Speed hold

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Speed hold

Postby dswanson » 04 Aug 2007, 09:53

Hi,

in FS2002 you could set the speed hold facility via the cfg and .air files for any aircraft and it would hold the speed set in the autopilot window. This doesn't seem to be the same in fs9.

When the speed is set in the a/p window the throttle just seems to close slowly with no reference to the set speed.

I've set the cfg to have autothrottle on, no manual arming and no go-around and these are mirrored in the .air file. The max throttle setting and change rate are set to the MS default of 90% and 10% respectively.

Are there any other settings I've missed ?
Regards,

Degsy
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Postby Filonian » 04 Aug 2007, 16:03

Which aircraft Degsy?

Graham
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speed hold

Postby dswanson » 04 Aug 2007, 16:45

Graham

Any aircraft really. I'm practising formation flying by setting up recorder flights but want to keep the recorded flight at a fixed airspeed altitude and heading. I'm using a Lancaster and Mosquito
Regards,

Degsy
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Postby petermcleland » 04 Aug 2007, 17:59

Degsy,

You need to have an autothrottle specified in the .air file for speed control to work...The idea being that if the real aircraft doesn't have it, then it doesn't work :smile:
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speed hold

Postby dswanson » 05 Aug 2007, 12:05

Peter,

Thanks. I added the set of ap switches to the .air files using aired and turned them "on"

The confusing thing is that the sequence I described above always got the speed hold working in FS2002 - I'm looking for the difference in FS9 as to why it doesn't work there :dunno:
Regards,

Degsy
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Re: speed hold

Postby petermcleland » 05 Aug 2007, 14:56

dswanson wrote:Peter,

Thanks. I added the set of ap switches to the .air files using aired and turned them "on"

The confusing thing is that the sequence I described above always got the speed hold working in FS2002 - I'm looking for the difference in FS9 as to why it doesn't work there :dunno:


Degsy,

The difference is that the Aircraft.cfg file will override or adjust settings in the .air file...So you should now look at the autopilot section of the Aircraft.cfg file...Here is a good example:-

[autopilot]
autopilot_available= 1
flight_director_available= 1
default_vertical_speed= 500
autothrottle_available= 0
pitch_takeoff_ga=8.0
max_pitch=10.0
max_pitch_acceleration=1.0
max_pitch_velocity_lo_alt=2.0
max_pitch_velocity_hi_alt=1.5
max_pitch_velocity_lo_alt_breakpoint=5000
max_pitch_velocity_hi_alt_breakpoint=10000
max_bank=25.0
max_bank_acceleration=1.8
max_bank_velocity=3.00
max_throttle_rate=0.10
nav_proportional_control=20
nav_integrator_control=0.25
nav_derivative_control=0.0
nav_integrator_boundary=1.5
nav_derivative_boundary=0.0
gs_proportional_control=15
gs_integrator_control=0.5
gs_derivative_control=0.0
gs_integrator_boundary=0.5
gs_derivative_boundary=0.0
yaw_damper_gain = 0.0
default_pitch_mode=1 //1= pitch hold 2=alt hold
default_bank_mode=1 //1= wing level 2=bank hold

Note that "autothrottle_available= 0"...this is from an aircraft that does not have autothrottle and that would certainly need to be changed from 0 to 1 :smile:
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Postby johnhinson » 05 Aug 2007, 20:45

Apart from the entry in the aircraft.cfg file that Peter mentioned, you need to watch whether it needs arming to activate it:

autothrottle_available=1
autothrottle_arming_required=1

You may need to change the second one above to "0".

You also need a gauge on which you can set the required speed.

Take a look at the MS default aircraft (such as the Boeing 737-400) for details, the autothrottles on these do work in FS2004.

I've never had to change the air file, I'm sure you can do all from the aircraft.cfg.

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Re: Speed hold

Postby dswanson » 09 Aug 2007, 21:34

Hi,

After some web browsing and experimentation I've found a solution that will work with any plane, MS or 3rd party, prop, turboprop or jet !! (not tried a helo)

Three components must be in place as below:

First, an autopilot gauge with a speed hold/ autothrottle switch and a digital means of setting the desired mach/IAS

Second, the following lines in the aircraft.cfg file
[autopilot]
autothrottle_available=1 This enables the speed hold
autothrottle_arming_required=0 zero here means operates directly on speed hold switch operation
autothrottle_takeoff_ga=0 1 here means TOGA available
autothrottle_max_rpm=10000 //90.0 default 90.0 operates on jets only, for prop/turboprop, set to big number as here
max_throttle_rate=0.1 this controls the rate of change - default OK

Third, the .air file must contain section 329 Advanced Autopilot - Speed Hold switches
The three factors should be set as
Airspeed hold available=true
Mach Hold available=true
A/T arm switch avaialable=FALSE
If not present in the .air file you can copy & paste this from a default jet using the AIRED utility. Once in place you cans et them manually or setting the .cfg file as above will put them right

ps I like the new site
Regards,

Degsy
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