As I awaken from my fifteen-year rocketry slumber and take a look around the market for altimeters is very different1. All the vendors I was familiar with–BlackSky, AED, Transolve, Olsen, G-Wiz, Adept–are gone. Cheap, powerful microcontrollers, and even whole computers, can be easily fit into rockets thanks to Arduino, Raspberry Pi, Beagleboard, and others. Why not grab an accelerometer breakout board from Sparkfun (like this one, rated to 200g!) wire it up, and gather all the data your heart desires?

I might take this approach for electronic payloads in the future but I do not want to trust the safe recovery of my rocket to my embedded programming skills. It would be one thing if all I wanted to know is how high the flight was2, but, as it is, I expect a lot more from my avionics.


Here’s what I want:


The players (in alphabetical order):


Great. No products on the market–at least that I could find–meet all of my criteria. Given the field, my recommendations are:

  1. Featherweight Altimeters Raven 4 ~$160
  2. Altus Metrum EasyMini (available from Apogee Components) ~$93
  3. PerfectFlite StratoLoggerCF with USB adapter ~$100 total

HONORABLE MENTION: Marasa Systems Marsa33LHD (~$200) is super cool–it’s got that serious flight computer look and the specs to back it up. Because of its size, it is only suitable for HPR. Marasa Systems feels like the spiritual successor to AED.

I’m holding out hope that the FlightSketch Sport will be released soon because it is the only product I’ve found that ticks all the boxes.

  1. I know because I am in the market for an altimeter. Technically, I have one already: an AED R-DAS mini that has been sitting in a cardboard box for the better part of a decade. Have the capacitors degraded? Does it need to be calibrated? I don’t know. Also, AED went out of business last year and the only copy I have of the control software is sitting on a 3.5” floppy. It probably still works fine but I’ll have to use a USB-serial adapter and hope Windows Compatibility mode can sort everything out (assuming I can find a floppy drive somewhere). 

  2. If you join NAR they send you a copy of the “NAR Member Guidebook” that has all kinds of helpful information. “How High Does It Go? Electronic Altimeters” by Bernard Cawley has a detailed breakdown of 8 model-rocket-sized maximum altitude altimeters. They are all competition certified. 

  3. Reasons for this include low polling rates, low resolution, and worse yet if the rocket breaks the sound barrier there will be a pressure wave that makes the readings unstable during the mach transition. (This used to cause all kinds of problems with old altimeters–like parachutes deploying when the rocket is traveling at maximum speed because of a sharp decrease in pressure registered as an apogee event. Then “mach” timers were included to prevent deployment charges from firing for a set number of seconds. Now, I hear this is all avoided with better software but I’m still wary.) 

  4. By “safe” I mean: “Don’t start the second stage if unless it is flying straight up or at a safe angle of attack.” This is why you need sophisticated embedded programming at the heart of your avionics.