Why are university HPR teams having such difficulty with airstarts?

[Steve Shannon]

But the HEI igniter can be installed after the motor is in rocket.
People usually think of the igniter (a screw in type similar to the one Tony references) going in vertically from the top. If it screws in horizontal from the side it can be installed last through an access panel in the assembled rocket.
I did a 98mm motor doing this, used Holex igniter. It was single stage but had it been multiple stage or cluster the only difference would be the wires going to the onboard electronics rather than the launch control.

M

Thanks Mark, that’s the sort of thing I envisioned.

 

[djs]

Or maybe a simpler thing is that the ignitor is installed in the HEI closure, but there's a switch that disconnects it electrically from the electronics until you're ready to go? Doesn't account for all failure modes, but maybe is a compromise?

 

[jsdemar]

Requiring a specific type of upper stage ignition system could essential eliminate multi-stage rockets for most people. This could be due to expense, weight, motor type, or other design limitations.

Many things that have been talked about could add unintended additional risk factors. Onboard relays? Not a good idea. Screwing in an igniter into the motor while on a ladder with the rocket vertical? Not a good idea.

A head-end igniter pre-installed can be done safely.

• The igniter pyrogen must not be static sensitive. It should also be shielded such that there is no path for static discharge through the igniter (passively or electrically).
• The primary igniter must be shunted AND disconnected from the electronics from point of assembly of the motor through the time the rocket is vertical.
• The shunt must handle full current of the electrical system without burning open. The shunt and connectors must be low-enough resistance not to allow parallel current to the igniter above its no-fire current. (I have seen shunted igniters fire).
• Arming of the electronics must be done by one person. The removal of the shunt (after arming) should be mechanical (such as a pull string), and not with someone near the rocket on a ladder.
• Disarming the electronics, in case of an abort, must be carefully planned. One person inserts the shunt and fully disconnects all power to the staging electronics while the rocket is vertical.
• Remotely arming and disarming via an active onboard remote system should be discouraged. There would always be a path of failure that could put current through the igniter if power is not fully disconnected.
• Onboard relays should be discouraged. Unless it's an expensive aerospace-rated relay, it will be susceptible to vibration and g-forces. A remote arming system that is total ground-based would be acceptable to electromechanically arm/disarm the electronics and to electromechanically remove/insert the shunt.
• A safety procedure and checklist must be followed.

 

[JimJarvis50]

I don't use HEI and don't plan to. I hope anyone considering it will not do so unless they know exactly what they are doing.

I don't use it because of two things. First, I don't want to have the igniter in the rocket any sooner than is necessary. I think this factor contributed to the Balls accidents. Second, I like to fully test the electronics, including the path to the igniter, just before loading the rocket, but with the igniter out. This is the last line of defense. After this "all up" test, you turn everything off, load the rocket and then repeat turning everything on. No surprises (hopefully).

My setup for Balls this year was:
- Wifi switch to provide power to Easymega
- Easymega with staging permissives that include minimum altitude (a safety factor both on the ground and in the air)
- Disconnecting and shunting switches on the path to the igniter.

My startup sequence this year was:
- With rocket horizontal, turn on wifi power, verify easymega does not boot up
- Use switches to put igniter in line
- Raise rocket remotely (no one near the rocket when the rocket is moving)
- Activate wifi switch (no one near the rocket)
- Verify the easymega continuity remotely via FM

If required to take the rocket down:
- Turn off wifi switch remotely (with option to climb the ladder to isolate igniter if necessary)
- Lower the rocket remotely

This procedure isn't perfect, but it lets me test everything just before flight, keeps me off the ladder and keeps people away from the rocket for the most part.

Jim

 

[Ted Cochran]

That’s also the problem with all traditional multiple stage amateur rocket vehicles. The booster is the only stage which allows the initiator to be installed after the entire rocket is assembled, on the pad, and pointing in a safe direction.

It's not too bad for smallish HPR rockets and motors (J to I, say) if the booster is not actively separated and the upper stage has separate recovery and ignition electronics with separate disconnects: The stages are prepped with motors inserted and igniters left out (if we're careful with the igniter, it can be connected but left out of the motor).

After check in, the stages are loaded onto the rail separately and kept apart, e.g. with a standoff. After the rail is raised, the sustainer deployment electronics can be armed; the sustainer igniter inserted (but NOT armed), and the sustainer lowered onto the booster. The booster electronics are armed, the booster igniter is inserted, and then the sustainer igniter is armed (that way you're not fooling around at the bottom of the booster with a live sustainer igniter over your head). Finally the booster igniter can be hooked up and the pad armed.

But you are correct in general--that does involve more exposure time with armed ejection charges, and for sure all bets are off if there are separation charges, shear pins, or other complexities to fiddle with. And I did say for small rockets--once ladders are involved it just gets too sporty, in my opinion.

 

[Dave A]

I agree; that should be the minimum for now. I also would like to see a mechanical system like Mark has mentioned developed as a TRA Standard Initiator. Once developed, that should become the new minimum.
What is needed? Why do you doubt the will to do so?

A switch across the output of the ignition device will certainly shunt the device. If the igniter is shorted it's the same as twisting the wires together. (Just don't forget to open it before you walk away!)
I plan to add that to my 2 stage BumperWAC

 

[Dave A]

Would make sense to have a switch (shunt) across the upper stage igniter leads, closed, until the vehicle is vertical, armed and ready to fly? Obviously the most vulnerable period is from when the igniter leads are untwisted and connected to the ignition electronics. That step should always be done when:
1) It is pointed away from the flight line
2) No persons should be inside a 90° wide path in front of the vehicle until it is vertical.
3) Probably best if only one person is making the last connections.
4) Always raise the vehicle before any electronics are armed.
5) I would only turn on the staging electronics after ALL altimeters are on and ready.

I forgot this one: I ALWAYS boot up my timer, in the trailer, without an igniter installed. I double check that the battery is not installed in reverse. A timer CAN fire when switched on and when the power source is installed backwards.

 

[Steve Shannon]

It's not too bad for smallish HPR rockets and motors (J to I, say) if the booster is not actively separated and the upper stage has separate recovery and ignition electronics with separate disconnects: The stages are prepped with motors inserted and igniters left out (if we're careful with the igniter, it can be connected but left out of the motor).

After check in, the stages are loaded onto the rail separately and kept apart, e.g. with a standoff. After the rail is raised, the sustainer deployment electronics can be armed; the sustainer igniter inserted (but NOT armed), and the sustainer lowered onto the booster. The booster electronics are armed, the booster igniter is inserted, and then the sustainer igniter is armed (that way you're not fooling around at the bottom of the booster with a live sustainer igniter over your head). Finally the booster igniter can be hooked up and the pad armed.

But you are correct in general--that does involve more exposure time with armed ejection charges, and for sure all bets are off if there are separation charges, shear pins, or other complexities to fiddle with. And I did say for small rockets--once ladders are involved it just gets too sporty, in my opinion.

You’re exactly right, Ted.

 

[Steve Shannon]

https://www.rocketryforum.com/threa...lty-with-airstarts.148953/reply?quote=1830225
A switch across the output of the ignition device will certainly shunt the device. If the igniter is shorted it's the same as twisting the wires together. (Just don't forget to open it before you walk away!)
I plan to add that to my 2 stage BumperWAC

Depending on the resistance of the shunt, the resistance and energy needed to ignite the initiator, a simple shunt may simply delay ignition.
It’s much better to open the circuit between the staging controller and initiator as well as shunting the legs together of the initiator. Open and shunt can be done to both legs of the initiator with a DPDT switch or to one leg with a DPST switch.

 

[High Desert Rocketry]

But the HEI igniter can be installed after the motor is in rocket.
People usually think of the igniter (a screw in type similar to the one Tony references) going in vertically from the top. If it screws in horizontal from the side it can be installed last through an access panel in the assembled rocket.
I did a 98mm motor doing this, used Holex igniter. It was single stage but had it been multiple stage or cluster the only difference would be the wires going to the onboard electronics rather than the launch control.

M

Our old 'Dual Pulse' motor that made our 2-stage rocket into a single stage for the Sugar Shot to Space project was scary...imagine 2-stage rocket with a single nozzle. In place of a sustainer nozzle was a 4" thick pyro bulkhead that took about 15 seconds to burn away when the 'booster' was fired. The HEI on the 'sustainer' motor would then fire using copper thermite igniting the sustainer motor that fired through the burned away pyro bulkhead, through the 'booster' case and out the 'booster' nozzle. The problem we had was thermal heat soak causing the previously fired 'booster' motor case to fail (CATO).

The 'scary' part was after the two motors were connected together. It essenually made the 'sustainer' motor into a b-o-m-b as it was completely sealed up with no nozzle since an aluminum bulkhead and the pyro bulkhead plugged the ends. Fortunately, we scapped that design going to traditional 2-stage rocket design but still had vertically inserted HEI. Like Mark, I made a new bulkhead that allowed an igniter to be screwed into the bulkhead horizontally but using a simple 1/2" hole in the airframe. Never used that bulkhead since our vertical HEI always worked using shunt, disconnect and power off to the sustainer motor.

Many different possibilities for igniting second stage motors, every one that could fail if procedures not followed or designed poorly or not ground tested adaquately. We even tried igniting a motor with a laser through a thick glass port eliminating anything electrical. Still looking for the ideal foolproof method.

 

[FredA]

"I agree; that should be the minimum for now. I also would like to see a mechanical system like Mark has mentioned developed as a TRA Standard Initiator. Once developed, that should become the new minimum.
What is needed? Why do you doubt the will to do so?"

When the org has enough moxie to codify something simple like the switch [which you agree should be the minimum] then I'll believe we MIGHT be able to do more. We can't even outlaw "twist and tuck" so I'm not holding my breath.

As far as a standard HEI device:
- Who will do the engineering?
- Who will do the manufacturing?
- What HW will it support - if not ALL, who do you "bless" for first usage?
- What are the rules REQUIRING usage and outlawing alternative?

Lots of work to do - doubt it will get done.
Call me a pessimist.

 

[JimJarvis50]

Depending on the resistance of the shunt, the resistance and energy needed to ignite the initiator, a simple shunt may simply delay ignition.
It’s much better to open the circuit between the staging controller and initiator as well as shunting the legs together of the initiator. Open and shunt can be done to both legs of the initiator with a DPDT switch or to one leg with a DPST switch.

Shunts need to be designed properly and then tested. It is not that hard to do the calculations to determine the current that will flow through the igniter if the electronic fire. Then, the system can be completely ground tested to verify that it provides the expected protection. Other things that can be done to make shunts more reliable is to use 9-volt batteries rather than lipos and to use electronics with a short latch time (or select a short latch time).

Last year, I did the above shunt testing with the EasyMegas in my second and third stages. Due to an altimeter bug, that was the testing that later caused the second stage not to light. No good deed .... But my point is, I actually do this testing, I don't just talk about it.

Jim

 

[djs]

. The booster electronics are armed, the booster igniter is inserted, and then the sustainer igniter is armed (that way you're not fooling around at the bottom of the booster with a live sustainer igniter over your head).

So here's my dilemma on this. The sustainer ignition electronics are also the electronic ejection (DD) electronics. My first concern of safety is recovery safety- if the booster were to ignite (yes, i know it's not connected to the electronics, but still), I have the potential to put the sustainer in the air without deployment.

What I'm doing is the method described where the sustainer electronics are first armed on the rail without the ignitor in the motor. Turned off, then inserted, and restarted. Presumably at this point, I have a reasonable assumption that the second restart will not fire the ignitor/start the motor.

Usually my rule of thumb is "proceed from least dangerous activity to most dangerous".. meaning the first thing I always do is arm the camera, and last thing is put the ignitor in the motor. But here, I don't know

The other option is to convert all my electronics to something wireless (like an eggtimer quantum or the new thingie they came out with), which keeps me off a ladder and farther away?

 

[mikec]

After check in, the stages are loaded onto the rail separately and kept apart, e.g. with a standoff.

How do you put the second stage on the rail when it doesn't have any rail guides?

This thread seems to be focused on technology and process. I'm not saying that all accidents can be summarized this way, but you can't 100% fix stupid with technology and process.

 

[UhClem]

What I'm doing is the method described where the sustainer electronics are first armed on the rail without the ignitor in the motor. Turned off, then inserted, and restarted. Presumably at this point, I have a reasonable assumption that the second restart will not fire the ignitor/start the motor.

You should have a safe/arm switch between the altimeter and the ejection charges/igniter. Power up the altimeter, make sure it is sane, then close the arm switch. Even better would be testing the altimeter output before closing that switch.

 

[Steve Shannon]

This thread seems to be focused on technology and process. I'm not saying that all accidents can be summarized this way, but you can't 100% fix stupid with technology and process.

You’re right; we cannot fix stupid, but we shouldn’t certify stupid either. The certification process is intended to be a test of skills, knowledge, experience, and judgement. We have to be more vigilant in that regard. Given a chance we can cure ignorance with education, we can improve skills with practice, and we can increase experience by insisting on more and diverse flights. Judgement is something that’s a bit more difficult to teach and test. It’s usually learned by example with experience playing a large role.
Once someone becomes certified we expect those four traits (knowledge, skill, experience, and judgement) to continue to improve. If we find that people have been certified who pose a risk to themselves or others, the leadership has a responsibility to do something about it. Unfortunately, that may be too late. That’s why we have to be more careful during certification.

 

[mikec]

That’s why we have to be more careful during certification.

Since certification doesn't require anything like the complexity of staging, I don't see the direct relationship. Short of adding another certification level, all we can do is define some best practices and educate people about them. Recall that this thread started out being about uncertified and poorly-supervised university teams.

I am personally opposed to hard-and-fast mandates for technology and practices, at least the way they tend to get defined by committees. In the end, staging prep should be done in a remote, sterile location with no uninvolved parties and everyone present taking responsibility for the process and its outcome. I think the existing safety code is sufficient to keep everyone else at the launch safe.

 

[BDB]

The other option is to convert all my electronics to something wireless (like an eggtimer quantum or the new thingie they came out with), which keeps me off a ladder and farther away?

It seems like it should be possible to use something like eggfinder WiFi switches to open/close shunts and to arm electronics and igniters remotely.

 

[Steve Shannon]

Since certification doesn't require anything like the complexity of staging, I don't see the direct relationship. Short of adding another certification level, all we can do is define some best practices and educate people about them. Recall that this thread started out being about uncertified and poorly-supervised university teams.

I am personally opposed to hard-and-fast mandates for technology and practices, at least the way they tend to get defined by committees. In the end, staging prep should be done in a remote, sterile location with no uninvolved parties and everyone present taking responsibility for the process and its outcome. I think the existing safety code is sufficient to keep everyone else at the launch safe.

Actually the university teams had certified members leading them. That’s why I mentioned certifications.

 

[mikec]

Actually the university teams had certified members leading them. That’s why I mentioned certifications.

Based on what I've seen elsewhere, the team that had the major accident at BALLS was flying without their mentors present and against their advice. If someone on the team was L3 certified (and I assume that has to be true, else they wouldn't have been flying at a TRA event at all) then this is just evidence that an L3 certification by itself doesn't insure that someone can safely execute a complex staged flight.

After all, there is nothing about the certification process as it exists today that requires any experience with such a flight. One can argue that TAPs/L3CCs should apply other criteria ("good judgement" for example) to a prospective L3 beyond the specific requirements, but IMHO that both puts an unreasonable burden on TAP/L3CC members and confronts fliers with nebulous and unwritten rules that may not be consistently applied.

 

[MattJL]

Just my two cents, given that the topic has shifted to a debate about the certification process:

I agree with the assessment that creating another level beyond L3 is probably a step too far, given that extreme high-altitude launches aren't going to be that frequent (I'm ballparking that the motors alone cost about $10-12k). That being said, uni teams should really have an extra level of scrutiny applied to them because they combine inexperience with hubris - a bad combination at best, and dangerous at worst. It's extremely fortunate that nothing terrible has happened, but I don't have an interest in pressing that luck any further than it has to go. If it's not currently being considered - at the very least, space shot-ambitious teams should be staffed with at least two people with L3 certifications, and get their designs reviewed by two or more mentors. I recognize that TRA is a volunteer association, and that the manpower just might not exist to do this, but everyone would benefit from having additional sanity checks and better readiness on the team end.

This being said, I am myself part of a collegiate high powered rocketry team, and I suspect that fulfilling those requirements will be difficult for most uni teams to accomplish - even the most safety conscious ones. While I don't want to disclose our financial situation to the general public, it's not all that great, and prevents us from sponsoring more than one L3 while still doing all the things that we want to. Additionally, few universities have reliable access to test ranges to go out and do more than a handful of certification flights per year - we're lucky enough to have three or four fields within five hours' drive - and that definitely impacts the amount of experience that college teams can accrue.

It's a really difficult question to deal with. I can't claim to have a solution - I'm part of the problem, after all - and I'm not sure if there is a solution that both solves the safety problems and is easy for university teams to abide by. I'm left with the feeling that a lot of this should have been discussed with TRA and NAR before a collegiate space race even emerged, but the barn door's wide open and the horse is two counties over by now. The most I can do as a collegiate team representative is go out into the community and talk to people with experience, so that my own team can do things as safely and smartly as humanly possible. Hopefully other teams follow suit.

 

[ksaves2]

Requiring a specific type of upper stage ignition system could essential eliminate multi-stage rockets for most people. This could be due to expense, weight, motor type, or other design limitations.

Many things that have been talked about could add unintended additional risk factors. Onboard relays? Not a good idea. Screwing in an igniter into the motor while on a ladder with the rocket vertical? Not a good idea.

A head-end igniter pre-installed can be done safely.

• The igniter pyrogen must not be static sensitive. It should also be shielded such that there is no path for static discharge through the igniter (passively or electrically).
• The primary igniter must be shunted AND disconnected from the electronics from point of assembly of the motor through the time the rocket is vertical.
• The shunt must handle full current of the electrical system without burning open. The shunt and connectors must be low-enough resistance not to allow parallel current to the igniter above its no-fire current. (I have seen shunted igniters fire).
• Arming of the electronics must be done by one person. The removal of the shunt (after arming) should be mechanical (such as a pull string), and not with someone near the rocket on a ladder.
• Disarming the electronics, in case of an abort, must be carefully planned. One person inserts the shunt and fully disconnects all power to the staging electronics while the rocket is vertical.
• Remotely arming and disarming via an active onboard remote system should be discouraged. There would always be a path of failure that could put current through the igniter if power is not fully disconnected.
• Onboard relays should be discouraged. Unless it's an expensive aerospace-rated relay, it will be susceptible to vibration and g-forces. A remote arming system that is total ground-based would be acceptable to electromechanically arm/disarm the electronics and to electromechanically remove/insert the shunt.
• A safety procedure and checklist must be followed.

Question and not a troll. How does one test a shunt to prove it actually works for a given installation without cooking their electronics? I've been vehemently arguing against shunts........
unless it's been proven to do the job it's supposed to do in a given installation. "Do the math" is a lame answer if that's all that's done. I remember a video that showed a shunted augmented ematch and the lithium battery simply blasted enough parallel current to blow it. Having some Joe Blow say they put an unproven "shunt" in an upper stage ignition circuit is kidding themself and could find out the hard way if there is a primary equipment failure.
I think with smaller projects a remote switch along the lines of the Egg products are acceptable but in the really large motors, I'd like a proven fully functioning shunt to take the heat
to avoid a mishap. Kurt

 

[MattJL]

Question and not a troll. How does one test a shunt to prove it actually works for a given installation without cooking their electronics? I've been vehemently arguing against shunts........
unless it's been proven to do the job it's supposed to do in a given installation. "Do the math" is a lame answer if that's all that's done. I remember a video that showed a shunted augmented ematch and the lithium battery simply blasted enough parallel current to blow it. Having some Joe Blow say they put an unproven "shunt" in an upper stage ignition circuit is kidding themself and could find out the hard way if there is a primary equipment failure.
I think with smaller projects a remote switch along the lines of the Egg products are acceptable but in the really large motors, I'd like a proven fully functioning shunt to take the heat
to avoid a mishap. Kurt

This is a great point. I lean towards the ultra-reliable shunt and multi-stage rocket being two different engineering problems. HEI doesn't seem to be a prerequisite for multi-stage high altitude flights, and I think suggesting it is is asking for trouble.

I'd like to see a TRA-certified HEI rig, and I'd like to see the same for a shunt, but we just don't have either one of those right now. And, pessimistic as I might be, I don't anticipate a uni team creating one that's up to par.

 

[JimJarvis50]

Question and not a troll. How does one test a shunt to prove it actually works for a given installation without cooking their electronics? I've been vehemently arguing against shunts........
unless it's been proven to do the job it's supposed to do in a given installation. "Do the math" is a lame answer if that's all that's done. I remember a video that showed a shunted augmented ematch and the lithium battery simply blasted enough parallel current to blow it. Having some Joe Blow say they put an unproven "shunt" in an upper stage ignition circuit is kidding themself and could find out the hard way if there is a primary equipment failure.
I think with smaller projects a remote switch along the lines of the Egg products are acceptable but in the really large motors, I'd like a proven fully functioning shunt to take the heat
to avoid a mishap. Kurt

Kurt, once again ....

Shunts are a two part thing. You first do the math, which involves determining the current capability of your battery (google), the resistances of the shunt circuit and the igniter circuit, and the no-fire current for the igniter. Then, you do the math. If you don't like the safety factor, just put a resistor on the igniter circuit. I do that.

Part two is to test the shunt. It's good to use a 9 volt if you can, but shunts will work with lipos. You can check the current capabilities of the switches in your altimeter, and you can adjust most of them to provide a short latch time. Since altimeters can be "fired" by computer, you can set up exactly the same circuit, with the actual shunt, the same wiring lengths and the same igniter that you will actually use, and then test the shunt. It's simple. The testing is easier than a ground test.

I have tested Ravens with 9 volt batteries and EasyMegas with large lipo batteries. No problem. No cooking.

Jim

 

[FredA]

"Shunts need to be designed properly and then tested. It is not that hard to do the calculations to determine the current that will flow through the igniter if the electronic fire."

NOT IF YOU DISCONNECT THE ELCTRONICS!!!! DISCONNECT AND SHUNT.
Then the shunt is there to short out any induced current that might be present due to high RF fields.
Just twist the wires and no "shunt sizing" needed.

I've said the above [what seems like] a million times now.

And for another thing I've said a million time, but to quote someone else:

"The certification process is intended to be a test of skills, knowledge, experience, and judgement. We have to be more vigilant in that regard. Given a chance we can cure ignorance with education, we can improve skills with practice, and we can increase experience by insisting on more and diverse flights."​

USE THE CERT PROCESS TO DEMONSTRATE COMPETENCY! L3's should be required to go mach. No "sloppy certs" that didn't fly as planned, but were "safe" so they pass.....

It's not supposed to be easy!

OK - back to HEI.
Screw it in from the top - a bolt that is a larger diameter than the initiator and some JBWeld is all you need.
Keep the wires twisted as they go to the [real physical] DT switch that disconnects and shunts the circuit.
Arm and Dis-Arm the switch as required while the rocket is vertical.

Just make sure your firing electronics does NOT test continuity on any motor circuits [which can be dangerous] and you can test your electronics all you want as it will ignore the open circuit at the switch.

 

[JimJarvis50]

"Shunts need to be designed properly and then tested. It is not that hard to do the calculations to determine the current that will flow through the igniter if the electronic fire."

NOT IF YOU DISCONNECT THE ELCTRONICS!!!! DISCONNECT AND SHUNT.
Then the shunt is there to short out any induced current that might be present due to high RF fields.
Just twist the wires and no "shunt sizing" needed.

Fred, I use both a disconnect and a shunt. The disconnect is "upsteam" of the shunt on the altimeter side of the shunt. I first close the disconnect switch. I want the shunt to be funtional at that point, which means it has to be sized and tested. I verify continuity of the altimeter at that time. If all is well, I open the shunt. I believe I am agreeing with you, but just adding one more layer of safety.

Jim

 

[JimJarvis50]

"Shunts need to be designed properly and then tested. It is not that hard to do the calculations to determine the current that will flow through the igniter if the electronic fire."

NOT IF YOU DISCONNECT THE ELCTRONICS!!!! DISCONNECT AND SHUNT.
Then the shunt is there to short out any induced current that might be present due to high RF fields.
Just twist the wires and no "shunt sizing" needed.

Actually, Fred, I realize that I am perhaps not agreeing with you. If I understand what you do correctly, you are using a single switch that simultaniously opens the shunt and connects the leads to the igniter? How do you know whether or not the altimeter leads have any potential on them at the moment you activate that switch?

Jim

 

[mikec]

Then the shunt is there to short out any induced current that might be present due to high RF fields.

I'd like to see some analysis that says this is an actual concern with the RF levels likely to be present at an amateur rocket launch.

I'm way more concerned about stored energy in the electronics from earlier test runs and unexpected power-on behavior or RF interference to the electronics. In my opinion, an open switch in the ignition circuit is better insurance than a shunt, although both have their value as long as they don't make arming so complicated as to risk human error.

 

[plugger]

Jim, do you think you could link to some of the shunts that you've used successfully with the EasyMega + LiPo combination? And was the LiPo you used 1S or 2S? And are you using MJG J-Tek LF e-matches for sustainer ignition duties or something else?

I've got to be honest, I don't believe I've ever seen a shunt, much less used one. Given this I think it might make sense to ask those who do have experience such as yourself (along with copious bench testing) to ensure my staging wiring is as safe as I can make it.

 

[Jmhepworth]

Jim, do you think you could link to some of the shunts that you've used successfully with the EasyMega + LiPo combination? And was the LiPo you used 1S or 2S? And are you using MJG J-Tek LF e-matches for sustainer ignition duties or something else?

I've got to be honest, I don't believe I've ever seen a shunt, much less used one. Given this I think it might make sense to ask those who do have experience such as yourself (along with copious bench testing) to ensure my staging wiring is as safe as I can make it.

Yes, Jim. Please.

Joe