Martin Spott schrieb: > > I don't claim the helicopter FDM in FlightGear is perfect, but turning > it down just because a few details are missing, whereas most of the > actual in-flight behaviour is pretty well done, is unjustified, > ...... ......
> Usually it _is_ my intention to stay within aircraft limits. It seems > we see different goals in the FlightGear helicopter simulation: > > I want to see a simulation of what is supposed to happen during a > flight and I'm quite satisfied for now. Apparently you want to see a > simulation of what is _not_ supposed to happen during a flight, so your > expecations and your valuation of what's already there differs > significantly. > > Sometimes things are _so_ simple :-) > Martin. Well, Martin, sometime things are *not* so simple as the seem to be :-) I did not want to go into this discussion to prevent a further flamewar but as you obviously are insisting on your wrong opinion I have to say some words to back Josh: I like the FG BO105 very much and do a lot of sim-flights with the helo, of course equipped with some sufficient precise controls (pedals, sep. collective,stick). But we have only a FDM derivative from fixed wing FDM and the helicopter sometimes behaves like that. You can't train somehow realistic procedures. These are not "a few details" it is the whole thing itself what is unrealistic when you want it as a *simulation*. True, it gives some very nice general helicopter feeling taking it as a *game*, especially hovering and low speed maneuvers - and this is why I like to fly the BO105, though, and this is why especially newcomers can learn basic aspects of vertical flight, *playing* with it. If you speak over a somehow realistic helo FDM in a *simulation* it is a *must* to have autorotation capability, at least ground effect for the rotor-disk at a whole (is more complicated in reality), translational lift, vortex-ring-state and a at least simple model of air-downwash reaction to helicopter body, I won't think here of refined stuff (ie interaction of rotor-downwash and tail-rotor). You also should have some realistic instrument readings regarding rotor RPM and engines (ie. to have the splitting needles when autorotating). But most annoying are the *normal* inflight effects where the helo behaves more like a wing aquipped a/c (sample below at the bottom). Ok, you are right saying that I am *no* helicopter pilot and might be wrong. But under blind man that one who has at least some visus on one eye migh be the king: I am flying a R/C helicopter, have the chance to discuss all that stuff regarding real flight procedures/behaviour versus simulated behaviour with real life pilots - which I did very often over the last years as I am regularly flying as a crew member many hours a week. I worked through a lot of helicopter training books the last years . I have been flying a lot of hours with FLY!II and X-Plane helos a followed what real-life turbine and piston helo pilots said about the weak points of these FDMS. So after all, I at least have some clue how to check the validity of a helicopter *simulation*. Only one *very simple* example which everybody can test himself: Take the BO105 and goo for a straight and level flight with 100-120 knts. Then push the collective down. A real helicopter is immediately in a "hot" autorotation state. It simply nearly "falls down" from heaven without collective pitch set at a vertical speedrate of ie 2500 ft/min. You can't hold it in straight and level flight for a relevant time even with the cyclic stick full back. Try it with the BO105 - see what happens? You are not only able to hold height with pulling the stick back but to climb with up to 1500 ft/min until speed is low. *This* is how I would expect a fixed wing to behave after reducing throttle because you reduce power but have the lift of the wings. A helicopter simply has only very small lift at the blades when reducing blade pitch although the engine(s) is/are running and rotor RPM is constant. This is not only important for a "hot" autorotation (described here) but for normal descend procedures. Due to the "fixed wing behaviour" you have to fly *some* circles to reduce speed and height with the FG BO105 when at some altitude with higher speed whereas in reality you would reduce the collective and when turning to reduce speed you are already going down pretty soon. Another example are the nearly *lacking* torque forces when increasing/decreasing collective - you might only recognize this when using pedals (of course with --disable-auto-coordination). And the unsufficient tail-rotor power ... and .. After all, I don't want to make all bad. We just have to be honest that we don't have an acceptable standard for helicopter-flight at the moment in FG despite all that wonderful work Maik Justus did for all FG helicopter fans and the very nice 3D-model of the BO105 thanks to Melchior Franz. But at the moment, just let us take the actual flightmodel as a nice *game* addon for our *simulation*, then we all can be happy with it and enjoy flying the BO105 (and the nice R22 which I also take for a ride sometimes). We have to wait until there is anyone with skills as well in the coding as in the helicopter aerodynamics stuff area interested to do a better FG helo FDM (or improve the actual one with some patches as a first aid). Have nice flights with the BO105, one can really enjoy it despite this discussion! Georg EDDW _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
