Thread: Engine Survey
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Old 04-15-2012, 01:24 PM
Carl@Semroc's Avatar
Carl@Semroc Carl@Semroc is offline
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Join Date: Mar 2005
Location: Knightdale, NC
Posts: 1,470
Default 29mm engines

I am still working on the Ex numbers and decided to put the 29mm back in. It turns out our current machine will make 29mm engines up to 3.25" long. It will take a totally new machine to go over 3.25" (bummer!)

I had missed the fact that Centuri bought the Coaster engine machine that made 1.0625" (27mm) x 8" long engines and sold them for a short while and then changed over to 1.125" (29mm) x 7.75" and 4.75". There was quite an evolution over a few year period.

1.062" x 8" F11-3 49N-sec It and 54 sec Isp (low grade BP) same as Coaster 20lb

1964 1965 1966
1.062" x 8" F11-3 49 N-sec It and 54 sec Isp (still low grade BP ) called Hercules
1.062" x 5" E3.3-2 29 N-sec It and still low Isp called Atlas

1.125" x 7.75" F14-4 37 N-sec It and 65 sec Isp ( higher grade BP) now called MINI-MAX 'PB'
1.125" x 4.75" E3.5-4 25 N-sec and 64 sec Isp now called MINI-MAX 'PB'

1.125" x 7.75" F94-4 52.5 N-sec It and 85 sec Isp (highest grade BP) (metric labelling)
1.125" x 4.75" E7-4 25 N-sec and 54 sec Isp (large throat)

1.125" x 7.75" F16-4 57.8 N-sec It and 94 sec Isp (highest grade BP) End burning
1.125" x 4.75" E15-4 39.6 N-sec and 83 sec Isp

replaced by Enerjets, new case sizes are 1.125" x 3" and 5"

The LT-110 was the engine tube for the early Coaster engines and was replaced by the LT-115 for the 29mm engines and Enerjets.

The new engine survey shows some decision points. The 3/4E21 at 26 N-sec is the largest with 30.0 g or less of propellant. So all the 29mm engines in the 2.75" long casing would be able to be mailed via USPS ground with no additional charges. The full E20 at 3.25" and the 3/4F19 would have to be shipped with HAZMAT. The 3/4F19 at 62.5 g of propellant would be the largest we would ever make. The BATFE discussions we have had made us decide to never go more than 62.5g. We would have to sell them to certified users only, HAZMAT fees, and track each engine from cradle to grave. As long as we keep each engine under 62.5 g, we only track them until they are produced. Once they are packed in the casings, the BATF has no further interest in the BP or the engines.

Let us know what you think about the 29mm engines.
Carl McLawhorn
NAR#4717 L2
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