RMS Delay Drilling Help Needed!

[Lowpuller]

For example I have both:

G76-10
G76-7

No. 1. If I set the tool at 4 seconds does the following happen:

G76-10 becomes G76-6
G76-7 becomes G76-3



No. 2. If I set the tool at 8 seconds does the following happen:

G76-10 becomes G76-2
G76-7 becomes CATO



No. 3. Why is the 10 second delay element shorter than the 7 second delay element, different chemical make up?



No. 4. Why do some reloads require the masking tape on the end of the grain? I thought you needed to light grain and delay at the same time.



Thanks for any info you can provide.

 

[Steve Shannon]

For example I have both:

G76-10
G76-7

No. 1. If I set the tool at 4 seconds does the following happen:

G76-10 becomes G76-6
G76-7 becomes G76-3



No. 2. If I set the tool at 8 seconds does the following happen:

G76-10 becomes G76-2
G76-7 becomes CATO



No. 3. Why is the 10 second delay element shorter than the 7 second delay element, different chemical make up?



No. 4. Why do some reloads require the masking tape on the end of the grain? I thought you needed to light grain and delay at the same time.



Thanks for any info you can provide.

1. Yes, theoretically, but most instructions I've read say never attempt to shorten to less than four seconds.
2. Yes, forward burn through which does a real number on the inside of your rockets. I wouldn't trust the one that appears to be shortened to 2 seconds either.
3. I've never seen a faster (shorter delay time) be physically longer, but Aerotech's older delay matrix does list a standard and a slow formulation for their grains.
4. The more important thing in the process of lighting the motor is to light the forward end of the propellant grain. The combustion of the propellant will light the delay grain, but the combustion of the delay (with that much gap) might not ignite the propellant! In motors where there's a gap between the delay and propellant, if you slide the igniter all the way to the igniter there's a good chance you would just light the delay.


Steve Shannon

 

[dhbarr]

1b, 2a, & 2b are all very likely to burn up your rocket as Steve mentioned.

The only AT HDK with a different formulation is .750 slow, HDK 23.

g76-4 is HDK 15 @ 12/32" = 0.375in
g76-7 is HDK 25 @ 15/32" = 0.469in
g76-10 is HDK 19 @ 18/32" = 0.562in

HDK 20 makes it about 11-12 sec, HDK 21 around 13-14 sec. These are not certed, and therefore experimental.

https://docs.google.com/spreadsheet...cVEcUGcFRjfZyOA0cqzaaT_0/pubhtml?gid=90280042

 

[Steve Shannon]

1b, 2a, & 2b are all very likely to burn up your rocket as Steve mentioned.

The only AT HDK with a different formulation is .750 slow, HDK 23.

g76-4 is HDK 15 @ 12/32" = 0.375in
g76-7 is HDK 25 @ 15/32" = 0.469in
g76-10 is HDK 19 @ 18/32" = 0.562in

HDK 20 makes it about 11-12 sec, HDK 21 around 13-14 sec. These are not certed, and therefore experimental.

https://docs.google.com/spreadsheet...cVEcUGcFRjfZyOA0cqzaaT_0/pubhtml?gid=90280042

DHBarr,
So is there an HDK-23 with a standard formula and an HDK-23 with a slow formula? The Aerotech delay matrix at https://www.aerotech-rocketry.com/c...Flyers_Data_Sheets/aeroTech_delay_lengths.pdf only lists HDK-23 with the standard formula. Only a few delays are listed as slow and under the RDK column they're listed as n/a.
It's obvious you've done a lot of work on this. Your spreadsheet is very helpful. I've just recently had to develop a better understanding of delays so I appreciate your info.
Steve


Steve Shannon

 

[Lowpuller]

G76-10




G64-7, new unopened package, just got from AT about 3 weeks ago.

 

[tfish]

G76-10 https://www.aerotech-rocketry.com/c..._assy_dwgs/29mm_mr_rms/29-40_g76-10g_assy.pdf 10 sec delay is 0.562" long

looks like...G64 2 grain motors take shorter grains then the old one grain motors

G64-7 2 grain. https://www.aerotech-rocketry.com/c...sy_dwgs/29mm_mr_rms/29-40_g64-7w_2gr_assy.pdf delay 0.593" long
G64-7 1 grain https://www.aerotech-rocketry.com/c...s_assy_dwgs/29mm_mr_rms/29-40_g64-7w_assy.pdf delay 0.657" long

your delay looks..... not right

Tony

View attachment G64 size delays.pdf

 

[dhbarr]

HDK 22 is 3/4" standard delay
HDK 23 is 3/4" slow delay

https://www.aerotech-rocketry.com/u...-b849-b9d11cb57f3d_aerotech_delay_lengths.pdf confirms this; I think it may be just a newer version of the info. previously posted.

There is indeed a difference between the old and new g64w delay, I'll try and get that sorted by adding a line. My intent is to have complete coverage of every 29/40-120 load. I need to add nozzle size, grain length, and spacer tube color details someday.

If the 29/40-120 red retains the g71r moniker, I expect that delay to change as well. Maybe they'll work this time .

Finally, I anticipate that all 29/40-120's will in the next few years come in only one large delay, similar to the g138t. If the red reissue and new dark matter come that way, I'll be fairly certain.

 

[Steve Shannon]

HDK 22 is 3/4" standard delay
HDK 23 is 3/4" slow delay

https://www.aerotech-rocketry.com/u...-b849-b9d11cb57f3d_aerotech_delay_lengths.pdf confirms this; I think it may be just a newer version of the info. previously posted.

There is indeed a difference between the old and new g64w delay, I'll try and get that sorted by adding a line. My intent is to have complete coverage of every 29/40-120 load. I need to add nozzle size, grain length, and spacer tube color details someday.

If the 29/40-120 red retains the g71r moniker, I expect that delay to change as well. Maybe they'll work this time .

Finally, I anticipate that all 29/40-120's will in the next few years come in only one large delay, similar to the g138t. If the red reissue and new dark matter come that way, I'll be fairly certain.

I see what I did. The Aerotech matrix I posted lists no HDK delays, only RDK delays. I looked at the chart, found RDK-23, which has a standard formula, then I referred to it incorrectly as HDK-23 in my post. Thanks again.


Steve Shannon