AV Bay building - alternate methods?

[dr wogz]

Another thread on AV bays (the ‘all-thread’ thread) got me thinking. Thinking about my L2 build, and the AV bay I’ll soon be putting together.

I had planned to build a standard style AV bay: AV tube (coupler material) internal & external bulk plates on each end (to make the ‘can’), 2 lengths of all-thread to hold it together, and either eye bolts or U bolts for cord attachments..

But as someone in the other thread mentioned, why not glue a bulkhead into the AV bay tube, and have the other end removable. Why do they both need to be removable? And to further that, why not have the removable one fit inside the AV bay tube, and fasten to a ring or support inside the tube, like we do for NC mounted AV bays? (Although there isn’t much savings doing it that way.. Except a reduced access due the securing brackets or ring..)

And, is the band around the AV necessary? (The piece of BT fitted about the AV bay) I understand it to be used to stop the AV bay sliding up & down inside the BTs.. But it is typically secured to the upper BT with either buttons or screws. So, my thought is to just use screws (into blind nuts secured inside the AV tube) to secure it to the upper BT. As long as the holes all line up, I see no real issue..

My intent is to use what’s supplied in the kit already (Madcow Super DX3) to minimize extra purchases. I plan to use the coupler as the AV bay (as described above) and need only buy and extra two bulk plates. (heck, I can cut these myself!) Obviously some threaded rod & other bits of hardware are needed to bring it all together

Comments?

 

[Nytrunner]

From my experience with an M-powered IREC rocket, both bulkheads being removable made adjusting wiring and setting up deployment igniters Waaaay easier to do. No reason you couldn't fix one though.
We fixed the sled in position on the rods, hooked up one bulkhead's connections, secured it to the sleds, slid the bay-tube over it, then connected the other lid.

Your internal bulkhead idea is cool. A ring or a couple shelf pieces to support an internal bulkhead just like a nose-bay. Tightening down the bulkheads would keep everything compressed and still leave the threaded rods as the primary lead bearing members (which, being metal, are the prime candidates).

I'm also evaluating the switch-band. If you aren't separating the payload AT the AV-bay, or mounting switches to the coupler wall, I don't see the band as 100% necessary. I use rivets for removable pieces (75# break strength rumored)

 

[SpaceManMat]

Agree that a switch band is not necessary. I have a Caliber ISP built with an av bay and no switch band. It just uses rivets to hold it in place. Of course if you want an external switch then I would probably Think a switch band should be used, but my preference is for pull pins.

 

[MikeyDSlagle]

Paul,
It seems you and I think a lot a like, at least here recently. I was looking at this very thing on one of my current builds. The internal bulkplates that is. Will be a good seal against ejection gases, from that end anyway. With one plate fixed firmly to the AV bay, it would be much easier to align the sled to any access holes you may need.

Mikey D

 

[KenRico]

...

But as someone in the other thread mentioned, why not glue a bulkhead into the AV bay tube, and have the other end removable. Why do they both need to be removable?

My intent is to use what’s supplied in the kit already (Madcow Super DX3) to minimize extra purchases. I plan to use the coupler as the AV bay (as described above) and need only buy and extra two bulk plates. (heck, I can cut these myself!) Obviously some threaded rod & other bits of hardware are needed to bring it all together

Comments?

I may have been the one who said make one side fixed in the other thread.

My story is that my first avBay i followed a CJ build thread and marked, measured , cut and did things as suggested . He even used a quarter hole method that did not use a vent band .. and used some wires through the vent hole for a switch.

This was good , i got the flight off and did dual deployment. What i remember most is my rats nest of wire .

Each sled after that , I tried to make things easier in the field ..but rather than tell it all i will just list a few things i like now

I like lids ..and can make my own out of G10 (eplastics/ridout) , love doghouse terminal blocks (the originals ,now @ binder design) , 2s lipos and jst connecters, doghouse charge wells (binder design) , aluminum all thread 1/4 20 (grainger) , 1/4 inch nylon standoff mf 4/40 (grainger), g10 sled that almost kisses the coupler sides including lids (eplastics/ridout) , wildman shoulder style eyebolts , 1/4 inch igniter or launch lug tubes for sled runners (not needed, but helps with wire routing and orientation) and wifi switches and quantums or shruter switches if getting physical. Oh and nylon style 1/4 20 stainless lock nuts .

The vent band is helpful and can be painted to match fins or nose for some style .

Kenny

 

[RocketFeller]

Our AV bay is NC mounted, no all-thread and very lightweight.

 

[OverTheTop]

I have done AV bays with a fixed end or both removable. Because the electronics is generally on a sled there is almost no difference in prepping the rocket from my POV. I would let other constraints drive whether you go one fixed or both removable. Ease of use had no significant difference (but it could be just the way I built the bay too!).

The sealed end does have far less chance of ejection gases getting into the electronics.

 

[BDB]

Our AV bay is NC mounted, no all-thread and very lightweight.

View attachment 310719

View attachment 310720

Impressive! I really like the idea of building a NC bay and then using a JLCR for pseudo-dual deploy. I'm planning to do that on my two 54 mm builds-in-waiting, but maybe I should think about it for bigger rockets too.

Here is my crapy drawing of an idea for a new AV bay that I posted on the "all-thread" thread. I get annoyed by disconnecting bulkheads too, so I'm considering building a bay that has two fixed bulkheads and a coupler that is split down the middle.

 

[Nathan]

My upscale Onyx has the av bay in the nose for apogee ejection and then also uses a JCLR to release the chute at 500 ft.

 

[Nytrunner]

My upscale Onyx has the av bay in the nose for apogee ejection and then also uses a JCLR to release the chute at 500 ft.

That read in my head as the Jolly Chute Logic-Release!


Another option is a chute cannon. Piece of tubing attached to the bay with the chute packed inside and a charge at one end.
Don't have a good schematic atm.

 

[RocketFeller]

Impressive! I really like the idea of building a NC bay and then using a JLCR for pseudo-dual deploy. I'm planning to do that on my two 54 mm builds-in-waiting, but maybe I should think about it for bigger rockets too.

Here is my crapy drawing of an idea for a new AV bay that I posted on the "all-thread" thread. I get annoyed by disconnecting bulkheads too, so I'm considering building a bay that has two fixed bulkheads and a coupler that is split down the middle.

View attachment 310755

Thanks! We have a set of cable-cutters for head-end dual deployment, but so far our flights (~800' and ~1900') haven't warranted it.

I like your idea, it looks like it could be a nice easy way to access the electronics without taking apart the whole AV bay.