Jack,
Check out the attached message from the JSBSim developer list. Jon From: castle...@comcast.net [mailto:castle...@comcast.net] Sent: Wednesday, August 29, 2012 7:52 PM To: FlightGear developers discussions Subject: [Flightgear-devel] Gear transit times Hi, Is it possible to specify gear up and down transit times for each gear? In real airplanes the gear never ( well rarely, maybe ) sequence in perfect unison. In reviewing the xml files for the 737, I note there are transit times defined for each flap position, but the kinematics for the gear is only a single value for up or down based on gear selection state. Is this something in Nasal? or native code or something in JSBsim? Thanks Jack _____
--- Begin Message ---> Happy New Year everybody. > > I have been working on individual gear motion and failure for > the last week and I think the result is usable. > This change deals with the following: > > a) The gear position is computed for each individual gear if > it is retractable and stored in a property named > gear/unit[n]/pos-norm. The current implementation holds all > gear positions in the property gear/gear-pos-norm. > The suggested implementation does not break existing > configurations that use gear/gear-pos-norm. > > b) To make a gear prone to failures, a <actuator> element may > be used to drive each individual gear instead of a > <kinematic> element. > > My configuration for the landing gear looks like this: > > <channel name="Landing Gear"> > <actuator name="Gear Nose Actuator"> > <input>gear/gear-cmd-norm</input> > <rate_limit>0.1</rate_limit> > <output>gear/unit[0]/pos-norm</output> > </actuator> > <actuator name="Gear Left Actuator"> > <input>gear/gear-cmd-norm</input> > <rate_limit>0.13</rate_limit> > <output>gear/unit[1]/pos-norm</output> > </actuator> > <actuator name="Gear Right Actuator"> > <input>gear/gear-cmd-norm</input> > <rate_limit>0.15</rate_limit> > <output>gear/unit[2]/pos-norm</output> > </actuator> > </channel> > > Three files have to be changed for this: > FGLGear.h > introduces the method GetGearUnitPos() and two variables > GearPos for the current gear unit position and useFCSGearPos, > a flag for backward compatibility. > > FGLGear.cpp > - implements GetGearUnitPos() which returns the current gear > unit position. It checks if the useFCSGearPos flag is set or > the gear/gear-pos-norm property has changed. This is for > backward compatibility > - binds and unbinds the gear/unit[n]/pos-norm properties the > the GearPos variable > > JSBSim.cpp > use the new gear->GetGearPos() method instead of FCS->GetGearPos() > > I have succesfully testet this with an existing unchanged > configuration for the 737 and a modified configuration using > the above example for the SenecaII. > > Here are FlightGear screenshots demonstrating the new feature: > http://www.t3r.de/fg/gear-failure-1.jpg > http://www.t3r.de/fg/gear-failure-2.jpg > http://www.t3r.de/fg/gear-failure-3.jpg > > I hope this finds its way into JSBSim - it's fun to try a > landing on a partially failed gear. Comments are welcome. > > The attached diff is against FlightGear cvs, but I can > provide one against current JSBSim cvs. > > Sorry for the long posting. > > Torsten Hi, Torsten: Hey, don't apologize for the long posting - it usually means a lot of work has been done. :-) In theory, treating each landing gear individually seems like a good idea. In retrospect, I don't know why we didn't do it that way in the first place. The changes seem sensible. I'll look at this more at lunchtime. Unless anyone has any objections, I'll try to get this into JSBSim cvs in the next day or two. If I don't, please remind me and/or post a Feature Request at the JSBSim web site. I've been trying to address some of those in the past few days, and having the feature request and bug reports has been very helpful. Next, we probably should think about doing something similar for the spoilers, flaps, etc. - that is, treating them individually. I have some thoughts on that, but that's another topic. Jon ------------------------------------------------------------------------- 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/ _______________________________________________ Jsbsim-devel mailing list jsbsim-de...@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jsbsim-devel _______________________________________________ The JSBSim Flight Dynamics Model project http://www.JSBSim.org _______________________________________________
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