On Thursday 22 November 2007 12:03, John Denker wrote: > On 11/22/2007 04:58 AM, LeeE wrote: > > I've slowly been fixing the aircraft I've done that have been > > broken by updates in the FG code and I've noticed that we no longer > > seem to have access to the aircraft yaw in the property tree. > > > > When I first set up the rear-wheel steering for the B-52F I was > > told to use /orientation/side-slip-deg and not > > /orientation/yaw-deg, which is in the tree but doesn't seem to be > > updated. Using the side-slip-deg node worked ok though, so it > > seemed fine at the time. > > > > However, now that property only seems to give the side-slip in > > turns, which is perhaps correct, given it's name but that means > > we're back to not being able to access the yaw value. > > > > Co-incidentally, the original hard-coded hud still shows yaw but > > the newer xml hud does not - perhaps this is not too surprising if > > it's trying to use yaw-deg. > > > > Anyone know what's going on? > > First, please clarify what "yaw" means to you, and what you plan > to do with it once you have it. > -- For example, do you want the angle that would be indicated > (approximately) by a yaw string? That's properly called the > slip angle, and commonly called the sideslip angle, but should > not be called the yaw angle. This angle should be very large > when parked with a crosswind or tailwind; if not, that's a > nasty bug, and should be called a slip angle bug, not a yaw > bug. > -- Or do you want aircraft heading relative to North? That's > properly called the heading, and is available in the tree. > -- Or do you want the yaw /rate/ in degrees per second? That's > in the tree.
Yaw, to me means the difference between the direction that the aircraft is pointing and the direction that it is moving. Flying directly into, or with, any wind would produce no yaw but flying in a cross-wind would produce yaw. When sitting stationary on the ground, any cross-winds would result in an effective airspeed, so yes, I would expect there to be a large yaw element under those circumstances. As to what I would do with it - I assume you are asking out of curiosity - it's needed to set the steering in tandam/quadracyle landing gear aircraft so that they can take-off and land in cross-winds. I would also use it for off-setting terrain elevation look-ahead scans, so that I'm scanning the terrain that I will actually be passing over and not the terrain slightly to one side of the true course. FWIW I also spotted that the coded hard-coded hud has problems around headings of 180 deg so that if you are heading slightly to one side of 180 deg and there's enough of a cross-wind to swing the direction indicator to the other side of 180 deg it disappears, probably due to a wrap-around type error. LeeE ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
