Calculate the altitude for a rocket

Hello everyone, I am using a translator so sorry if I am not clear. I have a project to make a rocket (40cm high 4cm wide) and I would like to integrate a sensor to calculate the maximum altitude of the rocket. I have seen several types of sensor but I do not know if they are reliable and suitable for my project. It should be as small as possible (therefore arnuino nano), fairly precise and that the maximum height from the ground remains displayed on a mini screen. Do you have any leads on the sensors to help me? Thank you very much good day !

Hello sir!
i have a small suggestion , you can try using this two sensor
MPL3115A2 or HMC5883L
The first one can read the pressure on the atmosphere etc
And the second one can sense the gravitational force taking two axis X and Y

It sounds as though you are intending to have the screen attached to the Nano that takes the altitude reading in the rocket. If so, that sounds like a bad idea. The screen will add weight and take space and will not store the value should the power to it be interrupted.

It would almost certainly be better to log the altitude to a file on an SD card at intervals and to read the file on a PC or tablet when it is recovered from the rocket

Wow, thank you for your quick and comprehensive responses! I like the MPL3115A2 sensor, it seems to me suitable for the project and is very small. Will it work inside the rocket? Because the internal and external pressure of the rocket will not be the same? In addition, the rocket will reach its maximum height in about 2s, will it take time to calculate and store the information?

Thank you for your answer, in fact I first thought of putting the information on an SD card but then it would have to be dismantled and a computer used to read the information. Do you know of a module small enough to connect the arduino to the SD card? Thank you !

So if it is possible to make a small hole , in which the the pressure of the atmosphere come in contact with the sensor , Maybe without disturbing the internal circuit could help you a lot
And i wish luck for what you are doing
With regard from Lucky

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Yes, it will take time but it would take about the same time to read and display it anyway and having the display on board sounds like a really bad idea

How high do you anticipate the rocket will reach in 2s ?

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Ok, I will try, thanks @justinlucky !

I don't really know, the original creator of the rocket is this person: CAMÉRA EMBARQUÉE DANS LA FUSÉE ENDURANCE ! - YouTube
The rocket is about 120g according to him (without the modifications that I made), and the engines are a D9-0 (https://www.miniplanes.fr/motorisation-fusees/moteur-propulseur-d9-0- x6-p-68130html) which pushes 8.7N for about 2.1s (I'll try to calculate from that). Yes i think like you now the sd card is the best way :smiley:

This is a question that comes up here moderately frequently, often relating to deciding when to pop the parachute. Try searching the site to see what others have done.

Here one can see how a failed parachute can effect electronics in a rocket:

Unless the rocket is too heavy for the engine, it will coast upward for considerably longer than two seconds.

Hi, @GuillaumeARR
Welcome to the forum.
Have you goolged;

arduino rocket altimeter

You will find many projects doing what you are building.

Tom... :grinning: :+1: :coffee: :australia:

Thanks for the video ! The parachute ejection system is very simple because the rocket itself is very simple, I don't think there is much of a problem.

Yes, sorry I misspoke :sweat_smile:

Ok, thanks, I'll see that !

Famous last words

I do not know if I specified it but the atimeter is only for information purposes, the opening of the parachute is done with a separate system, which uses an inclination sensor.

yeah try checking the MO20 SD card module
I think that will be helpful if you really have to store the data
BEST OF LUCK

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I just made the calculations using software. Engine pushing time 2.1s, maximum altitude reached 4s and total flight time 9s. Maximum altitude: from 65m to 90m according to estimates :grinning_face_with_smiling_eyes:

Thanks you :+1:

Do you need an SD card?

If all you are interested in is the maximum altitude (lowest pressure reading?), then can you not store the value in the internal EEPROM. You can continuously compare current pressure with the lowest pressure and once the pressure starts increasing (i.e. rocket descending), just store the lowest pressure reading in the internal EEPROM.

Or is removeable storage a requirement?

I deliberately did not suggest using EEPROM due to the complication that it would be dreadfully easy to overwrite the recorded value should a reset occur, which I suspect is very likely when the rocket arrives back to Earth. There is also the extra complication of getting the data out of the EEPROM to be analysed at the flying field

There are, of course, ways round this, but using an SD card would be much simpler all round

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Yes, the SD card seems to me the most suitable for recovering data. It only remains to know if the arduino will have time to store and transmit the altitude to the SD card, in 4-5s. Thank you all for helping me :wink: