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29/40-120 HDK Chart : AKA g76 Is The Best

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dhbarr

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There, that title ought to be :hot: inflammatory :hot: enough.

1516242517181920XX21YYZZ2223
E16W2.047
E23T1.658
F22J3.357
F40W2.14710
F52T1.45811
G33J4.457
G53FJ1.75710
G64W2.14710
G71R1.54710
G76G1.54710
G138T1.114
0.3750.4060.4380.4690.5000.5310.5620.5930.6250.6570.6880.7190.750s.750


The 29/40-120 delay sequences had been nagging at the back of my mind for a while, and this weekend it all finally lined up.

As far as I know, this should be all of the reload and delay options ever offered for this case. g33 & g71 are OOP, and g138 requires an L1 cert in the US.

It seems apparent that a g76 with an hdk20 would be about an 11 sec delay ; hdkXX could be drilled from hdk21 ( 13-14ish? ) , hdkYY and hdkZZ from hdk22.

Hope this helps someone out! Remember that changing out the delay element makes it an EX load, but drilling per manufacturer's recommendations does not.

I wouldn't be surprised to see AT offering fewer HDKs in the near future, and further emphasizing the DDT.

Bonus: if you're using electronic deployment, the hdk22 and especially hdk23 should put out tracking smoke for a lot longer ; may hibachi the forward closure and/or other components though.
 
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Tonimus

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In regards to the bonus, if AT uses a 14 second delay in a G138 with a 1.1 second burn time, you should be safe with any total delay burn (including motor burn) under 15 seconds.
 

dhbarr

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In regards to the bonus, if AT uses a 14 second delay in a G138 with a 1.1 second burn time, you should be safe with any total delay burn (including motor burn) under 15 seconds.
As Rex R reminds us on the other thread, the burn rate of the delay element during the thrust phase is dependent on the chamber temperature and pressure. g76 w/ hdk21 is going to be about 13s, hdk22 around 16s.

The only wild card is any use & drilling of the slow.750 hdk23. You'd have to remove somewhat less than 1/32" per second, and we have no characterization other than two relatively low pressure long burning loads.

Edit: I picked it up on a re-read. As long as your total doesn't exceed 14-15s, you shouldn't cook your case. Great observation!
 
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MikeyR.Saginaw

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Lined up, except the table doesn't line up on my iPad. Any way to get a PDF?
 

emckee

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what's the difference between HDK 22 and 23? The bottom row (which I assume to be delay length) lists the first as 0.750 and the second as s.750... What's the "s" mean?
 

dhbarr

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AT has a 'standard' composition and a 'slow' composition. Not enough data points to extrapolate how slow is slow, but at a guess it's a similar burn rate at standard temperature and pressure, slower at low motor pressure.
 
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