Simple e-match connection through av bay bulkhead?

[AtomicStorm]

Interested to see if anyone has any good ideas on how to connect your e-match through the bulkhead of your av bay. I have an idea, let me know what you think or what you've came up with.

 

[Alby]

Interested to see if anyone has any good ideas on how to connect your e-match through the bulkhead of your av bay. I have an idea, let me know what you think or what you've came up with.

I'm building out my AV-Bay and had the same question. Although my current answer is to run a permanent
wire between the inside (connected to the flight computer) and the outside (connected to a terminal block).
This way I can close the hole with the wire using epoxy and wire up the eMatch to the terminal block.
Also as the terminal block becomes degraded, I can always replace it with a fresh one.

 

[DragonRocketry]

 

[Antares JS]

Alby's idea works well. I have a few avionics bays that do exactly that.

Another method is to have a long screw with a spacer and a couple of washers under the head and under the bulkhead. Wires are sandwiched between the washers to bring current to the outside of the bulkhead through the conductive screw.

 

[AtomicStorm]

Thanks dragon, thats a clean looking av bay!

 

[rharshberger]

I use a rubber well nut, the ematch wire attaches directly to the altimeter so fewer connections to worry about. The hole for the well nut has a slot in the side of it the width and thickness of the ematch wire. The picture shown is the only one I have on my phone so it doesnt show the slot which is under the rubber well nuts flange. The open center hole is for the eyebolt. The well nut seals the avbay from ejection gases and pressure, attaching new ematches does require opening up the avbay to attach them to altimeter though. IMO the fewer wire connections the fewer possible failure points, a terminal block has 6 wire connections, 2 at altimeter, 2 at terminal block, and 2 for the ematch to terminal block, the method I prefer has 2 the ematch to the altimeter.

 

[Handeman]

I use the Eaton terminal blocks found here.
https://www.eaton.com/content/dam/e...cb0-single-row-terminal-blocks-data-sheet.pdf

I use either 2 or 4 pole versions #A00110207 for two terminals or A00110407 for a 4 terminal version. Some ATV to seal it and a couple 4-40 screws to mount it to the bulkhead and it works great!

I buy them through Mouser

 

[tOD]

I've become a big fan of the line of AV items from
http://binderdesign.com/store/Dog-House-Rocketry.html
I've been updating some of my older bays using their products. The nice thing is they supply in reasonable quantities, no need to buy 100 of something you need two of.

 

[David Schwantz]

The simplest way is just to run your E match wire through a hole in the bulkhead and then seal with the poster putty. Only connection is at the alt. But let it be said, I have done every way as above and all work well.

 

[kevin.mcgee]

I run a pair of wires from the terminal block on the altimeter through the bulkhead to a terminal block mounted on the exterior of the bulkhead. I don’t permanently mount (epoxy) the terminal block or the wire pass through in case I have to change out one of them. One type of terminal block I have mounts with a screw. The other I just use a friction fit with the holes through the bulkhead.

 

[AtomicStorm]

Wow lots of ideas, just what a indecisive guy needs lol

 

[SkywackerJim]

I’ve ordered some of these from Lab Rat, supposed to arrive Saturday. I haven’t used them before but seen photos on here from others that look like these or something similar.

https://www.labratrocketry.com/product-page/electrical-connectors
I have used some like Dragon shows above. Think I got them from Radio Shack years ago, sure you can find them a lot of places.

I’m working on a 38mm alt bay and need something with a small footprint so see if the Lab Rat ones can fit.

You can also use your threaded rods as a terminal similar to what Antares is talking about. Like if you are doing motor ejection at apogee and doing main only with altimeter. Or if you are using altimeter for both events you could use one rod for apogee, the other for main. Still need one additional terminal at each end, and you better make sure not to get the rod connections backwards!

 

[Neutronium95]

The simplest way is just to run your E match wire through a hole in the bulkhead and then seal with the poster putty. Only connection is at the alt. But let it be said, I have done every way as above and all work well.

I really like this solution. I've only used it once so far, and I didn't get any more leakage than what it replaced. It's dead simple, and it's super compact, which is great for the designs that I build.

 

[OZRoc]

Just saying that any terminal block / connection above the bulkhead is prone to corrosion from the BP charge.
If you use this type and fly often you'll be replacing the connection maybe yearly.
Covering the connection up with putty, silicon lube or anything else will prolong the usage.
DAMHIK
Cheers,
Mark

 

[Handeman]

Just saying that any terminal block / connection above the bulkhead is prone to corrosion from the BP charge.
If you use this type and fly often you'll be replacing the connection maybe yearly.
Covering the connection up with putty, silicon lube or anything else will prolong the usage.
DAMHIK
Cheers,
Mark

Not sure what kind of terminals you used, but I've never had to replace terminal blocks above the bulkhead on any of my DD rockets. One lasted 9 years and 50 flights without any type of covering over the connections like the ones Dragon Rocketry showed in post #3.

They will get very dirty, but they never stopped working without issue.

 

[GlueckAuf]

I use 3/4" or 1" long, 6/32" stainless steel button screws mounted from inside the bulkhead to its outside. These screw into stainless steel tee-nuts epoxied to the outside of the bulkhead. The ends of my ejection squib's two pairs of leads are coiled and sandwiched between two stainless steel washers on the four posts, and rubber well nuts (for protection against shorting) secure each terminal.

This, in my view, is a simple, non-corroding solution. Pictured below are outside and inside views of the redundant apogee circuits of my e-bay lower bulkhead.

NOTE--For this, my Level 3 candidate design, I only use the apogee circuit for BP ejection. A pair of Jolly Logic Chute Releases
handle the main chute's deployment. The two JLCRs are linked in series to provide the L3-mandated recovery system redundancy.



Outside of the redundant apogee event bulkhead:




Inside of redundant apogee event bulkhead. Red leads are from the primary altimeter, green are from the backup altimeter:




Redundant e-match squib with a pair of leads for both primary and backup apogee circuits from the two on-board altimeters:



Good skies,

GlueckAuf

 

[prfesser]

The simplest way is just to run your E match wire through a hole in the bulkhead and then seal with the poster putty. Only connection is at the alt. But let it be said, I have done every way as above and all work well.

Instead of sealing with poster putty, I had some Teflon-coated wire almost the same size as my ematch wires. Drilled a 1/8" hole thru the bulkhead, filled it with silicone caulk, pushed the Teflon wire through, allow to cure completely, remove Teflon wire. To use, push ematch wire through. It gives a virtually airtight seal to alleviate concerns about ejection charge gases.

Best -- Terry