Revision to Tripoli Rule Regarding Wireless Remote Switches

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This rule purports to make it safer for handling rockets on the ground, prior to launch. In effect, it infers that a magnetic switch (or a WiFi switch) is more likely to fail while being transported/handled on the ground than a mechanical switch under a high-G, supersonic flight. Moreover, it equates the danger of a possible errant ejection charge with that of a rocket coming in ballistic.
Twist and tape is backwards. Embrace the technology!
NikeMikey
 
This rule purports to make it safer for handling rockets on the ground, prior to launch. In effect, it infers that a magnetic switch (or a WiFi switch) is more likely to fail while being transported/handled on the ground than a mechanical switch under a high-G, supersonic flight. Moreover, it equates the danger of a possible errant ejection charge with that of a rocket coming in ballistic.
Twist and tape is backwards. Embrace the technology!
NikeMikey
100 percent agree solid state switching is proven and safe technology used across several industrial applications. Failure of mechanical switches have always been higher than solid states. That is a fact this rule does nothing but degrade safety and inconvenience people
 
All indications thus far have been that this change was made without any actual data that served as the basis for determining a change was needed to reduce a known risk. Why assume that actual data would change the decision????

I agree with you that it doesn’t appear that actual data was used as the basis for this decision. Why assume that actual data would change the decision. Well I would answer that with the opposite. Why assume that it wouldn’t change the decision.

I had an engineering manager that had a sign in his office that said “In God we trust, all others bring data”. He was a licensed professional engineer. I fully agree with him on that.

TRA tests every motor they certify. If they are going to approve the electronics we use the why wouldn’t they hold that to just as high of standard as motors. At least analyze them at the minimum or test if they can’t/aren’t able to analyze the failure modes of them.
 
Lots of folks have been arguing about this or that with the new ruling, and only four devices are CURRENTLY approved, maybe the solution is that the other manufacturers of wireless switches whether Wifi, magnetic or whatever need to submit their products for approval.

So, what's the advantage to being "approved" by Tripoli? They still force you to use a mechanical break with any electric switch. The approved switch lets you use a prep table. Big whoop.
 
Thanks, I only get 6 launches a year now I get to skip this weekend cause a rocket I have flown well over 20 times to 10K+ uses a wifi switch for the backup altimeter. And I do not have time to redesign the avbay so I can't fly it or any of the other rockets that have wifi switches.
You are forcing us to fix something that wasn't broken.
What's next?
 
So, what's the advantage to being "approved" by Tripoli? They still force you to use a mechanical break with any electric switch. The approved switch lets you use a prep table. Big whoop.
There is no TRA "approval" of any electronics. What they did was allow those remotely operated devices to have a slight exemption from the mechanical disconnect rule... you do not have to actually be on the rail and pointed "up" in order to power on the electronics, since the arming of the electronics is done remotely. As some people have mentioned, you may WANT to do it on the rail anyway under certain circumstances (i.e. for a device that performs an airstart), but you are not required to do so.
 
I agree with you that it doesn’t appear that actual data was used as the basis for this decision. Why assume that actual data would change the decision. Well I would answer that with the opposite. Why assume that it wouldn’t change the decision.

I had an engineering manager that had a sign in his office that said “In God we trust, all others bring data”. He was a licensed professional engineer. I fully agree with him on that.

TRA tests every motor they certify. If they are going to approve the electronics we use the why wouldn’t they hold that to just as high of standard as motors. At least analyze them at the minimum or test if they can’t/aren’t able to analyze the failure modes of them.
I do not disagree with you. What you are suggesting is very logical. The chorus of responses to this thread provides at a minimum a compelling anecdotal case that electronic switches are a safe, effective means of isolation. That coupled with the fact TRA has explicitly stated there are no indications whatsoever that electronic switches are unsafe or faulty leads me to believe the rule is not based on actual data. In my experience more data doesn't help in situations where data was not the basis for the original decision.

An actual question .... does the TRA board publish meeting minutes or notes of some kind documenting their proceedings?
 
Ok can't make it past page 4. Thread is diluted and annoying. It's obvious that the decision is made to prevent potential accidents and not to have this rule written because of an accident and to curb any potential insurance liability issues etc...are the current products engineered properly and safe? Yes.

Do I agree? Kinda but I trust my electronics. Do I think it sucks, yeah. But that's not up to me.

So what does my hardware stack look like now?
What is the minimum requirement?
Where must switches be placed?
Clarify this new rule with actual setup ups, MD, 2 stage, etc.
 
There is no TRA "approval" of any electronics. What they did was allow those remotely operated devices to have a slight exemption from the mechanical disconnect rule... you do not have to actually be on the rail and pointed "up" in order to power on the electronics, since the arming of the electronics is done remotely. As some people have mentioned, you may WANT to do it on the rail anyway under certain circumstances (i.e. for a device that performs an airstart), but you are not required to do so.

Uh, see post #1: "The current list of Tripoli approved wireless remote switches includes:" That sounds pretty official to me.

Yes, I understand what the rule says. You say "slight exemption." I say the slight exemption is "big whoop."
 
Do I think it sucks, yeah. But that's not up to me.

Option 1: Rebuild all your av-bays. Option 2: Join NAR and launch under NAR rules as an alternative. At least as of today.

If a business or organization takes my money and makes things inconvenient/unacceptable to me, then I will look elsewhere.
 
There is no TRA "approval" of any electronics. What they did was allow those remotely operated devices to have a slight exemption from the mechanical disconnect rule... <snipped>....
Cris, maybe you can point out where this rule is in the TRA or NFPA safety code? I’ve not been able to find any reference to the requirement of a mechanical disconnect written any where, only the word inhibit. And in none of the written definitions is inhibit defined as a mechanical disconnect. I’m sure it must be somewhere but I’m just missing it.

Thanks,


Tony
 
Cris, maybe you can point out where this rule is in the TRA or NFPA safety code? I’ve not been able to find any reference to the requirement of a mechanical disconnect written any where, only the word inhibit. And in none of the written definitions is inhibit defined as a mechanical disconnect. I’m sure it must be somewhere but I’m just missing it.

Thanks,


Tony
That's one for the TRA BoD. I'm just a lowly member who happens to be a vendor as well.
 
Can I propose a thought experiment?

Let’s say you’ve got a house with all the nice high tech “smart home” switches and motion sensors.

Now I have a problem with the overhead light not working, so I hire an electrician.

Does anybody think for a moment the electrician will touch anything without physically cutting all power to the circuit?

Is the fact the “smart switch” is turned “off” and requires a specific set of instructions over WiFi to turn on going to sway the electrician’s mind?

Yet somehow, Volunteer RSO’s are supposed to just smile and pick up your rocket and it’s wired up black powder charges that work on the same principles as the smart home switch?

It’s pretty clear the industry standard of physically cutting all power has something going for it. Maybe it’s because they’re written in blood.

You apparently do not know very many electricians... I have seen with my own eyes more than one electrician check for live wires with a fingertip. Lick fingertip, smack wire quickly. it won't hurt you but you know whether the wire is live without spending time hunting for a breaker box. Not all electricians work with a helper....
 
If my job was setting explosives in a building I would insist the ignition system be totally electrically dead (zero potential energy). I would never accept my safety or other's safety to depend on a properly operating PN junction, firmware, construction quality and the use history of the live electronics. But hey, that's just me.

No John, you are not the only one. Without a mechanical break in the circuitry, controlled by mechanical action, such as a screw switch or other type mechanical activated switch, it is nothing but taking a chance nothing bad will happen. This applies to all electronic controlled switches, as well as magnetic switches. Good on the TRA BOD for addressing this issue.
 
Option 1: Rebuild all your av-bays. Option 2: Join NAR and launch under NAR rules as an alternative. At least as of today.

If a business or organization takes my money and makes things inconvenient/unacceptable to me, then I will look elsewhere.


Looks like we abandon Triploi and fly under NAR.
 
Let’s think about the risk TRA leadership is trying to minimize.

We’re not talking about accidental motor ignition — igniters can’t be installed until at the pad anyway! If a connected, but uninstalled igniter, is accidentally triggered — “big whoop”!

So what we are concerned with is the unintended firing of ejection charges. The amount of BP in these can range from maybe half a gram to 5, 10, 20 or more grams. Are we really going to treat all cases the same? If we are so worried about getting thumped by a plastic (or maybe balsa?) nosecone — maybe we should get another hobby.

Or, maybe we could exempt rockets having less than say 2.5 grams of BP?
Or maybe we could have a rule that requires the rocket to be transported in a vertical orientation? A nosecone blasting into the air might cause you to soil your pants, but it’s unlikely to kill or seriously injure anyone.

A rocket coming in ballistic (because charges did NOT fire) on the other hand IS a serious threat!

In attempting to reduce the likelihood of an accidental firing of an ejection charge — by intentionally introducing a point of failure (an unnecessary switch) — we are greatly increasing the likelihood of anomalous (ballistic) recovery events. Which is more dangerous?

Someone should do an engineering analysis of the probability of the two types of failure — unintended charges going off on the ground versus charges failing to go off in the air. I contend that the likelihood (probability) of the former is very much lower than that of the latter. I also contend that the danger of the latter is very much greater than the former.

But I don’t have data to back me up; and neither does the TRA BOD!

Just my two cents’ worth.

NikeMikey
 
From a risk analysis point of view, I'd be interested in knowing if the risk of an unintended firing on the ground from a failed-closed electronic switch is higher than the risk of a failed deployment due to a mechanical switch failing open. Which event is more likely, and which event carries the greater risk of injury? From my experience (purely anecdotal, of course), in-flight failures are much more frequent, and have the potential to cause much more serious injuries.
 
Where are all of these dangerous mechanical switches you guys are complaining about? All of my rockets have these switches in them. 0 failures from them. You are afraid of forgetting to turn them on??? Then how can you miss the fact that none of your altimeters are turning on? That your wifi switch doesnt work?? The chance of actually getting hit by a ballistic rocket are extremely low. The chance of being injured by a nosecone when someones charges go off at the RSO table are near 100%. Suck it up, install a switch.
 
Are there any statistical studies for injuries (or "incidents") at TRA launches? How many are ground events, and what were the causes? How many are ballistic flights, and what were their causes? How many were unstable flights, or flights whose path crossed the flight line, and what were their causes? What were the severity of the resulting injuries, or what was the potential for injury from those incidents?
 
Regardless of how you feel about the merits of the new policy, one thing is certain, the announcement has been completely bungled. If you are going to announce something you know is going to cause a controversy and is going to be disruptive to some members you need to handle it better.

First, the wording of the written announcement is not as clear as it should be. Some members here, on the Tripoli Facebook group, and on at least one of the club email lists I’m on have interpreted the announcement to mean exactly the OPPOSITE of what it means. They’ve understood it to mean that the use of wireless remote switches are now REQUIRED. It’s because the announcement is poorly written. It starts off by describing wireless remote switches as reducing risk of injury, and it ends with a list of “approved devices”. The middle section talks about a requirement for a mechanical disconnect from power, but it doesn’t come out and clearly say in plain language that wireless remote switches do not provide a mechanical disconnect, so if that’s what you are using, you need to add a mechanical switch or disconnect your battery. I think it’s very easy to see how someone could misinterpret it. It reads like, “Remote switches reduce risk, you are required to have a disconnect, here are your approved devices.”

Next, if you are going to announce something controversial that will impact your members, you need to be ready to defend the decision. Explain your decision process. Why the change? It really hasn’t been justified in a clear way. It still seems like the answer is that there have been no safety incidents, but something we can’t really describe might possibly happen someday. When members ask detailed technical questions about the redundancy built into these devices and possible failure modes, the answers are not seeming to come from the Board or other decision makers — they are coming from other members. That’s ridiculous. Explain and defend your decisions. Don’t leave your members to fight about it!

And the last thing, which is really the most infuriating, is the decision to make the change effective immediately and the cavalier attitude shown to people who hear an announcement on Monday that means they won’t be able to fly on Saturday. It comes off as, “This is a change based on a worry over something that has never happened before, but we need to take action immediately, and if that means our members can’t fly next weekend, TOUGH!” That attitude toward membership is really disappointing.
 
Are there any statistical studies for injuries (or "incidents") at TRA launches? How many are ground events, and what were the causes? How many are ballistic flights, and what were their causes? How many were unstable flights, or flights whose path crossed the flight line, and what were their causes? What were the severity of the resulting injuries, or what was the potential for injury from those incidents?

A Tripoli prefect should be required to report any recordable event, ie, an event that caused injury or damage. At work we even record near misses where somebody reported an unsafe action that could have caused an injury.
 
A Tripoli prefect should be required to report any recordable event, ie, an event that caused injury or damage. At work we even record near misses where somebody reported an unsafe action that could have caused an injury.
Yeah, you'd think that policy would have been in effect a long time ago...
 
I can understand the rationale for the change (preventing un-commanded deployment charge ignition until "in the field" is a good thing) but am asking for a clarification with dual-battery setups

I have a 4" av-bay that includes an Eggtimer Proton as a primary and an Eggtimer Quantum as a backup. The av-bay has 4 batteries - The Proton is connected to a battery for the computer, and is also connected to a second deployment-only battery via a mechanical screw switch. The Quantum is wired identically with two different batteries. Make sense so far?

Similarly, the batteries have mechanical disconnects (XT30U plug pairs) as there's no need to keep the batteries connected at all times.

During transport and prior to av-bay assembly, none of the 4 batteries are connected to their XT30U connector mates. At the site (aka the zone of glory), I assemble the av-bay using my checklist, first verifying that both screw switches are open, then connecting all 4 batteries. At this point there is zero power available for the deployment charges, even though the Proton and Quantum computers are powered up. After checking out both computers using WiFi, final assembly commences and is completed before heading over to the RSO. Again, at this point the deployment charges are mechanically disconnected, even though the computers are running.

Post RSO nod, the action shifts to the rail, where after going vertical, I reconnect the deployment batteries using the screw switches and validate deployment ematch continuity (and the rest of the at-the-rail checklist, including accelerometer calibration, which goes very fast as the Proton's computer has been running for a while and the accelerometer has warmed up).

I'm certain that this setup follows the spirit of the rule change. I'm aware that this setup might be disallowed, however, as the Proton and Quantum computers (even though they are disconnected from any source of deployment current) are running at the RSO table.

Thoughts? Do I go to altimeter jail for this setup, or am I compliant with the intent and spirit of the rule change?

-Kent

p.s. I really am interested in the data behind the decision, and if there's a trend behind the rationale.
 
Where are all of these dangerous mechanical switches you guys are complaining about? All of my rockets have these switches in them. 0 failures from them. You are afraid of forgetting to turn them on??? Then how can you miss the fact that none of your altimeters are turning on? That your wifi switch doesnt work?? The chance of actually getting hit by a ballistic rocket are extremely low. The chance of being injured by a nosecone when someones charges go off at the RSO table are near 100%. Suck it up, install a switch.
Don't know where you source your switches, but there are some EXTREMELY crappy switches all over eBay and Amazon, especially bad are keyed switches and PC mount switches. Even for toggle and slide switches many of the plastic housings on cheap switches do not withstand the rigors of (poor) hobbyist soldering techniques, and in this case, you are deploying a ticking time bomb as the contact spacing and throw dimensions get compromised. As has been mentioned, the screw switches sold by Missleworks and others are often your best bet. Saying that, the large size of screw switches often don't fit the physical profile of high performance airframe designs. And screw switches are not immune from problems; at Airfest two years ago I had one jar open due to a shock during apogee deployment leading to loss of power to one altimeter in my av-bay, which unfortunately led to loss of GPS tracking making recovery painful.

Sorry, I am a bit anal about switches as my first job out of college was with AT&T Bell Labs testing the quality and reliability of phone system handset switch pads.
 
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Kent

I think your setup meet the intent of the rule. Since the revised rule states: Such disconnection May be done between the pyrotechnic battery and the device OR between the device and any pyrotechnic initiator device(s).
 
No John, you are not the only one. Without a mechanical break in the circuitry, controlled by mechanical action, such as a screw switch or other type mechanical activated switch, it is nothing but taking a chance nothing bad will happen. This applies to all electronic controlled switches, as well as magnetic switches. Good on the TRA BOD for addressing this issue.
In an informal survey I took of experienced flyers in our local club, every single unintended ejection charge event occurred in a system that used a mechanical switch. No one, including those of us who have used electronic switches for years, could recall an unwanted event in a system with an electronic switch. Of course there have been many more flights with mechanical switches, so that clearly plays a role. But if you go purely by the numbers, mechanical switches would have been banned long ago on the premise of safety due to the number of incidents they are associated with.

Simple thought experiment for those of you who like them, which is a better scenario: a few well characterized and known electronic switches designed by software and electrical engineers, or 1000 different solutions to the same problem designed by each individual flyer. Which group is more likely to create a safe and reliable system?


Tony
 
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