Jump to content

Recommended Posts

I've been having some problems with various autopilots recently. The most common problem is the inability to follow a flight plan. This has led to me having to direct the plane entirely using the "HDG" option which is possible but takes up a lot of the pilots time. As planes get more complex they also need more attention. If however the pilot - and in FSX that is mostly a single person - is having to concentrate on keeping the plane on course then things can be missed which can lead to a disastrous situation being developed.

To allow the pilot to concentrate on the important things in life it is essential to have an autopilot that can do two simple things: 1 - Follow the flight plan and 2 - Follow the height instructions and climb to the predetermined height.

Unfortunately recently many of the most recent aircraft that I have don't do either or both of these jobs. At the only moment the only aircraft that I fly regularly now - the RealAir Duke Turbine V2 - will do both these specified jobs without any problems.

In the majority of cases, even after setting up a flight plan and setting the autopilot to use the "NAV" function  the aircraft will suddenly go off on a tangent - and in many cases just fly around in circles. This is true of a whole variety of aircraft from a whole variety of flight sim aircraft manufacturers.

I've been flying flight sims from the middle 1970's so I have some experience. I also have real life experience but sadly not with an autopilot.

So after that preamble I come to my question: Does anyone know how autopilots are constructed in FSX?

It seems to me that it could be done in two ways:

1. FSX contains a basic autopilot mechanism and supply a method for a manufacturer to interface with this code.

2. Manufacturers write their own autopilot code.

3. (There is a third option?)

Because this is happening across aircraft from several different manufacturers I am beginning to wonder if the first option is the true one. If this is the case then it assumes there is a problem with the FSX autopilot code. In which case does anyone have any idea how to fix it?

If option 2 is the correct answer then the situation is more complex. I've found out that some firms will be helpful but can't really do much to help. And one or two will just refuse to admit the existence of a problem. (No names, no packdrill!)

Anyway I would appreciate any help that anyone can give.

Malcolm Wright

Computer: ACPI x64-based PC:

Intel(R) Core(T) i7-7700K CPU @ 4.2GHz (8 Cores)

Nvidia GeForce GTX 1070

Samsung SSD SCSI Disk Device 500gb Drive 😄 Only used for OS and FSX and related items.

ST1000DM 010-2EP102 SCSI Disk Device Drive 😧 Everything else!

Memory 16MB

Share this post


Link to post
Share on other sites

Hello Malcolm.  It's most likely limited to you or your setup, else everyone else would have the same problem.  Going from your post only:  

  1. Is there a flight plan loaded in your navigation system.  
  2. If so, is your navigation system set to "GPS" vs "NAV" mode?  

I'm sure we'll get this solved. 

Dave  

Share this post


Link to post
Share on other sites

Dave,

     Thanks for your help. The answer to your questions are:

1. Yes there is always a flight plan loaded unless I'm just buzzing around at random and in that case I wouldn't use the autopilot.

2. As far as I can judge the navigation in all the aircraft is set to use the GPS. I set the autopilot to NAV and in the cases where the auto pilot works that works fine.

I mainly use the GTN750 as my directional source and I build the flight plans in that (assuming the aircraft is fitted with the GTN750 however even in some of the aircraft fitted with the GTN750 it doesn't work well - sometimes not at all.)

I have 197 different aircraft - including multiple differing set ups for the same basic aircraft and including some AI's. So I haven't actually tested all the possibilities!

I am  quite happy to accept that there is something wrong with my system - however finding out exactly what that is, and fixing it, is another problem.

I fly only in FSX - boxed version. You can see my rig set up in my original post and in addition I have several Saitek extras. These include:

Autopilot - which works well with some aircraft but not with all. When it works  with the aircraft I make all autopilot changes/commands using the device. I have tested disabling the Saitek device to see if that is causing the problem but first indications suggest there is not a problem there, though it might benefit from some more testing in that area.

Radio box - which works well for comms. No input to navigation as I use radio sources fairly rarely.

Switch Panel

Proflight Yoke System with and extra throttle unit which allows me to assign two throttles, two pitch and two mixtures.

All the best

Malcolm Wright

 

Share this post


Link to post
Share on other sites

Do you use waypoints?  I find if I don't enter the flight plan course before encountering the 1st waypoint, it will not follow the NAV tracking...  Try the "direct route" plan: You can hook-up with the flight plan just about any time before your final destination.  (And, of course, depending on the panel, you must use either the LNAV, or the APPROACH gauges to follow the flight plan tracking).  

 

 

Share this post


Link to post
Share on other sites
23 hours ago, Malcolm Wright said:

As planes get more complex they also need more attention. If however the pilot - and in FSX that is mostly a single person - is having to concentrate on keeping the plane on course then things can be missed which can lead to a disastrous situation being developed

Jeez it is just flight simming.  Real people aren't going to die if FSX:SE screws up.  Relax and enjoy the hobby.  🙂

I like overspeed3's advice.  In addition, if you could give an example of a flight plan (heck, can you upload it?) with an example of an aircraft (hopefully default?) that doesn't cooperate with your autopilot expectations, I'm sure we would be happy to try it ourselves and verify if it also do not work for us.

Share this post


Link to post
Share on other sites
22 hours ago, Malcolm Wright said:

I mainly use the GTN750 as my directional source

Malcom,

Is this the GTN 750 sold by Flight 1?  Like others have suggested and selecting one airplane where its autopilot doesn't follow lateral navigation in a flight plan, could you list the aircraft and the flight plan?  

Dave

Share this post


Link to post
Share on other sites

Dave,

      Yes it is.

      I am about to test most of the planes that I fly regularly to identify which work and which don't. Though this may take some time!

      The following is a flight plan that I use to test various aircraft. The one that I know, off hand, that fails is the Carenado DA62- even with, or without,  a mod  to replace the G1000 with the GTN750. (One thing I should point out is that I have a fault in the G1000 flight plan where the individual leg is calculated correctly but placed in the wrong sequence. I.e. the first leg, instead of going from EGMD to EGKK goes from EGMD to EGGW (As I recall)

     This route takes place in the South East of the UK. It starts and ends at EGMD:

EGMD - EGKK - EGGW - EGMD - DVR - EGMD

Cheers and thanks for your help.

Malcolm Wright

Share this post


Link to post
Share on other sites

Thanks for the response Bullpup,

I know only so well that we are in a simulation. I have a PPL (now no longer current) and have a number of hours in real life so I can tell the difference.

However if you spend time setting up a flight and it then goes wrong because of an unknown reason then it is very annoying. Also it means that flying a complex aircraft becomes impossible.

Malcolm

Share this post


Link to post
Share on other sites

Malcom,

Thank you.  As I do not own the Flight 1 GTN 750 I won't be of much help.  I suspect there's a problem with how it is interfaced with the various airplanes, but I'm not sure.  I'm sure, though, that someone who owns the product will be able to help.  Another suggestion, if you haven't done it, is to post this at the Flight 1 forum.  Good luck.

Dave

Share this post


Link to post
Share on other sites
Posted (edited)

OK... let me try to add some information to this discussion.

Of the three options in the first post, the first option is correct.

Very few airplanes have a truly custom coded autopilot, most use the basic FS autopilot in some way.

Now, having said that, interfacing the GTN with the FS autopilot is not that simple, and each new release of the GTN introduces the potential of interfacing problems.  (which then typically get fixed in a subsequent release..)

Add to this that Flight1 and RXP are very much focused on P3D in their development, so the possibility of an FSX bug going undetected is certainly there..

The best thing is for you to post the exact circumstances of your NAV failures and others can try to reproduce them on their system.

Secondly, your desire to have the autopilot level off at a target altitude.. The FS autopilot has that capability, but not all real world autopilots have that feature installed. In the popular Bendix-King autopilot series, this is optional on several autopilots.. so you may be looking at a "realistic" implementation.

Lastly, Carenado has a shaky reputation when it comes to avionics function, and it is not unknown for Carenado airplanes to require fixes to their autopilot code, especially in combination with the GTN option..

So, without knowing what you are specifically experiencing on your system, it is hard to guess at the underlying cause.. but these things are usually fixable.. so please give us something to work with, so we can help! :smile:

 

Edited by Bert Pieke
  • Like 1

Share this post


Link to post
Share on other sites

Bert,

      Thanks for your comments, much appreciated.

      I have thought all along that it is probably a failure in the connection between the GPS source and the autopilot and it is encouraging to see that you think that the basic FSX autopilot is what is mostly used. I don't know if you happen to know if Real Air built their own autopilot as it is really the only autopilot, that I have that is reliable.

      The other problem is that not all the aircraft have the GTN750. Some have the G1000 setup, but I find that difficult to use. I find in general that apart from the GTN750 the various FMC systems are the best.

      I have started out setting up my system to carry out a whole series of tests using most, though not all, of the aircraft I fly. However this will probably take some time. If I come across anything of interest I will post it here.

All the best,

(Your mod to the Phenom 100 works fine! Thanks for that.)

Malcolm Wright

Share this post


Link to post
Share on other sites

As best I know, RealAir also relies on the FS autopilot.. so the basics seem to work.. :smile:

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...