Basic doubt about arming rocket electronics

[julimc]

Why do several recommendations state that the rocket should be vertical on the pad to arm the recovery electronics?

 

[Rschub]

So that the parts go up in case of unforeseen problems. There is usually no-one standing above the rocket when it is vertical. The rocket is a loaded gun and when arming it you are messing with the trigger.

 

[user 30299]

Why do several recommendations state that the rocket should be vertical on the pad to arm the recovery electronics?

If your deployment charges decide to fire when you turn on the electronics, the rocket's sections are going
to safely go straight up the launch rail - and not into a crowd of people.

If you have a two-stage rocket, that uses electronics to ignite the 2nd stage, the rocket's 2nd stage is going
to safely go straight up the launch rail - and not into a crowd of people.

The rocket must also be in the vertical position when you insert the motor's igniter.

 

[kjhambrick]

@julimc --

Great Q !

All of the above are most important ( what @Rschub and @QFactor said )

In addition, if you've got an accelerometer-based altimeter, then rotating the rocket from horizontal to vertical results in a change in linear acceleration from 0-G to 1-G.

Such a change should not trigger a launch detect event, but one never knows and it could detect liftoff which might be followed by a deployment event.

-- kjh

 

[Voyager1]

@julimc --

Great Q !

All of the above are most important ( what @Rschub and @QFactor said )

In addition, if you've got an accelerometer-based altimeter, then rotating the rocket from horizontal to vertical results in a change in linear acceleration from 0-G to 1-G.

Such a change should not trigger a launch detect event, but one never knows and it could detect liftoff which might be followed by a deployment event.

-- kjh

All of the above.
In fact, some altimeters with accelerometers will not arm unless the rocket is vertical.

 

[user 30299]

All of the above.
In fact, some altimeters with accelerometers will not arm unless the rocket is vertical.

If I remember correctly the Raven4 needs to be vertical.

 

[Buckeye]

The rocket must also be in the vertical position when you insert the motor's igniter.

This may be a local club recommendation, but it is not stated in any NAR or Tripoli Safety Code.

 

[kjhambrick]

If I remember correctly the Raven4 needs to be vertical.

Ouch, that could be worse if you mean that the Raven 4 altimiter won't arm unless vertical and you were unaware that deployment was not armed at launch.

EDIT: Oops, sorry ! @Voyager1 said it first !

-- kjh

 

[Voyager1]

This may be a local club recommendation, but it is not stated in any NAR or Tripoli Safety Code.

Yes. Perhaps the code should be less ambiguous about this. The Tripoli Safety Code states:

7-2	While installing an igniter and at all times afterward, the rocket must remain pointed in a safe direction (away from all people.)

 

[user 30299]

This may be a local club recommendation, but it is not stated in any NAR or Tripoli Safety Code.

Ok

But I have not come across a club or a competition that allows you to insert the igniter until
the rocket is in the vertical position, and the electronics are turned on (if there are any).
This is in the case of mid and high power motors.

I've always understood this, and seen this to be a standard (and common sense) safety practice.

2-Stage rockets are the exception, but clubs and competitions expect heightened safety & awareness
in handling the rocket so as to not have an accidental ignition.

 

[Buckeye]

Yes. Perhaps the code should be less ambiguous about this. The Tripoli Safety Code states:

7-2	While installing an igniter and at all times afterward, the rocket must remain pointed in a safe direction (away from all people.)

and NAR HPR Safety code states:

...igniters that are installed in the motor only after my rocket is at the launch pad or in a designated prepping area.

There is nothing ambiguous about the codes, and they are just fine as they are. The rocket does not need to be vertical on the launch rail. Hell, non-HPR motors are prepped with the igniter anytime and anywhere.

I install a HPR igniter while the rocket is horizontal on the rail, pointed away from the range head. Getting on your hands and knees, squinting up into the sun, and fighting gravity in order to install an igniter is not needed.

 

[Antares JS]

Some motors come with nozzles too small to fit their igniters through, partiularly the J615ST with the aerospike nozzle, necessitating the removal of the nozzle to install the igniter. It is best to install your igniter when the rocket is vertical, as the last thing you do before leaving the launch pad, but we definitely do NOT want a strict requirement to install igniters only when vertical because of these edge cases.

 

[user 30299]

I install a HPR igniter while the rocket is horizontal on the rail, pointed away from the range head. Getting on your hands and knees, squinting up into the sun, and fighting gravity in order to install an igniter is not needed.

You forgot to add "kneeling in the dirt or mud" in a harvested cornfield.

 

[Buckeye]

You forgot to add "kneeling in the dirt or mud" in a harvested cornfield.

Yep. If there is an accidental ignition when inserting an igniter (unlikely), I would rather be on my feet than having my face under the nozzle.

 

[Buckeye]

Some motors come with nozzles too small to fit their igniters through, partiularly the J615ST with the aerospike nozzle, necessitating the removal of the nozzle to install the igniter. It is best to install your igniter when the rocket is vertical, as the last thing you do before leaving the launch pad, but we definitely do NOT want a strict requirement to install igniters only when vertical because of these edge cases.

If you mean "hooking up the ignition leads to the igniter" is the last thing you do, then yes, I agree.

 

[Antares JS]

If you mean "hooking up the ignition leads to the igniter" is the last thing you do, then yes, I agree.

Okay, you're right, hooking up the leads is always the last thing you do, and installing the igniter should be the second to last thing you do unless you have an edge case that requires motor disassembly.

 

[cls]

Twice I've had altimeters fire the ejection charges as they were powered on. In both cases, the rocket was vertical, on the pad. So it wasn't much of a safety issue, for bystanders. Was a change my shorts moment for me.

(Different altimeters, both had always been reliable. Dry static conditions both days, though.)

Also, several times I've seen other people's rockets' ejection charges go off unexpectedly. Once, vertical but through the awning canopy. Ha ha! Another time, horizontal on the bench, not pointing downrange, but sideways at the next door folks. Not ha ha.

 

[FredA]

Okay, you're right, hooking up the leads is always the last thing you do, and installing the igniter should be the second to last thing you do unless you have an edge case that requires motor disassembly.

Here's my steps for a normal rocket:
Load and make vertical
Install igniter with wires shorted.
Arm electronics and verify proper arming
Un-short the igniter and attach launch control clips.

The arming is the last time I really touch the rocket - no movement after armed.

 

[OverTheTop]

The rocket must also be in the vertical position when you insert the motor's igniter.

and the electronics should be armed before inserting the igniter. That makes sure if it goes up it is likely to deploy.

 

[cls]

A couple more ideas:

Can wire up the empty charges and check continuity etc with much reduced risks.

Fill the charge containers with BP at the pad. Then turn on everything and insert the igniter, etc.

... Also, we should talk about pad abort disarming procedures. Seems obvious until it's needed. And you realize you can't get to the twisted wires shoved in the ebay vent hole. Or, forgot to bring the special tool for the super elegant arming switch. Or, need a ladder. Etc.

 

[Titan II]

Fill the charge containers with BP at the pad. Then turn on everything and insert the igniter, etc.

Seriously? That is asking for problems.

 

[Steve Shannon]

Yes. Perhaps the code should be less ambiguous about this. The Tripoli Safety Code states:

7-2	While installing an igniter and at all times afterward, the rocket must remain pointed in a safe direction (away from all people.)

It also says:
13-8 Electronic recovery or devices shall remain inhibited until the rocket has been raised to launch position but before the launch igniter is connected to the launch control system.

 

[user 30299]

and the electronics should be armed before inserting the igniter. That makes sure if it goes up it is likely to deploy.

I made sure to address that in Post #10.

You've had teams at Spaceport Cup - try skipping that step. lol

 

[kjhambrick]

It is harder to forget to 'arm the AltAcc' (*) when your checklist says to arm your deployment electroinics and THEN connect the ignitor.

-- kjh

(*) - been there, done that and I am embarrased to say more than one time !

 

[Buckeye]

Fill the charge containers with BP at the pad. Then turn on everything and insert the igniter, etc.

Seriously? That is asking for problems.

Totally agree. If nothing else, fiddling with BP and re-securing ebays at the pad is a sure-fire way to piss off your fellow fliers waiting to launch.

 

[watheyak]

Fill the charge containers with BP at the pad. Then turn on everything and insert the igniter, etc.

Weighing BP charges at the pad, in the wind, on a ladder, then repacking a whole recovery system isn't just crazy and unsafe, it's inconsiderate to the other flyers.

This silliness would get you sent back you your prep table to contemplate your bad manners at a TRAPHX launch.

Our launches are only two days long.

 

[cls]

Seriously? That is asking for problems.

How? Reduced risk of consequences from uncontrolled charges firing, vs distance safety and controlled access at flight line, at the cost of more field assembly. Probably most appropriate for projects with 5g and 10g charges. Not your mpr stuff.

 

[cls]

Weighing BP charges at the pad, in the wind, on a ladder, then repacking a whole recovery system

Why would you do it that way? Seems dangerous.

I'm sure you can think of protected ways to accomplish the same thing.

 

[watheyak]

Why would you do it that way? Seems dangerous.

I'm sure you can think of protected ways to accomplish the same thing.

This is completely insane. At the risk of completely derailing the OP's thread, I want to quash this before it gains any traction. Your suggestion, however you propose it, is not a viable option and absolutely compromises safety.

Have you ever flown a high power rocket before? Seems like no, because you don't seem to understand the basic anotomy.

How exactly do you plan on doing this?? Most rocket's charges are buried under a bunch of deployment laundry, dog barf, and a hat-trick of shear pins.

The flight line is not the place to be doing major rocket assembly. It's rude, unsafe and sounds like a total pain in the butt.

Please stop with the crazy and alarmist suggestions.

 

[Titan II]

How? Reduced risk of consequences from uncontrolled charges firing, vs distance safety and controlled access at flight line, at the cost of more field assembly. Probably most appropriate for projects with 5g and 10g charges. Not your mpr stuff.

How? Just give it some serious thought. Have you actually done that? As watheyak says, it is insane.

Twice I've had altimeters fire the ejection charges as they were powered on. In both cases, the rocket was vertical, on the pad. So it wasn't much of a safety issue, for bystanders. Was a change my shorts moment for me.

You have problems. I have never had one fire accidently and you have had two. You also say it wasn't much of a safety issue. What about the person setting up their rocket on the next pad?