Jim Sower wrote:
Paul wrote:
Troy wrote:
Colby saw him take off at night in the rain. What got his attention was
after start there was no delay with a quick power up and taxi to the east
end. He did do a mag check but was obviously in a hurry to see his
girlfriend in Arizona. He penetrated rain and clouds on departure with a
quick turn west to east. No amount of devices would have saved him pushing
resources like he did. If he had a graphic display like your picture, would
he have avoided vertigo? Does the display show the numerous transmission
lines across his path? This fellow was doomed the second he made the
decision to take off. A needless tragedy similar to J. F. Kennedy Jr.'s.
Troy
Troy has a point here. It would be nice if the pictured tilted on
the screen when you were in a bank. That would let you know when you
were turning and it would jibe with the attitude gyro to reduce the
possibility of vertigo.
The software could take in attitude data from the attitude gyro.
Some, as I recall, have outputs to auto pilots.
On second thought it might not be necessary as the GPS puts out
heading information if the heading is changing you are in a turn.
Same goes for altitude. If it is changing you are climbing or diving.
Sort of a solid state, no moving parts, attitude gyro.
Paul Lamar
With the clear understanding that no amount of technology can substitute for
common sense and good judgment, GPS alone wouldn't work very well. In gusty
conditions sudden oscillations in heading would be interpreted as wild and
massive oscillations in bank. The picture would go crazy. But there were folks
a while back who were mounting 4 GPS antennas to get differential readings for
attitude. An even better (and perhaps far cheaper) solution might be Rutan's
idea of a very inexpensive radar that does nothing but paint the horizon. Depict
that, along with flux gate heading input and you have pretty much what you want.
Just a theory, Jim S.
I think the GPS does not sense an instantaneous heading change like you
would get in turbulence. It actually measures your position once each
second and compares it with the last one second heading and determines
your heading from that. Now there is such a thing as "selective availability"
which is a fancy way of saying the defense department screws up the signal.
I have written a program for a PC that reads the GPS data and records it
on the hard disk. With a GPS sitting still you get weird data like
this. This is updated every two seconds. Later GPS's update every one second.
Notice the time is from the atomic clock in the satellite and is accurate
to the nearest microsecond.
Time Lat. Long Kts Heading
"200401.253925","3420.789","N","11903.953","W","0000.4","288",""M
"200405.253920","3420.794","N","11903.961","W","0000.0","233",""M
"200407.253917","3420.796","N","11903.964","W","0000.1","169",""M
"200409.253914","3420.798","N","11903.966","W","0000.1","213",""M
"200411.253912","3420.801","N","11903.968","W","0000.3","251",""M
"200413.253909","3420.802","N","11903.970","W","0000.4","201",""M
"200415.253907","3420.804","N","11903.971","W","0000.4","242",""M
"200417.253904","3420.804","N","11903.973","W","0000.6","253",""M
"200419.253901","3420.805","N","11903.973","W","0000.3","189",""M
"200421.253899","3420.805","N","11903.975","W","0000.5","213",""M
"200423.253896","3420.806","N","11903.976","W","0000.4","246",""M
"200425.253893","3420.806","N","11903.977","W","0000.6","226",""M
"200427.253891","3420.805","N","11903.979","W","0000.7","212",""M
In an actual C182 situation you get data that looks like this.
Slightly different format from the program I wrote.
Sentence Time Valid Lat Long Kts Head Date Chk sum
^ ^ ^ ^ ^
$GPRMC,163324.706222,A,3833.745,N,12000.648,W,0120.5,166,060793,,,*29M
$GPRMC,163326.706220,A,3833.680,N,12000.627,W,0121.0,166,060793,,,*2CM
$GPRMC,163328.706219,A,3833.614,N,12000.606,W,0122.0,166,060793,,,*25M
$GPRMC,163330.706218,A,3833.548,N,12000.585,W,0123.2,166,060793,,,*2CM
$GPRMC,163332.706216,A,3833.481,N,12000.565,W,0123.7,167,060793,,,*2EM
$GPRMC,163334.706215,A,3833.413,N,12000.549,W,0124.1,170,060793,,,*29M
$GPRMC,163336.706213,A,3833.345,N,12000.535,W,0125.0,171,060793,,,*23M
$GPRMC,163338.706212,A,3833.276,N,12000.522,W,0125.8,171,060793,,,*23M
$GPRMC,163340.706211,A,3833.206,N,12000.505,W,0126.7,169,060793,,,*28M
$GPRMC,163342.706209,A,3833.137,N,12000.485,W,0127.4,167,060793,,,*27M
$GPRMC,163344.706208,A,3833.069,N,12000.461,W,0127.9,165,060793,,,*2FM
$GPRMC,163346.706207,A,3833.000,N,12000.436,W,0128.2,164,060793,,,*2AM
$GPRMC,163348.706205,A,3832.932,N,12000.409,W,0128.4,163,060793,,,*22M
$GPRMC,163350.706204,A,3832.865,N,12000.380,W,0128.4,161,060793,,,*2DM
$GPRMC,163352.706203,A,3832.798,N,12000.349,W,0128.2,160,060793,,,*27M
$GPRMC,163354.706201,A,3832.731,N,12000.316,W,0128.7,159,060793,,,*25M
$GPRMC,163356.706200,A,3832.664,N,12000.284,W,0129.2,159,060793,,,*29M
$GPRMC,163358.706199,A,3832.596,N,12000.251,W,0130.1,159,060793,,,*29M
$GPRMC,163400.706197,A,3832.528,N,12000.217,W,0131.0,159,060793,,,*2AM
$GPRMC,163402.706196,A,3832.460,N,12000.183,W,0131.5,159,060793,,,*2FM
$GPRMC,163404.706195,A,3832.392,N,12000.150,W,0132.1,159,060793,,,*29M
$GPRMC,163406.706193,A,3832.323,N,12000.118,W,0132.6,160,060793,,,*26M
$GPRMC,163408.706192,A,3832.253,N,12000.088,W,0132.5,162,060793,,,*26M
$GPRMC,163410.706190,A,3832.182,N,12000.060,W,0132.3,163,060793,,,*23M
$GPRMC,163412.706189,A,3832.112,N,12000.034,W,0132.2,164,060793,,,*27M
$GPRMC,163414.706187,A,3832.041,N,12000.009,W,0131.7,164,060793,,,*20M
Note also the heading does not change instantaniously.
(My main point in all of this.) This airplane was
hand flown so I am wandering around a bit :-)
I will agree the altitude will probably have to be longer
term filtered in software or the pressure altitude
measured.
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