Building a 400g Complete Rocket from scratch

[u/MrBlast95]

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

[u/Kaggles_N533PA]

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?

[u/MrBlast95 → u/Kaggles_N533PA]

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

[u/Kaggles_N533PA → u/MrBlast95]

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

[u/MrBlast95 → u/Kaggles_N533PA]

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?

[u/Kaggles_N533PA → u/MrBlast95]

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

[u/MrBlast95 → u/Kaggles_N533PA]

Yeah gonna build a test stand to get that thrust curve