- May 1, 2009
- Reaction score
Also, Alex, your altimeter comparison spreadsheet doesn't appear include the AltusMetrum TeleMini.
That list can be sorted by Fit the smallest are the PicoAlt PICO-P1 and the Adrel BMP, the first fits a 12mm tube (BT-5) and the second a 13mm tube, the prices have probably increased a bit from $40 and $55. There may be other newer ones that will fit small airframes but those are the smallest two listed.I saw that before,but it didn't help much.
Great job Alex.My attempt to simplify it resulted in an extensive list of all currently available model rocket altimeters and their parameters, such as dimensions, weight, sensors being used, interfaces, pyro options, battery and voltage requirements, etc. All data was compiled from vendor datasheets and manuals. If it's something TRF community finds useful, I'd keep maintaining it.
Link: Model rocket altimeters: Comparison guide.
Now here's how you could help: I'm missing some data for few altimeters (look for question marks), mostly related to dimensions and recording functions. If you have one, measure it / post a file with a recorded flight, and I'll update the guide accordingly.
All comments (except negative ones) are welcome!
Like AltimeterTwo, AltimeterThree expects one engine, so that's what it will report (and while some stats like apogee will be fine, otherslike max speedmay not). The second engine will be ignored, or in rare cases may fool the ejection detection and muck up some of the timing stats and the ejection altitude.One data point that might be worth adding - support for staged rockets - my emails to @John Bean last week confirmed that the Altimeter3 will likely not understand a multi staged rocket... Given he's on the thread, he might be able to expand...
consider this my formal RFE (Request For Enhancement)!!With a slight tweak to software, we could add "2 Stage Analysis." That would lengthen the list of stats shown in the app, and add a stat for interstage coast. Max speed would continue to be calculated and would presumably occur during second stage boost.
Indeed I am! (Arduino/BMP though, so no humidity)Hello!
I'm Rich and today is the first day I'm posting to the forums.
I'm interested in using off-the-shelf components to assemble flight instrumentation.
This past weekend I flew a Lance Delta with two (2) units to record the altitude profile; a RRC3 and a bme280 polled by a Raspberry Pi Zero.
The apogee readings agree to with approximately one (1) foot, at ~970 feet, the shape of the profile graphs also agree very well.
The big difference appears to be the RRC3 is recording data about twice as fast as the RPi.
I had the RPi programmed to poll the bme280 at 10/sec.
Next month I hope to fly a similar configuration to 3-4k feet.
Is anyone else experimenting with off-the-shelf components and specifically the bme280?
That dealer is North Coast Rocketry and they do have current stock. Also some who sell NCR stuff (eRockets.biz, for example) have them. The price has gone up a bit relative to what’s in the comparison table though. It’s $65 for the unit and $87 for the “kit” (altimeter, battery, charger/computer interface device).iirc there is supposed to be a Adrel dealer in the US, someone on TRF mentioned it not long ago.
Bosch makes very high quality pressure sensors, and that's been mostly what Jolly Logic has used historically. They are digital and temperature-compensated (definite requirements these days), but you have to do a fair amount of math to turn the raw pressure and temperature output into temperature-compensated pressure, as you probably know by now. Other pressure sensors like those made by ST do all of that internally, rather than make you do it.Is anyone else experimenting with off-the-shelf components and specifically the bme280?
That is a setting to choose how much altitude change the device needs to "see" before it's decided it's flying. This capability is not unique to the Adrel.I was just looking at the Adrell ALT-BMP on their website. It states that "detection of takeoff" can be set for 2m - 100m.
Does that mean that you LOSE 2m of actual altitude ( minimum ) when the unit reports ?
Also, the unit measures 1 time per second . . . A second is a long time in a rocket !
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Just noticed the reply on this relatively old query. Thanks for the tips.Bosch makes very high quality pressure sensors, and that's been mostly what Jolly Logic has used historically. They are digital and temperature-compensated (definite requirements these days), but you have to do a fair amount of math to turn the raw pressure and temperature output into temperature-compensated pressure, as you probably know by now. Other pressure sensors like those made by ST do all of that internally, rather than make you do it.
Whether you use Bosch parts or not, one tip is to convert all of your math to integer math rather than doing any floating point calculations (ever). No Jolly Logic products have ever used a floating point calculation on the altimeter (even when they show decimals on the screen). Floating point calcs are a huge waste of cycles and energy. Everything—even GPS coordinates—can be stored and calculated as integers, oftentimes MUCH more efficiently. Just a tip.