Re: [Flightgear-devel] Modeling a Flexwing Microlight
--- Joacim Persson wrote: On Fri, 8 Dec 2006, Stuart Buchanan wrote: - There is no trimming for different flight phases. Vertical speed is purely controlled by power. Many trikes has a trim function, just like all non-trainer hang glider has nowadays. Many do, but mine doesn't :) Even by microlight standards, my aircraft is very basic. My panel has 5 instruments: ASI, Altimeter, Compass, EGT, RPM. Plus a stopwatch stuck on with velcro... However, I am talking about a directly controlled pilot-controlled trim system rather than the side-effects of the wing flexing. (I know the Airborne trike we use for aerotowing has it.) This trim is usually operated by a line, the trim line, which is drawn to the speedbar (on a HG) or on a sidebar (on a trike) and most noticeably it adjusts the tension of the cross beam (which is divided in two parts connected with a hinge at the centerline). (Compare with the kick or sheet on a sailboat mainsail.) There are however more functions coupled with the trim than cross beam tension. On kingpost HG's (like your trike), there is something called luff lines connected to the trailing edge via the kingpost, on the newer topless hg's there are sprogs at the wing tips filling the same function. Luff lines and sprogs act like an elevator trim under certain circumstances, and is primary a safety detail to prevent an uncontrollable dive. The setting of those are also altered along with the trim setting. I believe I can alter the luff lines on the ground, but I doubt it is something I'll be doing in the near future. The cross-beam isn't fixed to the keel. When the wing is un-folded a pulley system is used to pull the crossbeam into position and tie it off against the keel, but I guess it will still have some lateral movement. I didn't know that trim affected the cross-beam. I So the trim on a HG or trikes changes: 1. The camber of the whole wing. (cross beam tension) This affects L/D ratio, stall speed. 2. Apex (follows from sail tension) and dihedral (not much). 3. The elevator trim function of sprogs or luff lines. Your trike may have the cross beam fixed to the keel (can't tell by the photo) and would then be a bit stiffer in handling (but more course stable) than a hang glider with the trim fully loose, but with a floating cross beam (i.e. not connected to the keel) as all hang gliders have today, the first effect of moving the weight to one side (shifting the keel sideways with respect to the cross-beam and wing tubes) is that the wing you move away from gets less camber and the other gets more camber. This in turn makes the outer wing tip fly a bit faster than the inner wing tip, generating some rudder and aileron effect. A hang glider with a non-floating cross beam is rather slow in turns. This difference in camber between the wing halves is less the more the pilot tighten the trim. So we can add a fourth function of the HG trim: 4. Sets the amount of rudder and aileron effect from shifting weight sideways -- indirectly by adjusting the cross beam tension and thus the difference in tension of the trailing edge on each wing half. In short: when circling thermals or coming in for landing, you release the trim, when flying straight between thermals you tighten the trim (fully or to a wanted trim speed). But that is perhaps a bit beside the point -- a trike pilot doesn't have to worry much about L/D ratio, and there is plenty of weight for steering with pure CG shift on a trike. So, should I use YASim or JSBSim for this project? Or larcsim? The only hang glider model in FG (airwaveXtreme150, a larcsim model) has an invisible motor+propeller attached to it, so we could call it a trike. It doesn't have a trim function anyway. (I'm quite sure the original has.) I did consider using larcsim, but decided not to on the basis that it is no-longer developed much (if at all). ___ To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre. http://uk.security.yahoo.com - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modeling a Flexwing Microlight
On Fri, 8 Dec 2006, Stuart Buchanan wrote: - There is no trimming for different flight phases. Vertical speed is purely controlled by power. Many trikes has a trim function, just like all non-trainer hang glider has nowadays. (I know the Airborne trike we use for aerotowing has it.) This trim is usually operated by a line, the trim line, which is drawn to the speedbar (on a HG) or on a sidebar (on a trike) and most noticeably it adjusts the tension of the cross beam (which is divided in two parts connected with a hinge at the centerline). (Compare with the kick or sheet on a sailboat mainsail.) There are however more functions coupled with the trim than cross beam tension. On kingpost HG's (like your trike), there is something called luff lines connected to the trailing edge via the kingpost, on the newer topless hg's there are sprogs at the wing tips filling the same function. Luff lines and sprogs act like an elevator trim under certain circumstances, and is primary a safety detail to prevent an uncontrollable dive. The setting of those are also altered along with the trim setting. So the trim on a HG or trikes changes: 1. The camber of the whole wing. (cross beam tension) This affects L/D ratio, stall speed. 2. Apex (follows from sail tension) and dihedral (not much). 3. The elevator trim function of sprogs or luff lines. Your trike may have the cross beam fixed to the keel (can't tell by the photo) and would then be a bit stiffer in handling (but more course stable) than a hang glider with the trim fully loose, but with a floating cross beam (i.e. not connected to the keel) as all hang gliders have today, the first effect of moving the weight to one side (shifting the keel sideways with respect to the cross-beam and wing tubes) is that the wing you move away from gets less camber and the other gets more camber. This in turn makes the outer wing tip fly a bit faster than the inner wing tip, generating some rudder and aileron effect. A hang glider with a non-floating cross beam is rather slow in turns. This difference in camber between the wing halves is less the more the pilot tighten the trim. So we can add a fourth function of the HG trim: 4. Sets the amount of rudder and aileron effect from shifting weight sideways -- indirectly by adjusting the cross beam tension and thus the difference in tension of the trailing edge on each wing half. In short: when circling thermals or coming in for landing, you release the trim, when flying straight between thermals you tighten the trim (fully or to a wanted trim speed). But that is perhaps a bit beside the point -- a trike pilot doesn't have to worry much about L/D ratio, and there is plenty of weight for steering with pure CG shift on a trike. So, should I use YASim or JSBSim for this project? Or larcsim? The only hang glider model in FG (airwaveXtreme150, a larcsim model) has an invisible motor+propeller attached to it, so we could call it a trike. It doesn't have a trim function anyway. (I'm quite sure the original has.) - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] Modeling a Flexwing Microlight
Hi All, I recently bought a flex-wing microlight (aka trike, ultralight, hang-glider with a lawnmower engine). Specifically, a Mainair Flash 2 Alpha. There is currently a picture of it here: http://www.sites.ecosse.net/graeme.ritchie/eosm/home.asp?txtMenu=forsale Obviously, I want model it in FG. However, as flexwings are quite different from the normal aircraft that we model, I need some advice as to what FDM to use. To give an idea of how flexwings differ from normal aircraft, here are some details: - They have single hang-glider style wing, no tail and a very small fixed rudder. - The wing pivots on a point that is pretty close to the center of lift during all phases of flight, and from which the trike unit hangs during flight. - The pilot controls the aircraft by moving the entire wing in the required direction. The back end of the wing flexes, to help turns. - The rudder on the wing provides limited yaw control as it is attached to the wing rather than the trike. - There is no trimming for different flight phases. Vertical speed is purely controlled by power. - My aircraft has a 50HP two-stroke Rotax 503 engine (pull start!) with reduction gear to reduce maximum RPM form 7000 to approx 4000 on the fixed prop. - Typical cruise is 55mph, stall 35mph and Vne 70mph. - Empty weight is around 200kg, MAUW 390kg. - Flex-wing flying is very much seat-of-the-pants using external visual references to maneuver the aircraft rather than instruments. So, should I use YASim or JSBSim for this project? -Stuart ___ All new Yahoo! Mail The new Interface is stunning in its simplicity and ease of use. - PC Magazine http://uk.docs.yahoo.com/nowyoucan.html - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modeling a Flexwing Microlight
On Friday 08 December 2006 12:06, Stuart Buchanan wrote: Hi All, I recently bought a flex-wing microlight (aka trike, ultralight, hang-glider with a lawnmower engine). Specifically, a Mainair Flash 2 Alpha. There is currently a picture of it here: http://www.sites.ecosse.net/graeme.ritchie/eosm/home.asp?txtMenu=forsale Obviously, I want model it in FG. However, as flexwings are quite different from the normal aircraft that we model, I need some advice as to what FDM to use. To give an idea of how flexwings differ from normal aircraft, here are some details: - They have single hang-glider style wing, no tail and a very small fixed rudder. - The wing pivots on a point that is pretty close to the center of lift during all phases of flight, and from which the trike unit hangs during flight. - The pilot controls the aircraft by moving the entire wing in the required direction. The back end of the wing flexes, to help turns. - The rudder on the wing provides limited yaw control as it is attached to the wing rather than the trike. - There is no trimming for different flight phases. Vertical speed is purely controlled by power. - My aircraft has a 50HP two-stroke Rotax 503 engine (pull start!) with reduction gear to reduce maximum RPM form 7000 to approx 4000 on the fixed prop. - Typical cruise is 55mph, stall 35mph and Vne 70mph. - Empty weight is around 200kg, MAUW 390kg. - Flex-wing flying is very much seat-of-the-pants using external visual references to maneuver the aircraft rather than instruments. So, should I use YASim or JSBSim for this project? -Stuart YASim relies upon having an elevator so you'll have to use JSBSim, or possibly UIUC. LeeE - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modeling a Flexwing Microlight
On Friday 08 December 2006 12:06, Stuart Buchanan wrote: Hi All, I recently bought a flex-wing microlight (aka trike, ultralight, hang-glider with a lawnmower engine). Specifically, a Mainair Flash 2 Alpha. There is currently a picture of it here: http://www.sites.ecosse.net/graeme.ritchie/eosm/home.asp?txtMenu=forsale Obviously, I want model it in FG. However, as flexwings are quite different from the normal aircraft that we model, I need some advice as to what FDM to use. I expect you could do this using JSBSim. Jon - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
