Aerotech RMS motor delay questions

[SRBell]

Got half a dozen Aerotech G76-4G motors. For a lot of the rockets, like the MiniMagg a 4 sec delay is perfect. But some of the kids smaller rockets need maybe 7 to 10 sec delay according to Rocksim. So we bought a delay kit, HDK-19 Delay parts to make E16-4W, G76-10G. So with a number of issues due to drilling I thought I'd ask. We had the Minimagg with a HDK-19 delay drilled at 6/32 (3/16) which should have taken 6 seconds off. Not sure the actual time, but the rocket hit the ground and then the chute ejected. My youngest son's rocket, he was pretty sad. I would say a good 10 seconds lol! Rocksim puts 10 sec ejection on the ground as well. Drilled hole was facing the grain as well. I'm a little leery about drilling now lol! Could it be a bad delay? Also, why would a E16 be a 4 sec delay and a G64 be 10 sec ? Is the E16 case pressure higher or burning hotter?

 

[tfish]

The rocket flying with the E16, won't go very high. It will have a short coast time to apogee,,4 seconds(?)

the same of similar rocket flying on the G76...which has 118 newton Seconds n/S, compared to the E16, which has 37.7 n/S. The rocket will coast much longer, to a much higher apogee will need a longer delay. (7-10 sec)

Tony

 

[dhbarr]

Yes, taking off 6/32 or thereabouts should have been about right for turning an hdk19 into an hdk15 or so.

Did you use the tool or a hand-twisted bit; and what width?

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

 

[dpower]

Got half a dozen Aerotech G76-4G motors. For a lot of the rockets, like the MiniMagg a 4 sec delay is perfect. But some of the kids smaller rockets need maybe 7 to 10 sec delay according to Rocksim. So we bought a delay kit, HDK-19 Delay parts to make E16-4W, G76-10G. So with a number of issues due to drilling I thought I'd ask. We had the Minimagg with a HDK-19 delay drilled at 6/32 (3/16) which should have taken 6 seconds off. Not sure the actual time, but the rocket hit the ground and then the chute ejected. My youngest son's rocket, he was pretty sad. I would say a good 10 seconds lol! Rocksim puts 10 sec ejection on the ground as well. Drilled hole was facing the grain as well. I'm a little leery about drilling now lol! Could it be a bad delay? Also, why would a E16 be a 4 sec delay and a G64 be 10 sec ? Is the E16 case pressure higher or burning hotter?

So to be clear, you bought G76-4 motors, then instead of using the included 4s delay, used a HDK-19, which would make a G76-10, then drilled 6/32" to make a G76-4? The Mini-Magg was launched on this G76? Did the rocket fly straight up, or did it weather-cock (fly at an angle) into the wind?

 

[rcktnut]

So to be clear, you bought G76-4 motors, then instead of using the included 4s delay, used a HDK-19, which would make a G76-10, then drilled 6/32" to make a G76-4? The Mini-Magg was launched on this G76? Did the rocket fly straight up, or did it weather-cock (fly at an angle) into the wind?

That's the impression I'm getting also, which doesn't make any sense to me unless the reloads are very old and OP wanted fresh delays.