AT Delay Question

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Lowpuller

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Example a G76 comes in a 4, 7 and 10 second delay

Whereas a G138T only comes in a 14A delay, I assume the A means adjustable

I have the RMS Delay drilling tool, can I only use it on an "A" adjustable delay? I have been under the impression I could use it on any RMS delay.

If I can use my delay drilling tool on any RMS delay, why are some RMS delays listed as adjustable?

Thank you for any clarification you can provide.
 

noffie79

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As I understand it, you can only use the delay tool on the adjustable delays. I could be wrong, but that's my understanding. I'm sure others will chime in.
 

Rex R

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tis my understanding that one should Not try drilling a 4 second delay, but the others are fair game.
Rex
 

qquake2k

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When I buy any RMS reload, I always buy the 10 second version (G64W-10, G76G-10 G53FJ-10, etc.). That way I can drill them to whatever delay I need for the particular rocket.
 

noffie79

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So, does the drilled side of the delay face aft or forward?
 

T-Rex

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The delays all drill the same. A 3/16" (or 1/4") diameter hole, drilled 1/32" depth for each second removed. (If you drill it 1/16 deep, you have removed about 2 seconds)
(Rex is correct, NEVER try to drill to a delay shorter than 4 seconds)

The "A" delays are part of a marketing strategy to compete with the popularity of the CTI motors. The theory being that in the end, the user didn't have to be worried about having purchased the correct delay. They would all be the "long" delay and the end user could just drill as appropriate (Just like CTI). This saves manufacturing cost & reduces packaging error. At the same time, it would in theory boost the sales of drilling tools. (This morphed into the EZ reload, but that is a different lesson in marketing)

The drilled side by convention goes toward the propellant grains. I have read in more than one place that it doesn't matter. The one time I tried it on the BP side (for the added space for BP) , my 5 second delay became a 2 second delay with a serious zipper. I can't say for sure that was the cause, but I will never do it again.
 

rharshberger

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The delays all drill the same. A 3/16" (or 1/4") diameter hole, drilled 1/32" depth for each second removed. (If you drill it 1/16 deep, you have removed about 2 seconds)
(Rex is correct, NEVER try to drill to a delay shorter than 4 seconds)

The "A" delays are part of a marketing strategy to compete with the popularity of the CTI motors. The theory being that in the end, the user didn't have to be worried about having purchased the correct delay. They would all be the "long" delay and the end user could just drill as appropriate (Just like CTI). This saves manufacturing cost & reduces packaging error. At the same time, it would in theory boost the sales of drilling tools. (This morphed into the EZ reload, but that is a different lesson in marketing)

The drilled side by convention goes toward the propellant grains. I have read in more than one place that it doesn't matter. The one time I tried it on the BP side (for the added space for BP) , my 5 second delay became a 2 second delay with a serious zipper. I can't say for sure that was the cause, but I will never do it again.
The type of reload will determine the orientation of the drilled hole to the bp,RMS- EZ's (and DMS motors) are drilled from the top and have a large hole in the powder well for that purpose, RMS and RMS-PLUS have a small hole in the powder well and if the drilled delay is placed with the hole facing the bp well some will leak into the cavity in the delay reducing the effect of the ejection charge.
 

pyrobob

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When I buy any RMS reload, I always buy the 10 second version (G64W-10, G76G-10 G53FJ-10, etc.). That way I can drill them to whatever delay I need for the particular rocket.
++1
 

dhbarr

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Having a small collection of appropriately sized HDKs + spacers is nice in a pinch, too.
 

jimzcatz

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As I understand it, you can only use the delay tool on the adjustable delays. I could be wrong, but that's my understanding. I'm sure others will chime in.
Yep, wrong. You can adjust any delay. 1/32nd inch is minus 1 second. Been doing so for 25 years.
 

jimzcatz

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tis my understanding that one should Not try drilling a 4 second delay, but the others are fair game.
Rex
This is 100% totally true. You might get away with minus 1 sec, maybe, just once.... See where this is going? Don't try it. The motor needs that grain to hold pressure while burning, if you cut it too close, instant cato!
 

T-Rex

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The type of reload will determine the orientation of the drilled hole to the bp,RMS- EZ's (and DMS motors) are drilled from the top and have a large hole in the powder well for that purpose, RMS and RMS-PLUS have a small hole in the powder well and if the drilled delay is placed with the hole facing the bp well some will leak into the cavity in the delay reducing the effect of the ejection charge.
Good point. My apologies for spreading not quite correct info....
 

dhbarr

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This is 100% totally true. You might get away with minus 1 sec, maybe, just once.... See where this is going? Don't try it. The motor needs that grain to hold pressure while burning, if you cut it too close, instant cato!
I wouldn't say CATO, but the ratio of nozzle throat to ejection touchhole is approximately the amount of fire that's going to come out each end. On a longer burn you'd likely slag your forward.
 

ksaves2

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The type of reload will determine the orientation of the drilled hole to the bp,RMS- EZ's (and DMS motors) are drilled from the top and have a large hole in the powder well for that purpose, RMS and RMS-PLUS have a small hole in the powder well and if the drilled delay is placed with the hole facing the bp well some will leak into the cavity in the delay reducing the effect of the ejection charge.
Found that out the hard way. Wanted to "perfectly" size a motor ejection rocket that had a shearpinned nosecone. Put an ematch canister through an empty motor casing with
.95grams of powder and shot it off. Nice ejection and rocket body jerked forward on the ground. Put the same amount in the motor well and rocket goes in ballistic. Charge fired nicely
but rocket failed to separate! I presumed too much powder leaked aft and blew out aft instead of forward. Did a rebuild, plopped all 1.38gms that came with the motor in and
haven't had a failure to separate on that bird since. Reason for failure. All that powder in the canister blew out forward as none leaked back with the sealed canister. It was not a faithful/valid reproduction of what occurs with motor ejection and is not a valid simulation. Kurt
 

Buckeye

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When I buy any RMS reload, I always buy the 10 second version (G64W-10, G76G-10 G53FJ-10, etc.). That way I can drill them to whatever delay I need for the particular rocket.
Hobby motors give the delay in seconds. HPR motors are labeled S, M, L. The user is expected to know that means nominally 6, 10, 14 seconds. I never understood that, but it fits perfectly with Aerotech's confusing naming conventions.
 
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