On Sunday 23 December 2007 07:59, Syd&Sandy wrote: > On Sun, 23 Dec 2007 02:16:00 -0500 > > Chris Metzler <[EMAIL PROTECTED]> wrote: > > Something bad happened to the b1900d FDM in CVS sometime in the > > last two weeks (since my previous update from CVS). With the > > flaps fully extended and the gear down, it's impossible to fly > > above stall speed unless the aircraft is in a > 20 degree nose > > down attitude. > > > > -c > > Yes Ive tried to correct the FDM a bit and should have left it > alone. I dont do much with it anymore since many others have been > modifying it. Some parts are difficult to model since the > turboprop engines aren't complete... There is no prop drag , > reverse , and the feathering doesn't seem to work... Also the > specs show a wing twist of about 5 degrees ... but seems to also > create too much drag... If you want to attempt to adjust it and > send me the file , I'd be happy to test it and update ... I > should mention too that takeoff/approach flap setting is 17 > degrees ... about halfway... Cheers and merry Xmas
I've noticed some funny YASim prop-pitch behaviour and problems while working on the TU-114. The first thing I noticed is that the prop-pitch is normalised and this would seem to make it impossible to reverse the pitch for reverse-thrust braking. A possible solution to this might be to use the src0, src1, dst0 & dst1 params to widen the range but before I got around to trying that I found that fully-fine pitch seemed to correspond to a normalised pitch setting of 1.0, with the full-coarse/feathered setting corresponding to 0.0, which seems the wrong way around. Secondly, while experimenting with prop-pitch, I set up PID controllers for each engine to control the prop-pitch. The reason behind doing this was that the TU-114 operated at two prop rpm settings - 840 max/takeoff-rpm and 750 cruise-rpm - and I wanted to see the range of prop-pitch values that was required at each of the two rpm settings under different flight conditions. What I found was that for a given prop-rpm setting the prop-pitch didn't vary with the flight conditions. At a prop-rpm setting of 840 rpm the pitch was clamped to 1.0 and for a prop-rpm setting of 750 rpm it was clamped at 0.357 but these values didn't change according to altitude or speed, which isn't what I would have expected. Having said that, I do see a small variation in the prop-pitch while the throttle was actually changing i.e. while the aircraft was accelerating or climbing in cruise, but once things stabilise again the prop-pitch settles back down to 0.357, regardless of the new conditions. I'm not very familiar with turbo-prop characteristics and operation but I would have thought that, for example, if the altitude is kept constant but the airspeed is increased the prop-pitch should get coarser. This is only the second time I've used YASim propellers so this could be because I've badly mis-configured the propellers but other than the prop-pitch anomaly they seem to be performing ok. I also haven't got around to checking the prop-pitch behaviour with piston engines yet either. LeeE ------------------------------------------------------------------------- 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/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
