Mini rocket altimeter system (power supply)

Projects General Guidance
1

Hello everyone

I would like to send a mini rocket (~30 centimeters high) with a friend, and I am in charge of the circuit for the altimeter. As I am beggining in Arduino, I wanted to know if 2 AAA batteries would be enough to power the whole circuit, that would consist of an Arduino nano, a BMP180 barometer and supposedly a storage device, but I'm not sure if this is really needed.
As I said, I'm pretty much a beginner, so I don't know at all how much power that would require, but I guess it shouldn't be a lot, as well as for the storage (maybe the Arduino card would be sufficient ?)

Thank you for your answers :slight_smile:

2

Planeuge:
Hello everyone

I would like to send a mini rocket (~30 centimeters high) with a friend, and I am in charge of the circuit for the altimeter. As I am beggining in Arduino, I wanted to know if 2 AAA batteries would be enough to power the whole circuit, that would consist of an Arduino nano, a BMP180 barometer and supposedly a storage device, but I'm not sure if this is really needed.
As I said, I'm pretty much a beginner, so I don't know at all how much power that would require, but I guess it shouldn't be a lot, as well as for the storage (maybe the Arduino card would be sufficient ?)

Thank you for your answers :slight_smile:

Well, that is quite a dilemma! Here you have the components right in front of you can probably have them all connected and working and you have to ask the forum is they will run as long as the rocket will fly.

Consider trying the assembly powered by 2 AAA batteries and see how long they will run!

Paul

3

Please post a link to the "supposed" storage device. You will need something to record measurements, although about 250 pressure measurements could fit into the Arduino EEPROM.

Consider the SparkFun OpenLog. It consumes very little power, will run on 3V, and no programming other than Serial.print() is required.

4

If your using AAA Alkalines do remember they will be about 1.2V each or lower, when around 50% discharged.

So 2.4V might be a marginal supply for some of the components, here the datasheets for the devices are your friend, but you have to read them.

AAA Lithium energizers are a far better power supply, light, and will be around 1.5V each for most of their life. Good to around -40C, and thus a common power supply for high altitude balloon trackers.

5

So how long is a flight of a 30 cm rocket, really? It'll measure in the seconds, maybe minutes. Not hours, let alone days.

2xAAA is a problem for a Nano which expects 5V, and which needs 4-4.5V for the processor to work with the 16 MHz clock.

So replace that with a Pro Mini 3.3V/8MHz. It'll do fine on two AAA batteries and is about half the weight of a Nano. You may be able to run the whole contraption off a 3V coin cell, saves you more weight.

The BMP180 works at 1.8V up to 3.6V so that's a perfect match. 3xAAA would require a regulator for that guy.

The storage - well, only if the internal 2kB EEPROM is not enough. For extra storage, maybe the 24AA256 external EEPROM, it also works at 1.8V (the more common 24LC256 is 2.5V up, but that one would work with a 3V lithium cell but maybe not with 2xAAA alkaline as most of the battery life the voltage is about 1.2-1.3V). You'd have to find a way to read it later, maybe over the Serial interface.

6

Planeuge:
I would like to send a mini rocket (~30 centimeters high) with a friend, and I am in charge of the circuit for the altimeter. As I am beggining in Arduino, I wanted to know if 2 AAA batteries would be enough to power the whole circuit, that would consist of an Arduino nano, a BMP180 barometer and supposedly a storage device, but I'm not sure if this is really needed.

Would such a small rocket have a motor powerful enough to lift a 'logger' that would weigh around 20g ?

7

Paul_KD7HB:
Here you have the components right in front of you can probably have them all connected and working and you have to ask the forum is they will run as long as the rocket will fly.

The thing is that I don't have them, and I would like to know if that works before I buy and use them (but if I had sufficient funds to, I would just have tried by myself, don't worry :slight_smile: )

jremington:
Please post a link to the "supposed" storage device.

That's the whole point of the question, I was wondering if there could be enough memory in the card itself.

jremington:
Consider the SparkFun OpenLog. It consumes very little power, will run on 3V, and no programming other than Serial.print() is required.

I Don't really know what it consists of, as I said, I REALLY am a begginer, but I will certainly consider that :slight_smile:

srnet:
AAA Lithium energizers are a far better power supply, light, and will be around 1.5V each for most of their life.

I had no idea at all about that, thanks a lot for the tip !

wvmarle:
You may be able to run the whole contraption off a 3V coin cell, saves you more weight.

The problem here, isn't really the weight, but the size, with a very limited diameter of 3.8 centimeters, but it still seems alright to meFor the storage, I'll try to figure it out later, but I'll keep that in mind :slight_smile:

srnet:
Would such a small rocket have a motor powerful enough to lift a 'logger' that would weigh around 20g ?

Yeah, I guess so ^^'

8

Planeuge:
The problem here, isn't really the weight, but the size, with a very limited diameter of 3.8 centimeters, but it still seems alright to meFor the storage, I'll try to figure it out later, but I'll keep that in mind :slight_smile:

Yeah, I guess so ^^'

So your only guessing that your rocket can carry the weight of the logger ?

Might it be an idea to ask in a 'Rocket' forum how much extra weight your choice of rocket and motor can carry.

Not a lot of point in designing a logger if it wont get off the ground.

9

If you're only sending the rocket ~30cm high, is an altimeter really necessary?

10

From what I have heard (between reading here on the forum about people playing with drones, using commercial airliners and watching documentaries about space flight) weight is a pretty important factor for anything that has to take flight. Every gram or fraction of it counts.

On-board space is of course another concern but usually less so.

Storage: you can get a good estimate of how much storage you need by taking the typical duration of the flight of your rocket, the sampling frequency of your data, and the actual amount of data you want to log.

Without such basic parameters you can't design a system that fits your rocket and will offer you the data you want.

11

Keep in mind a heavy object can throw off the center of balance on a rocket also. You will need to consider the placement of the payload.