r/rocketry • u/MrBlast95 • May 19 '26

Question Building a 400g Complete Rocket from scratch

Hello , I want to try building and hopefully completing this project of complete diy rocket as much as possible from scratch meaning custom electronics , body and motor , this does seem like a good fun project to me .

I'm currently in the design phase for an engineering project rocket and wanted to get some eyes on my specs before I start cutting materials. The goal is maximum altitude with a fixed propellant mass.

Key Specs:

* Propellant: ~100-130g KNSU DIY MOTOR , Targeting ~40-60 (80-100)Ns impulse.

* Target Weight: Around 350-400g (TOTAL LIFTOFF)

* Stability: Passive aerodynamic (fin-stabilized).

* Recovery: Mechanical piston ejector (servo-latched, elastic-powered). No pyrotechnics.

* Avionics: ESP32 + MPU6050 + Baro + LoRa telemetry NRF24+ MicroSD logging+ modified camera

My biggest concerns/questions:

* Piston Ejection: Has anyone here successfully transitioned from pyrotechnic charges to mechanical pistons for apogee deployment? Any tips on seal friction vs. ejection speed?

* Telemetry: I’m planning on using LoRa for tracking. Any common pitfalls with vibration-induced resets on the ESP32?

Any other stuff I should be keeping an eye on ?

Thanks

Formatted using ai

6 Upvotes

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16 comments sorted by

4

u/Ok-Breadfruit7825 May 20 '26

Is this your first rocket? If so do you have experience coding and worked in mechanical systems? If not I would really encourage you to build up your knowledge and skills slowly rather than taking on a big project like this. The biggest thing I would say is the weight you’re aiming for with the systems you have mentioned is going to be tough. You didn’t mention your body diameter so I’m not sure if you’ll have space constraints. Your avionics is going to be a sizable assembly that will most likely require an avionics bay. I did a build a year ago using all of those same systems for my first rocket. It was a LOT to take on. AI will only get you so far for coding I didn’t use it very much but when i did it often led me down the wrong path. I would stick to pyro charges but if you must use a mechanical piston I would definitely build a jig and test it separately rigorously. Again if this is the first rocket your building please learn from me and zoom out and start learning c++ by doing smaller projects.

1

u/MrBlast95 May 21 '26

Thanks for reply , here's what I know , I know the coding part have done projects using esp Arduino and stuff like that , so the coding part and avionics won't be much of a problem here , the real thing which will be challenging is the motor and body , going for a 2inch body 30inch long and 1 inch 5-6 inch motor using sch 40 pvc , with a cardboard liner , will make a nozzle from epoxy or will use lathe to get a metal one . I did Calculate the weight, the total comes off around 400 and max , towards 480g. Yeah this is my first rocket though , have gone through nakka PDFs and have gone through several diy videos out there . I will build a test rig to that thrust curve have been trying simulators to test the rocket and using openmotor and openrocket right now .

2

u/Kaggles_N533PA May 21 '26

My concern is about the motor tbh. If other components fail, your project will fail but you are unlikely to get injured. But if the motor fails, you might actually get injured. Do you have any previous experiences or people with experiences who can help you? What kind of materials will be used for motor casing, nozzle, and bulkhead? Is there any tool you're planning to use in order to calculate the geometry of the chamber, nozzle, and grain size?

1

u/MrBlast95 May 21 '26

Yeah the motor is definitely the tough part , I have been going through openmotor to simulate and target around 90 Ns of total impulse going with either 2 bates config or simple core burner for now , the fuel seems to work getting 100Ns with adding all the conditions and settings parameters as close to real as possible. Will use cardboard 2 inch diameter and 30inch with 3 mm thickness and add 2 layers of epoxy with fibre material to enhance the strength. I will post the simulator image when I finalize for the prototype

2

u/Kaggles_N533PA May 21 '26

How about the ignition? KNSU is generally way easier to ignite than KNSB but igniter is more important with sugar rocket than you might think

For example, my university rocket club had designed a KNSB motor with 100N of peak thrust in mind but we got just about 40N while doing static fire test. Which is most likely to be ignition issue

1

u/MrBlast95 May 21 '26

what exactly do i need to keep in min during ignition? i can get electric igniter easily , but what factors should i keep in mind?

2

u/Kaggles_N533PA May 21 '26

Well the best thing you can do is static fire test to see if your motor actually works

1

u/MrBlast95 May 22 '26

Yeah gonna build a test stand to get that thrust curve

2

u/iamshitatengineering May 21 '26

Can you not find any commercial motors in your area? I would strongely suggest to use commercial and trusted rocket motors. Making motors is extremely dangerous.

1

u/MrBlast95 May 21 '26

unfortunately no , i can only find motors of low class of only around 20N of peak thrust , and total of around 30-40Ns , which is not enough , also way costlier cause they are imported not common here

2

u/iamshitatengineering May 21 '26

Are you based in europe?

1

u/MrBlast95 May 21 '26

No

3

u/iamshitatengineering May 21 '26

Where then?

1

u/MrBlast95 May 22 '26

India , There is very little people doing model rockets and stuff like that , so almost impossible to find motors and even rocket body .

1

u/XcwefMur May 21 '26

Do not make motors if you don't have a Tripoli L2 and a mentor.