## flightgear-flightmodel — Flight model discussions

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 [Flightgear-flightmodel] Wind calculation From: - 2016-01-13 11:29:25 Dear flightmodel community, i have to use flightgear for my master thesis. Currently I am trying to understand how flightgear calculates the wind. I think in the line vTotalWindNED = vWindNED + vGustNED + vCosineGust + vTurbulenceNED; in FGWinds.cpp of the FDM JSBSim the total wind is determined, isn't it? I've interpreted vWindNED (Calculation with the method SetWindspeed) as the mean wind and I think vCosineGust (Calculation with the method CosineGust) describes the 1-cosine gust shape and vTurbulenceNED (Calculation with the method Turbulence) the atmospheric turbulence?! But I don't understand the meaning of vGustNED and where it is calculated? Further information about the background: I am using JSBSim only in combination with flightgear. According to my knowledge the situation is as follows: The decision which flight dynamic model (FDM) flightgear will use is determined by the aircraft which you are flying (You find in the internet the follwing sentence: ''Every aircraft simulated by FlightGear must use one of these models.'' And after this sentence you get a list of possible FDM used by flight gear, amongst other things JSBSim). In the file aicraftname-set.xml (e.g. c172p-set.xml for the cessna) you find an specific entry for the using FDM: David Megginson early production 3 4 5 4 jsb c172p . . . In the future I will only use aircrafts which can be connected to the FDM JSBSim because it is better documented in the internet than for example the YASim model. The aim of my master thesis is to implement a 3D turbulent wind velocity field simulated by the LES model PALM for a specific region so that the airplane fly through a ''real'' wind field. After I will implement the 3D windfield I will determine the differences referring to the flight attitude. Therefore I am very interested in how flighgear calculates the atmospheric parameters especially the wind(mean wind, turbulence, gusts?). I've found out that flightgear provides its own atmophere model by default but can also uses the atmosphere model from JSBSim (look at: http://wiki.flightgear.org/JSBSim_Atmosphere) . I dont know which one is better or which one can handle better with the detailed weather settings you can set at the beginning and during flight, but let us assume that the we use the default variant (FlightGear provides the atmosphere model). Now I'm not really sure where the total wind is calculated and where the wind influences the forces on the airplane and therefore the flight attitude. I think this must happen all in the FDM JSBSim. As a consequence, I found the file FGWinds.cpp in the code and the informations in the internet confirm me that, at least, the turbulence is calculated in JSBSim and not in the atmosphere model of flightgear (http://wiki.flightgear.org/JSBSim_Atmosphere). So maybe Flightgear uses only the turbulence calculation of JSBSim (vTurbulenceNED) and not vTotalWindNED but how? If so, only the lines in FGWind.cpp where the turbulence is calculated where relevant. I hope you can undestand my English and my problem of understanding :-(. I hope some of you can help. That would be great! Best regards, Sebastian PS.: vGustNED is set in the FGWinds.h file, isnt't it (vGustNED(eNorth)=gn; ...? Where are the values gN, gE, gD come from? 
 [Flightgear-flightmodel] Flight model for AW 139 From: Siju - 2014-12-17 11:39:18 Attachments: Message as HTML Hello, Please help me out in buying 'AW-139' flight model for flight gear. Please do advise where to check out for this if it is not available in the current repository. Thanks & Regards, SIJU JOSEPH Assistant Project Manager, FDMA SHEOREY DIGITAL SYSTEMS LTD. Software Lab & Tech Support Center Bengaluru 560017 India Tel: (+9180) 67188383 Cel: (+91) 7795004767 Website: ; http://www.sds.co.in 
 [Flightgear-flightmodel] PBY Catalina, F8-E Crusader, Alouette III GPL FG 3.2 Compliant From: grtuxhangar team - 2014-07-18 12:39:05 Attachments: Message as HTML Hello, all FG end users, Since the outdated versions which are longer staying within fgdata won't fly with FG 3.2 You may want the last version. Here the download link at our gitorious.org/eekpo project ; PBY Catalina ; F8-E Crusader ; Alouette-III ; Enjoy Regards Josh https://gitorious.org/eekpo https://sites.google.com/site/grtuxhangar/ 
 [Flightgear-flightmodel] Alouette-III UPDATE From: grtuxhangar team - 2014-06-30 17:00:48 Attachments: Message as HTML Hello, Right now Alouette-III last version is compliant with the coming FG 3.2. the last GIT (gpl) version is available there Alouette-III ; This is the last UPDATE of the existing outdated (*which won't fly with FG 3.2*) one. Up to any user to download. Up to any devel to upload/commit to fgdata. Regards Josh https://gitorious.org/eekpo https://sites.google.com/site/grtuxhangar/ 
 Re: [Flightgear-flightmodel] Alouette-III F-8E-Crusader Pby-Catalina SR71-BlackBird against FG 3.00 From: grtuxhangar team - 2014-06-30 16:58:56 Attachments: Message as HTML Hello, Right now Alouette-III last version is compliant with the coming FG 3.2. the last GIT (gpl) version is available there Alouette-III ; This is the last UPDATE of the existing outdated (*which won't fly with FG 3.2*) one. Up to any user to download. Up to any devel to upload/commit to fgdata. Regards Josh https://gitorious.org/eekpo https://sites.google.com/site/grtuxhangar/ On 21 February 2014 16:15, grtuxhangar team wrote: > Hello, All > Since FG 3.00 is right now released, you may want to update your fgdata > with these models accordingly > The eekpo git project can be your friend git web page > ; > > It should propose the Gerard aka GRTUX 's models update > Right now only those models have been updated, the others should come > later on. > > the direct download links are > > Alouette-III > ; > > F-8E-Crusader > ; > Pby-Catalina > ; > > SR71-BlackBird > ; > > > > ; > > I hope that could help > > > > All the best > > Ahmad > 
 Re: [Flightgear-flightmodel] Need help! From: John Clary - 2014-03-25 06:34:54 You have a model with a corrupted graphic file. On Tue, Mar 25, 2014 at 1:26 AM, haseeb ahmed wrote: > I'd like to take assistance in cracking the error i get when i run the > Flightgear simulation via. Matlab. > > The program is written in such way that the airplane for example, the > running time should be 500 seconds, airplane must be at 30000 ft height, 120 > deg heading, Mach 0.50, KSFO airport (12L runway), etc,. That is the > simulation must start with the airplane being mid-air at mentioned speed. > > After running the MATLAB program successfully and the opening of FlightGear > tool in MATLAB, the FlightGear opens up and the airplane remains static and > is not moving at any direction. I also get the error which i cannot able to > recognize and rectify. Kindly visit the url. (I've taken a snapshot of the > error box) > > http://imagizer.imageshack.us/a/img560/5394/3lt2.jpg > > Looking forward for someone to solve the issue! > > ------------------------------------------------------------------------------ > Learn Graph Databases - Download FREE O'Reilly Book > "Graph Databases" is the definitive new guide to graph databases and their > applications. Written by three acclaimed leaders in the field, > this first edition is now available. Download your free book today! > http://p.sf.net/sfu/13534_NeoTech > _______________________________________________ > Flightgear-flightmodel mailing list > Flightgear-flightmodel@... > https://lists.sourceforge.net/lists/listinfo/flightgear-flightmodel > -- Opus Always. Expect. Ninjas. 
 [Flightgear-flightmodel] Need help! From: haseeb ahmed - 2014-03-25 06:26:08 Attachments: Message as HTML I'd like to take assistance in cracking the error i get when i run the Flightgear simulation via. Matlab. The program is written in such way that the airplane for example, the running time should be 500 seconds, airplane must be at 30000 ft height, 120 deg heading, Mach 0.50, KSFO airport (12L runway), etc,. That is the simulation must start with the airplane being mid-air at mentioned speed. After running the MATLAB program successfully and the opening of FlightGear tool in MATLAB, the FlightGear opens up and the airplane remains static and is not moving at any direction. I also get the error which i cannot able to recognize and rectify. Kindly visit the url. (I've taken a snapshot of the error box) http://imagizer.imageshack.us/a/img560/5394/3lt2.jpg Looking forward for someone to solve the issue! 
 [Flightgear-flightmodel] Alouette-III F-8E-Crusader Pby-Catalina SR71-BlackBird against FG 3.00 From: grtuxhangar team - 2014-02-21 15:15:16 Attachments: Message as HTML Hello, All Since FG 3.00 is right now released, you may want to update your fgdata with these models accordingly The eekpo git project can be your friend git web page; It should propose the Gerard aka GRTUX 's models update Right now only those models have been updated, the others should come later on. the direct download links are Alouette-III; F-8E-Crusader; Pby-Catalina; SR71-BlackBird; ; I hope that could help All the best Ahmad 
 Re: [Flightgear-flightmodel] About Terrain Database(Didn't got answere in forum) From: Mathias Fröhlich - 2013-07-13 13:37:05 Hi, On Friday, July 12, 2013 00:12:47 pankaj thapliyal wrote: > Hello > I have actual aircraft data ( latitude,longitude,altitude,pitch > angle ,roll angle and yaw angle ) .These six parameters i am giving input > to FlightGear and i am trying to fly the aircraft but it is hitting hills > and going inside ground level. > thats why i want to ask about terrain database. > and what reference you are using to create terrain(eg. SRTM, NED etc ). Flightgear uses WGS84 elliptical coordinates or the cartesian coordinates with this WGS84 ellipse together with srtm elevation. Where the landcover stems from is more complex, but should not harm for your question. Where do you feed your data? May be there is something in between? Mathias 
 [Flightgear-flightmodel] About Terrain Database(Didn't got answere in forum) From: pankaj thapliyal - 2013-07-11 18:42:56 Attachments: Message as HTML Hello I have actual aircraft data ( latitude,longitude,altitude,pitch angle ,roll angle and yaw angle ) .These six parameters i am giving input to FlightGear and i am trying to fly the aircraft but it is hitting hills and going inside ground level. thats why i want to ask about terrain database. and what reference you are using to create terrain(eg. SRTM, NED etc ). -- With Regards Pankaj 
 Re: [Flightgear-flightmodel] [Flightgear-devel] Atmospheric Light Scattering From: geneb - 2013-04-30 19:46:46 On Tue, 30 Apr 2013, Heiko Schulz wrote: >> If I can't remember what ALS stands for, can I call it Lou Gehrig's >> Renderer? > > Is the name "Charcot's Renderer" to complicated for you? ;-) That whooshing sound you just heard was your joke screaming over my head at some significant fraction of c. :) g. -- Proud owner of F-15C 80-0007 http://www.f15sim.com - The only one of its kind. http://www.diy-cockpits.org/coll - Go Collimated or Go Home. Some people collect things for a hobby. Geeks collect hobbies. ScarletDME - The red hot Data Management Environment A Multi-Value database for the masses, not the classes. http://www.scarletdme.org - Get it _today_! 
 Re: [Flightgear-flightmodel] [Flightgear-devel] Atmospheric Light Scattering From: Heiko Schulz - 2013-04-30 19:31:51 > If I can't remember what ALS stands for, can I call it Lou Gehrig's > Renderer? Is the name "Charcot's Renderer" to complicated for you? ;-) 
 [Flightgear-flightmodel] Aerosonde uav From: Simin Jahangard - 2013-01-27 13:15:12 Attachments: Message as HTML Hello, I need airplanes model of Aerosonde uav to Flight Gear and I didn't find to download. Anybody help me? Thanks 
 Re: [Flightgear-flightmodel] A little help From: Ron Jensen - 2012-10-14 13:40:29 On Saturday 13 October 2012 19:22:11 Leandro Santos de Lima wrote: > Hi, good evening! > > I am studing some features of JSBsim and I need to get some flight and > simutation properties. Many of them I have no trouble but some have been > hard to get. They are: > > > - Drag force; > - Lift force; > - Inside force; > - Traction force; > - Roll moment; > - Yaw moment and > - Pitch moment. > > I have used a property-list protocol like this: > > > > > > > > > false > > \t > > \r\n > > t\t VT\t alfa\t beta\t phi\t theta\t psi\t P\t Q\t R\t > > H\t deltaA\t deltaE\t deltaR\t D\t L\t Y\t T\t \bar{L} M\t N\t > > > > > > > > /fdm/jsbsim/sim-time-sec > > float > > %.4f > > > > > > > > /velocities/airspeed-kt > > float > > %.4f > > > > but I have no idea of the property node to get those properties. > > > Could someone help me? > > All the best, > Leandro Lima Assuming you're using FlightGear, look in /fdm/jsbsim, you'll find these folders: accelerations - output accelerations aero - working folder for aerodynamics atmosphere - output on what the atmosphere is locally attitude - yaw pitch roll fcs - working folder for the flight control system * forces - forces acting on the model in various frames gear - working folder for contact points ic - initial conditions inertia - vehicle mass and cg inertial - navigation stuff metrics - data on vehicle lengths and areas * moments - moments acting on the model in various frames position - output position propulsion - working folder for engines and thrusters simulation - simulation control stuff systems - model systems, fuel control or other things velocities - output velocities It sounds like you're looking for: (the w in fwx is for wind frame) forces/fwx-aero-lbs == drag forces/fwy-aero-lbs == side forces/fwz-aero-lbs == lift (the b in fbx is for body frame) forces/fbx-prop-lbs == thrust (longitudinal) forces/fby-prop-lbs == side component of thrust forces/fbz-prop-lbs == vertical component of thrust moments/l-total-lbsft == roll moment moments/m-total-lbsft == pitch moment moments/n-total-lbsft == yaw moment Hope that helped, Ron 
 [Flightgear-flightmodel] A little help From: Leandro Santos de Lima - 2012-10-14 01:22:40 Attachments: Message as HTML Hi, good evening! I am studing some features of JSBsim and I need to get some flight and simutation properties. Many of them I have no trouble but some have been hard to get. They are: - Drag force; - Lift force; - Inside force; - Traction force; - Roll moment; - Yaw moment and - Pitch moment. I have used a property-list protocol like this: > > > false > \t > \r\n > t\t VT\t alfa\t beta\t phi\t theta\t psi\t P\t Q\t R\t H\t > deltaA\t deltaE\t deltaR\t D\t L\t Y\t T\t \bar{L} M\t N\t > > > > /fdm/jsbsim/sim-time-sec > float > %.4f > > > > /velocities/airspeed-kt > float > %.4f > but I have no idea of the property node to get those properties. Could someone help me? All the best, Leandro Lima 
 Re: [Flightgear-flightmodel] Force instead of lift From: Bill Galbraith - 2011-10-01 12:28:03 Attachments: Citation_aero.xml In this case, the Cl is roll moment coefficient, not CL, the lift coefficient The attached file shows a new format for JSBSim files that I came up with. It works just as well as the older format, but the formulation of the coefficients more closely matches classical aerodynamic textbook equation buildup. Feel free to use this, or the older format. They are both equally valid. Bill > -----Original Message----- > From: Oleksiy Frolov [mailto:Oleksiy.Frolov@...] > Sent: Saturday, October 01, 2011 12:03 AM > To: Flight dynamics model discussions > Subject: Re: [Flightgear-flightmodel] Force instead of lift > > Hello Bill > > This is a good suggestion, thank you. > > I understand about calculating 2(4) different CL-s. > > Do I also understand correctly we will than have use > something you guys did to the flaps once: > > > ................. > > > Roll Moment Coefficient due to Asymetrical > Fowler Flaps Deflection > calculated as difference between left and > right flap lift coef, > times distance from centerline to MAC of surface. > > > 21.28 > > aero/coefficient/CLdF3R > aero/coefficient/CLdF3L > > > > > > in order to calculate the moments due to difference in > individual CLs ? > > With best regards, > Oleksiy Frolov > > > > > > >> -----Original Message----- > >> From: Oleksiy Frolov [mailto:Oleksiy.Frolov@...] > >> Sent: Friday, September 30, 2011 3:43 PM > >> To: flightgear-flightmodel@... > >> Subject: [Flightgear-flightmodel] Force instead of lift > >> > >> Hello > >> > >> I am trying to simulate the effects of the differential > wing lift. > >> Such as single wing stall due to the propwash loss at a low speed, > >> and the effect of the icing on a single wing (which can > happen during > >> a deicing failure on that wing). All of these are important > >> aerodynamic effects. > >> > >> Now, we know we only have one wing in jsbsim currently, not 2. My > >> idea is therefor to try using 2 records to > simulate the wings > >> separately, instead of the usual CL record. > >> This however would require some kind of algorithm to > define how the > >> force origin moves to overlay with center of lift for each wing, > >> which is probably not an easy task > >> > >> I was wondering if anyone have tried a similar approach > before, and > >> if this problem pechaps has an easier solution ? > >> > >> Thank you > >> > >> regards, > >> Oleksiy Frolov > >> > > > > > > No reason that you couldn't build this inside of the > existing JSBSim > > format without using the external forces. Divide your wing into > > panels, maybe (on each side) one that is influenced by the > propeller > > slipstream, one not. > > Sum > > all of your lifts to apply them at the aero reference > point. So with a > > two engine aircraft, you might have a total of four panels, two per > > wing half, one inboard in the slipstream, one outboard in > clean air. A > > mismatch of forces left/right would normally shift the aero > reference > > point left or right, but that can be resolved with a moment. > > > > You have a couple advantages doing this. A force at a distance is a > > moment, so if the outer panels are experiencing different > lift forces, > > that lift times its arm creates a moment. If the aircraft > is rolling, > > each wing sees a different angle of attack, and therefore different > > lift. This is usually handled other ways, but your method has the > > advantage of spinning properly. > > There are disadvantages, though. > > > > If you are going to that trouble, you might consider > keeping the flaps > > and ailerons seperate as well, unless the actuator mechanism is > > guaranteed to never give you different flap or aileron angles. > > > > Bill > > > > > > > ---------------------------------------------------------------------- > > -------- All of the data generated in your IT infrastructure is > > seriously valuable. > > Why? It contains a definitive record of application performance, > > security threats, fraudulent activity, and more. Splunk takes this > > data and makes sense of it. IT sense. And common sense. > > http://p.sf.net/sfu/splunk-d2dcopy2 > > _______________________________________________ > > Flightgear-flightmodel mailing list > > Flightgear-flightmodel@... > > https://lists.sourceforge.net/lists/listinfo/flightgear-flightmodel > > > > > > -------------------------------------------------------------- > ---------------- > All of the data generated in your IT infrastructure is > seriously valuable. > Why? It contains a definitive record of application > performance, security threats, fraudulent activity, and more. > Splunk takes this data and makes sense of it. IT sense. And > common sense. > http://p.sf.net/sfu/splunk-d2dcopy2 > _______________________________________________ > Flightgear-flightmodel mailing list > Flightgear-flightmodel@... > https://lists.sourceforge.net/lists/listinfo/flightgear-flightmodel 
 Re: [Flightgear-flightmodel] Force instead of lift From: Oleksiy Frolov - 2011-10-01 04:03:31 Hello Bill This is a good suggestion, thank you. I understand about calculating 2(4) different CL-s. Do I also understand correctly we will than have use something you guys did to the flaps once: ................. Roll Moment Coefficient due to Asymetrical Fowler Flaps Deflection calculated as difference between left and right flap lift coef, times distance from centerline to MAC of surface. 21.28 aero/coefficient/CLdF3R aero/coefficient/CLdF3L in order to calculate the moments due to difference in individual CLs ? With best regards, Oleksiy Frolov > > >> -----Original Message----- >> From: Oleksiy Frolov [mailto:Oleksiy.Frolov@...] >> Sent: Friday, September 30, 2011 3:43 PM >> To: flightgear-flightmodel@... >> Subject: [Flightgear-flightmodel] Force instead of lift >> >> Hello >> >> I am trying to simulate the effects of the differential wing >> lift. Such as single wing stall due to the propwash loss at a >> low speed, and the effect of the icing on a single wing >> (which can happen during a deicing failure on that wing). All >> of these are important aerodynamic effects. >> >> Now, we know we only have one wing in jsbsim currently, not >> 2. My idea is therefor to try using 2 records to >> simulate the wings separately, instead of the usual CL record. >> This however would require some kind of algorithm to define >> how the force origin moves to overlay with center of lift for >> each wing, which is probably not an easy task >> >> I was wondering if anyone have tried a similar approach >> before, and if this problem pechaps has an easier solution ? >> >> Thank you >> >> regards, >> Oleksiy Frolov >> > > > No reason that you couldn't build this inside of the existing JSBSim > format > without using the external forces. Divide your wing into panels, maybe (on > each side) one that is influenced by the propeller slipstream, one not. > Sum > all of your lifts to apply them at the aero reference point. So with a two > engine aircraft, you might have a total of four panels, two per wing half, > one inboard in the slipstream, one outboard in clean air. A mismatch of > forces left/right would normally shift the aero reference point left or > right, but that can be resolved with a moment. > > You have a couple advantages doing this. A force at a distance is a > moment, > so if the outer panels are experiencing different lift forces, that lift > times its arm creates a moment. If the aircraft is rolling, each wing sees > a > different angle of attack, and therefore different lift. This is usually > handled other ways, but your method has the advantage of spinning > properly. > There are disadvantages, though. > > If you are going to that trouble, you might consider keeping the flaps and > ailerons seperate as well, unless the actuator mechanism is guaranteed to > never give you different flap or aileron angles. > > Bill > > > ------------------------------------------------------------------------------ > All of the data generated in your IT infrastructure is seriously valuable. > Why? It contains a definitive record of application performance, security > threats, fraudulent activity, and more. Splunk takes this data and makes > sense of it. IT sense. And common sense. > http://p.sf.net/sfu/splunk-d2dcopy2 > _______________________________________________ > Flightgear-flightmodel mailing list > Flightgear-flightmodel@... > https://lists.sourceforge.net/lists/listinfo/flightgear-flightmodel > 
 Re: [Flightgear-flightmodel] Force instead of lift From: Bill Galbraith - 2011-09-30 21:46:36  > -----Original Message----- > From: Oleksiy Frolov [mailto:Oleksiy.Frolov@...] > Sent: Friday, September 30, 2011 3:43 PM > To: flightgear-flightmodel@... > Subject: [Flightgear-flightmodel] Force instead of lift > > Hello > > I am trying to simulate the effects of the differential wing > lift. Such as single wing stall due to the propwash loss at a > low speed, and the effect of the icing on a single wing > (which can happen during a deicing failure on that wing). All > of these are important aerodynamic effects. > > Now, we know we only have one wing in jsbsim currently, not > 2. My idea is therefor to try using 2 records to > simulate the wings separately, instead of the usual CL record. > This however would require some kind of algorithm to define > how the force origin moves to overlay with center of lift for > each wing, which is probably not an easy task > > I was wondering if anyone have tried a similar approach > before, and if this problem pechaps has an easier solution ? > > Thank you > > regards, > Oleksiy Frolov > No reason that you couldn't build this inside of the existing JSBSim format without using the external forces. Divide your wing into panels, maybe (on each side) one that is influenced by the propeller slipstream, one not. Sum all of your lifts to apply them at the aero reference point. So with a two engine aircraft, you might have a total of four panels, two per wing half, one inboard in the slipstream, one outboard in clean air. A mismatch of forces left/right would normally shift the aero reference point left or right, but that can be resolved with a moment. You have a couple advantages doing this. A force at a distance is a moment, so if the outer panels are experiencing different lift forces, that lift times its arm creates a moment. If the aircraft is rolling, each wing sees a different angle of attack, and therefore different lift. This is usually handled other ways, but your method has the advantage of spinning properly. There are disadvantages, though. If you are going to that trouble, you might consider keeping the flaps and ailerons seperate as well, unless the actuator mechanism is guaranteed to never give you different flap or aileron angles. Bill 
 Re: [Flightgear-flightmodel] Force instead of lift From: Bill Galbraith - 2011-09-30 21:44:44  > -----Original Message----- > From: Oleksiy Frolov [mailto:Oleksiy.Frolov@...] > Sent: Friday, September 30, 2011 3:43 PM > To: flightgear-flightmodel@... > Subject: [Flightgear-flightmodel] Force instead of lift > > Hello > > I am trying to simulate the effects of the differential wing > lift. Such as single wing stall due to the propwash loss at a > low speed, and the effect of the icing on a single wing > (which can happen during a deicing failure on that wing). All > of these are important aerodynamic effects. > > Now, we know we only have one wing in jsbsim currently, not > 2. My idea is therefor to try using 2 records to > simulate the wings separately, instead of the usual CL record. > This however would require some kind of algorithm to define > how the force origin moves to overlay with center of lift for > each wing, which is probably not an easy task > > I was wondering if anyone have tried a similar approach > before, and if this problem pechaps has an easier solution ? > > Thank you > > regards, > Oleksiy Frolov No reason that you couldn't build this inside of the existing JSBSim format without using the external forces. Divide your wing into panels, maybe (on each side) one that is influenced by the propeller slipstream, one not. Sum all of your lifts to apply them at the aero reference point. So with a two engine aircraft, you might have a total of four panels, two per wing half, one inboard in the slipstream, one outboard in clean air. A mismatch of forces left/right would normally shift the aero reference point left or right, but that can be resolved with a moment. You have a couple advantages doing this. A force at a distance is a moment, so if the outer panels are experiencing different lift forces, that lift times its arm creates a moment. If the aircraft is rolling, each wing sees a different angle of attack, and therefore different lift. This is usually handled other ways, but your method has the advantage of spinning properly. There are disadvantages, though. If you are going to that trouble, you might consider keeping the flaps and ailerons seperate as well, unless the actuator mechanism is guaranteed to never give you different flap or aileron angles. Bill 
 Re: [Flightgear-flightmodel] Force instead of lift From: Oleksiy Frolov - 2011-09-30 21:04:08 Thank you. You are right, I meant the clause in the external force section. Thank you for the links, I will study your work on this issue. With best regards, Oleksiy Frolov > On Friday 30 September 2011 13:43:24 Oleksiy Frolov wrote: >> Hello >> >> I am trying to simulate the effects of the differential wing lift. Such >> as single wing stall due to the propwash loss at a low speed, and the >> effect of the icing on a single wing (which can happen during a deicing >> failure on that wing). All of these are important aerodynamic effects. >> >> Now, we know we only have one wing in jsbsim currently, not 2. My idea >> is >> therefor to try using 2 records to simulate the wings >> separately, >> instead of the usual CL record. >> This however would require some kind of algorithm to define how the >> force >> origin moves to overlay with center of lift for each wing, which is >> probably not an easy task >> >> I was wondering if anyone have tried a similar approach before, and if >> this problem pechaps has an easier solution ? >> >> Thank you >> >> regards, >> Oleksiy Frolov > > A better place to ask might be on the JSBSim user list > JSBSim user questions > > In the aerodynamics section of a JSBSim configuration you are only allowed > one > force vector, applied at aerorp, and consisting of lift, drag and side or > normal, axial and side. You can also specify the moments for yaw, pitch > and > roll. > > An alternative is to use the 'external force' section of JSBSim. This > allows > you to specify an arbitrary number of forces, each of which can be applied > at > separate points on the airframe and can be computed in different axis > systems. > > I've played a little with doing the vertical stabilizer as external forces > in > the JSBSim config I did for the Gloster Meteor: > https://gitorious.org/ron-s-hanger/gloster-meteor > > The JSBSim config is here: > https://gitorious.org/ron-s-hanger/gloster-meteor/blobs/master/gloster-meteor-jsb.xml > And the systems file that computes the external force is here: > https://gitorious.org/ron-s-hanger/gloster-meteor/blobs/master/Systems/external_reactions.xml > > This was a quick exercise, and I didn't fully validate the trig used to > compute the axial/normal/side components. > > Ron > > ------------------------------------------------------------------------------ > All of the data generated in your IT infrastructure is seriously valuable. > Why? It contains a definitive record of application performance, security > threats, fraudulent activity, and more. Splunk takes this data and makes > sense of it. IT sense. And common sense. > http://p.sf.net/sfu/splunk-d2dcopy2 > _______________________________________________ > Flightgear-flightmodel mailing list > Flightgear-flightmodel@... > https://lists.sourceforge.net/lists/listinfo/flightgear-flightmodel > 
 Re: [Flightgear-flightmodel] Force instead of lift From: Ron Jensen - 2011-09-30 20:52:41 On Friday 30 September 2011 13:43:24 Oleksiy Frolov wrote: > Hello > > I am trying to simulate the effects of the differential wing lift. Such > as single wing stall due to the propwash loss at a low speed, and the > effect of the icing on a single wing (which can happen during a deicing > failure on that wing). All of these are important aerodynamic effects. > > Now, we know we only have one wing in jsbsim currently, not 2. My idea is > therefor to try using 2 records to simulate the wings separately, > instead of the usual CL record. > This however would require some kind of algorithm to define how the force > origin moves to overlay with center of lift for each wing, which is > probably not an easy task > > I was wondering if anyone have tried a similar approach before, and if > this problem pechaps has an easier solution ? > > Thank you > > regards, > Oleksiy Frolov A better place to ask might be on the JSBSim user list JSBSim user questions In the aerodynamics section of a JSBSim configuration you are only allowed one force vector, applied at aerorp, and consisting of lift, drag and side or normal, axial and side. You can also specify the moments for yaw, pitch and roll. An alternative is to use the 'external force' section of JSBSim. This allows you to specify an arbitrary number of forces, each of which can be applied at separate points on the airframe and can be computed in different axis systems. I've played a little with doing the vertical stabilizer as external forces in the JSBSim config I did for the Gloster Meteor: https://gitorious.org/ron-s-hanger/gloster-meteor The JSBSim config is here: https://gitorious.org/ron-s-hanger/gloster-meteor/blobs/master/gloster-meteor-jsb.xml And the systems file that computes the external force is here: https://gitorious.org/ron-s-hanger/gloster-meteor/blobs/master/Systems/external_reactions.xml This was a quick exercise, and I didn't fully validate the trig used to compute the axial/normal/side components. Ron 
 [Flightgear-flightmodel] Force instead of lift From: Oleksiy Frolov - 2011-09-30 20:33:08 Hello I am trying to simulate the effects of the differential wing lift. Such as single wing stall due to the propwash loss at a low speed, and the effect of the icing on a single wing (which can happen during a deicing failure on that wing). All of these are important aerodynamic effects. Now, we know we only have one wing in jsbsim currently, not 2. My idea is therefor to try using 2 records to simulate the wings separately, instead of the usual CL record. This however would require some kind of algorithm to define how the force origin moves to overlay with center of lift for each wing, which is probably not an easy task I was wondering if anyone have tried a similar approach before, and if this problem pechaps has an easier solution ? Thank you regards, Oleksiy Frolov 
 Re: [Flightgear-flightmodel] I have a question. From: Curtis Olson - 2011-09-27 15:23:03 Attachments: Message as HTML Hi, We have an RC scale aircraft called the "Rascal 110" available for download here. http://www.flightgear.org/download/aircraft-v2-4/ I'm working on a 92" flying wing model, but it's not quite ready for first release. All FlightGear aircraft can be flown from a variety of vantage points including a "cockpit" view, tower view, chase view, fly-by view, etc. And there are ways to create your own views if you want to dig under the hood a bit. Even full scale aircraft can be flown from a tower view ... but the Rascal is probably the best developed FlightGear aircraft that has RC scale and performance characteristics. Regards, Curt. 2011/9/27 鳥枝亮介 > I am a Japanese college student. > I am looking for the web site where the radio control model of flight-gear > appears. > If you know, please let me know. > Thank you for your consideration. > > > > ------------------------------------------------------------------------------ > All the data continuously generated in your IT infrastructure contains a > definitive record of customers, application performance, security > threats, fraudulent activity and more. Splunk takes this data and makes > sense of it. Business sense. IT sense. Common sense. > http://p.sf.net/sfu/splunk-d2dcopy1 > _______________________________________________ > Flightgear-flightmodel mailing list > Flightgear-flightmodel@... > https://lists.sourceforge.net/lists/listinfo/flightgear-flightmodel > > -- Curtis Olson: http://www.atiak.com - http://aem.umn.edu/~uav/ http://www.flightgear.org - http://gallinazo.flightgear.org 
 [Flightgear-flightmodel] I have a question. From: 鳥枝亮介 - 2011-09-27 06:42:36 Attachments: Message as HTML I am a Japanese college student. I am looking for the web site where the radio control model of flight-gear appears. If you know, please let me know. Thank you for your consideration. 
 [Flightgear-flightmodel] RE : Re: There are questions about FlightGear. Please answer my questions. From: Frederic Bouvier - 2011-09-06 06:37:55 Attachments: Message as HTML e. You already read the wiki and the official docs and you think it's not sufficient to build a plane, and you need additional sources -fred -Frederic Bouvier Ron Jensen a écrit : On Monday 05 September 2011 08:20:29 Ron Jensen wrote: > On Monday 05 September 2011 06:05:28 kunai090@... wrote: > > 2. Could you tell me websites which were written how to make the > > FlightGear models without wiki and official site ? >  José answered your second question with another, very valid, question. > What is wrong with using the wiki and other official site documentation? Just to help you understand why we ask this question we have a few theories on why you asked for non-official sources: a. You want to develop payware and want non-official sources trying to avoid GPL Liability. b. You think secondary sources would be more accurate and technically complete than the official documentation. c. Your are looking for obscure sources in an attempt to cheat in some kind of school report work. d. We are totally misunderstanding what you are trying to ask. Sometimes too broad a question is too hard to answer correctly. Ron ------------------------------------------------------------------------------ Special Offer -- Download ArcSight Logger for FREE! Finally, a world-class log management solution at an even better price-free! And you'll get a free "Love Thy Logs" t-shirt when you download Logger. Secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsisghtdev2dev _______________________________________________ Flightgear-flightmodel mailing list Flightgear-flightmodel@... https://lists.sourceforge.net/lists/listinfo/flightgear-flightmodel 

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