Flight Data Recorder

JOddino JOddino at socal.rr.com
Sat Jul 12 12:32:46 AKDT 2003


Earl,
What kind of battery voltages did you see in flight?  Is the sample rate fast enough to see voltage glitches when servos start?  
Jim
  ----- Original Message ----- 
  From: EHaury at aol.com 
  To: discussion at nsrca.org 
  Sent: Sunday, June 29, 2003 10:26 AM
  Subject: Flight Data Recorder


  An ad in the latest MA by Eagle Tree Systems for a Flight Data Recorder attracted my attention. Being able to record airspeed / altitude / servo commands, etc., for review after a flight would seem to be a useful tool for pattern and this device is advertised to do just that for a reasonable price ($150). Details are at: www.eagletreesystems.com

  The first good sign is service, ordered Tues. morning and received Fri. Second good sign is that the software loaded on my PC without a hitch. The recorder calibrated as described and was in a Hydeout and in the air in no time (still Friday). Lastly, data from the flight transferred to my PC for evaluation. (A supplied USB cord between the recorder and PC.)

  It's tricky to interpret the data from the supplied graphics in that you need to figure out just where in the pattern the data were generated. I flew a take off sequence with a level 180 to enter the pattern, so altitude data were consistent for a while and the first pull-up was obvious. With the playback on slo-mo, altitude changes and elevator inputs allow one to follow a pattern pretty well.

  The data can be transferred to Excel and manipulated to provide graphics of the data of interest. It took about 45 min. to build charts of airspeed, elev, and altitude for the Square on Corner (I'm a bit Excel rusty). The data clearly show the entry altitude, the altitude gained (or lost) between elevator inputs, max altitude, finish altitude, and the airspeed through the maneuver. Pretty nifty!

  The device comes set to capture data at the rate of 4/sec which will give 22 min. of record. I found that 8/sec is probably better for our use (10/sec max available) and that will give about 13 min of record. When the buffer is full it stops collecting until reset. I've made no effort to verify speed and altitude measurements except that with the recommended altitude calibration it knows the runway is 0 altitude. (Relative numbers are of good value anyway.)

  Overall this device looks to be a useful tool to help one improve practice sessions. There is no realtime downlink or closed loop control, so nothing outside the rules. (Hmmm - judge thinks entry and exit altitudes differ, wonder if he / she would like to see the real numbers?) 

  Earl

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