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Aerotech delays?

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MikeyDSlagle

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Just doing a little research. I have the delay drilling tool with the spacer and I have got the jist of how that works. But that is about all I have.

The H97J in AT 29/240 is the motor in question and so I will use that. Open Rocket says I need a 7.57 delay, not 100% accurate as I do not have my chutes and harnesses yet, but close enough for now. The available delays are 6 or 10. I only ever see H97J-M. So the 'M' is medium, correct? This motor has a (approximate) 10 second delay. I can take the drill, put the delay in the 4 second side, slide on the spacer and I will take 2 seconds off. Leaving me with an 8 second delay. Am I right?

Thanks folks,
Mikey D
 

Viking

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Correct. But please check the drilling tool, 4 second side should be shallow, 8 second side deep. Mine has the label reversed! :facepalm:
 

rharshberger

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Correct. But please check the drilling tool, 4 second side should be shallow, 8 second side deep. Mine has the label reversed! :facepalm:
Also make sure the tool is zero'd properly, by placing the delay holder on a flat surface, insert the drilling part if a gap is visible between the drill knob and the delay holder the bit is too long. If the bit doesnt touch the flat surface its too short, the bit is easily adjusted by loosening the set screw on the knob and moving the bit and re-tightening. Also make sure the bit is securely tightened in the knob or it can move during drilling (dont ask me how I know).
The 8 second delay would be almost perfect for the 7.57 OR suggested.
 

MikeyDSlagle

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Correct. But please check the drilling tool, 4 second side should be shallow, 8 second side deep. Mine has the label reversed! :facepalm:
Good to know, I'll check mine to make sure.

Also make sure the tool is zero'd properly, by placing the delay holder on a flat surface, insert the drilling part if a gap is visible between the drill knob and the delay holder the bit is too long. If the bit doesnt touch the flat surface its too short, the bit is easily adjusted by loosening the set screw on the knob and moving the bit and re-tightening. Also make sure the bit is securely tightened in the knob or it can move during drilling (dont ask me how I know).
The 8 second delay would be almost perfect for the 7.57 OR suggested.
Thanks, I remember reading something along those lines about properly zeroing the thing.


Simply drill 1/32nd inch for each second of delay you wish to remove.
1/32 is pretty precise. By the time I fumble around and get something measured and marked, it will not be on the money, 32nd wise. But good to know if I need to drill out an odd number.

Thanks folks, one less mystery to deal with come launch day.

If I wanted to fly without an ejection charge for whatever reasons, what would my options be for that? One option would be a plugged forward closure? Assume I don't have one, because I don't. Simply leave the charge out and fill the void where it should be with something like dog barf or grease?

Mikey D
 

rharshberger

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Good to know, I'll check mine to make sure.



Thanks, I remember reading something along those lines about properly zeroing the thing.




1/32 is pretty precise. By the time I fumble around and get something measured and marked, it will not be on the money, 32nd wise. But good to know if I need to drill out an odd number.

Thanks folks, one less mystery to deal with come launch day.

If I wanted to fly without an ejection charge for whatever reasons, what would my options be for that? One option would be a plugged forward closure? Assume I don't have one, because I don't. Simply leave the charge out and fill the void where it should be with something like dog barf or grease?

Mikey D
If no ejection charge is required I usually pack the charge well with dog barf and tape tightly.
 

DavidMcCann

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don't forget, delays are not precise at all. their burn varies. I wouldn't loose too much sleep over a second off optimum drilling.
 

MikeyDSlagle

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don't forget, delays are not precise at all. their burn varies. I wouldn't loose too much sleep over a second off optimum drilling.
Yeah, that is one reason (approximate values)I intend to use electronics for most of my launches in the future, where feasible of course. But like you say, I'm not gonna sweat 1 second too much.

I had intended for my level 1 attempt to use electronic deployment, but I haven't used electronic deployment before and not sure if I want my cert flight to be my first try with it. I do have a partizon I can use for a test rocket, but getting time to finish my level 1 rocket is tough enough, let alone get another set up for dual deploy. Sure the next launch is about 2 months away, but 100+ temps does nothing to help motivation.
 

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