IAS / Mach speed sync

#1
Hi Everybody,

I'm Robert from The Netherlands and from time to time I startup my FSX with some addons and fly all over my virtual world :)

I'm having a problem that I can't solve on my own. I hope there is someone out there who can help me with this. I think everybody knows that FSX has a bug that when you change to Mach on the AP and you are climbing or descending altitude the IAS doesn't change with it. Normally if I'm on HI altitude in Mach setting IAS should decrease as altitude increase and Mach stays the same. In FSX IAS stays the same and the plane will continue way over the Mach setting until you switch a little on the speed button, than it will sync for once but not automatically when altitude changes.

So I have been searching for a solution and found one.... Well that is what I was hoping for....
FSUIPC has a option to fix this bug so I purchased the full version of FSUIPC and did some flying to try. Well, it works perfectly on all my Boeing planes but not on my Airbus planes. And there is the thing, I mostly fly in Airbus planes.... :rolleyes:
I fly all freeware planes. Mostly A330, A340 and A380. I think they are all from Project Airbus. They all have the same problem. The fix in FSUIPC is only working in my freeware Boeing planes.

Thanks for thinking along with me! :D;)

Robert.
 

Heretic

Resource contributor
#2
First, this is not a user support forum. Expect pointers, but do the thinking and any work yourself.

Second, why do you want this constantly synced?
 
Last edited:
#3
I'm very sorry. That was not entirely clear to me. I thought that the people with the right knowledge were here (someone told me) that is why I posted this here. If I'm completely at the wrong place here, I will ask a moderator to delete it.

For your second question:
Well, when I'm at FL 25.000 I switch to Mach speed on the AP. But AP won't stay on the intended Mach speed, it will overspeed because the AP is still going for the last known IAS speed when changed to Mach speed. To correct this you will have to change your setting on the AP a little (+1 and back -1) the IAS indicator for the AP will sync for ones. But you have to do that the entire climb to cruise altitude otherwise the plane will overspeed.
It is explained in This tread

This fix with FSUIPC works fine with all my Boeing planes but not with the Airbus ones. So therefor I was searching for a way to do the same thing for the Airbus planes. But don't know where and in witch file I have to look to make a fix on this. Maybe it is linked to the gauges or something. A lot of freeware planes use basic gauges from FSX. Airbus mostly from the base model of the A320. Than can explain why there is a difference between Boeing and Airbus, they use other gauges.

Oh the reason I didn't sign up for that forum and asked my question there is because that is impossible. Some error with the security check (even when you answer the question right). When you try to contact the forum Admin you get the same security check that gives the error. Just impossible. Tried it several times.
 

Heretic

Resource contributor
#4
Gauges do define autopilot functionality alright, but if you don't even know where to look - or at least possess the curiosity to dig through the parts that make up an add-on aircraft yourself - for the source of the problem in the first place, how do you expect to ever fix it?

Find compare the autopilot gauge code (if possible) from the Boeing with the code of the autopilot from the Airbus and see where the code related to speed hold differs.
 
#5
Well, it is what I'm trying to do. Understanding how the aircraft's are build up in FSX. Especially the functions and characteristics. I'm not asking anyone to make a script or something that is just a fix, just asking to think with me so I can get in the right direction. Maybe I will get there, or maybe not. But I find it very interesting to look further in to FSX aircraft's. Finding the source of the problem is indeed the first thing to do. I'm a noob at this but I'm trying :)

Thanks for your input so far. I will search (and if found) look in to those codes to compare them. Also looking if I can find what FSUIPC exactly is doing to fix the problem in the planes where the fix is working.
 

n4gix

Resource contributor
#7
Regular airspeed hold uses this command: (>K:AP_AIRSPEED_HOLD) which of course hold the speed based on desired IAS dialed in.

Hint: Switch to (>K:AP_MACH_HOLD) which will hold the desired mach speed dialed in
 
#8
Hi Bjoern and Bill,

Thanks for the help so far! It did help a lot!
So it is solved now. The IAS indicator decreases in climb and increases in decent when in MACH mode so the plane stays at the right MACH speed. The key was the hint from Bill. I already was looking in to ''Autopilot Speed Switch.xml'', ''Autopilot IAS-Mach Switch.xml'' and ''Autopilot IAS-Mach Selector.xml''. These are gauges files for my Project Airbus A380 VC. They where packed in to a .CAB file and I also figured out how to create a new .CAB file after editing the gauges. However, the solution was in the ''Autopilot Speed Switch.xml'' file. So by experimenting I changed "AP_PANEL_SPEED_HOLD" to "AP_PANEL_MACH_HOLD" after reading the hint from Bill. This worked to fix the problem. There is one side effect, the switch itself in the VC normally becomes dark grey ("PB_SPD_ON.bmp") when pushed on and light grey ("PB_SPD_OFF.bmp") when pushes off. After this edit I made it only change to dark grey ("PB_SPD_ON.bmp") when in IAS mode. When I use another switch to change to MACH the main speed switch stays light grey (looking like it is OFF). Normally the switch should stay dark grey when using MACH on the AP. But that is just a little thing.

I didn't tried with the FSUIPC MACH bug function off so that is another try to do. I'm expecting this edit made the ''FSUIPC MACH bug fuction'' to work. I will figure that out later I hope. Also I'm going to look in to the other Airbus aircrafts if changing the same code will solve the problem in them too. Even in the default A321 it is the same problem with the MACH / IAS sync in climb and decent.

The original:
<Gauge Name="Autopilot Speed Switch" Version="1.0">
<Element>
<Select>
<Value>(A:Autopilot airspeed hold, bool)</Value>
<Failures>
<SYSTEM_ELECTRICAL_PANELS Action="0"/>
</Failures>
<Case Value="0">
<Image Name="PB_SPD_OFF.bmp" ImageSizes="25,23"/>
</Case>
<Case Value="1">
<Image Name="PB_SPD_ON.bmp" Bright="Yes" ImageSizes="25,23"/>
</Case>
</Select>
</Element>
<Mouse>
<Area>
<Cursor Type="Hand"/>
<Click Event="AP_PANEL_SPEED_HOLD"/>
</Area>
</Mouse>
</Gauge>

The edit one:
<Gauge Name="Autopilot Speed Switch" Version="1.0">
<Element>
<Select>
<Value>(A:Autopilot airspeed hold, bool)</Value>
<Failures>
<SYSTEM_ELECTRICAL_PANELS Action="0"/>
</Failures>
<Case Value="0">
<Image Name="PB_SPD_OFF.bmp" ImageSizes="25,23"/>
</Case>
<Case Value="1">
<Image Name="PB_SPD_ON.bmp" Bright="Yes" ImageSizes="25,23"/>
</Case>
</Select>
</Element>
<Mouse>
<Area>
<Cursor Type="Hand"/>
<Click Event="AP_PANEL_MACH_HOLD"/>
</Area>
</Mouse>
</Gauge>
 

Heretic

Resource contributor
#9
You'll also need the corresponding A: var to drive the button display conditions. "(A:Autopilot mach hold, bool)", I think.


P.S: Good work so far.
 
Top