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Lee3 Regular Member Joined: 17/09/2014 Location: AustraliaPosts: 57
Posted: 01:25am 04 Oct 2014
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My first micromite project is complete - a model rocket altimeter. Fairly bare bones really - just the micromite, a BMP085 pressure sensor, and a pair of LEDs (more for debugging/testing), powered by a little 100mAh 1S lipo. I incorporated a 1N4001 in series with the battery to drop the voltage to 3.3V.
The on/off 'switch' is a jumper, which, when removed clears a header pin that I can charge the battery from.
I haven't included a display (weight/size reasons), so just power off the altimeter, connect to laptop via serial, turn on - the first part of the program displays previous flight data saved in the flight.
The most enjoyable electronics project yet!
Lee
viscomjim Guru Joined: 08/01/2014 Location: United StatesPosts: 925
Posted: 04:02am 04 Oct 2014
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Hi LeeIII, nice project!!!! Can you provide some more details and results. Very good use of uMite.
Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9502
Posted: 02:25pm 04 Oct 2014
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101 uses for heatshrink - a project box!
Nice one.
I'm glad you are enjoying yourself.(as I am sure, is everyone else)Smoke makes things work. When the smoke gets out, it stops!
Lee3 Regular Member Joined: 17/09/2014 Location: AustraliaPosts: 57
Posted: 05:49pm 04 Oct 2014
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Thanks guys....
Flight testing today was successful.
Output from micromite -
(it was a bit warm on the oval!)
Most recent flight
Temp: 40.3 degrees C
Ground data: 1011.78hPa - height AMSL: 12.2284m
Apogee of flight AGL: 57.4377m (pressure: 1004.91hPa)
Previous flight
Temp: 34.4 degrees C
Ground data: 1011.92hPa - height AMSL: 11.0394m
Apogee of flight AGL: 57.9583m (pressure: 1004.99hPa)
A third flight was reported as 75m, one did seem to go higher, is difficult to tell with the sun so high. The motor manufacturer claim 10% tolerance in motor output.
Hopefully will get a chance to try with a bigger motor soon, too windy today! Didn't really want to leave it in a tree on the first outing....
At present I have it log a series of 1000 pressures over a 20s period, 2 min after power-on, my next job is to code a launch detect function, so it will log on launch, probably once it detects a predetermined altitude/pressure differential.
centrex Guru Joined: 13/11/2011 Location: AustraliaPosts: 320
Posted: 10:15pm 07 Oct 2014
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Hi Lee3
A very interesting project any chance of some pictures of the type of rocket used and the software to produce the results that you obtained.
When is your next flight.
regards
CliffCliff
JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4004
Posted: 05:41am 09 Oct 2014
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Any chance this could be used to measure CO2 (and CH4 and other "greenhouse" gases) as it ascends?
John
Lee3 Regular Member Joined: 17/09/2014 Location: AustraliaPosts: 57
Posted: 09:50am 09 Oct 2014
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The rocket is just a little hobby rocket - cardboard, 32mm diam (I think) weighs around 90g.....
The software - the output I posted is a cut/paste from the terminal emulator.
I'll post the program in a moment - the guts of it ie driving the BMP085 is from TassyJim's code on mmreference - I added the parts to collect/analyse data.
Lee
Lee3 Regular Member Joined: 17/09/2014 Location: AustraliaPosts: 57
Posted: 09:51am 09 Oct 2014
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No idea - I suppose if you had the sensors and a large enough rocket... (This one went 200' high in a park don't forget) - a balloon might be better....
Lee
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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