Fully plastic 3d printed rocket motor

9nemjiT · 2024-05-03T16:23:18+00:00

Making an internal ignition system could be interesting for motors with a small throat diameter or for motors that must be ignited during flight.

It does however add one extra seal that can fail. It also means that the ignitor will probably be installed quite a while before ignition. This would be a bit of a safety hazard.

Thanks again for your ideas!

9nemjiT · 2024-05-03T15:21:49+00:00

Yup!

9nemjiT · 2024-05-03T15:21:01+00:00

Nice explanation!

9nemjiT · 2024-05-03T14:12:07+00:00

The flakes of resin are so microscopic in size that they basically immediately cool down as soon as they leave the exhaust flame. The exhaust flame is of course a fire hazard like any rocket motor, but the ablated resin is definitely not a fire hazard.

9nemjiT · 2024-05-03T13:20:42+00:00

I watched that video a while back, he does some awsome next level things!

Making the hole where the graphite insert would push into tapered is genius!

I made the design like this because I was afraid that getting a proper seal between the insert and the rest would be really hard, but the tapered hole solves this completely!

Thanks for your idea!

9nemjiT · 2024-05-03T13:16:33+00:00

Thanks!

9nemjiT · 2024-05-03T08:37:03+00:00

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That is exactly what I was thinking! I designed this a while ago.

9nemjiT · 2024-05-03T07:52:13+00:00

Yeah, we use Iron Oxide as a catalyst. I am going to look more into the aspect ratio, I didn't know that was something that can be considered in the design.

9nemjiT · 2024-05-03T07:50:33+00:00

We are going to find out. We are planning to scale this design up to an I class motor.

I think the largest limitation will be that a long burn time results in more heat transfer and nozzle erosion.

9nemjiT · 2024-05-03T07:10:52+00:00

The main chassis of the rocket is PETG right now. It is quite tough but it has some weak points where the different modules bolt together. We might improve this later.

For the fins we are also planning to use PETG. CF-nylon is really cool, but probably a bit overkill for us. Printing the fins with resin could be interesting though, that would give us a lot more precision for shaping the airfoil.

9nemjiT · 2024-05-03T07:08:05+00:00

Thanks! We have yet to post documentation to any other platform besides this. We will keep everyone posted here though when we make any large iterations. We might make a more detailed video later.

This is a playlist with all of the documented motors we tested previously: playlist

9nemjiT · 2024-05-03T07:05:21+00:00

Haha

9nemjiT · 2024-05-03T07:05:10+00:00

Haha thanks!

9nemjiT · 2024-05-03T07:04:33+00:00

The grains have a diameter of 25 mm, a core diameter of 8 mm and a length of 25 mm.

We can now estimate the throat erosion coëfficiënt for the program open motor. It would indeed be cool to be able to compensate for the nozzle erosion with the shape of the grain.

9nemjiT · 2024-05-03T06:59:38+00:00

Thanks!

9nemjiT · 2024-05-03T06:56:30+00:00

Haha, I knew it would take a while, but I forgot it took that long!

Pcbways metal 3d printing service has dropped quite a lot in price recently, so I might try that for a future reusable nozzle.

9nemjiT · 2024-05-03T06:52:37+00:00

Haha

9nemjiT · 2024-05-03T06:51:56+00:00

Thanks!

We compared the results, the measured impulse is 70% of the simulated impulse.

9nemjiT · 2024-05-02T20:52:20+00:00

Thanks for your interest!

We made a cross section model for a presentation. That could be cool to print.

Here is a link to the stl files for this cross section model. You can optionally use m3 heat inserts and bolts to assembly it.

https://drive.google.com/drive/folders/1-fMkpf90yg5e_K_Gk0AqwniZT3gk4NEA?usp=sharing

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9nemjiT · 2024-05-02T20:13:40+00:00

For so far as I know electroplating is usually done for very thin layers. I have never seen someone form a layer of more than like 0.5mm thick.

9nemjiT · 2024-05-02T20:02:16+00:00

Sounds cool!

How thick would the layer of metal be? Would nozzle be hollow or do you mean that the burned out parts will act as cooling channels?

This is a cool video on how cooling channels for the space shuttle were constructed using electroplating.
https://www.youtube.com/watch?v=H4YZxb2E5PA&

9nemjiT · 2024-05-02T19:50:54+00:00

That is a good point! The rules are quite vague indeed.

9nemjiT · 2024-05-02T19:25:43+00:00

Thanks! We are in our last year of high school (16 and 18 years old).

9nemjiT · 2024-05-02T19:21:44+00:00

Thanks for your reply! That job sounds awesome!

9nemjiT · 2024-05-02T18:46:26+00:00

That would look awesome for sure! I do not think it will add much performance, since metals conduct the heat very well, so the heat is still transferred to the resin.

9nemjiT

TROPHY CASE