EZ Electronics Bay

I don't have the November 1995 issue of High Power Rocketry magazine in front of me to refer to, but I happen to know that this is the issue that has the information I need...

There's an article in it describing how to build an electronics bay that fits diameters from 2.26 to 7.67 and beyond. The basic design starts with two bulkhead assemblies [two couplers and two plywood bulkheads]. The instructions have you fit one coupler inside the other, then the bulkheads are held in place at each end of the assembly by a single long bolt.

If anyone happens to have this issue, could you please let me know what type of bolt the instructions specify to use. I built this once successfully years ago, but forgot exactly what hardware was used. I'm trying to build another one for a new project and, of course, I don't have the first one I built OR the original article in 11/95 HPR to refer to.

Thank you very much. BTW, if anyone else is curious as to the basics of how this goes together, I'll be happy to provide what I know if asked.

I would love to have all the details of that project. I'm currently designing an extreme altitude rocket and a level 2 rocket. I'm caught on how to do the electronics bay. I've had experience with the PML CPR3k but am having trouble locating info on any other alternatives.

Thanks

You're doing a 38mm minimum diameter project, aren't you? I'm sure there's a way to do that one, but I think this particular article said that the smallest you could do was 2.26...probably because this "bolt" I'm inquiring about goes down through the middle of the assembly.

The basic design of this is pretty simple. Cut about 1/2 inch off the length of one of the couplers, and then a 3/4 inch gap down the length of this same coupler. You should be able to put this inside of the other coupler, and you'll have 1/4 inch at each end for the bulkheads to fit on. Glue the "sleeve" in place, and then glue one [and only one] of the bulkheads in place. This much I remember clearly.

The part that gets fuzzy is what hardware the instructions indicate hold the other bulkhead in. This bolt also serves as a place to hold the altimeter [or your favourite electronic device] in place. The only eye bolts long enough to go through the whole assembly [6 or 7 inches] are over 3/8 inch thick and seem heavier than the hardware I used the first time I did this.

Hmmmm... I'm a picture guy. Do you have any pictures? I hope someone has the article, maybe they can scan it for everyone to see.

I took some pictures just for you.

https://www.necromantic.net/deadparrot/images/bulkhead01.jpg

The first picture shows the parts as they need to be before you glue anything in place. Here, I have two 3.00 bulkhead assemblies. I've taken the eye bolts and washers off of both plywood bulkhead plates. To one of the coupler tubes, I've shortened it by 1/2 inch, and cut a gap of about 3/4 inch down the length. This second cut doesn't need to be straight as an arrow; all it does is allow you to put the tube inside of the other coupler tube.

https://www.necromantic.net/deadparrot/images/bulkhead02.jpg

The second picture shows the "sleeve", the coupler you shortened and cut a gap into, down inside the other coupler tube. Notice one of the plywood bulkhead plates in place at the bottom of the assembly. The outer coupler tube is sitting flush on the work surface. Notice, also, that the inner coupler is recessed below the top of the outer coupler by about 1/4 inch; the thickness of each plywood bulkhead plate. The gap in the inner tube is also visible. It won't matter how big this gap is inside of the tube, as long as you cut it wide enough that it can be fit within another coupler of the same size.

It should be noted here that holes will obviously need to be drilled in each bulkhead plate in order to use a dual deployment altimeter.

The second bulkhead plate does NOT get glued on the assembly, unlike the first one. I know somewhere along the line, you're supposed to use a single bolt long enough to span the entire assembly, which in this case, happens to be 7 inches. The likely suspect, or so I thought, was a single eye bolt. The "eye" end sticks out past the stationary bulkhead [which eventually gets glued into the payload section of your rocket], and a wing nut was employed to fasten the other bulkhead plate in place for each flight. On this detachable bulkhead plate, I would presume you would fasten another eye bolt [the one that originally came with the bulkhead assembly?] for attachment of the recovery system.

As I say, I'm pretty sure it was in the November 1995 issue of High Power Rocketry. If not that issue, then one near it. It was definitely before July 1996, because I had flown the rocket I built one of these assemblies for at LDRS XV.

Ahhh, now I get it. Thanks. I guess you would then have to create an aparatus to hold the altimeter, etc.

OT: necromantic.net??? I gotta know, why necromantic.net? The only Necromantic I know of is that German movie. Bad, bad, bad...

Holding the altimeter shouldn't be a problem. You could probably make some foam spacers to hold it in place and absorb hard landings. Part of the design of having a bolt going through the length of it is to have a place to keep the altimeter mounted on something solid. Glue a launch lug on the back of the altimeter and slide it onto the bolt.

As for necromantic.net; necromantic.com was already taken.

I found the original article at long last! It was written by Bruce Kilby [not Kelly] in the November 1995 issue of HPR.

Anyways, the original question I had posed was what was being used to hold both bulkheads in place. The answer, it turns out, is a 1/4" x 8" eye bolt. Months ago, I went through a couple of different hardware stores and did not see an eye bolt matching these dimensions. That is not to say, however, that they do not exist anymore.

For the rocket I wanted to use it on, I cannibalized it from another rocket I buolt 5 years ago.

A few things left out from my hazy recollection of the original article:

- Both bulkheads should have a small hole drilled in them to pass the wiring harness through.

- Sponge rubber is used to pad the electronics.