Comments on: More Erosive Formulas http://www.tdkpropulsion.com/2008/12/more-erosive-formulas/ Research 2.0 Fri, 14 Oct 2011 04:22:15 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Geoff Huber http://www.tdkpropulsion.com/2008/12/more-erosive-formulas/comment-page-1/#comment-237 Geoff Huber Wed, 23 Dec 2009 00:55:51 +0000 http://www.tdkpropulsion.com/?p=63#comment-237 David, I see you share my obsession with the double taper core. My latest one was flown at Balls 2009. 4" dia 0.125 wall case bonded O motor. ~25,000 ns (probably 28,000 due to increased ISP in a motor this size. My core was (from memory) 1.5" dia at the top, tapered to 1.1" ~18" from the top and opened up to 1.3" at the nozzle. Nozzle throat was 1.125" I made a spreadsheet to calculate the mass flux every 1/10 of an inch the legnth of the core. I set it up so that I could plug in 4 numbers (top dia, mid dia, bottom dia and mid distance from top) and thus play with the core to see what it did with to the mass flux. The core was 54" long and the mass flux dropped as I raised the center choke point up higher. While the interstage coupler failed, the motor worked. Geoff David,
I see you share my obsession with the double taper core. My latest one was flown at Balls 2009. 4″ dia 0.125 wall case bonded O motor. ~25,000 ns (probably 28,000 due to increased ISP in a motor this size.

My core was (from memory) 1.5″ dia at the top, tapered to 1.1″ ~18″ from the top and opened up to 1.3″ at the nozzle. Nozzle throat was 1.125″

I made a spreadsheet to calculate the mass flux every 1/10 of an inch the legnth of the core. I set it up so that I could plug in 4 numbers (top dia, mid dia, bottom dia and mid distance from top) and thus play with the core to see what it did with to the mass flux. The core was 54″ long and the mass flux dropped as I raised the center choke point up higher.

While the interstage coupler failed, the motor worked.

Geoff

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