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  #1  
Old 11-05-2014, 09:15 AM
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Solomoriah Solomoriah is offline
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Default I've got a weird question

I was reading about dual burn engines, where the engine burn pauses, the rocket coasts upward, and then the burn resumes. It's supposed to allow a rocket to reach a higher altitude.

So my question... will the ejection charge of a standard engine ignite an upper stage? Or is the rocket doomed to tumbling and lawn-darting?

In other words, could I fly a 2 stage rocket with, say, a B6-2 initial stage?
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Old 11-05-2014, 09:43 AM
jbuscaglia jbuscaglia is offline
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Quote:
Originally Posted by Solomoriah
I was reading about dual burn engines, where the engine burn pauses, the rocket coasts upward, and then the burn resumes. It's supposed to allow a rocket to reach a higher altitude.

So my question... will the ejection charge of a standard engine ignite an upper stage? Or is the rocket doomed to tumbling and lawn-darting?

In other words, could I fly a 2 stage rocket with, say, a B6-2 initial stage?


I know that some research was done in the "old days". I remember reading articles in either Model Rocketry or Model Rocketeer magazines.

That may have been in the days of paper end caps, which could be easily removed. The few attempts that I've tried with motors with clay caps have been less than successful.
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Old 11-05-2014, 10:20 AM
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Solomoriah Solomoriah is offline
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That's what I was looking for... someone who had tried it. Thanks!
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Old 11-05-2014, 12:47 PM
Daddyisabar Daddyisabar is offline
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I have seen a second stage ignite from a single stage ejection charge after the delay. Not pretty. RSO was rather pissed that newby misrepresented motor used on flight card. Using a single stage motor as a booster motor is not a good idea. Think about it.
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Old 11-05-2014, 02:08 PM
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If you remove the clay cap and ejection charge as well, the burn-thru of the delay WILL ignite the upper stage.
I have successfully done it with a B6-2 and B4-2 several times in the booster, but it was at least 20-25 years ago.
The rocket I used was always an Astron Delta with an A8-5 in the top stage; it ALWAYS flew higher than with a B6-0 to A8-5.

One attempt was made using a Centuri Stilletto with a B14-5 in the booster and an A8-5 in the upper stage.
the sustainer was pointed almost straight down when the sustainer ignited, resulting in the expected and HILARIOUS POWR-PRANGG.
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Old 11-05-2014, 02:45 PM
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astronwolf astronwolf is offline
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Quote:
Originally Posted by Solomoriah
In other words, could I fly a 2 stage rocket with, say, a B6-2 initial stage?

No. Consider that if what you are asking about actually worked, everybody would be doing it already.
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Old 11-05-2014, 03:03 PM
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I will qualify the answer I provided above.
If using an UN-modified NAR approved B6-2 in a booster, no it will not RELIABLY ignite an upper stage.
If you are flying on private land/unsactioned launch, then yes, if you modify the motor, a B6-2 can EASILY be made to work.
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Old 11-05-2014, 04:39 PM
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Solomoriah Solomoriah is offline
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Really, astronwolf, don't behave as if I'm a newbie here. I was pretty sure the ejection charge would kick the sustainer out of line, but I was hoping to find someone with actual first-hand knowledge of the issue. jbuscaglia, Daddyisabar, and the venerable ghrocketman have all provided useful first-hand knowledge of the subject; your interjection was unneeded.

Heh. If nothing else, I figured gh was crazy enough to have tried it.
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Old 11-05-2014, 07:51 PM
jbuscaglia jbuscaglia is offline
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There's a article on delayed staging by Jay Apt in the February, 1974 issue of Model Rocketeer, if you can find a copy. NARTS has a CD-ROM with all the issues from the 1970's available for sale.
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Old 11-06-2014, 02:50 AM
matthew matthew is offline
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I've never flown a two stage rocket, so I've never really thought much about -0 motors. My understanding was the only difference was the delay element (or lack thereof), but from reading this thread there's other differences? Would someone mind clueing me in, please?
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