Re: [Flightgear-devel] Gear transit times
Am 30.08.2012 03:51, schrieb castle...@comcast.net: 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? I use the actuator in JSBsim to model the gear in the SenecaII, using the rate_limit property implement the transit time. The flightgear autopilot system has a so called noise-spike filter that can model transit times. The flightgear xml based autopilot system can run at FDM rate or at frame rate, btw. Using a autopilot tag in your aircraft's -set.xml adds the autopilot at fdm rate, using a property-rule runs the same config at frame rate. Torsten -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Gear transit times
Nice piece of code -- adds some realism It normally takes longer to retract the gear than to extend. You could also tweak the times based on air loads, hydraulic pressure, G loads, roll, pitch, yaw, etc and get down in the weeds on the matter ;-) Varying transit times based on direction of gear travel is enough. :-) Not all that familiar with the actuator model; is it possible to set the rate_limit based on gear-cmd-norm setting as in the kinemaic model? And is it necessary to explicitly set the use FCSGearPos flag or does it happen internally based on the xml file? Cheers Jack - Original Message - From: Torsten Dreyer tors...@t3r.de To: FlightGear developers discussions flightgear-devel@lists.sourceforge.net Sent: Thursday, August 30, 2012 5:15:21 AM Subject: Re: [Flightgear-devel] Gear transit times Am 30.08.2012 03:51, schrieb castle...@comcast.net: 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? I use the actuator in JSBsim to model the gear in the SenecaII, using the rate_limit property implement the transit time. The flightgear autopilot system has a so called noise-spike filter that can model transit times. The flightgear xml based autopilot system can run at FDM rate or at frame rate, btw. Using a autopilot tag in your aircraft's -set.xml adds the autopilot at fdm rate, using a property-rule runs the same config at frame rate. Torsten -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[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 - Original Message - -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Gear transit times
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 _ ---BeginMessage--- 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 inputgear/gear-cmd-norm/input rate_limit0.1/rate_limit outputgear/unit[0]/pos-norm/output /actuator actuator name=Gear Left Actuator inputgear/gear-cmd-norm/input rate_limit0.13/rate_limit outputgear/unit[1]/pos-norm/output /actuator actuator name=Gear Right Actuator inputgear/gear-cmd-norm/input rate_limit0.15/rate_limit outputgear/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/vse012070mrt/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 ___ ---End Message--- -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed
Re: [Flightgear-devel] Gear transit times
Yes there are two or three aircraft that do this. I've modified the A380 in flightgear to use three groups with different times. I'm not near my desktop at the moment but can send you what I had modify to make it work. If you wanted detailed realism you could make different config for each gear and add a small offset depending on hydraulic pressure which could have some random filter applied.. S. castle...@comcast.net wrote: -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Gear transit times
Thanks, Jon judging by the date on the msg and looking over the code in an older 2.4 ( released around 2010 ) would appear the suggested change is in. And the property rate-limit sets the rate at which the actuator moves. Correct? node-getChild(position-norm, 0, true)-setDoubleValue(gear-GetGearUnitPos()); is the line of code in JSBSim.cxx. And to simulate a gear failure, one would set the rate limit property to zero? Neat! I'll give it a try tomorrow. Just installed a new gear system and gear indicators in the 737. Yes, downsizing the sim from a 747 to a 737 to make room for the new collimated displays. As Gene put it, serving as his first victim for the big iron display. The next few months will be interesting ;-) Jack - Original Message - From: Jon S. Berndt jonsber...@comcast.net To: FlightGear developers discussions flightgear-devel@lists.sourceforge.net Sent: Wednesday, August 29, 2012 9:10:30 PM Subject: Re: [Flightgear-devel] Gear transit times 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 - Original Message - -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Gear transit times
Hi Scott, Yes, please send me your mods when you have a moment. Thanks Jack - Original Message - From: Scott Hamilton scott.hamil...@popplanet.biz To: FlightGear developers discussions flightgear-devel@lists.sourceforge.net Sent: Wednesday, August 29, 2012 9:27:52 PM Subject: Re: [Flightgear-devel] Gear transit times Yes there are two or three aircraft that do this. I've modified the A380 in flightgear to use three groups with different times. I'm not near my desktop at the moment but can send you what I had modify to make it work. If you wanted detailed realism you could make different config for each gear and add a small offset depending on hydraulic pressure which could have some random filter applied.. S. castle...@comcast.net wrote: 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 - Original Message - -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
