RE: [Flightgear-devel] FlightGear Wind and Turbulence

2005-06-20 Thread Jon Berndt
 I used this command line:

 fgfs [EMAIL PROTECTED] --aircraft=c172r --turbulence=0.0

 This set up the winds as I wanted. However, even though turbulence was set 
 to zero,
 there was still lots of noise present in the wind velocity coming from 
 FlightGear. The
 wind seemed to vary +/- 5 to 10 ft/sec. Also, the variance rate of chance was 
 on the
order
 of tens of milliseconds. I was logging data at 20Hz, and at one time step the 
 wind
 velocity would be at 10 ft/sec, the next it would be at 20, and the next it
 would be back at 10. Obviously, that's physically impossible.

 Jon

Never mind  :-/  The spikes I was seeing were artificial, and due to the test 
setup I was
using.

Jon


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Re: [Flightgear-devel] FlightGear Wind and Turbulence

2005-06-20 Thread Lee Elliott
On Sunday 19 Jun 2005 15:22, Jon Berndt wrote:
 What does FlightGear do in the way of wind and turbulence? I
 assume that winds are set in FlightGear in NED coordinates and
 that those change slowly? Turbulence is modeled in the FDMs,
 but parameters are passed in? FlightGear does not model
 turbulence itself, does it?

 I am debugging the gear jittering in JSBSim and I am seeing
 windNED spike every so often and I have commented out
 turbulence code in JSBSim, so I am wondering if these wind
 spikes are coming from FlightGear.

 Jon

It's possible that you're seeing the same problem I have here 
where the wind (and visibility) gets set incorrectly on an 
apparently random basis.

I've reported it a few times now but no-one else seems to be 
experiencing, or perhaps noticing it.

In one or two of the more recent a/c I've done I've included a 
simple 2d instrument to show the wind speed and direction and 
this makes it clearly apparent when the wind (and visibility) 
setting are incorrect.

does anything happen if you open the weather settings dialogue 
and repeatedly apply the settings?  (you don't need to change 
any of the settings for the conditions to change)

LeeE

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RE: [Flightgear-devel] FlightGear Wind and Turbulence

2005-06-19 Thread Jon Berndt
 What does FlightGear do in the way of wind and turbulence? I assume that winds
 are set in
 FlightGear in NED coordinates and that those change slowly? Turbulence is 
 modeled in the
 FDMs, but parameters are passed in? FlightGear does not model turbulence
 itself, does it?


What is WEATHER_CM? I am looking in JSBSim.cxx and wonder what the defined 
WEATHER_CM is
set to by default. I'm determining which code is compiled in in the atmosphere 
code.

Jon


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RE: [Flightgear-devel] FlightGear Wind and Turbulence

2005-06-19 Thread Jon Berndt
 I am debugging the gear jittering in JSBSim and I am seeing
 windNED spike every so often and I have commented out turbulence
 code in JSBSim, so I am wondering if these wind spikes are
 coming from FlightGear.

OK, in working to fix the gear jitter I've discovered some things about the 
winds modeled
in FlightGear.

I used this command line:

fgfs [EMAIL PROTECTED] --aircraft=c172r --turbulence=0.0

This set up the winds as I wanted. However, even though turbulence was set to 
zero,
there was still lots of noise present in the wind velocity coming from 
FlightGear. The
wind seemed to vary +/- 5 to 10 ft/sec. Also, the variance rate of chance was 
on the order
of tens of milliseconds. I was logging data at 20Hz, and at one time step the 
wind
velocity would be at 10 ft/sec, the next it would be at 20, and the next it 
would be back
at 10. Obviously, that's physically impossible.

Can someone shed some light on FlightGear's modeling of winds and turbulence?

BTW, I'm using current code out of FlightGear CVS.

Jon


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