Electronics in 38mm nosecone. Options?

I'd like to mount some electronics in a 38mm "thin-wall" polycarbonate nosecone and am looking for options. Right now my main priority is less on getting a working electronics set in, and more about setting up a recovery harness anchor that won't preclude them in the future (i.e. epoxying on a bulkplate).

The ID of the cone is 1.36", and the wall is 0.075" thick. That's not a lot of room to work with. It's definitely too narrow to use the common solution of epoxying in an annular ring and bolting a bulkplate to that.

Here are the options as I see them:

[] Cut a thick wood bulkplate and axially tap in countersunk screws through the nosecone shoulder. I worry about the wood being thick enough to not splinter at the screws under recovery forces, and am dubious the NC wall is thick enough to really countersink flush into.

[] 3D print a bulkhead, mount same as above. Probably a better option than a wood bulkhead, though I'm still worried about strength.

[] Get someone to lathe an aluminum bulkhead, mount same as above. Stronger still, but potentially expensive.

[] Get someone to lathe a threaded insert to the ID of the nosecone. Screw in a matched threaded bulkhead. This works around the worries about tapping screws through the shoulder. However, the insert would have to be quite narrow to still allow electronics to fit through. This is also likely considerably more expensive than other options.


What I'd really like is some way to mount my existing Eggtimer TRS. However, I think it's simply too big. As is, stuffed as far as it'll go into the nosecone, it still protrudes about 0.6" past the shoulder. Is there a way to mount electronics beyond the NC shoulder?

Looking for options. Thanks.

I have a solution available:

https://www.ape-rc.com/#!/Head-End-...Molded-Nose-Cone/p/49409110/category=11909535

Will your materials allow you to cut off the existing shoulder, and then use a new piece of coupler to, in effect, create a new extended shoulder? I have done this with BlueTube in the past.

This is my solution - it uses the same thin wall polycarbonate NC as you're asking about. It has a stratologger, 2x Lipo and EggFinder. It's a really tight fit but it works.

Worsaer said:

Will your materials allow you to cut off the existing shoulder, and then use a new piece of coupler to, in effect, create a new extended shoulder? I have done this with BlueTube in the past.

Click to expand...

Ditto, or use the existing shoulder and a bodytube to sort of get an extended payload bay. I did that with a TRS and the antenna was the only thing that would fit in the nosecone.
An Atlus Metrum Tele-GPS will fit in a 38mm nosecone for tracking purposes but it's a very snug fit.
Kurt

ChrisAttebery said:

I have a solution available:
https://www.ape-rc.com/#!/Head-End-...Molded-Nose-Cone/p/49409110/category=11909535

Click to expand...

That looks like a really cool product. Definitely an option.

Worsaer said:

Will your materials allow you to cut off the existing shoulder, and then use a new piece of coupler to, in effect, create a new extended shoulder? I have done this with BlueTube in the past.

Click to expand...

I don't think so. There's no "step" beyond the top of the shoulder so I don't think a coupler would fit.

Zebedee said:

This is my solution - it uses the same thin wall polycarbonate NC as you're asking about. It has a stratologger, 2x Lipo and EggFinder. It's a really tight fit but it works.

Click to expand...

Nice rig. Is the sled actually hardmounted or is it just too tight to bounce that much?

ksaves2 said:

or use the existing shoulder and a bodytube to sort of get an extended payload bay.

Click to expand...

That's a really good idea. Hm, I'd need to buy some coupler, and find someone with the tooling to cut fiberglass... or use my jeweler's saw and patience.

(I wish this forum supported proper multiquote. Doing it by hand is a PITA)

Zeroignite said:

Nice rig. Is the sled actually hardmounted or is it just too tight to bounce that much?

Click to expand...

It's shaped to match the inside of the cone and wedged in at the bottom by the bulkhead so it does not move during flight and recovery. One of these days I might change it up with a fiberglass sled and a couple of small metal brackets to attach to the bulkhead.

I did this on my 54mm minimum diameter project this year:
https://www.rocketryforum.com/showthread.php?122968-The-City-Slicker-was-The-Space-Cowboy-rides-again

ksaves2 said:

Ditto, or use the existing shoulder and a bodytube to sort of get an extended payload bay.

Click to expand...

I've got a TeleMetrum mounted in a 38mm nose by epoxying two lengths of all-thread inside the nose and using those to secure a bulkhead. The TM is mounted on a sled along with the battery and a power switch which slides inside the nose and rests against the bulkhead. Flown many (many) times on some pretty fast motors without any trouble at all. It just uses apogee deploy currently; makes for some nice hikes to go fetch, but GPS tracking means I haven't lost it (yet).

Could you try tapping the wall of the shoulder for a screw?

here is mine.

Very cool stuff here, guys. I'm gonna have to man up and cut into a nose cone!