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It's been a slow go...

A project log for 3DPMRS - 3D Printed Modular Rocket System

Collaborative rocket design.

Mike MalukMike Maluk 04/15/2016 at 21:356 Comments

I haven't been able to devote too much time to this project lately. However, I've just taken two weeks of leave, so I'm sure I'll be able to get some things done. I'm hoping to knock out (or at least start) on:

-Fiberglass body tube (just need to wrap and glass...)
-Larger 3D printed motor mount and nose cone
-Updated interchangeable motor cage to allow for a variety of motors
-Multi-stage?
-3D printed motor (or at least test the viability of a one time use motor...)

Hopefully I'll be back with updates soon!

Discussions

J. M. Hopkins wrote 04/17/2016 at 02:56 point

For the 3D printed motor, what materials, propellant chemistry, geometry, etc are you planning?

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Mike Maluk wrote 04/17/2016 at 15:02 point

I'm still doing research, but I was looking at  the KNDX (potassium nitrate and dextrose) propellant mix. I'm curious to see how the motor would hold up after the burn. I have no plans to make the motors re-usable; if I could get one fire without it failing I'd be overjoyed. 

As for the nozzle design... I've got a few options. I've got a small mill that I can use to cut a graphite nozzle insert with. This would be more expensive (not to mention difficult), and I feel it would take away from the repeatability and ease that I'm going for with a printed motor, but it would hold up extremely well (and probably be able to be transplanted from motor to motor). Another option is to use anchoring cement to form an internal nozzle like the Estes motors... What I'd love to be able to accomplish would be to print a nozzle and coat it to resist the heat of the propellant. Maybe JB weld would be able to resist the high nozzle temps for a short period of time? Any ideas for a coating?

I've been reading Nakka's blog (http://www.nakka-rocketry.net) and trying to absorb as much as I can. There's a fantastic amount of detail there and it's been a huge help.

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J. M. Hopkins wrote 04/17/2016 at 15:33 point

Nakka's site is indeed quite a wealth of information.

I've done quite a bit of development with single use sugar motors, and would suggest a few things.
Join the experimental amateur rocketry group on Facebook https://www.facebook.com/groups/1396488870646273 there is an awesome collection of people there, many with experience with sugar motors.
I imagine you are looking at smaller motors, so look at this video: 

Depending on the size of your motors, different techniques are more applicable.

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Mike Maluk wrote 04/18/2016 at 00:21 point

That's a really simple way to do it, thanks for the link to the video.
I'll also check out the group. I don't currently have a facebook
account, but it might be worth it for that.



Thanks again for the help!

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J. M. Hopkins wrote 04/18/2016 at 00:29 point

I'm kind of anti Facebook myself, keeping only family members as "friends" for sharing pictures of the kids, but the group had really helped me put me in contact with the right people. Rick Mascheck admins the group, and is working the SS2S (sugar shot to space) program with Nakka and a few others, they are great resources. 

I'll be moving to southern California here soon, and one of the perks will be access to the FAR (Friends of Amateur Rocketry) site for some serious rocketry experimentation. That's where the SS2S program tests, along with some other notable teams and personnel.

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Mike Maluk wrote 04/18/2016 at 15:49 point

I'll definitely have to check it out. The SS2S project sounds awesome, I saw a few mentions of that on Nakka's blog. 

That's great news on the field, I'm looking forward to seeing more launches at the new site with your project. I've just joined the NAR myself and there's a club that's pretty close in KC that I'm looking forward to visiting. Also NARAM is pretty close to where I live (3ish hours), so I'm looking forward to attending. Even the NSL even is close in Tennessee, totally do-able drive. Should be a productive summer.

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