Two D15 grains makes a ???

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The larger throat reduces the chanber pressure to compensate for the added burn area of the longer grain.
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For a slot-core motor,the area of the ends rapidly lessens in effect.

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Alcoa did :)

Since these are C-slots, the tape would be used to keep the alignment of the slots.
(Impakt) writes:
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.

On 30 May 2005 12:30:57 -0500, kaplow snipped-for-privacy@encompasserve.org.TRABoD (Bob Kaplow) wrote:
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Who said anything about HPR?? I said G33 - If I wasnt so lazy, I'd pull my G33 apart and check.
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Sigh..ok, I should have said Perth.
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No argument from me on that point.
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Ah. Ok. Well I know I have used multigrains (sounds like a type of bread) in my 29-40/120
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No offence to anyone, but I dont give a rats backside about NAR or TRA as they mean nothing here.
Thanks for all the info folks. Theres more to it than I thought.

(Impakt) writes:
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The G33 is an HPR reload. Check the cert data for it on the NAR web site.
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Sorry. I missed the ".au" in your post and didn't realize how far away you were...
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety. -- Benjamin Franklin Historical Review of Pennsylvania. 1759

On 31 May 2005 14:29:08 -0500, kaplow snipped-for-privacy@encompasserve.org.TRABoD (Bob Kaplow) wrote:
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I thought that HPR starts with J's and that G is the top end of MPR. Learn something new every day.
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THATS WHY I HAVE TO YELL! <grin>

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1. Generally, HPR starts with H motors (>160Ns). But there are some other scenarios considered HPR.
2. Any single motor with more than 62.5g of propellant (the case of the G33)
3. Total (combined) motor propellant mass > 125g (eg, cluster)
4. Total rocket weight in excess of 1500g
5. Motor with average thrust in excess of 80N (eg, F101, G125)
6. Total (combined) impulse > 320 N (eg, cluster of three G80's, which also exceeds the propellant mass threshold)
At a NAR or TRA sanctioned launch, any of these 6 scenarios requires NAR/TRA HPR certification. And the TRA is indeed present in Oz, so it could apply to you (if you attend a TRA launch)
In the US, items 3 and 4 require FAA waivers, so even if someone is running an independent launch, they must still abide by those rules.
Surely Australia has similar airspace rules and regulations, no?
Anyway, in the States, besides H and higher motors, there several other ways to be flying HPR.
Doug

On Wed, 1 Jun 2005 23:23:53 +0000 (UTC), "Doug Sams"
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In WA we have the 320N rule and the 1500g rule...civil aviation safety authority enforce thoes rules. I don't believe the others apply - at least they are not enforced by anyone. I think I have seen the 62.5g propellant rule, but no one pays any attention to that, including my supplier of motors who are fairly strict about the supply of motors.
We use the NAR rules as a guide, but we are not forced by anyone to adhere to them...only thoes specificaly stated by people like CASA.
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Well that would be no big deal. If I lived in the states I'd join NAR and get my level 3 but would fly mostly on F-H reloads. I doubt I would cluster (It costs me a fortune to launch my viper 3 - and thats only 24mm!).

In article
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Which is why the rules need to be changed to a firm 160ns, or 125g-240ns, threshold.
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If they burned simultaneously it's an E30
Dale Greene

(Impakt) writes:
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Actually an E30, since they both burn at the same time. AN E15 would be if you burned one, ThEN burned the second one.
What you made is essentially the grain in the e28 reload kit.
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
The problem with governments is that citizens need to keep them on a short leash; unfortunately the nature of the beast is such that governments can usually arrange it so that only they hold their own leash.

On 29 May 2005 08:14:12 -0500, kaplow snipped-for-privacy@encompasserve.org.TRABoD (Bob Kaplow) wrote:
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Cool. Thanks for the info.

I think this may be an equivalent way to determine what you had. Per the cluster table on the ROL site 2 D15 motors would give you almost 9 pounds of thrust or 100% of an "E" motor.
Three D15 motors would give you almost 13.5 pounds of thrust or 75% of an "F" motor.
Andrew Grippo
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According to my calculations this modification increased the motor chamber pressure to nearly 1,500 PSI, with a peak thrust of over 18 lbs and a burn time of just under 1 second.
Gary
In article cZIme.3269$ snipped-for-privacy@fe03.lga, Andrew Grippo at snipped-for-privacy@charter.net wrote on 5/30/05 12:30 PM:
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Nice motor for a 24mm casing! Does this mean we can only do this on EX days? I hope so, I need a good excuse to go to Black Rock.
Andrew
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Right, not a certified configuration. Plus, it's probably on the ragged edge of blowing off one of the closures at ignition.
See you at BR.
Gary
In article 61Lme.40484$ snipped-for-privacy@fe04.lga, Andrew Grippo at snipped-for-privacy@charter.net wrote on 5/30/05 2:51 PM:
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So in other words, optimal.
:)

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And a Blue Thunder F39 would not make the same?

Jim Yanik wrote:
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Different nozzle size, therefore different chamber pressure.
-Kevin

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The F39 doesn't have the cut down the center, increasing the burn area.
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety. -- Benjamin Franklin Historical Review of Pennsylvania. 1759