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Odd Autopilot Actions

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Why does the autopilot vertical speed setting jump to minus 700 or 1000 fps when the Alt button is pressed? Also, the airplane's heading will be locked without activating the Hdg button. I have to activate and deactivate the heading lock to get it to release.

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The AP Vert Speed setting is aircraft specific and can be modified in the aircraft.cfg file under the autopilot section.By default in fs when you turn on the AP it automatically turns on the wing leveler function. There is a way to disable this, can't remember what it is. Maybe someone else can help with that or you could search the forum.JoeThe best gift you can give your children is your time.

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Why does the autopilot vertical speed setting jump to minus 700 or 1000 fps when the Alt button is pressed?I have found that FS tends to zero the elevator when the AP is engaged. The resulting sudden VSI climb or descent is due to the elevator position at the time the AP is engaged.The aircraft should be trimmed for a climb, not using heavy back pressure on the elevators, or the reverse.Also having the elevator trim far out of position means the AP will take a longer period of time before getting the trim set to control the rate of climb.If the aircraft and AP are correctly matched and the speed is correct - the aircraft should meet the desired rate of climb with only trim changes.Of course the real world works on the angle of trim, not a VSI rate setting - so their autopilots don't have these FS issues.It's a concession to the beginner in the design of FS.

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juat to add to the other posts.This is the section from the aircraft.cfg file for the default 737 which I have modified over time to suit my needs.you can experiment with it by adding it to yours, cut/paste , make backup b4 doing so.you will notice that the vert setting is set to zero,( there are a few other changes as well) so when engaged you simply dial in the rate you require resulting in a smooth transition from lvl flight tp either ascend/descent.[autopilot]use_no_default_pitch = 0 // 0 = Default to current pitch mode, 1 = No default pitch mode.use_no_default_bank = 1 // 0 = Default to Wing Leveler mode, 1 = No default bank mode.autopilot_available=1flight_director_available=1default_vertical_speed=0.00autothrottle_available=1autothrottle_arming_required=0 //original 1autothrottle_max_rpm = 90autothrottle_takeoff_ga=1pitch_takeoff_ga = 8;max_pitch_velocity_lo_alt_breakpoint=20000.0max_pitch_velocity_hi_alt_breakpoint=28000.0max_bank=25.0max_bank_acceleration=1.8max_bank_velocity=3.00max_pitch=10.0max_pitch_acceleration=1.0max_pitch_velocity_lo_alt=2.0max_pitch_velocity_hi_alt=1.5max_throttle_rate=0.100000 //0.40 //0.10 originalnav_proportional_control=9.000000 //12.00nav_integrator_control=0.250000nav_derivative_control=0.00nav_integrator_boundary=2.50nav_derivative_boundary=0.00gs_proportional_control=9.520000 //25.0gs_integrator_control=0.26000 //0.53gs_derivative_control=0.00gs_integrator_boundary=0.70gs_derivative_boundary=0.00yaw_damper_gain =0.000000 //1.0default_bank_mode=0Douglas

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Thanks Douglas. Your reply gave exactly what I needed to know. I should have looked at the aircraft config files. Under autopilot default_vertical_speed, they all list exactly what shows on the autopilot when the alt button is pressed. I changed this to 0.0 for each aircraft so now when I engage the autopilot while at level cruise, the aircraft won't suddenly dive until I can change the setting.The next question is why did the aircraft developers make it the way they did. Is this to set a rate of desent for autoland or something? I will now have to check to make sure that A1 aircraft land properly.

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>The next question is why did the aircraft developers make it>the way they did. Is this to set a rate of desent for>autoland or something? I will now have to check to make sure>that A1 aircraft land properly.Glad it worked!I could only guess as to why the A/P was set this way. You might find that all the AI aircraft.cfg files have that 1800fpm setting as well.Note** the setting(1800 or what ever is under default) only is active during descent/climb whilst during an ILS approach the vertical informaion to the A/P is supplied by the glideslope(VSI rate changes depending on speed etc) the alt hold and vert hold are inactive during this phase.Douglas

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As others have said, FS remembers things we don't necessarily want it to from saved flight to flight. If you had set up a flight in a high performance aircraft and saved it, then switched to a lower performance aircraft, the autopilot settings for default vertical speed and approach and original altitude are often retained for the original aircraft, even if you subsequently save the flight again in with the lower performance aircraft. Therefore the autopilot immediately tries to seek some lower or higher altitude than you intended or use a different default VS, even though you set a new altitude or VS in the window. Strange but true.I found the way to clear it was to go to Create a Flight mode and start from scratch. 1. Choose a different aircraft and click OK, then rechoose the aircraft you want.2. reset the weather to the weather you want.3. reset the location to a field you want or set up a new flight plan.4. After clicking the Fly Now button, save that flight as the default or use the World Menu to configure a different location, time and wx, then save as default.Now you should find the autopilot engages and disengages as published. You may need to use that default as a base when creating other flights and trash previously saved flights since they are corrupted with the faulty autopilot info.HP Laptop, XP Home SP2, AMD Turion 64 ML-37 1.99GHz, 1.37GB RAM, ATI Radean Xpress 200M

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