like FSI told you , they came up to pressure a little slower and seldom catoed for me.
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Did the chicken really cross the road, or did the road move beneath the chicken? Albert Einstein You Can't break the laws of physics but they can break you. Christine McKinley Dale Greene Mentor, Penn Manor Rocket Club VISIT SPAAR 2010 Calder Cup The Old West 2009 Calder Cup " Speaking the Truth in times of universal deceit is a revolutionary act. " George Orwell |
#22
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Tried at the top of the core as in the directions and in the middle of the core based on the advice of several others.
Middle-core ignition seemed to help the F100 but did nothing for the E60's. Kaboomed so often I used up my remaining 4-5 of them in the early 90's by gluing dowels to them and launching them "bottle rocket style". At least two of those blew up in "M-80" fashion as well. Total rubbish waste of $$$.
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When in doubt, WHACK the GAS and DITCH the brake !!! Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't ! Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY. ALL systems are GO for MAYHEM, CHAOS, and HAVOC ! |
#23
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Unfortunately too easy to do. I recall a Mirv Gryphon flying in an Imagination Celebration at a NARAM with what had to have been expired certification A10-0Ts. <rant> OK, my turn to yell a little bit from atop of that there soapbox. One side says that OOP motors should not be safety certified forever. They state some liability reasoning. The other side says that if I am allowed to fly a forty-year-old A8-3 which had been through who knows what kind of torture and waterboarding, then why should I not be allowed to fly a ten-year-old A10-0T which has been carefully stored and preserved? And if Estes comes through with their promise to resume production, then suddenly, my old motors are golden again? What we have now is the NAR expired motor testing program which I fully believe is a head-fake. Those who want to fly their old motors are happy because they can do so with a small amount of paperwork. Those who collect old motors are happy because the supply of them is being used up, making the stashes ever more valuable. The problem falls into the lap of those club officers who organize and run launches. Suppose that Roy's Scout had an errant flight, landing where it should not and causing damage or starting a bad fire. Insurance adjusters, upon discovering the uncertified motor, rules that the incident is not covered by the policy. My position is and always have been that faulty motors should be decertified for safety reasons. All other motors should remain certified regardless of their manufacturing status. Tripoli made a good move in allowing previously certified motors in their Research program. If only they can find a way for NAR-only members to participate... </rant> Bill |
#24
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If the motors are being flown under the Old Motor Testing Program, then the NAR insurance is in effect - there is no question about that. If you fly uncertified motors without the approval letter from the OMTP, then there is no insurance coverage. I'll be flying some C5-3 motors at our next two launches. I've got the printed letter of approval. So far, all of them from this batch have worked. Previous batches tested were not so good - especially the FSI motors.
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-Fred Shecter NAR 20117 (L2) Southern California Rocket Association, NAR Section 430 |
#25
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Here's the lie of the "top of the core" in their instructions: of course, they told you to put the thermalite all the way to the top, but that just holds it in. You put the clips on at the bottom, which is where the themalite lights, and it burns up into the core as a fuse. The first place it hits in the core is at the bottom. When I started having problems with F100's is when I started using wire-wrapped thermalite igniters, which were 1" segments of themalite at the end of a long section of wire-wrap wire. These were popular at the time for igniting composite motors, so of course they were placed all the way to the top of the core. Most of my F100's kaboom-ed after that, until someone suggested just using a Solar igniter with the paper tape section holding it in the nozzle. Worked like a charm. I just wish there was something I could do to get any of my F7's to not blow.
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Roy nar12605 |
#26
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Ejection was right at apogee on both flights, and the charge itself was softer so the motor didn't blow out of the thing. Both immediately started tumbling perfectly. I do need to try it on an adapted 1/2A3-4t.
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Roy nar12605 |
#27
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Wow- you had problems with F7's ?
I don't think I ever had one of those cato, they just would not safely lift any rocket over about 5oz. Less useful than the Estes E9...any rocket that would fly safely on them would go nearly into orbit with about zero hope for recovery.
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When in doubt, WHACK the GAS and DITCH the brake !!! Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't ! Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY. ALL systems are GO for MAYHEM, CHAOS, and HAVOC ! Last edited by ghrocketman : 09-16-2010 at 03:27 PM. |
#28
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It is obvious that Roy did not have OMTP paperwork because he was not aware the motors had expired certification. The range crew at NARAM also missed it. Insurance, except for any personal liability coverage that Roy may have had, did not cover his two flights. Fortunately for all concerned, the flights were flawless. One of the requirements for the testing program is to report back to the NAR whether the motor functioned properly. How much data do you think they have accumulated so far? I would think by now that we have plenty of indication that A10-0T and C5-3 motors are still safe to fly, but FSI motors are suspect. Bill |
#29
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The old Coaster motors were designed to be ignited at the bottom versus the top, as that's how they ignited their pyrotechnic skyrockets predecessors. The skyrockets were made with a 60-30-10 of BP, i.e "slow" BP while of course the later day Coasters, and FSI core burners were made with "faster" 75-15-10... This introduced a problem during ignition that evidently the Reese's failed to understand.
[disclaimer] I have no historical info that the Coasters or FSI engines were made with 75-15-10 BP versus any other possible formula. Estes used this formula as it produced the most energy per weight of any other combination. So my comments above are pure speculation. It's sem reasonable to me to assume that if it was goos enough for estes, it would be good enough for the other manufacturers. Trip Barber did some ignition test on B14's and FSI motors back in the early 1970's....he re-discovered the fact that the motor thrust profile could be changed depending on where the ignite r was placed in core burner type rocket engines, i.e the top versus the bottom. If you ignited them at the bottom, peak chamber pressure ie thrust build up much slower and much lower than if you ignited the versus the same rocket engine at the top where you got much higher initial chamber pressures and peak thrusts. These chamber pressures that were generated by igniting the motors at the top versus the bottom often resulted in shot nozzles because the chamber pressure was greater than the mechanical pressure of the nozzle paper casing interface. These higher chamber pressures also causing fracturing of the grains causing catos, and also shot grains..... I would also take an un-educated guess that Thermalite igniters are not idea for cored motors at the top at they have such ignition force that they could also cause the grain to fracture. Terry Dean
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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them. |
#30
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nevermind ahhh KP Burst composition Potassium Percholrate/Charcoal and Sulfur.... that probably would only result in an explosion...... it's called "burst" for a reason. Terry Dean
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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them. |
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