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  #21  
Old 05-20-2020, 01:57 PM
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ghrocketman ghrocketman is offline
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Gary-
Thanks for the explanation about Mohave Green not being sensible for 18mm.
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  #22  
Old 05-20-2020, 06:32 PM
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5x7 5x7 is offline
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Gary, here is a version 1 A3 (Original release) on the left and the revised A3, that has the case diameter nudged down. Note the difference in nozzle size which surprised me, later version being larger. Can you share what the design thinking was on this change?
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  #23  
Old 05-20-2020, 06:51 PM
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Jerry Irvine Jerry Irvine is offline
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The exit cone is surprisingly short so is under expanded. They might be slightly better off by increasing the expansion angle to >30 degrees, perhaps 45 degrees. Heck, make it a curved shape since it is SU ceramic!
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  #24  
Old 05-21-2020, 07:05 AM
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I don’t think the throat on those has been changed, it may have used an older version of the tool or there could be a bit of ceramic “flashing” in the throat.

Quote:
Originally Posted by 5x7
Gary, here is a version 1 A3 (Original release) on the left and the revised A3, that has the case diameter nudged down. Note the difference in nozzle size which surprised me, later version being larger. Can you share what the design thinking was on this change?
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http://www.aerotech-rocketry.com
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  #25  
Old 05-21-2020, 07:08 AM
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The nozzle expansion ratio is actually pretty close to optimum for the motor operating pressure, which is low by typical composite propellant model rocket motor standards.

Quote:
Originally Posted by Jerry Irvine
The exit cone is surprisingly short so is under expanded. They might be slightly better off by increasing the expansion angle to >30 degrees, perhaps 45 degrees. Heck, make it a curved shape since it is SU ceramic!
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Questions about this post or other topics concerning AeroTech products? Please contact AeroTech via phone, fax, email or our Facebook page at:

AeroTech Consumer Aerospace
Division of RCS Rocket Motor Components, Inc.
2113 W 850 N
Cedar City, UT 84721
435-865-7100 (Ph)
435-865-7120 (Fax)
http://www.aerotech-rocketry.com
http://www.facebook.com/pages/AeroTe...e/159005948954
customerservice@aerotech-rocketry.com
warranty@aerotech-rocketry.com
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