Model Rocketry Braking System

Lately I've been trying to come up with a way to use airbrakes on a model rocket to reach a target altitude.
My goal is to feed out telemetry data from a PerfectFlite PNUT altimeter into an small and light weight Arduino. Then the Arduino would use a equation to determine the best time to deploy the airbrakes.
While being experienced with model rocketry, I am not very experienced with the Arduino side of things. Any guidance on how I would get the telemetry data to the Arduino and then how to control the servo that deploys the airbrakes via the Arduino would be helpful. Also, I don't really know what Arduino I should use, however I want one lightweight and small. It has to fit in a BT-70 tube (5.54 mm diameter)

Thanks!

There are no Arduinos that would fit into a 5.54mm diameter tube.

However you could easily fit one in a 55.4mm tube.

JohnLincoln:
There are no Arduinos that would fit into a 5.54mm diameter tube.

However you could easily fit one in a 55.4mm tube.

My bad. I meant centimeters.

so what Arduino system would you sue to accomplish this >

Arduino Nano or clone. Small and light, but a full-featured ATmega328, plug&play with your USB ports.
There are smaller and lighter versions (pro-mini, trinket, digispark, etc) but they are "special" enough that I wouldn't rate them as good a choice for an Arduino beginner. (needs external usb/serial cable, doesn't support Serial.print, doesn't match the majority of tutorials, etc...)

westfw:
Arduino Nano or clone. Small and light, but a full-featured ATmega328, plug&play with your USB ports.
There are smaller and lighter versions (pro-mini, trinket, digispark, etc) but they are "special" enough that I wouldn't rate them as good a choice for an Arduino beginner. (needs external usb/serial cable, doesn't support Serial.print, doesn't match the majority of tutorials, etc...)

Alright, thanks!
I'll be sure to look into this.

I'd use an Arduino Nano with no headers. That way, you can just solder the wires directly to the board to save space.

As for an altimeter, might be able to use something like this directly on the rocket, connected to the Arduino.

I've never used an altimeter like that one before, but I imagine you could find a way to easily communicate with it. Once you get near the target altitude, you send a servo command (i.e. Servo.write(180)) to change the position of the speed brake.