Controlling pitch and altitude

[webmailusr-msn]

Hello:

I am flying a supersonic airplane and have some problems controlling it, even when using AP.

I would like that if the airplane reaches some altitude, it does not climb anymore. Also, I want to avoid the airplane pitch exceeds 40 deg, since it easily enters in lost.

For that, I am using this in my autopilot:

<update id="UpdateAP">
<script>
        (A:PLANE PITCH DEGREES, radians) -0.61 &lt;= if{ -0.61 (&gt;K:AXIS_PAN_PITCH, radians) }			
	(A:PLANE ALTITUDE, feet) 40000 &gt;= 
		if{ 
				0 (&gt;L:AtFr,bool)
				1 (&gt;K:FREEZE_ALTITUDE_TOGGLE, bool)
				40000 (&gt;K:FREEZE_ALTITUDE_SET, feet) 
				(A:VERTICAL SPEED, feet) 0 &lt;= if{ 0 (&gt;K:FREEZE_ALTITUDE_TOGGLE, bool) }
				1 (&gt;L:AtFr,bool)
			}			
<script>
</update>

The above code checks pitch, and if it is less than -40 deg ( -0.61 rad ), it would set the pitch to the limit: -0.61 rad (note that less pitch would be -45, -50 deg... it's measured in negative numbers when pitch points upwards)
This part of code does not work.
Next segment checks altitude, when 40000 feet are reached, FSX does freeze altitude: airplane does not climb anymore. But it won't descend, I can't unfreeze it. Maybe I could use pitch indicator, but... I am confused!

Thanks!

 

[n4gix]

0 (>K:FREEZE_ALTITUDE_TOGGLE, bool)

That won't work because the key_event is already a toggle. If it is off, it will be turned on. If it is on, it will be turned off.

Also, it's unnecessary to include a units with toggle or on/off key_events.

Try:

(A:VERTICAL SPEED, feet) 0 <= if{ (>K:FREEZE_ALTITUDE_TOGGLE) }

 

[webmailusr-msn]

0 (>K:FREEZE_ALTITUDE_TOGGLE, bool)

That won't work because the key_event is already a toggle. If it is off, it will be turned on. If it is on, it will be turned off.

Also, it's unnecessary to include a units with toggle or on/off key_events.

Try:

(A:VERTICAL SPEED, feet) 0 <= if{ (>K:FREEZE_ALTITUDE_TOGGLE) }

Thanks... I will try it later
And do you have something for pitch?

 

[webmailusr-msn]

0 (>K:FREEZE_ALTITUDE_TOGGLE, bool)

That won't work because the key_event is already a toggle. If it is off, it will be turned on. If it is on, it will be turned off.

Also, it's unnecessary to include a units with toggle or on/off key_events.

Try:

(A:VERTICAL SPEED, feet) 0 <= if{ (>K:FREEZE_ALTITUDE_TOGGLE) }

Hi n4gix:

Seems first I have to work on attitude (pitch) issue. My problem is that I can't change it!

Here is the code:

1 (>K:FREEZE_ATTITUDE_SET) 
-0.25 (>A:PLANE PITCH DEGREES, radians)  			
-0.25 (>K:AXIS_PAN_PITCH, radians)

Attitude is frozen, but I can't change the pitch (it is kept the pitch at the moment of freezing it)

 

[n4gix]

You are barking up the wrong tree...

"Freeze" means simply what it implies. Once "frozen" no other inputs will be accepted!

Try using:

AP_ATT_HOLD_OFF
AP_ATT_HOLD_ON
AP_ATT_HOLD (toggles on/off)

 

[webmailusr-msn]

You are barking up the wrong tree...

"Freeze" means simply what it implies. Once "frozen" no other inputs will be accepted!

Try using:

But those Events work for auto pilot, don't they? My problem is that when airplane exceeds some speed (~2.1 Mach) it will climb up despite AP is trying to keep some altitude. That is because pitch degree turns too small (<-30°)

What I want to do is make FSX correct pitch, even though I have to violate physics laws!

 

[n4gix]

But those Events work for auto pilot, don't they?

No, they don't. That was my entire point! This entire group of events are intended for use by a SimConnect module for custom AI interaction.

 

[webmailusr-msn]

You are barking up the wrong tree...

"Freeze" means simply what it implies. Once "frozen" no other inputs will be accepted!

Try using:

No, they don't. That was my entire point! This entire group of events are intended for use by a SimConnect module for custom AI interaction.

Ok, so maybe I am not using them properly. This is my code for Pitch<-0.25 rads:

1 (&gt;K:AP_ATT_HOLD_OFF)
-0.25 (&gt;ALANE PITCH DEGREES, radians)

I tested it unconditionally but It did not work. ( I expected my plane to keep a constant pitch of -0.25)

BTW, I have realized there is another problem: AP only accepts holding speed <990knots (~1.6Mach), despite FSX can handle up to 3.0mach. Do you know how can I change the upper limit? There is nothing in the xml files that states it.

 

[n4gix]

Ok, so maybe I am not using them properly. This is my code for Pitch<-0.25 rads:

1 (&gt;K:AP_ATT_HOLD_OFF)
-0.25 (&gt;ALANE PITCH DEGREES, radians)

I tested it unconditionally but It did not work. ( I expected my plane to keep a constant pitch of -0.25)

You cannot "write a value" to a "read-only variable!" (except via a SimConnect module)

A:var_name is "Aircraft_read-only"
K:command is "Key_command"

In the FSX SDK, there are two separate lists:

1. Event IDs = Key_commands = (>K:command)

2. Simulation Variables = read-only = (A:var_name,units)

There is no Key_event for setting your pitch directly, unfortunately. There are only three Key_events available:

AP_PITCH_REF_INC_UP
AP_PITCH_REF_INC_DN
AP_PITCH_REF_INC_SELECT (works only with +/- keyboard commands)

(ALANE PITCH DEGREES, radians) returns the current pitch of the a/c in radians.

You would need to write your controller using that A:var as a conditional referent

(A:PLANE PITCH DEGREES, radians) 0.25 <= if{ (>K:AP_PITCH_REF_INC_UP) }

*not tested!

 

[BASys]

Hi Folks

BTW, I have realized there is another problem:
AP only accepts holding speed <990knots (~1.6Mach),
despite FSX can handle up to 3.0mach.

webmailusr-msn -
Your auto-pilot probably trips out
because your aircraft's .cfg is improperly configured,
i.e. insufficiently stable at high speed.

HTH
ATB
Paul

 

[webmailusr-msn]

Hi Folks


webmailusr-msn -
Your auto-pilot probably trips out
because your aircraft's .cfg is improperly configured,
i.e. insufficiently stable at high speed.

HTH
ATB
Paul

I don't think it is necessarily the cause: if you choose the cessna 172sp, (fsx included, so .cfg should be ok) you could set AP to keep altitude of 99900 ft! of course the airplane is not designed for that, so there should be a way to limit the altitude. As well as to increase the limit of speed of my concorde.

 

[BASys]

Hi Folks

webmailusr-msn -
If your aircraft's .cfg is improperly configured,
i.e. insufficiently stable at high speed
then your AP will trip out.
Until you fix the porpoising,
your AP will not stay engaged.



Altitude and max speed are controlled by various parameters in the aircraft.cfg.
See the SDK - Aircraft Configuration.

For maxspeed,
if thrust is already correctly set
you'll then need to tweak the [flight_tuning] section



Suggest setting up as AI
and observing performance externally,
thus without interference from user-inputs,
or even better, approach the aircraft's developer.



HTH
ATB
Paul