On Sunday 23 December 2007 20:28, Hal V. Engel wrote: > On Sunday 23 December 2007 11:13:03 Martin Fenelon wrote: > > On Friday 21 December 2007 22:42, Dan Lyke wrote: > > [snip] > > > > > I took the c172p up to 500 feet, cut the engine, pulled all > > > the way back on the stick (yeah, I know, it's not authentic, > > > but I have a stick, not a yoke), and as the speed dropped to > > > 50kts or so the plane started into this sort of kite-like > > > sink, but the ailerons were still pretty responsive. > > > > The stall 'g' break of the real thing is certainly missing too. > > I can't get an 'autorotating' spin either. > > > > Martin > > Some of the available models do a better job of modeling > stall/spin/snap characteristics. The PA24-250 is one example. > But most of the models currently available for flighgear do not > do a good job of modeling stall/spin/snap characterisics. Some > aircraft should be particularly difficult to handle during a > stall. For example the P-51D has a very critical wing and should > be very difficult to handle when a stall occurs. But it mushes > stright ahead like a (very fast) trainer when stalled. There is > also no buffeting in most of the models when approaching stall. > > On the other hand modern lower performance GA aircraft will in > general have very forgiving stall charaterisics. I have not > piloted a C172 but I have spent some time flying a Piper > Tomahawk. In the Tomahawk if you enter a (non-accelerated) stall > striaght ahead the ailerons will remain affective even after the > stall is fully developed and you are sinking at 1000+ feet per > minute with the yoke all the way back. I suspect that the C152 > and C172 are not too much different in this regard. But a P-51D > and most other high performance aircraft should not act this way > when stalled. > > Hal
There are a few of significant factors regarding stalls and uncontrolled flight in flight-sims. First, I guess, is the fdm itself. JSBSim, which is tables based, can handle stalls perfectly if the data is available - but usually it isn't. YASim on the other hand, which incorporates aircraft geometry, has some capability built in to it and I've certainly seen it work quite well. I played with an automated spin-recovery feature in the SU-37 and didn't have any problems getting it to spin - infact, it was because I was getting into so many spins while trying some of the manuevers that the vectored thrust SU-30 series aircraft are capable of that I wrote it, so I didn't have to keep resetting after crashing:) Another factor is that simulated aircraft are usually perfectly symmetrical aerodynamically whereas real aircraft are always going to be slightly out due to slight manufacturing variations and masses not being perfectly on the centerline. I've found that when I've incorporated asymmetrical aerodynamic features e.g. an appropriately sized fuselage element to simulate a wing-mounted pitot probe, it does have an effect in stalls. Lastly, the simulated air we fly through is uniform across the airframe whereas in real life it won't be - there will nearly always be slight variations which will cause a wing to drop one way or the other. 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-users mailing list Flightgear-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-users
