Astra V
title: ASTRA - Autonomous Stabilised Thrust Recovery Ascent
author: Manan Sharma (@Manan)
description: A basic paraffin powered rocket which goes up, falls down and lands on 4 legs.
created_at: 2025-07-14
Total hours - 93 hrs
14th July, 2025 - Doing research, I've been researching for about 5-6 hours now and i came to a conclusion - I am going to use hybrid oxidising motor to power my rocket as i can control them and make them work the way I want. I am locking in paraffin wax and n2o chargers for the fuel for now. I am gonna use whipped cream chargers as they suit the requirements here. Other than that I am right now studying how solenoid valves work and how can I effectively use them. Packing up for today - Its 4am.
hours - +4
15th July, 2025 - Did a little more research and finalised everything - the structure and layout of everything including the positioning of the parts etc. now time to search for all the crucial hard to find parts and start with the cad model.
hours - +2
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Started with Open Rocket - made a basic model of our rocket. Going to complete this tomorrow and simulate some test flights. signing off for today.
hour - +2.5
hours - +2
29th July, 2025 - Need to speedrun this project in the next 3 days. ran some simulations, things look good.
hours - +4
30th and 31st July, 2025 - Completed the cad model, with the calculations for Centre of Gravity and everything else. Decided the dimensions of the things like landing legs etc. hours - +7
-- Also completed the research for the fuel system - the way everything will work and like the flow of the energy. Finalised the chamber design for parrafin wax and no2 chargers and all the other things. Also started working on the flight controller - researched for the parts and found the suitable things which complement each other - rn we are using - 2 lidars on either side, STM32 L052K8U6 as the MCU, MPU6050 as gyro, and BPM280 as the altimeter. Also using a RF module to make the launching system's trigger. hours - +14
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Completed the schematics -
hours - +5
August 1st and August 6th - well while making this thing - i submitted it for an event but soon i realised that the pcb ive made is quite cooked, i should not use a stm as a first timer. so rn my goal is to remake this whole thing in the coming 3 days and ask for a rereview. lets see - these are the current things.
this pcb took around - 17 hrs
August 10th - Remade some of the schematics, gonna complete all tomorrow.
hours - +4
August 15th - Continued with the schematics, also had to go through a lot of things which made me go down and wanted to leave on this thing a lot of times, the thing which messed the most was the spark plug thing - the thing is that im using a 7.4V battery and a 5v buck converter to power pico and servos/lidar. But the thing is that i wasn't able to find any spark plug that could work with the 7.4V battery or the 5v buck converter thing. So i just felt like this thing isnt going anywhere as 5v or 7.4v for once is too less for something like this. So I did some more research to find if im able to find something to produce the spark working in the desired voltage, so i kinda gave up on the project as same was gonna happen with the solenoid valve, so i just slept for straight 12 hrs and woke up to do some research for the last time and surprisingly enough i found something, not a typical spark plug but a arc ignitor, i stumbled across it once before but kinda didn't look at it because it just felt too unreliable and I had spark plugs in my mind. So yeah i thought that i'd just use an arc ignitor with a power from pcb power rail and like control using gpio from pico using logic shifters or something if needed but then i realise that the only arc ignitor available here is a breakout with a button to put it up fire, so its like a plasma thing between two closely placed naked wires, so depression came in again, but then i realised that i am getting a bambu a1 mini real soon from shipwrecked so i just decided that i'd make a gear system with a servo motor controlled by the flight controller to press the button to put it up and roll back when it is not supposed to be pressed, so yeah thats it. Now i gotta figure out to use solenoid valves with the voltage limitation as im only finding 24v valves which can actually control the gas etc. and then gotta finalise the fuel system.
hours - +7
August 19th - ok so the thing is that we are on the verge of completing the pcb, i just routed everything and completed everything - might add some capacitors and decoupling caps for safety other than that the core thing is done. i decided to go with just gaseous fuel for now than a oxidiser and fuel thing - so we are using butane and not gonna use solenoid valves, we just gonna use canisters with a 3d printed apparatus which will push and spray the gas into a chamber via tube when servo motor pulls it, and the servo will be controlled with the flight contoller, yep so did research - routed everything and compiled the BOM. Just finishing touches left.
hours - +11
August 20th -
hmmm SOOO the pcb is done, complete! yup so i made a system on what im gonna do with the fuel system as solenoid is something that cant be used with this pcb like this, so we made a setup to use a butane can and use a servo to press and release gas into a combustion chamber through a tube, and the servo will be controlled with the flight controller. yup so other thing is that i changed the thick 5v traces with a 5v plane finally, so we have two planes one for ground. So yeah PCB is done, added all the capacitors for all the components - 0.1uf ceramic at every component, 100uf electrolytic at every cluster of power consuming comps like servos and lidar, and 470uf electrolytic and a 10uf at the same place. We are using a 11.1v battery and a stepdown converter converting it to 5V which is powering the pico, servos and LiDar, and the 3v3 pin of the pico is powering MPU6050, BMP280 and the nrf module. Also added a few sketches and texts on the silkscreen - one is a rocket sketch i found online, one is GSLV - an indegenious launch vehicle developed by ISRO and a sketch of Neil Armstrong on the moon.
hours - +6
September 13th -
So yeah a big break, i was done with the initial design everything, then a while ago i felt like making a thrust vectoring system to ensure that it stays straight as I was 100% of it getting tilted, so yeah other than that - i also optimised the flight controller pcb by a lot, I am done with the pcb now and below are the images, also yeah I got a 370$ grant to build this thing irl, so yeah im going to finalise everything tomorrow and then start ordering stuff.
hours - +10