You’re actually both correct, my smoke grains burn at 1/8”/sec under pressure and 1/32”/sec at ambient, I assume the commercial motor delays perform the same.You know that’ll stick in some poor rocketeers head, right?
For those who don’t know, it’s 1/32” per second.
Certification Pass or Fail
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Yes, that about right depending on the pressure and smoke grain formula. I calculated once that an Aerotech motor burned at 5/32” per second while the motor was burning. But the part that affects the ejection delay is that which burns at ambient pressure.
Off subject, but NFPA 1125 requires that ejection delays be measured at or corrected to sea level, even though none ever burn there in a rocket that’s flying vertically.
Given all the opinions that were provided here, any thoughts about how you would attempt Level 3 and what you would build for it?
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He already got his L2, with this flight.
Oops, thanks, I'll update the question above.
I have had no thoughts about attempting level 3.
loopy
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Wait...you had someone tell you that you shouldn't use a reload for your L1?
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How long ago was this inane statement made? I certified TONS of folks using reloads for their L1 flights back in the 90s.
-Slick-Ice
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Early Aug? I got my L2 in Sept.How long ago was this inane statement made? I certified TONS of folks using reloads for their L1 flights back in the 90s.
Rschub
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Lol, I had someone tell me that if I preferred to use Cesaroni motors then maybe HPR wasn't for me.
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Someone needs to have a talk with whomever recommended this to you. Reloads are so common place, now, that telling someone they shouldn't cert L1 with a reload is ridiculous.
rcktnut
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How long ago was this inane statement made? I certified TONS of folks using reloads for their L1 flights back in the 90s.
For us folks that certed back then(90's) we did not have much of a choice other than reloads.
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Not true. Vulcan had lots of single-use motors, as did/does Aerotech. I certed on single-use for L1, a Plasmajet. As a matter of fact, in the 90s, there weren't a lot of reloads, compared to single-use.
My guess is that it was either a time issue (late in the day flight) or no prior reload experience and the advice was for the sake of simplicity.
-Slick-Ice
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NAR Very specifically says
Level 1 High Power Certification Candidate must assemble the reloadable motor, if used, in the presence of a Certification Team member.
My oldest case is from 2/15/2000 SN 2455 . I only use the 29/120 or 29/180 in the Athena because the SU 29mm motor doesn't have enough ejection charge for this rocket.
Level 1 High Power Certification Candidate must assemble the reloadable motor, if used, in the presence of a Certification Team member.
My oldest case is from 2/15/2000 SN 2455 . I only use the 29/120 or 29/180 in the Athena because the SU 29mm motor doesn't have enough ejection charge for this rocket.
Based on what I have seen over the years... I'm not sure having the certifier watch the assembly would add any benefit in a lot of cases. I can also count on one hand how many times I've see a certifier watch the assembly of a motor for a cert flight. I saw one were they supposedly did and they did not stop a flier from putting in a CTI reload in a motor tube WITHOUT a case. As you can imagine... that went fantastic (for the spectators). The pilot was not pleased... but he was at least half to blame if not more.
Did he pass the L1 at the discretion of the certifier
No, but we were able to roast marshmallows and sing Kum bah Ya!Did he pass the L1 at the discretion of the certifier
loopy
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Building a reload only take a few minutes. I typically build my motors at the field for my flights. Just seems odd they would tell you not to use a reload for a cert flight.
loopy
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That I could understand...just seems odd someone would say to not use a reload.
SecondRow
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It’s for the same reason they say you should cert “low and slow” with 3FNC — to not overcomplicate the cert attempt. Under NAR rules the reload assembly has to be viewed by the cert team, which adds time and complication.
Both of my certs were as far from low and slow as you can get. Because I’m not interested in boring rockets, even for a cert. But both were on DMS because I didn’t want to waste my certifier’s time. He was already helping me out enough by taking his time to quiz me about my rocket. Who wants to watch someone else assemble a reload?
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First, I like that your certifications were done on the type of rockets that you enjoy flying. That's how it should be done.
As far as waiting while someone assembles a reload, I've done it many times. I don't mind it - it's part of the process. Pull up a chair next to me, I'm not going to stare intently as you do it, but I'm there if you have questions, I'll look over periodically to see how things are going, but I'm also doing something at the same time. The purpose is to make sure you do the assembly, not to watch over you like a hawk.
-Kevin
loopy
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Building a reload only takes a couple minutes, honestly, especially if you've built reloads for MPR rockets prior to your cert attempt. No reason to not use a reload, especially if the flyer plans on using RMS in the future, or has in the past. And the reloads are so much cheaper.
*EDIT TO ADD THIS*
Also, I'd rather watch someone assemble a reload than to have that person crash their rocket, certification attempt or not. I have no issue taking 5 minutes to make sure someone is doing it right and lowering the chances of a crash/cato.
loopy
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Exactly. I just kinda glance over and make sure the right o-rings are going in to the right spots, and answer questions.
If the certifying flyer doesn't have experience with reloads, then imo they shouldn't use them.
Heck, even experienced rocketeers have trouble with reloads that have destroyed their rockets.
This can also happen with su/dms, but at least with that, any flyer assembly error isn't a factor.
Heck, even experienced rocketeers have trouble with reloads that have destroyed their rockets.
This can also happen with su/dms, but at least with that, any flyer assembly error isn't a factor.
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I don't have a problem with using a reload for the first time on a cert flight. At the same time, I'll watch the assembly more closely and strongly encourage them to ask questions during the assembly process, if they're not sure of something.
-Kevin
Agreed, no need to have prior experience, especially with a cert mentor looking on and advising. I had loaded many 24/40 motors before I loaded the I284 for my L1, but there was nothing magically different about the latter. If anything, it was easier than dealing with taping the top of the slot on an E28. CTI's smaller motors look even easier, though I've yet to try them myself.
Nothing at all wrong with flying a disposable motor either, of course.
Troy3003
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I think having a cert mentor beside someone building their first reload would be one of the best times to start using reloads. Would seem less likely to fail and create a hazard or a damaged rocket.
rcktnut
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I would hope that the cert applicant could follow the directions for assembling the motor.
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