# How to make a timer for Rocket stage separation

Hi i make amateur rockets but i want to step in multiple stage rockets but i want to know if i can program an arduino UNO board as a timer to ignite the charges to separate the first stage and ignite the second motor and how can i do it since im new and i never had done an arduino robot thanks for your time

what is a typical time? An Arduino can count time in steps of 4 micro seconds .

Would it be not better to let the Arduin monitor the fuel level and decide on that, iso of a clock?

Can't you find a way for the second stage to be ignited automatically when the first burns out, or reaches a defined point in the burn sequence? I would have thought that relying on simple elapsed time would require a lot of experimentation to find out what the normal burn duration is, and would rely on the burn duration being consistent (I have no idea whether it would actually be consistent).

I use crushed match heads, but then, I'm pretty old-school.

I would use the ardunio to take pictures. I made a 3 stage 38 years ago made the paper Kansas city Kansan front page even first 12 year old to make a 3 stage it fired all of them. And i lost it so I would of like to had tracking.

I fired mine with the car battery

Yes, an arduino can do that, although you'll need to add some transistors to switch the larger currents required for a typical e-match/igniter, and you'll need some sort of sensor (e.g. accelerometer) to detect events like launch, burnout of the previous stage, etc.

An accelerometer based system is nice because different motors have different burn times. If you use a timer, the timer will have to be adjusted for each motor burn time.

-j

robtillaart: what is a typical time? An Arduino can count time in steps of 4 micro seconds .

Would it be not better to let the Arduin monitor the fuel level and decide on that, iso of a clock?

they are solid fuel motors so fuel level will be hard to measure and they last between 2 seconds in stage 0 to 5 in stage 3

AWOL: I use crushed match heads, but then, I'm pretty old-school.

i use a crushed hand lamp bulb in a little paper bag of gun powder when the current tries to turn on the bulb it ignites the gun powder

PeterH: Can't you find a way for the second stage to be ignited automatically when the first burns out, or reaches a defined point in the burn sequence? I would have thought that relying on simple elapsed time would require a lot of experimentation to find out what the normal burn duration is, and would rely on the burn duration being consistent (I have no idea whether it would actually be consistent).

i actually has tested the motors and they last almost the same in every firing with a diference of about .1 second and think i could program to when i ignite the stage 0 the timer start counting and the the motor runs out of fuel at 1.9 to 2.1 seconds at 2.5 the charges that will separate the stage fire and the upper stage is then fired this will not affect the rocket curse due the momentum it will have but i need to buil the rocket and flyit to test the hipotesis

kg4wsv:
Yes, an arduino can do that, although you’ll need to add some transistors to switch the larger currents required for a typical e-match/igniter, and you’ll need some sort of sensor (e.g. accelerometer) to detect events like launch, burnout of the previous stage, etc.

An accelerometer based system is nice because different motors have different burn times. If you use a timer, the timer will have to be adjusted for each motor burn time.

-j

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that could be an option when the acelerometer measures a disminution in the force of the rocket apply a delay and then fire the charges that will separate the stage and ignite the upper stage and i could also use a gyro to mantain a stable fly and use small aleirons to correct the course (im also a RC plane builder) and i could achieve a less balistic flight ang get a higher apogee

be80be: I would use the ardunio to take pictures. I made a 3 stage 38 years ago made the paper Kansas city Kansan front page even first 12 year old to make a 3 stage it fired all of them. And i lost it so I would of like to had tracking.

I fired mine with the car battery

thanks i didnt cosidered to use a dedicated timer or altimeter the thing of arduino is that you can program it to make a lot of stuff and its light but im ordering a timer from perfectflite.com to test on a smaller rocket before mounting the big one

Would it be not better to let the Arduin monitor the fuel level and decide on that, iso of a clock?

they are solid fuel motors so fuel level will be hard to measure and they last between 2 seconds in stage 0 to 5 in stage 3

You could add an accelerometer to detect propulsion has stopped ...

i could also use a gyro to mantain a stable fly and use small aleirons to correct the course (im also a RC plane builder) and i could achieve a less balistic flight ang get a higher apogee

You're crossing the line between a rocket and a missile. Most governments are pretty aggressive about maintaining their monopoly on missiles. :|

Use simulation and modeling (e.g. openrocket or rocksim) to simulate the rocket's flight. If you feed measurements and test flight data back into it, the simulation will be quite accurate.

Among the simulation inputs are the launch rail angle, rail length, cross wind, etc. Getting all these right will accomplish a maximum altitude about as good as you could get, even with active control, and it'll be a lot easier and safer than trying to implement active control.

-j

robtillaart:

Would it be not better to let the Arduin monitor the fuel level and decide on that, iso of a clock?

they are solid fuel motors so fuel level will be hard to measure and they last between 2 seconds in stage 0 to 5 in stage 3

You could add an accelerometer to detect propulsion has stopped ...

^ I like this one, itd be pretty easy to implement. Wouldn't need a full-scale arduino either since it'd be your only sensor. Ok make it so that your uController does your ignitions. After the accelerometer maxes out during the first stage (this would be the trigger for the arduino), it waits till it goes to a lower state, then fires off the second one. No timer needed. Some If Then statements, and a bunch of spent rockets later. youll have a working system.

How big a rocket are you talking about? You might want to look into http://www.nar.org/ if you are not currently involved with them http://www.nar.org/pdf/FARrockets0209.pdf This document will tell you what is allowed by law (at least in the US). Most multistage class 1 rockets just let the motors push the depleted stage off (talking A,B,C,D motors). The first stage uses a motor like a C6-0 that ignites the second stage by firing forward and that helps disconnect the stages. If you are talking about actively controlling the direction of the rocket, you are no longer talking about a class 1 rocket and have entered a whole new ball game.