Auto Pilot; Auto Throttle issue

lionheart · 17 Jan 2012

Hey all,

I have an issue with one of my planes. I have auto pilot in it, but not 'Flight Director'. When I activate 'auto throttle', the speed drops way down. If I increase the stock 90% setting up to say 100 or 120, it gets better, or closer, but never 'right on the mark'. It also seems to have a 'percentage range' that changes. For instance, if I have a setting of 120, it might do 85 knots. If I have a setting of 200, it could be more, like its unfocused or working off of a blind guess point.

Any idea's what is going on? Could it be that I need Flight Director for management of speed? Is this perhaps a bug? Can I code my own auto pilot?

This is the FSX version AP, which works the least best, (horrible).

[autopilot]
autopilot_available= 1
flight_director_available= 1
default_vertical_speed=1000
autothrottle_available= 1
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=9.52
gs_integrator_control=0.26
gs_derivative_control=0.00
gs_integrator_boundary=0.70
gs_derivative_boundary=0.00
yaw_damper_gain = 2.0
autothrottle_arming_required=0
autothrottle_takeoff_ga=0
autothrottle_max_rpm=90.00

This is for a single engine, four passenger 4,000 LB aircraft.

Bill

vololiberista · 17 Jan 2012

Code:

<Click>(A:AUTOPILOT AIRSPEED HOLD,bool) 1 == d (A:AUTOPILOT MACH HOLD,bool) 1 == r || if{ 0 (&gt;K:AUTO_THROTTLE_ARM) 0 (&gt;K:AP_MACH_OFF) 0 (&gt;K:AP_AIRSPEED_OFF) 0 (&gt;L:AT POWER,number) 0 (&gt;L:AT ENABLE,number) } els{ (A:Autopilot throttle arm, bool) 0 == if{ 0 (&gt;K:AUTO_THROTTLE_ARM) } 0 (&gt;K:AP_MACH_OFF) 0 (&gt;K:AP_AIRSPEED_ON) 1 (&gt;L:AT POWER,number) 1 (&gt;L:AT ENABLE,number) }</Click>

Code:

<Gauge Name="Autothrottle" Version="1.0">
   <Image Name="AT.bmp"/>
//---------Initialize-------------------
   <Element>
      <Select>
         <Value>(L:INITIALIZE AIRSPEED,number) 1 &lt; if{ (A:AUTOPILOT AIRSPEED HOLD VAR,knots) 180 &gt; if{ 180 (&gt;K:AP_SPD_VAR_SET) } 1 (&gt;L:INITIALIZE AIRSPEED,number) }</Value>
      </Select>
   </Element>
//---------Initialize if AT already switched on-------------------
   <Element>
      <Select>
         <Value>(A:AUTOPILOT AIRSPEED HOLD,bool) 1 == d (A:AUTOPILOT MACH HOLD,bool) 1 == r || if{ (L:AT ENABLE,number) 1 &lt; d (L:AT POWER,number) 1 &lt; r &amp;&amp; if{ 1 (&gt;L:AT ENABLE,number) } 1 (&gt;L:AT POWER,number) }</Value>
      </Select>
   </Element>
//---------------------
   <Element>
      <Position X="0" Y="0"/>
      <MaskImage Name="AT_MASK.bmp">
         <Axis X="59" Y="48"/>
      </MaskImage>
      <Image Name="NUMBER_ROLL_5.bmp" Luminous="1">
	<Axis X="0" Y="108"/>
      </Image>
      <Shift>
         <Value>(A:AUTOPILOT AIRSPEED HOLD VAR,knots) 100 / 10 % flr</Value>
         <Nonlinearity>
            <Item Value="0" X="0" Y="0"/>
	    <Item Value="10" X="0" Y="108"/>
         </Nonlinearity>
      </Shift>
   </Element>
   <Element>
      <Position X="0" Y="0"/>
      <MaskImage Name="AT_MASK.bmp">
         <Axis X="76" Y="48"/>
      </MaskImage>
      <Image Name="NUMBER_ROLL_5.bmp" Luminous="1">
	<Axis X="0" Y="108"/>
      </Image>
      <Shift>
         <Value>(A:AUTOPILOT AIRSPEED HOLD VAR,knots) 10 / 10 % flr</Value>
         <Nonlinearity>
            <Item Value="0" X="0" Y="0"/>
	    <Item Value="10" X="0" Y="108"/>
         </Nonlinearity>
      </Shift>
   </Element>
   <Element>
      <Position X="0" Y="0"/>
      <MaskImage Name="AT_MASK.bmp">
         <Axis X="93" Y="48"/>
      </MaskImage>
      <Image Name="NUMBER_ROLL_5.bmp" Luminous="1">
	<Axis X="0" Y="108"/>
      </Image>
      <Shift>
         <Value>(A:AUTOPILOT AIRSPEED HOLD VAR,knots) 10 % flr</Value>
         <Nonlinearity>
            <Item Value="0" X="0" Y="0"/>
	    <Item Value="10" X="0" Y="108"/>
         </Nonlinearity>
      </Shift>
   </Element>
//---------------------
   <Element>
      <Position X="24" Y="8"/>
      <Select>
         <Value>(L:AT POWER,number)</Value>
         <Case Value="0">
            <Image Name="AT_OFF.bmp"/>
         </Case>
         <Case Value="1">
            <Image Name="AT_ON.bmp"/>
         </Case>
      </Select>
   </Element>
//---------------------
   <Element>
      <Position X="50" Y="8"/>
      <Select>
         <Value>(L:AT POWER,number)</Value>
         <Case Value="0">
            <Image Name="AT_OFF.bmp"/>
         </Case>
         <Case Value="1">
            <Image Name="AT_ON.bmp"/>
         </Case>
      </Select>
   </Element>
//---------------------
   <Element>
      <Position X="88" Y="8"/>
      <Select>
         <Value>(L:AT POWER,number)</Value>
         <Case Value="0">
            <Image Name="AT_OFF.bmp"/>
         </Case>
         <Case Value="1">
            <Image Name="AT_ON.bmp"/>
         </Case>
      </Select>
   </Element>
//---------------------
   <Element>
      <Position X="114" Y="8"/>
      <Select>
         <Value>(L:AT POWER,number)</Value>
         <Case Value="0">
            <Image Name="AT_OFF.bmp"/>
         </Case>
         <Case Value="1">
            <Image Name="AT_ON.bmp"/>
         </Case>
      </Select>
   </Element>
//---------------------
   <Element>
      <Position X="24" Y="65"/>
      <Select>
         <Value>(L:AT POWER,number)</Value>
         <Case Value="0">
            <Image Name="AT_OFF.bmp"/>
         </Case>
         <Case Value="1">
            <Image Name="AT_ON.bmp"/>
         </Case>
      </Select>
   </Element>
//---------------------
   <Element>
      <Position X="57" Y="77"/>
      <Select>
         <Value>(L:AT ENABLE,number)</Value>
         <Case Value="1">
            <Image Name="AT_ENGAGE_1.bmp"/>
         </Case>
         <Case Value="2">
            <Image Name="AT_ENGAGE_2.bmp"/>
         </Case>
      </Select>
   </Element>
//-------------------------------------------
   <Mouse>
   <Help ID="HELPID_AUTOPILOT_AUTOTHROTTLE"/>
//------
   <Area Left="50" Top="73" Width="30" Height="41">
	<Cursor Type="Hand"/>
	<Click>
(A:AUTOPILOT AIRSPEED HOLD,bool) 1 == d (A:AUTOPILOT MACH HOLD,bool) 1 == r ||
if{ 0 (&gt;K:AUTO_THROTTLE_ARM) 0 (&gt;K:AP_MACH_OFF) 0 (&gt;K:AP_AIRSPEED_OFF) 0 (&gt;L:AT ENABLE,number) }
els{
   (A:Autopilot throttle arm, bool) 0 == if{ 0 (&gt;K:AUTO_THROTTLE_ARM) }
   0 (&gt;K:AP_MACH_OFF) 0 (&gt;K:AP_AIRSPEED_ON) 1 (&gt;L:AT POWER,number) 1 (&gt;L:AT ENABLE,number)
   }
</Click>
   </Area>
//------
   <Area Left="81" Top="73" Width="30" Height="41">
	<Cursor Type="Hand"/>
	<Click>
(A:AUTOPILOT AIRSPEED HOLD,bool) 1 == d (A:AUTOPILOT MACH HOLD,bool) 1 == r ||
if{ 0 (&gt;K:AUTO_THROTTLE_ARM) 0 (&gt;K:AP_MACH_OFF) 0 (&gt;K:AP_AIRSPEED_OFF) 0 (&gt;L:AT ENABLE,number) }
els{
   (A:Autopilot throttle arm, bool) 0 == if{ 0 (&gt;K:AUTO_THROTTLE_ARM) }
   0 (&gt;K:AP_MACH_OFF) 0 (&gt;K:AP_AIRSPEED_ON) 1 (&gt;L:AT POWER,number) 2 (&gt;L:AT ENABLE,number)
   }
</Click>
   </Area>
//------
   <Area Left="52" Top="45" Width="28" Height="18">
	<Cursor Type="DownArrow"/>
	<Click Repeat="Yes" MouseWheelFlip="Yes">(A:AUTOPILOT AIRSPEED HOLD VAR,knots) 180 &gt; if{ 180 (&gt;K:AP_SPD_VAR_SET) } els{ 0 (&gt;K:AP_SPD_VAR_DEC) }</Click>
   </Area>
//------
   <Area Left="80" Top="45" Width="28" Height="18">
	<Cursor Type="UpArrow"/>
        <Click Repeat="Yes" MouseWheelFlip="Yes">(A:AUTOPILOT AIRSPEED HOLD VAR,knots) 180 &lt; if{ 0 (&gt;K:AP_SPD_VAR_INC) }</Click>
   </Area>
//------
   <Area Left="113" Top="60" Width="12" Height="21">
	<Cursor Type="DownArrow"/>
	<Click Repeat="Yes" MouseWheelFlip="Yes">(A:AUTOPILOT AIRSPEED HOLD VAR,knots) 180 &gt; if{ 180 (&gt;K:AP_SPD_VAR_SET) } els{ 0 (&gt;K:AP_SPD_VAR_DEC) }</Click>
   </Area>
//------
   <Area Left="125" Top="60" Width="12" Height="21">
	<Cursor Type="UpArrow"/>
        <Click Repeat="Yes" MouseWheelFlip="Yes">(A:AUTOPILOT AIRSPEED HOLD VAR,knots) 180 &lt; if{ 0 (&gt;K:AP_SPD_VAR_INC) }</Click>
   </Area>
//------
   <Area Left="23" Top="8" Width="114" Height="26">
	<Cursor Type="Hand"/>
        <Click>(L:AT POWER,number) 0 &gt; if{ 0 (&gt;L:AT POWER,number) 0 (&gt;K:AP_MACH_OFF) 0 (&gt;K:AP_AIRSPEED_OFF) 0 (&gt;L:AT ENABLE,number) (A:Autopilot throttle arm, bool) 1 == if{ 0 (&gt;K:AUTO_THROTTLE_ARM) } } els{ 1 (&gt;L:AT POWER,number) }</Click>
   </Area>
//------
   <Area Left="22" Top="64" Width="25" Height="27">
	<Cursor Type="Hand"/>
        <Click>(L:AT POWER,number) 0 &gt; if{ 0 (&gt;L:AT POWER,number) 0 (&gt;K:AP_MACH_OFF) 0 (&gt;K:AP_AIRSPEED_OFF) 0 (&gt;L:AT ENABLE,number) (A:Autopilot throttle arm, bool) 1 == if{ 0 (&gt;K:AUTO_THROTTLE_ARM) } } els{ 1 (&gt;L:AT POWER,number) }</Click>
   </Area>
   </Mouse>
</Gauge>

vololiberista · 17 Jan 2012

The edit function doesn't work along with other functions :-(

The first code snippet is a clickable AT light. The second is the AT unit.
vololiberista

lionheart · 17 Jan 2012

Hey VoloLiberista,

I see you were perhaps having the same issue?

Does this work for your plane, maintaining speed?

I wonder what in the world would trip the system.... It 'should' maintain speed. Why would it hold 90 when its set for 135? And why isnt it constant, that if I reset power percentage for AT that it changes in ratio's rather then speed range?

I do not get it... I havent had this happen before, except with the Boeing 797 flying wing. I believe that one also had lower air speeds from what you would set the speeds to.

Bill

vololiberista · 17 Jan 2012

I have two issues. The AT is actually only intended for use at 180kts or below but linked to a simple AP with an airspeed dial it will follow any speed dialled up from that source. I have also two APs. One that has a basic airspeed hold and one that is intended to be used in the sim with the GPS etc which has a full range airspeed selector. As the a/c was/is never fitted with GPS (INS instead) I deleted it from the cfg file. So I use the Fs9 AP for part of the flight and the original for landings etc.
vololiberista

lionheart · 18 Jan 2012

Well, still no idea why my 'auto throttle' is not holding speed.

I am stumped.

n4gix · 19 Jan 2012

Which of the many K:events (commands) are you using, Bill? It's been years since I had to look at this, but I seem to recall that one set of commands will "capture the current airspeed and hold" and another set of commands will "accelerate up to the selected (desired) airspeed and hold."

I may actually be able to answer this question myself as I'm about to start scripting an antique (1960's) autopilot & flight director system today...

lionheart · 19 Jan 2012

Hey Bill

I was testing it this morning, trying to figure things out, what it might be.

Here is what I am using, 'and' the lock setting display code, which is what the plane is supposed to be doing, per the display. It occurred to me, what if the display lock setting isnt 'true' per what the airspeed is showing... That would be two different readings based on altitude.

Codes;

Code:

<!--  PFD Lock Setting  -->

     <Element>
         <Position X="1110" Y="74"/>
        <Visible>(A:AUTOPILOT AIRSPEED HOLD,bool) 1 ==</Visible>
        <Text Bright="Yes" X="43" Y="40" Length="3" Multiline="No" Fixed="Yes" Font="Nasalization" FontSize="26" Color="#666666" Adjust="Left" VerticalAdjust="Bottom">
        <String>%((A:AUTOPILOT AIRSPEED HOLD VAR, knots) 9999 min 0 max)%!3d!</String>
      </Text>
     </Element>


<!--  MFD Lock Setting (Same)  -->


      <Element>
        <Position X="439" Y="277"/>
    <FormattedText X="120" Y="100" Font="Nasalization" FontSize="64" LineSpacing="0" Adjust="Center" VerticalAdjust="Center" Color="#FF3399" Bright="Yes">
      <Color Value="White"/>
      <String>
        %((A:AUTOPILOT AIRSPEED HOLD,bool) 1 == )
        %{if}
        %((A:AUTOPILOT AIRSPEED HOLD VAR, knots) 999 min 0 max)
        %!3d!
        %{else}
        %\{clr2}
        %((A:AUTOPILOT AIRSPEED HOLD VAR, knots) 999 min 0 max)
        %!3d!
      </String>
    </FormattedText>
  </Element>




<!--  QUICK LOCK SPEED HOLD  -->

                     (&gt;K:AP_AIRSPEED_ON,bool)
                     (&gt;K:AP_MASTER)


<!--  ENTER/ACTIVATE AUTOTHROTTLE & AUTOPILOT  -->

                     (&gt;K:AP_AIRSPEED_ON,bool)
                      1 (&gt;K:AUTOPILOT_ON)

Also, I noted this morning that I have AP_AIRSPEED_ON as the activator for both buttons. One should lock, and one should 'activate' or arm. <sigh...>

Roy Holmes · 19 Jan 2012

Just a thought, 135 kilometres per hour is 73 knots?

Roy

lionheart · 19 Jan 2012

Hey Roy,

Roger that, but as you can see, everything is in 'knots'. That does sound like you would be right if it 'were' in KPH readout.

My proper 'enter' button code for on/off should be AP_AIRSPEED_SET

The other two which effect this same 'activate' code is
AP_AIRSPEED_ON
AP_AIRSPEED_OFF

As I am testing this, it is working right... heh... FSX is really trying to strain me.

Oddly, it doesnt seem to want to hold airspeed constant if the font for speed setting (lock setting) isnt showing.
Thus, if the locked setting isnt showing, the speed will begin dropping.

Mind you, this only happens in FSX. In FS9, it all functions properly.

lionheart · 19 Jan 2012

I found the issue.

Shift-Z on the readout in the upper left in FSX revealed that KIAS was exactly the same as the 'indicated locked airspeed setting' which means 'actual airspeed' wasnt the right thing to use, so I changed it to indicated. Testing now.

arrgh... All that...

lionheart · 19 Jan 2012

None of my FS2004 'command' codes will work to 'turn on' the preset speed setting. Either they do not turn on AT, or they turn on and lock the present airspeed. I have tried them all.

Off to search the FSX SDK to see if there is a new AT command.

lionheart · 19 Jan 2012

I.... I.. um.. cannot find 'Parameters' or 'EventID's' in the FSX SDK... @!? Did they get rid of those, or place them in a new location?

tgibson · 19 Jan 2012

If you open this it has most of the links you need to the other documents:

C:/Program Files/Microsoft Games/Microsoft Flight Simulator X SDK/SDK/sdk overview.html

C:/Program Files/Microsoft Games/Microsoft Flight Simulator X SDK/SDK/Core Utilities Kit/Variables/Simulation Variables.html

C:/Program Files/Microsoft Games/Microsoft Flight Simulator X SDK/SDK/Core Utilities Kit/Variables/Event IDs.htm

Hope this helps,

SkippyBing · 19 Jan 2012

Are you not using the fsxsdk.chtm file, just double click on that and then use the index to find Event IDs.

lionheart · 19 Jan 2012

tgibson said:
If you open this it has most of the links you need to the other documents:

C:/Program Files/Microsoft Games/Microsoft Flight Simulator X SDK/SDK/sdk overview.html

C:/Program Files/Microsoft Games/Microsoft Flight Simulator X SDK/SDK/Core Utilities Kit/Variables/Simulation Variables.html

C:/Program Files/Microsoft Games/Microsoft Flight Simulator X SDK/SDK/Core Utilities Kit/Variables/Event IDs.htm

Hope this helps,

Whewww... Yes, this helps Tom. You would think they would be in the gauges department.

Bill

n4gix · 20 Jan 2012

lionheart said:
None of my FS2004 'command' codes will work to 'turn on' the preset speed setting. Either they do not turn on AT, or they turn on and lock the present airspeed. I have tried them all.

Off to search the FSX SDK to see if there is a new AT command.

I just wrote earlier that there are two sets of "SPEED_HOLD" events...

Try:

AP_PANEL_SPEED_ON
AP_PANEL_SPEED_OFF

This event captures current airspeed:
AP_PANEL_SPEED_HOLD_TOGGLE

This event will hold preselected airspeed:
AP_AIRSPEED_HOLD

lionheart · 20 Jan 2012

n4gix said:
I just wrote earlier that there are two sets of "SPEED_HOLD" events...

Try:

AP_PANEL_SPEED_ON
AP_PANEL_SPEED_OFF

This event captures current airspeed:
AP_PANEL_SPEED_HOLD_TOGGLE

This event will hold preselected airspeed:
AP_AIRSPEED_HOLD

Hey Bill,

Took me all day to find that out, and just discovered it about 30 mins ago. But, many thanks. This will be good archive material for others in building AP's for FSX that will feature AT.

So many AT on's and only one that works with presettings... A long day.

Bill