Hi guys, Thanks for this. Gary, I gave your yasim xml a spin. (sorry, long mail ahead) I don't have enough experience with the plane yet to comment on everything. The real thing seems to behave a bit better on takeoff when there is no crosswind -- haven't done a crosswind takeoff or landing yet, so I can't comment on that. One problem with the model is that the support wheels shouldn't both touch the ground, they should allow the plane to tilt maybe 10-15 degrees in either direction. They also bend and flex when slammed hard, for shock absorbtion.
The airbrakes are definitely not efficient enough. My school sets down that we must always land the Falke with the engine stopped (they had people breaking the plane with powered landings early on, so they forbade it). Therefore we do a very 'glider-style' landing, pretty steep descent at around 60 knots with the spoilers extended all the way, levelling out just above the runway with the spoilers still out. You just release it back a little so you don't accidentally brake and nose over :) More on that later. This way you touch down at around 35-40 knots, but you must continue to hold the spoilers out, otherwise you might get airborne again above 30 (depending on weight which influences stall speed). See some pics of a landing here: http://www.avatarzenekar.hu/files/P1020616.JPG http://www.avatarzenekar.hu/files/P1020617.JPG http://www.avatarzenekar.hu/files/P1020618.JPG So the speedbrakes must be effective enough to be able to do this :) Regarding the speedbrake/brake link and flight controls... The Falke has a fixed prop and no mixture lever. I've read somewhere that the Limbach engine is actually an adopted VW engine, maybe that's why. Apart from the throttle, all you've got is a carb heat lever and on the C model and later, a cowl flap that helps regulate engine temperature (the B has a fixed cover that you install in the winter only). On landing, the spoiler is your primary glidescope control. I have a Saitek Aviator which has a split throttle -- I map one half to the spoiler and that works great. The problem with the config I submitted is that the brakes start working at around 50% travel. Like you said, this is not correct. Please read on for a somewhat long-winded explanation on how it's used in practice: The Falke's fuselage is welded metal tubing covered with canvas. The actual spoilers are spring-loaded and a fair bit of force is required to pull them out (if you'd let go of the lever, they would slam back down quite violently). There are two spoiler levers in the cockpit -- one on the left, and one between the two seats. When you open the spoilers all the way, the left lever hits one if the fuselage tubes (a vertical one). You've got to pull that lever inward slightly to be able to pull it further back and engage the brakes. Only the C version and newer have a parking brake -- which is actually a small, loose lever dangling on the same fuselage tube that can be used to jam the spoiler in the fully open position. This is the best pic I could find that shows this: http://www.alte-ems.de/flugzeuge/sf25c/sf25c_cockpit1.jpg.JPG The spoiler lever handles are blue, the fuselage tubing and the rest of the spoiler lever is grey. If you look carefully on the left of the pic below the placard you can see a little black knob -- that's the parking brake lever. I'll try to remember to take close ups next time I'll go flying. It's all very crude and simple but actually quite clever and efficient way to ensure that you don't land with the wheel locked. But it seems that it still happens sometimes: http://wap.airliners.net/photo/0003212/L/ :) I wish I had the skills to do these animations, but probably the best I can come up with would be a bit of nasal code to link the spoilers and the brakes. I can see that if we made it work like it does in the real thing, that might confuse and piss off FG users, who might expect that the parking brake, brake and spoiler work independently. Personally I'd prefer if they were linked the following way: 1. If you hit the brakes (b key or toe brake pedals, etc), the spoilers would open all the way. This would do for a handy shortcut for full spoilers. 2. If you set the spoiler controls to 80%, the spoilers should be fully open and you should start applying the brake instead (this would be needed for joystick control). 3. If you set the parking brake, that should apply full brake and full spoilers. This should either override any joystick controls, or it's also OK by me if you can't set the parking brake unless you have either set full spoilers or full brakes. 4. Parking brake should be released by using any of the brake or spoiler controls. What do you think? Is this doable? Does this require nasal coding? Cheers, Vik On 08/16/2011 02:25 AM, Gary Neely wrote: > Vik, > > Based on Maik's CG information and a little nosing around for > performance information online, I made an el-cheapo quick and dirty > FDM: > > http://ltts.crlt.indiana.edu/grn/flightgear/sf25b-yasim.xml > > Feel free to use it, lose it, abuse it, or whatever. > > It's a bit tricky to takeoff and land, especially in any kind of > crosswind-- it takes a fair hand on the rudder. It also likes to glide > and glide once it gets close to the ground, so you'll definitely not > want to approach over 50 kts or you'll never get down. I often > side-slipped to help me get down. I disabled the linkage of the > spoilers with the wheel brake-- According to the book, brakes are > engaged only on the maximum spoiler setting, but I got tired of > nosing-over when I landed. ;) You might want to restore that. > > I didn't try to match sink rate to real, I only tried to get the speed > range within reasonable norms and bring control surfaces effects to > something that felt reasonable. You might want to mess with the > spoiler settings, maybe increase the drag a bit, as the handbook says > they're pretty effective, and I tend to err on the understrength side. > I'm not a pilot, so definitely feel free to disregard anything I did. > > -Gary, aka Buckaroo > > ------------------------------------------------------------------------------ > uberSVN's rich system and user administration capabilities and model > configuration take the hassle out of deploying and managing Subversion and > the tools developers use with it. Learn more about uberSVN and get a free > download at: http://p.sf.net/sfu/wandisco-dev2dev > _______________________________________________ > Flightgear-devel mailing list > Flightgear-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/flightgear-devel > ------------------------------------------------------------------------------ uberSVN's rich system and user administration capabilities and model configuration take the hassle out of deploying and managing Subversion and the tools developers use with it. Learn more about uberSVN and get a free download at: http://p.sf.net/sfu/wandisco-dev2dev _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
