EuroHarmony Community Forums
Archive => Other Topics => Old Forum => Flight Simulation => Topic started by: EHM-1001 Robert on October 26, 2004, 11:13:12 pm
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Hi folks,
maybe some of you can answer this question. You may know, that inside the CFG file the maximum allowed weight of the aircraft (MTOW), and the empty weights are defined exactly in pounds. Next to it, the usual payload is defined, and you can set your amount of fuel when creating a flight.
Anybody knows about weight calculations? If the payload, and fuel load is over the MTOW weight, will the game reduce the payload automatically, and keep the fuel, or let the bird just fly overweighted? And if it cuts the payload, does it reduce all the "station-load" loads equally, or simply remove some of them? Or randomly reduce the given loads as local maximums?
It would be important to know for calculating the center of gravity, and tuning the fuel flow > adjusting the range of the aircraft...
Thanks.
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FS does not adjust the load automatically. How much and where you put the weight, FS simulates it. If the FDE of the aircraft is balanced correctly, an overweight aircraft will not lift off (not enough power)... If it is out of CoG limits, the aircraft may not pitch easily or too easily causing erratic control movements.
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Either it will not lift off or will lift off after lots of straining
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I had strange results with manipulating the loads. I think, the plane was overweighted, but could take off within the range of specs.
Then the autopilot could not keep it on a given altitude. I could "hit" the resonance of the autopilot quite easily, which resulted an oscillation between +6000...-6000 fpm. ;D The strange was, that say, on FL100 it happened, but not on FL60, or FL50... :o
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Well, could it be that when the plane reaches a certain altitude, the air gets thinner and hence provides less overall lift at the same speed. Hence, a higher speed is required to keep the aircraft afloat at these speeds, which could not be provided by the engines due to the overweight problems. Hence with insufficient lift and slightly changing air conditions, the airplane may suddenly experience a mini stall and dive down only to gain speed and have the autopilot force it to climb again.......not sure if this makes sense or even apply in the world of FS :P
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I think, the autopilot problem is a typical controlling/automation problem.
In simple: the system that had to be controlled (now, the aircraft) have always many parameters about responding an effect that moves it out from the stable state. The controller have principles, how to control the system, how much effect and when should it apply on the system, to keep in a stable state. These two functions have some common parts. In a good situation, the controller will keep the system in a stable state for every kind of outer effects. In a bad situation, the controller cannot follows the outer effects and will move the system into an unstable state, which means a typical oscillation of the system.
Lets turn it into aviation language: the aircraft have many aerodynamical parameters, like center of gravity, weight, different locations of loads, drag, lifting force, angle of attack... many parameters. The controller: autopilot, have some programmed principles, that how much vertical trim should it apply to keep the plane in the given descending/climbing rate. If you change the system -modifying the center of gravity, aircraft weight, loads...- without fine tuning also the controller, you will probably got an unstable working system, so the autopilot will not be able to keep the plane in a stable climbing/descending rate.
We are in a bad situation, because we can easily change the aircraft parameters, as these are all stored in the aircraft.cfg file, but we cannot change the autopilot response, because it is stored in the aircraft.air file, which is not perfectly discovered.
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In FS2004 they are also in the cfg file (check the [autopilot] section), although I don't quite understand what effects does those settings have...
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Indeed.... I suggest adjusting the pitch stability (lowering) in the [flight_tuning] section and observe the effect. The pitch oscillation is an age old problem dating back to FS98.... The MOI's are not properly configured for the offending aircraft. You should recalculate the MOI's.
Also, increasing/decreasing the elevator_trim_effectiveness value may help.
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Originally posted by YR-TGM
In FS2004 they are also in the cfg file (check the [autopilot] section), although I don't quite understand what effects does those settings have...
Well just modify some settings and see what happens! :P
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Originally posted by EHM-0962
Well just modify some settings and see what happens! :P
LOL ;D
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OK, will try that, I have not tried modifying those values yet. But I am afraid I should fine tune the autopilot responses.