Safest Arming Sequence

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mccordmw

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Maybe I'm overthinking this. I'm putting together my checklist, and I'm at the part where I'm loading the rocket on to the rod. I keep going back and forth on arming order.

1. arm avionics deployment devices for drogue and main
2. insert motor igniter

Isn't inserting the igniter dead last always safest?

-- OR --

I've seen checklists with this order...

1. insert motor igniter
2. arm avionics deployment devices for drogue and main

If I arm first and the motor accidentally ignites while inserting the igniter, at least there's a chance the drogue/main will pop and keep it from dangerously coming in ballistic.

However, do I really want to have my head near the motor with powder charges above armed? Could they accidentally deploy and cause an accidental motor ignition? What are those chances?
 

FredA

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Depends on how easy it is to insert the igniter.
If you need to jostle the rocket, then I install it before arming and keep it shorted and not attached to the launch system, then arm, then connect the igniter.
If it installs easily, then it is installed, and connect as the last step.
 

mccordmw

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Depends on how easy it is to insert the igniter.
If you need to jostle the rocket, then I install it before arming and keep it shorted and not attached to the launch system, then arm, then connect the igniter.
If it installs easily, then it is installed, and connect as the last step.
Thanks.

Here is my situation. Avionics are both Eggtimer Quantums for primary and backup. Those are wirelessly armed. The motor is a CTI I242 2 grain 38mm motor. Doesn't look difficult to insert an igniter.
 

rharshberger

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Most important is making sure the electronics are armed and ready before hooking up igniter. I prefer arming my electronics then inserting and connecting igniter when possible.
 
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DavidMcCann

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Electronics before igniters Unless unavoidable, which should be fairly rare.

on a safety scale, charges popping by your head, maybe, is safer than a sure ballistic return.
 
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mccordmw

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Electronics before igniters Unless unavoidable, which should be fairly rare.

on a safety scale, charges popping by your head, maybe, is safer than a sure ballistic return.
That was my assumption. I don't want bystanders endangered by a ballistic return. Plus, I'd prefer my rocket coming home intact. I still see a lot of checklists with this reversed. I'm surprised there isn't a highly visible document on NAR that has a prescribed order preferred.
 

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Arm

Insert igniter

Check leads to make sure they are not energized

Connect

At a launch last year as I hooked up the igniter leads to a CTI H195 if remember , the key was still in and cheap controller that we were using temporarily and this instantly ignited the motor. I had no hair to burn off but it did burn all the hair off my arm and the top of my head, and I couldn't hear out of my left ear for several hours, very scary. The altimeter was armed and rocket flew and recovered fine. This controller had a bulb for continuity which is enough to fire a CTI igniter, a lot learned that day for me.
 

MikeyDSlagle

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I've never flown with electronics but if your rocket has to be leaned over to insert your igniter, wouldn't you do that first, then arm electronics? I'm sure we all have seen those long igniters that require a stick to get into position. Seems like raising the rocket up to ready position could cause the electronics to start reading or something. Don't know, I just remember all the warnings that wind may set one off. Some reloads, albeit not HPR, require (per instructions) the igniter to be installed during assembly.

Of course the leads should be hooked up dead last...with the power off.
 

woferry

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Similar to Nick's, of course it's something that shouldn't happen, but I'll throw it out there because it sometimes does. At a local club launch earlier this year the launch controller was mis-configured, and a model rocket launch while the HPR pads were being loaded resulted in one of the HPR pads firing as well. The igniter was already wired-up, so the rocket took off with its owner very close to it (and I heard their iPad was sitting on the blast deflector, apparently it survived). I wasn't out at the pads but it was still startling even from the audience. But another reason to have all of your stuff collected and basically go from wired to continuity check to walking away, so you're only getting farther from the rocket once the leads have been connected. On my checklist the only thing I do later is set my pad camera to record (since it's 240fps the SD card fills quickly so I want to minimize recording time), but I do that over wifi so I don't need to be close to the pad to do it, I do it while walking away, having powered-up and aimed the camera before wiring up the igniter.
 

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Dave McCann my post a picture of LDRS 34 mishap of arming on the pad and the reason for having rocket vertical. I realize there may be some exceptions, but following a sequence is a great safety idea from the start. Glad you posted about this
 

mccordmw

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I should edit the electronics prep step to:

Clear camera SD card and put back in camera

Don't ask me why I'd include that step. :facepalm:
 

SpaceManMat

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After the igniter is installed I always recheck that my altimiters are in their ready to launch mode. Really important especially if you have bumped it around. I also get a general ready for flight check at this point, basically inspect the rocket and confirm everything is in place, ready for flight tags removed etc and do a mental check over the whole prep sequence.
 

SaturnV

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And after I first time in my life wrote my check list at the start I forgot to read it :)
 

cerving

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Yes, you should ALWAYS arm the deployment electronics first, then insert/connect the igniter. From a safety point of view, you want the deployments to be operable before you're launch-ready "just in case" you have an unplanned ignition. From a convenience point of view, if your electronics don't arm for some reason then you don't have to remove the igniter.
 

jadebox

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Yes, you should ALWAYS arm the deployment electronics first, then insert/connect the igniter. From a safety point of view, you want the deployments to be operable before you're launch-ready "just in case" you have an unplanned ignition. From a convenience point of view, if your electronics don't arm for some reason then you don't have to remove the igniter.
Inserting the igniter might require moving the rocket. So, that should be done before arming the altimeter. But, arming the altimeter should be done before hooking up the igniter.

Asking others to move way before arming the altimeter as well as before connecting up the igniter is a good idea. I had an ejection charge go off on the pad once and the nose cone of the rocket shot into the air and almost hit someone on its way down.

-- Roger
 

JDcluster

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I always work from the nose cone down to the ground.
It keeps things simple when dealing with more complex rocket; 2 stage and clusters.
Sustainer electronic deployment system first, stager/ timer next, booster deployment system , then booster igniter.

Sometimes I'll arm the timer / stager just before the booster igniter. Depending on length of rocket / pad arrangement.

JD
 

NateLowrie

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+1. Insert, arm, connect.
+1 from me as well.

This allows you to insert the igniter(s) without worrying about bumping the rocket too much but prevents the igniter from firing before the electronics are armed. It also allows you to keep the same procedure for all rockets because in certain cases (like a longer motor where the igniter requires support from a dowel) it's not possible to insert the igniter when the rocket is vertical.

My "At Pad" checklist is structured as:
- Load rocket onto rail
- Team Leader verbally confirms rail buttons did not bind.
- Insert igniter(s) into motor(s)
- Team Leader confirms rocket is raised into launch position and pad is secured.
- Move everyone back at least 15 feet and Team Leader arm Primary electronics.
- Team Leader arms secondary electronics
- Confirm launch system igniter leads are not hot.
- Scuff leads lightly with sandpaper.
- Team Leader connects igniter to launch system.
 
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