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As you may know the FS9 default Ford Tri-motor is not equiped with autopilot. I have tried to install an autopilot in this aircraft but with no success. I copied the autopilot section from another aircraft into the Tri-Motor's aircraft.cfg file. The plane will hold altitude but will not hold heading. It banks from left to right and gradually goes into a spin. I've tried tweeking the autopilot section a bit but no improvement. Any sugguestions out there?

Have you got the aircraft properly trimmed before switching on the AP?

As for elevator trim, yes. the plane climbs and descends just fine, it  just won't hold heading. I don't think the Tri-Motor has a rudder trim, maybe that's the problem. Thank's for your reply, Ozzy72.

Try adjusting your rudder a tiny bit manually, normally you can get it pretty close to spot on (I tend to use the keyboard for these fine adjustments).

Thanks again Ozzy, I wish you could try this experiment yourself because it's becoming apparent that the Tri-Motor is a "hands on" flying machine. It banks over and eventually spins and crashes even with the autopilot off. I'm looking to see if there is a way to edit something to allow this plane to fly in autopilot mode. The autopilot section has been copied from the DC-3 in the aircraft.cfg file but it obviously needs other changes. I have had success adding autopilot to other planes without autopilot but I can't get this aircraft to do it.

Ozzy, I'm posting my installed autopilot section, I've also installed a rudder trim wheel on the panel, balancing the aircraft before engaging autopilot does not help. Also when the AP is engaged the rudder trim wheel DOES NOT MOVE to correct itself.

[autopilot] //Original no autopilot available
autopilot_available=1
flight_director_available=0
default_vertical_speed=500.000000
autothrottle_available=0
pitch_takeoff_ga=8.000000
use_no_default_pitch=0         
use_no_default_bank=1 //What are these?
default_bank_mode=0
max_pitch=10.000000
max_pitch_acceleration=1.000000
max_pitch_velocity_lo_alt=2.000000
max_pitch_velocity_hi_alt=1.500000
max_pitch_velocity_lo_alt_breakpoint=20000.000000
max_pitch_velocity_hi_alt_breakpoint=28000.000000
max_bank=25.000000
max_bank_acceleration=0.300000 //Original 1.8
max_bank_velocity=0.750000     //Original 3.0
max_throttle_rate=0.100000
nav_proportional_control=9.000000
nav_integrator_control=0.250000
nav_derivative_control=0.000000
nav_integrator_boundary=2.500000
nav_derivative_boundary=0.000000
gs_proportional_control=9.520000
gs_integrator_control=0.260000
gs_derivative_control=0.000000
gs_integrator_boundary=0.700000
gs_derivative_boundary=0.000000
yaw_damper_gain=0.000000

I have tried to install an autopilot in this aircraft but with no success. I copied the autopilot section from another aircraft into the Tri-Motor's aircraft.cfg file.

Have you installed an autopilot gauge in this plane in addition to the aircraft.cfg mods?

If so, which one?

cheers,
Joe

Jobee, I have the Bendix King AP on a pop-up panel. The installed rudder trim wheel stays at 0 in AP mode, I think that's a clue. I wish someone beyond my expertise could try this experiment and solve this. The tri-motor is nearly imposible to fly cross-country without autopilot.

The tri-motor is nearly imposible to fly cross-country without autopilot.

Gives you a lot of respect for the pilots who did this back in the day.

For the autopilot to hold a heading it has to receive some heading input. This usually comes from a DG or HSI. Did you install anything like that?

Without some instrument to manage heading I can't imagine you will get heading hold with an autopilot.

You might also need a NAV/GPS switch too.

As I am in the middle of some PC maintenance I do not have FS installed right now, so I can't test this.

cheers,
Joe

Thank's again Jobee,
Yes, I have on my home-made pop-up panel a default Cessna directional gyro with heading bug and a NAV-GPS switch.
I have since discovered that other aircraft do not use rudder trim for autopilot operation so that clue may be useless.
I do indeed respect those old-school aviators but I can't sit and hold the joy stick for hours. I'm not giving up untill I fix this!
If anybody has any other ideas please drop me a line, be sure to read all my previous posts to know what I've tried.
Thank's J.P.

I copied this from the
tri-motor's aircraft.cfg

[direction_indicators]
//1 Type: 0=None, 1=Vacuum Gyro, 2=Electric Gyro, 3=Electro-Mag Slaved Compass, 4=Slaved to another
//2 Indicator number of slaving indicator if Type = 4
direction_indicator.0=0,0

Edit yours to read -
[direction_indicators]
//1 Type: 0=None, 1=Vacuum Gyro, 2=Electric Gyro, 3=Electro-Mag Slaved Compass, 4=Slaved to another
//2 Indicator number of slaving indicator if Type = 4
direction_indicator.0=1,0


and see if that helps.

cheers,
Joe

I was hopeing that was it but nope, no improvement.

SUCCESS!
Jobee's idea about the Directional Indicator was a good clue. I copied these sections below from Jens B. Kristensen's DH-91 Albatross into my tri-motor's aircraft.cfg and I'm not sure why but the Autopilot works superbly now. It works on manual heading and GPS navigation, not very historically correct but it makes the Tri-Motor a lot more useful. Thank's JoBee and Ozzy for all your help, I would have given up without you.
Here you are:

[direction_indicators] //DH-91
//1 Type: 0=None, 1=Vacuum Gyro, 2=Electric Gyro, 3=Electro-Mag Slaved Compass, 4=Slaved to another
//2 Indicator number of slaving indicator if Type = 4
direction_indicator.0=1,0
direction_indicator.1=1,0

[attitude_indicators] //DH-91
//Type: 0=None, 1=Vacuum Gyro, 2=Electric Gyro
attitude_indicator.0 = 1
attitude_indicator.1 = 1

[turn_indicators] //DH-91
//Type: 0=None, 1=Electric Gyro, 2=Vacuum Gyro
turn_indicator.0=2,0

[autopilot] //Original no autopilot available
autopilot_available=1
flight_director_available=0
default_vertical_speed=500.000000
autothrottle_available=0
direction_indicator=1
pitch_takeoff_ga=8.000000
use_no_default_pitch=0         
use_no_default_bank=1 
default_bank_mode=0   
max_pitch=10.000000
max_pitch_acceleration=1.000000
max_pitch_velocity_lo_alt=2.000000
max_pitch_velocity_hi_alt=1.500000
max_pitch_velocity_lo_alt_breakpoint=20000.000000
max_pitch_velocity_hi_alt_breakpoint=28000.000000
max_bank=12.000000
max_bank_acceleration=1.200000 //Original 1.8
max_bank_velocity=2.20000      //Original 3.0
max_throttle_rate=0.100000
nav_proportional_control=9.000000
nav_integrator_control=0.250000
nav_derivative_control=0.000000
nav_integrator_boundary=2.500000
nav_derivative_boundary=0.000000
gs_proportional_control=9.520000
gs_integrator_control=0.260000
gs_derivative_control=0.000000
gs_integrator_boundary=0.700000
gs_derivative_boundary=0.000000
yaw_damper_gain=0.000000

Excellent news! Glad to see you figured it out.

Now, stop tweaking and go fly the dang thing! hehe just kidding.

But seriously, go fly the thing.

cheers,
Joe