Head-End Ignition for Airstarts

[cerving]

How do you set up a certified motor (either CTI or Aerotech) for head-end ignition while keeping it "legal"? RCS/Aerotech sells an ignition device that screws into the threaded bulkhead of an AT motor, but it's not for certified motors. I'm trying to visualize how you'd run the igniter wire up the top of the motor (presumably through the delay grain somehow...) without modifying the motor beyond the certification point, and I can't see it. Anybody out there done this? How? Thanks in advance!

 

[rharshberger]

Subscribed!

 

[Ravenex]

My understanding was that all head end ignition setups fall under research rules.

 

[ColumbiaNX01]

I have spoke with gary at aerotech a while back. I am interested for my 2 stage. Using there new head end ignition. He said it would be research. Even though it is a certified motor if you use their system to head end ignite the motor it becomes research and falls under research rules. Nothing you can do about it. Maybe is the future if they certify the head end ignition with TRA then maybe yea but for now its research. He told me they soon will come out with a new forward closure specifically for the head end ignition. If I remember correctly then the smoke grain cannot be used. Beyond that I dont know.

 

[blackjack2564]

Anybody out there done this? How? Thanks in advance!

Yes, but it is a mod or complete new closure.

I have them in 29-38-54-75....for both CTI & AT.

Here's 54 version that works with any size CTI 54 case...yes it is re-usable & completely insulated.
Virtually identical to factory unit with grooves for inner liner as well [like seal disk]








You attach external wire to terminals on outside [which has eyebolt attach also for minimum's]
Internal I use 2 E-match's cut down to 2-3 in. On CTI I put the heads through hole in pellet.
For AT and CTI [large 54..all 75] I tape a BKNO3 pellet that I make between the 2 match heads.

For my slip connection to altimeter pyro channel... there is a set of terminal blocks on BP. with a 4-6 in. lead to a modified JST connecter [cut down to bare minimum].
On the head end side, other side of JST connector soldered to a lead wire. It is re-usable [sometimes] or may need another soldered to lead, depending on how violent separation is.

The set goes like this:
I have an extra JST with wires twisted together, this act like a shunt when plugged into lead going into motor. This stays in till rocket is on pad.

Motor prepped with matches and pellet.[you can use a pyrodex pellet] ignition wires then shorted with plug.
Electronics turned on at table with an e-match hooked up to pyro going to motor.[NOT THE ONE IN THE MOTOR] Never check continuity with direct motor hook up...do this first. The butt you save may be your own!

Lead wire pulled snug to one side of fincan. shock cord & drogue are wrapped in nomex protector. This slid into tube
alongside the nomex. [nothing can tangle this way]

Rocket taken to pad and placed on rail. Electronics again turned on [with match still in pyro channel ] All OK..reset electronics, remove match from pyro.
Now remove shunt/shorted pull from motor leads and plug pyro channel into motor lead. Hook up shock cord and slide av-bay/payload into position.

Remove everyone from pad area... but person arming the electronics. Continue with arming all remaining electronics and igniters in Booster.

Carolina Composites made all of mine. Cost only a bit more than standard closures from factory. Very reasonable.

 

[markkoelsch]

A head end could only be research now. If the manufacturer came out with head end ignition it would represent a significant design change that might push the cert orgs to look at it.

 

[AdAstraPerAspera]

Loki designed a head end setup, but could not get certification even though it proved reliable. My guess is that TRA does not want these to ever be something flown outside research rules.

 

[JohnCoker]

I was experimenting with one based on glow plugs a few years ago:
jcrocket.com/forward-igniter.shtml.

It appeared to work, but I haven't test-fired a motor with it yet.

 

[Steve Shannon]

Loki designed a head end setup, but could not get certification even though it proved reliable. My guess is that TRA does not want these to ever be something flown outside research rules.

Why wouldn't TRA want head end ignition to be considered certified? What are the advantages and disadvantages?


Steve Shannon

 

[dhbarr]

Why wouldn't TRA want head end ignition to be considered certified? What are the advantages and disadvantages?

Obviously I can't speak for TMT/BOD, but a wild guess takes me in the direction of having igniters inserted in HP things that aren't loaded on guide rods.

I'm guessing it's perceived as an in increase in risk. If it's still EX, then it's limited to L2 at the farther distance.

 

[Steve Shannon]

Obviously I can't speak for TMT/BOD, but a wild guess takes me in the direction of having igniters inserted in HP things that aren't loaded on guide rods.

I'm guessing it's perceived as an in increase in risk. If it's still EX, then it's limited to L2 at the farther distance.

You're right; currently head end ignition is limited to research, but I'm trying to figure out if it must remain there and if it really does represent incremental risk. Why is it perceived that way?


Steve Shannon

 

[JimJarvis50]

Why is it perceived that way?


Steve Shannon

I perceive it as a risk because having the igniter in the motor prevents an "all up" test of the electronics. What I do on any two-stage flight is to test the full electronics setup as it will be flown, but with the igniter out of the rocket. That step isn't possible if the igniter is buried in the motor. There are some things that can be done to make this safer, but at the moment, my preference is not to incur that incremental additional risk.

Jim

 

[AdAstraPerAspera]

I imagine that this may change in years to come just due to improvements that allow remote arming of electronics, but that may be far off still.

 

[Steve Shannon]

I perceive it as a risk because having the igniter in the motor prevents an "all up" test of the electronics. What I do on any two-stage flight is to test the full electronics setup as it will be flown, but with the igniter out of the rocket. That step isn't possible if the igniter is buried in the motor. There are some things that can be done to make this safer, but at the moment, my preference is not to incur that incremental additional risk.

Jim

Thank you, Jim. I appreciate the input very much.
With a removable head end igniter such as the Aerotech product, could you perform the "all up" test before screwing the igniter into the forward closure, leaving the sustainer motor out for the test? I know my question may reveal how little I know about how your projects are done and I'm prepared for the embarrassment, I think.




Steve Shannon

 

[JimJarvis50]

Thank you, Jim. I appreciate the input very much.
With a removable head end igniter such as the Aerotech product, could you perform the "all up" test before screwing the igniter into the forward closure, leaving the sustainer motor out for the test? I know my question may reveal how little I know about how your projects are done and I'm prepared for the embarrassment, I think.




Steve Shannon

Well, that might help, but the point of the all-up test is to actually have everything assembled as it would be on the pad. I literally go from the all up test to inserting the igniter to the pad.

I had a situation a few years ago where a motor might have lit on the pad while I was next to it. It was a situation where movement of the altimeter bay was thing thing that closed the circuit in combination with a circuit through the air frame - a one-in-a-million thing. It didn't light on the pad, but it did light on first movement of the rocket, and it wasn't good. In that particular case, the circuit was actually through the air frame of the rocket with the stages together (i.e., through the ends of the carbon air frame, one piece to the next). It would not have been possible to detect this unless the all up test was actually with the stages together (which is why I didn't find it), but my point is that the closer you can be to the actual configuration at launch, the more likely you are to detect a problem.

Notwithstanding the failure of the all up test on the above flight, I rely on the test to stay safe with staging. I design the rocket and the ground equipment to support it, and I actually do it on every launch. That the test can't be done with HEI is why I don't do it.

Jim

 

[Steve Shannon]

Thanks. I have to think about that. I'm not experienced enough with staging and the way you prep to understand the qualitative difference between doing the testing with the igniter uninstalled at the bottom or uninstalled at the top and sustainer motor out of its mount. Either way it seems you would have to separate the stages to install the igniter (with the additional step of installing the motor for the head end igniter).
I apologize for not fully understanding.

 

[markkoelsch]

I can see where head end would possibly be additional risk. You are depending on the electronics to not fire when you arm them. The possibility of a motor going off when someone is standing immediately next to it on a ladder is not a good thing.

Would making the arming sequence of the staging electronics a remote activation a safer/less risky proposition ala the egg timer wifi switch or other method?

 

[JimJarvis50]

Thanks. I have to think about that. I'm not experienced enough with staging and the way you prep to understand the qualitative difference between doing the testing with the igniter uninstalled at the bottom or uninstalled at the top and sustainer motor out of its mount. Either way it seems you would have to separate the stages to install the igniter (with the additional step of installing the motor for the head end igniter).
I apologize for not fully understanding.

Well, the testing is one stage at a time (I don't know how to get around that). But, each stage is completely assembled, and except for the igniter being out of the motor instead of in it, everything else is the same. I don't think doing a test with the rocket and motor in pieces is comparable.

At some point, I think a remote switch will help. I've been told by folks who know much more than me that the design of such switches in not all that easy. But it's on my list to test the ET. A system with this installed would still be subject to the same all up test.

Jim

 

[Steve Shannon]

Thanks. Interesting problem. I haven't tried the Aerotech HEI, but it looks like a person can have the motor fully assembled and simply remove the igniter from the top to test that stage. Of course that requires long leads to the igniter (no longer than a bottom inserted one) and the motor removed from the mmt. I guess the act of pushing the long leads up into the motor mount after the test poses a greater chance of causing problems. I can see that.
I absolutely agree that a 100% reliable when armed and 100% safe when safed remote means of connecting the igniter would be nice. I've been a SCADA engineer for 23 years and I don't know how to do that. There's always some compromise.
Thanks again for helping me understand.

 

[cerving]

I can see where head end would possibly be additional risk. You are depending on the electronics to not fire when you arm them. The possibility of a motor going off when someone is standing immediately next to it on a ladder is not a good thing.

Would making the arming sequence of the staging electronics a remote activation a safer/less risky proposition ala the egg timer wifi switch or other method?

That was one thing I was thinking of when I developed the WiFi Switch and the Quantum. I know I would be nervous arming the electronics on a ladder. With the Quantum, you can arm it from over 100' away.

 

[Loki Research]

AdAstraPerAspera said:


Loki designed a head end setup, but could not get certification even though it proved reliable. My guess is that TRA does not want these to ever be something flown outside research rules.

Why wouldn't TRA want head end ignition to be considered certified? What are the advantages and disadvantages?


Steve Shannon

To be clear, what we were trying to certify was a HEI system that consisted of a working smoke grain that had two wires enclosed within it that could carry the electrical signal to the user supplied ignition device. What I was trying to certify was getting the igniter wires through the bulkhead rather than the nozzle end and still having a certified motor.

It was to be offered only on L2 54/2800 motors and larger so it's certified use wouldn't have enable anything that wasn't already enabled under Research rules. It would have given the user some proven method to follow (with instructions for use) rather than having the user improvise on their own. I was told (in 2014?) it was ultimately about insurance and certifying our bulkheads for use with HEI would endanger that somehow. Given recent announcements on the topic in other areas of the forum, I'd like to know what if anything has changed since 2014 from the TRA BODs point of view on HEI.

Motor manufacturers have been trying to innovate in this area, but durring that time we haven't been given a pathway forward to certification. We've only be able to to throw it to the Research crowd and say, have at it boys and girls.

I do love this solution. https://www.rocketmotorparts.com/Low_Cost_Head_End_Initiator/p1577809_16501656.aspx

 

[SparkyVT]

Head-End Ignition would be a welcome innovation. I used a work-around to light my 76mm minimum diameter sustainer at altitude.

I taped flat copper wire down the length of the motor case.

https://www.adafruit.com/product/1128
I then soldered an e-match to the copper wires. The e-match was held at the top of the motor with a stick, which was held in place with a plywood plug. I cast three pyrodex half-pellets into the center of the smoke grain. The e-match lit the pyrodex, which lit the smoke grain, and then the smoke grain lit the motor. It took about 2-3 seconds to come up to pressure, but it worked like a charm.

In the end, I needed two sets of flat copper wire: one for the booster separation charge, and the other for the sustainer motor.

 

[Steve Shannon]

To be clear, what we were trying to certify was a HEI system that consisted of a working smoke grain that had two wires enclosed within it that could carry the electrical signal to the user supplied ignition device. What I was trying to certify was getting the igniter wires through the bulkhead rather than the nozzle end and still having a certified motor.

It was to be offered only on L2 54/2800 motors and larger so it's certified use wouldn't have enable anything that wasn't already enabled under Research rules. It would have given the user some proven method to follow (with instructions for use) rather than having the user improvise on their own. I was told (in 2014?) it was ultimately about insurance and certifying our bulkheads for use with HEI would endanger that somehow. Given recent announcements on the topic in other areas of the forum, I'd like to know what if anything has changed since 2014 from the TRA BODs point of view on HEI.

Motor manufacturers have been trying to innovate in this area, but durring that time we haven't been given a pathway forward to certification. We've only be able to to throw it to the Research crowd and say, have at it boys and girls.

I do love this solution. https://www.rocketmotorparts.com/Low_Cost_Head_End_Initiator/p1577809_16501656.aspx

At BALLS in 2016 (I think) Aerotech asked the board to consider their head end system. The board was and remains open to the idea and all we asked was for people who flew rockets using them (Research Launches) to submit data so we could understand risks versus benefits. I believe that if that’s done, and sufficient data is collected, the board would ask the Research Committee to help us evaluate the system. It’s entirely possible that the forward closure used by that system could even be approved at some time for use with certified motors. But it requires that flights be flown and data collected and evaluated.
The requirement that the ignition device not be installed in a motor until at a prepping area or at the pad isn’t going away.

 

[Loki Research]

"The requirement that the ignition device not be installed in a motor until at a prepping area or at the pad isn’t going away. "

Again, to be clear the above requirement isn't something that I have ever pushed for removing. The instructions that I submitted to TMT makes this pretty clear in the 2nd paragraph at the top. This can be found on the Documents page of our website. HEI instructions It hasn't been revised since it was DOA.

"At BALLS in 2016 (I think) Aerotech asked the board to consider their head end system. The board was and remains open to the idea and all we asked was for people who flew rockets using them (Research Launches) to submit data so we could understand risks versus benefits. "

Can you be more specific please? I ask because I was actually at BALLS in 2016 with a 2-stage HEI flight and this is somehow this first time I have heard of this request for data on HEI. When you say you are asking for data from users of HEI, what kind of data exactly are you looking for? Loki has had several universities use our motors on 2 stage flights using HEI since 2016. It would have been nice to know that data of some kind was being sought out by the board on HEI usage.

 

[Steve Shannon]

"The requirement that the ignition device not be installed in a motor until at a prepping area or at the pad isn’t going away. "

Again, to be clear the above requirement isn't something that I have ever pushed for removing. The instructions that I submitted to TMT makes this pretty clear in the 2nd paragraph at the top. This can be found on the Documents page of our website. HEI instructions It hasn't been revised since it was DOA.

"At BALLS in 2016 (I think) Aerotech asked the board to consider their head end system. The board was and remains open to the idea and all we asked was for people who flew rockets using them (Research Launches) to submit data so we could understand risks versus benefits. "

Can you be more specific please? I ask because I was actually at BALLS in 2016 with a 2-stage HEI flight and this is somehow this first time I have heard of this request for data on HEI. When you say you are asking for data from users of HEI, what kind of data exactly are you looking for? Loki has had several universities use our motors on 2 stage flights using HEI since 2016. It would have been nice to know that data of some kind was being sought out by the board on HEI usage.

It was announced during the flyers meeting the first day (I hadn’t met you then) and it was posted in the Tripoli forums later as well. It’s possible it was the 2017 BALLS, which is why I said “I think” after the year.

 

[Loki Research]

Fair enough on the year Steve. Still if it was 2017, as a manufacturer of HPR motors well suited to HEI use, and as one who has approached the TRA in the past about HEI certifications, it would be nice if the TRA board made it a policy to notify all motor manufacturers of data requests such as this one, especially when the requested data involves the use of the HPR motors we make.

I still don't know what specific data the board is looking to receive on HEI usage. Could you re-post the request here? It seems like a good place to post it or link to it.

 

[Johnly]

Joe Bevier and I flew a K1000/M685 two stage flight at the ARLISS/XPRS launch in 2020. My personal opinion is that HEI can be flown safely, but the needed safety measures are somewhat complex. The upper stage ignition was inhibited by a Fingertech switch that was closed after the airframe was vertical, next was an Eggtimer WiFi switch that was toggled "on" at ~100 ft., and finally when we were back at the flight line the AltusMetrum TeleMega altimeter was armed remotely. The flight was launched without issue and it all worked according to plan.

 

[Steve Shannon]

Scott,
I found the announcement. I made it to the Prefects Forum in January 2017 following the request at BALLS 2016. Rather than having everyone bombard us with their personal experiences with the RCS System we wanted the data to be collected by our Prefects.
Because it was specific to a proposal made by RCS, we would not have distributed it to other manufacturers.
I’m not going to publish a four year old plea for data here that was Tripoli internal business.
If you wish to propose something to Tripoli like RCS/Aerotech did, you’re welcome to do so.

 

[Loki Research]

"It was announced during the flyers meeting the first day (I hadn’t met you then) and it was posted in the Tripoli forums later as well."

"I’m not going to publish a four year old plea for data here that was Tripoli internal business."

The first, previous statement above led me to believe that this request for data was common public knowledge, available to any member at the time through the TRA forum and that it was to serve the purpose of reviewing HEI in general to be considered for certification use. It did not sound as if "Tripoli internal business" was being discussed in the BALLS fliers meeting or on the TRA forum. Had I interpereted it as such I would not have asked in such a way.

"At BALLS in 2016 (I think) Aerotech asked the board to consider their head end system. The board was and remains open to the idea and all we asked was for people who flew rockets using them (Research Launches) to submit data so we could understand risks versus benefits. I believe that if that’s done, and sufficient data is collected, the board would ask the Research Committee to help us evaluate the system. It’s entirely possible that the forward closure used by that system could even be approved at some time for use with certified motors. But it requires that flights be flown and data collected and evaluated. "

I don't know what the specific proposal made by RCS entailed when Aerotech "asked the board to consider their HEI system", but as I have already presented my proposal to TMT 2 to 3 years before RCS with motor/reload and instructions ready for review and certification, I was ultimately told no in the end and that I could only market it to the Research people. The motors themselves could have been tested by TMT for "data" but instead the same L-2050 motors were tested and certified with the exact same igniters on sticks up the nozzle. It was a missed opportunity in my view. I wasn't asked to gather any information after the fact either.

I still don't know what kind of specific data will help inform the board on HEI use, but are you saying I need to make another written proposal on HEI just to find out?

 

[Loki Research]

"It was announced during the flyers meeting the first day (I hadn’t met you then) and it was posted in the Tripoli forums later as well."

"I’m not going to publish a four year old plea for data here that was Tripoli internal business."

The first, previous statement above led me to believe that this request for data was common public knowledge, available to any member at the time through the TRA forum and that it was to serve the purpose of reviewing HEI in general to be considered for certification use. It did not sound as if "Tripoli internal business" was being discussed in the BALLS fliers meeting or on the TRA forum. Had I interpereted it as such I would not have asked in such a way.

"At BALLS in 2016 (I think) Aerotech asked the board to consider their head end system. The board was and remains open to the idea and all we asked was for people who flew rockets using them (Research Launches) to submit data so we could understand risks versus benefits. I believe that if that’s done, and sufficient data is collected, the board would ask the Research Committee to help us evaluate the system. It’s entirely possible that the forward closure used by that system could even be approved at some time for use with certified motors. But it requires that flights be flown and data collected and evaluated. "

I don't know what the specific proposal made by RCS entailed when Aerotech "asked the board to consider their HEI system", but as I have already presented my proposal to TMT 2 to 3 years before RCS with motor/reload and instructions ready for review and certification, I was ultimately told no in the end and that I could only market it to the Research people. The motors themselves could have been tested by TMT for "data" but instead the same L-2050 motors were tested and certified with the exact same igniters on sticks up the nozzle. It was a missed opportunity in my view. I wasn't asked to gather any information after the fact either.

I still don't know what kind of specific data will help inform the board on HEI use, but are you saying I need to make another written proposal on HEI just to find out?