Wiring Ejection Charges

I've heard this same story several times. I believe the current NAR policy encourages people to join Tripoli just to get their L3. I have nothing against TRA but as a NAR member and Section Advisor it bothers me when NAR members feel that their organization is not serving them.

I've been trying for the past two years to get the NAR to *consider* a change to this requirement. Every example that I've been given regarding unintended discharge of the ejection charges could have been avoided by following a strict checklist. For example, if you fly the G-Wiz for your L3 you better know about the reversed polarity problem (and it better be documented in your package). There should be a ground test *before* BP is introduced to make sure the altimeters power up properly and go through their self-check (this is what I do). In the case of the G-Wiz there should be very clear visual clues to the proper polarity to hook up the battery and it should be verified (as part of the checklist) before flight.

I believe that it is more important for the L3 candidate to learn and demonstrate proper safety *procedures* than it is to know how to wire up a multi-pole switch (FWIW I used a 4PDT switch for my L3, one per altimeter, so yes I know about both procedures and multi-pole switches).

If you agree that this area of the NAR L3 program should be modified please contact the NAR L3CC chair, David Schaefer, and the NAR Board of Trustees. Ask for this to be discussed by the entire board, not just the Sports Committee or the L3CC, at the next BoT meeting.

Alex Mericas NAR L3

Yeah, if all the years were odd, wouldn't that mean only 25 years of experience?

:)

Just out of curiousity, how does someone wire up a Gwiz backwards? Isn't the 9v battery pigtail soldered to the circuit board?

Yeahbut...does it help with restless leg syndrome?

Isn't that "the Jimmy legs"?

ROTFL

He said jimmy legs.

Good point Ted. One I have not considered. A key switch would have the same problem there, I also have used one of those. I already found a way to keep the switch from jamming. Maybe a screw in the airframe is better. Worth reconsidering in any case.

Layne

The connector for the electronics is soldered in, but there is a jumper that allows you to power the pyro channel with a separate battery. You remove the jumper and attach the battery wires. If you get the polarity wrong the pyro channel will activate as soon as you power up the altimeter. This is documented in the instruction manual and, as I said, should be reflected in the L3 package. I always test my altimeter / ematches before adding BP. If the Discovery channel flight had done this it would have fired the pyro channels during bench test before powder was present. Might require a change of undies but not much more.

It is the appropriate one.

The L3 program was developed by local NAR members so I remember it. If your memory needs jogging, just try the Internet archive. The oldest version of the L3 requirements archived there is from 1999 and the safe/arm requirements are identical to those of today.

A shunting requirement might have been inappropriately imposed by your local L3CC person but with persistence you could have overcome that.

There is not now nor has there ever been a "shunt" rule for NAR L3 certification!

I believe that the current requirement is a good thing. It compensates for many altimeters not having any sort of safe/arm provisions at all.

You are unlikely in the extreme of modifying the L3 requirement as it is now included in the newly revised NAR safety code for _all_ high power rockets:

"If my rocket has onboard ignition systems for motors or recovery devices, these will have safety interlocks that interrupt the current path until the rocket is at the launch pad."

You have it backwards, at least for the LC series. The soldered in 9V battery clip powers both the altimeter and the pyro outputs. If you want a separate battery you remove a jumper and connect another battery which powers the altimeter. The hard wired battery connector now powers the pyro channels only.

"To ?split? the pyro and computer power, remove the jumper between JP1 pin 5 and JP1 pin 7. The soldered-in battery wires now provide power to the pyro channels ONLY. The user must wire a second battery harness the JP1 pin 7 (+) and JP1 pin 8 (-)."

As I recall, the altimeter side does have a diode to protect the electronics from reversed power.

Of course you still have the problem of accidentally touching the clip to the battery backwards. Which is why a switch is still a very good idea.

This was discussed AT LENGTH on the NAR sections list and the conclusion was that this is NOT the same as the L3 requirement. An on/off switch for the altimeter satisfies the safety code.

Opps. You're right, I was doing it from memory. But still, this is well documented and any L3 candidate using such a device had better include procedures for avoiding this well documented design, er, feature. Back when I had a Gwiz I added an on/off switch to the altimeter power. A ground test in this configuration, without BP, would show polarity problems immediately.

And it results in people joining Tripoli just to get their L3.

Perhaps the Tripoli policy is the one that needs changing. Either way, they should be equivalent.

OK, they aren't identical requirements. But as they are adding something to the safety code it seems unlikely to me that something would be removed from the L3 requirements.

You may be right. But I'll keep pushing until the BoT votes on it and then I'll abide by their decision. Its a moot point for me since I already have my L3.

Right from the NAR website

See section 2.3/2.4

This is above what 1127 requires.

I know the guy that got the "shunt" BS adopted by NAR. His level 3 looked like the control panel of the space shuttle (lots of switches, and many points of potential failure). Lubliner, then still a L2, but head of the LC33, said "cool.. Lot's of switches, so it looks safe" (paraphrase). "I'll make you part of the L3CC, as you really know safety!" (paraphrase). But the Space Shuttle commander did become part of the L3CC soon after. And BTW, is no longer part of the L3CC.

I was planning my L3 at the time and knew that I'd be expected to provide a control panel much like the ISS if I was to make it past Lubliner (still a L2) and the captain of the Space Shuttle. (with one l3 under his belt).

So I joined TRA. Had TAPS that are well known - Mark Clark and Robin Meridith (if you don't know them, you should know who AHPRA is, or atleast heard of BALLS).

The "shunts or opens" to the ematches add SQAUT to safety. Many think "safety ends at the flight line". But adding more points of potential failure does nothing for the guy on the ladder, arming stuff on the pad, as occurred at a recent LDRS. It also does nothing for a bird coming in ballistic, because one of the additional points for failure, failed...

Moot point, as I've had my L3 for some time now (since 2000). The real trouble isn't the process, but the merit badge system. Some people just want to get to L3 too fast, without really having the background knowledge. Yes, I've had a few bad flights on L1/ L2 motors, but the important thing was that I learned from my mistakes. That's why I took my own time to move between levels. I think many that have attended a launch of any size know what a "heads up" flight is. We used to have "Hard hat" flights, where a few of the experienced folks would don construction hardhats, when a questionable flier was about to fly a questionable bird. And the funny thing is that questionable flights included some by the guy got his L3 under Lubliner, and quickly became part of the L3CC.

I've seen far to many people that had never seen a reloadable more prior to the day they did their L1 (there are G and below reloads, after all), and come back a month later to do their L2, and then come back a few months later to do a L3.

Been a NAR section advisor, as well as a TRA prefect, and trust me, I could tell you all some stories.......

As far as the guy that questioned my background, all I can say is that I've RSO'd Gate Bros flights. I've been involved in multi M motor flights.

Can the same bee said for anyone on the NARBOT?

I agree with AZWoody. Adding a switch or shunt to the ematch adds another failure point to the system. If you want a switch, add it where it will do the most good - to power your alt off and on. A voltage selector switch from a computer power supply is my favorite switch to use for that purpose.

Thank you.

Adding a shunt does not prevent stupid mistakes (wrong battery polarity, etc), but adds one more possible stupid mistake.

I for one, when preping a bird with electronics, will tie yellow "caution" tape on the bird. Once the bird is on the pad, and the electronics are armed, the tape comes off. (prevents not arming the electronics)

The reason I do this, is that from the flight line, I can tell of the "proper steps" were taken.

Also, one thing that I do is to do a "test arming" of the electronics during prep. Prior to any BP being anywhere near the ematch. Worst case is the ematch might pop if theres a problem, but can be done in a way to not present a safety issue.

Gentlemen I agree with both of you. I use an on/off switch only to power up the electronics. I have even gone so far as to eliminate the terminal board on the electronics bay bulkheads. I run the ematch wires directly to the boards, no junctions. Where the ematch wires penetrate the bulkheads I seal them using a fender washer with a soft rubber washer under it. This has worked so far and I have not noticed any evidence of ejection gas in the ebay.