Auto-Pilot is NOT Engaging

[kmanning 12]

On ‎10‎/‎7‎/‎2018 at 2:46 AM, Ephedrin said:

 

However you are correct if you compare it to a GA airplane without any hydraulics.

That's basically what I was comparing it to.

On ‎10‎/‎7‎/‎2018 at 2:46 AM, Ephedrin said:

As a conclusion, aftrr you have removed the centering springs/rubbers/function there is no chance for you to correctly and properly fly the Boeing and as long as the joystick is not in its center position the AP will definitely not engage in realistic settings. 

Where did you get that I removed the springs or any of the parts from my joystick? I have not removed them. I just have it disconnected from the cable that supplies the force feedback. My joystick is a force feedback, and can be turned off in the simulator. But for P3D simulators, if this cable is plugged in, it not only provides for feedback but also return to center force. In FSX, it only provides force feedback but with no return to center.

Ken.

[kmanning 12]

On ‎10‎/‎7‎/‎2018 at 2:40 AM, pete_auau said:

don't  know  if  you have  done  this,  have  you  tried   disconnecting  your  stick to see if  you have  the  same  issues 

I assume you're referring to the force feedback cable. It was already disconnected when the issue started.

Ken.

[kmanning 12]

On ‎10‎/‎7‎/‎2018 at 7:55 PM, MattS said:

Do you by chance have a force feedback joystick?

Yes. It's the Microsoft Force Feedback 2 which I had for years. The one thing I don't like about it is that it's not 64 bit compliant.

On ‎10‎/‎7‎/‎2018 at 7:55 PM, MattS said:

Your comment about having the yoke pulled back in the climb is a clue why you can’t engage. That is not normal. Your yoke/joystick should be nearly centered soon after takeoff (if trimmed properly). Disabling the centering function on your joystick will prevent you from engaging the autopilot. I am quoting from experience. 

I think I agree with you. I've noticed in videos how the pilot, at Vr, would pull the yoke back, but then it seems that immediately after lift-off, the pilot moves the yoke forward, and this is probably the center position y'all are referring to, or maybe near center.

Ken.

[kmanning 12]

Hi guys,

I've been going over all this information about trimming the aircraft and it seems to all make sense. So, what I gather is that the auto-pilot does not like it when the plane is out of trim, or you have to constantly keep force on the control wheel. It's by design that the airplane has to be trimmed before the autopilot will engage. So, what I will do is reconnect the cable so that the joystick will provide the return to center force. I wish there was a way that I can turn that on when flying commercial jets and turned it off when flying general aviation. This return to center force will work in P3D but there will be no return to center force in FSX.

By the way, I found what I've mentioned about when not to use the trim in that 737 FCTM. I knew I remember reading about it, but it says that you never use it during the take-off phase, that is, when you're going down the runway. But you can use it after you're airborne.

Ken.

[JRBarrett 3,128]

4 minutes ago, kmanning said:

Yes. It's the Microsoft Force Feedback 2 which I had for years. The one thing I don't like about it is that it's not 64 bit compliant.

I think I agree with you. I've noticed in videos how the pilot, at Vr, would pull the yoke back, but then it seems that immediately after lift-off, the pilot moves the yoke forward, and this is probably the center position y'all are referring to, or maybe near center.

Ken.

The pilot (while hand flying) will trim entirely by feel, activating the trim switch as required to relieve any pressure or physical effort required to hold the yoke in it’s current position. The yoke may or may not move as a result of trimming. The “neutral” position that is critical is the position of the elevators themselves in relation to the stabilizer, not necessarily the position of the yoke.

Of course once established in climb, the pilot will, at some point, (if he continues to hand fly), start to pitch down to begin accelerating for flap retraction, and will move the yoke forward to do that - again trimming as required to relieve any pressure.

One thing I can assure you is that the autopilot will not engage if the elevators are deflected into the airstream to any significant degree. Activating the “realistic autopilot engagement” option emulates that behavior in the sim, which is why trimming is so important.

When the autopilot is is engaged, the trimming is done automatically. If, for example, the aircraft is in level flight, and the pilot commands a climb using the autopilot, several things happen simultaneously. The auto throttle system (if equipped) increases thrust, and at the same time the electric elevator servo begins to deflect the elevators upward. As soon as this happens, the force sensor in the autopilot elevator circuit begins to generate a voltage proportional to the air load on the elevator. This will immediately command the horizontal stab trim to move to reduce the load on the elevator servo. If more pitch is required, the process continues - It’s a basic feedback loop. The effect is especially apparent on 737’s when pitch changes are commanded under autopilot control, since the trim wheel will constantly be moving one way or another which is very apparent both visually and audibly. 

There is another extremely critical reason why it is important that the elevators not be significantly deflected when the autopilot is engaged. If the elevators are not kept neutral in a climb or descent (by stab trim), and the autopilot is disengaged, it can cause a significant and sudden pitch up or down at the moment of disengagement. In some circumstances, this could result in a loss of control. 

[JRBarrett 3,128]

21 minutes ago, kmanning said:

Hi guys,

I've been going over all this information about trimming the aircraft and it seems to all make sense. So, what I gather is that the auto-pilot does not like it when the plane is out of trim, or you have to constantly keep force on the control wheel. It's by design that the airplane has to be trimmed before the autopilot will engage. So, what I will do is reconnect the cable so that the joystick will provide the return to center force. I wish there was a way that I can turn that on when flying commercial jets and turned it off when flying general aviation. This return to center force will work in P3D but there will be no return to center force in FSX.

By the way, I found what I've mentioned about when not to use the trim in that 737 FCTM. I knew I remember reading about it, but it says that you never use it during the take-off phase, that is, when you're going down the runway. But you can use it after you're airborne.

Ken.

I’ve never used a force feedback stick, or yoke, but have always been curious how they “feel” when used with a simulator. My own joystick is a Thrustmaster Hotas Warthog. Not 100 percent accurate to use with an airliner, but it is smooth as silk in both pitch and roll axes. It does have a strong return-to-center system, and trims very well. I use the hat switch for pitch trim, which feels very natural.

[kmanning 12]

53 minutes ago, JRBarrett said:

I’ve never used a force feedback stick, or yoke, but have always been curious how they “feel” when used with a simulator.

Hi Jim,

I don't use the force feedback either, and never liked it.

Quote

My own joystick is a Thrustmaster Hotas Warthog. Not 100 percent accurate to use with an airliner, but it is smooth as silk in both pitch and roll axes. It does have a strong return-to-center system, and trims very well. I use the hat switch for pitch trim, which feels very natural.

When I trim my airplane, I use the 2 buttons, but they are side-by-side rather than one being on top of the other. What is the best joystick that is 100 accurate to use with airliners? I was thinking about the Saitek Flight Simulator Yoke with the Throttle Quadrant. But I'm not sure if it will have, or simulate the return to center force. But I like the fact that it's shaped like the real aircraft yoke. You mentioned that yours has a smooth pitch and roll axes. Mines has always been a little too sensitive. I know the sim has sensitivity controls, but it doesn't seem to have any effect, no matter where I put the sliders. So, I just leave them in their default position. Another problem I don't like is that when I rotate, there's a little delay with the nose coming up and wind up going a little past V2. And there is also a jerkiness, meaning that it's not a smooth rotation but seems to just jerk up, or pop up all of a sudden. And the same thing happens when landing. When the wheels touch down, everything just jerks, pops to the ground all of a sudden. Or do I need to post this under hardware? But thanks guys for explaining things.

Ken. 

Edited October 9, 2018 by kmanning

[skelsey 765]

Hi Ken,

I wrote a piece about trimming here which you may find useful if you had not seen it:

In short: even with a GA aircraft, a centering force to pull/push against is essential and not so very far removed, really, from real life. As has been mentioned, as far as airliners are concerned actually the control column will almost invariably be centred when the aircraft is in trim because the whole horizontal stabiliser moves and therefore when the aircraft is in trim the elevator will be in the neutral position: i.e. with the control column centred.

Even in a light aircraft equipped with trim tabs, the principle is much the same; hold the attitude and trim off the force you are exerting. If you do not have any centreing force then you will have no feel at all.

Saying that, although I don't have a force feedback stick myself, are you aware of FSForce? I gather this replaces the default FS force feedback with a a much more realistic feel so may be worth looking at.

Regarding hardware -- I have the Saitek Cessna yoke myself and I find it very good for the money - the springs are solid enough to mean you really do feel it when the aircraft is out of trim -- stalling a light aircraft, for instance, requires a fairly hefty haul to the backstop (or I'm just weedy!). Personally I find the yoke provides excellent control for light aircraft and airliners (although I still prefer my old Sidewinder Pro 2 for the Airbus -- the slightly different flight control system and fly by wire implementation makes the stick a little more intuitive in that setting).

Re: sensitivity - always ensure that the sensitivity sliders in FS are set to maximum, because all they really do is limit the maximum input and/or introduce a lag in inputs, neither of which are much fun! It's also worth looking at FSUIPC if you don't already own a registered copy -- this provides the capability to adjust control response curves etc which can be quite useful.

[JRBarrett 3,128]

Ken,

Before I had the Warthog joystick, I used a CH yoke. I think the Saitek May be a bit better, but have never used one. They both use a physical spring to center the yoke in pitch and roll. The problem with the less-expensive yokes is that they use inexpensive potentiometers (variable resistors) as their motion sensors, which invariably become dirty over time, causing noise in the output. That can lead to control spikes, and “twitchy” response. 

The Thrustmaster Warthog uses electronic Hall effect sensors, which are very reliable - smooth linear output and spike-free.

The Warthog can be found for about $250 from many vendors, including Amazon. 

Unfortunately,  airliner-style flight sim yokes with Hall effect sensors tend to be extremely expensive, ($1000 +) and are  harder to find. The folks in the hardware forum might have good suggestions on what to buy. There is supposed to be a new yoke coming from a company in the UK that wil have Hall effect sensors, and a price target closer to the Warthog. An Avsim user tried a prototype at the recent Cosford flight sim event. I saw the post in my Avsim feed within the last couple of days, but don’t remember which forum.

[pete_auau 1,168]

7 hours ago, kmanning said:

I assume you're referring to the force feedback cable. It was already disconnected when the issue started.

Ken.

if  you had  disconnected  your  joystick  from  the  pc  and  still have  the  issue  than  its  not your joystick  than

[Ephedrin 418]

7 hours ago, kmanning said:

That's basically what I was comparing it to.

Where did you get that I removed the springs or any of the parts from my joystick? I have not removed them. I just have it disconnected from the cable that supplies the force feedback. My joystick is a force feedback, and can be turned off in the simulator. But for P3D simulators, if this cable is plugged in, it not only provides for feedback but also return to center force. In FSX, it only provides force feedback but with no return to center.

Ken.

Ah.. I see now what you mean. Anyway: for the AP to engage you need your joystick send 0/0 or at least close to it, depending on your setting (this percentage setting in tr PMDG options). 

You could look at Amazon. There are many good joysticks that really aren expensive. 20-30$... they are fine. And you can at least fly. Or you wait a bit and go for the Honeycomb when it‘s released. Looks like a great yoke.

[pete_auau 1,168]

5 minutes ago, Ephedrin said:

Ah.. I see now what you mean. Anyway: for the AP to engage you need your joystick send 0/0 or at least close to it, depending on your setting (this percentage setting in tr PMDG options). 

You could look at Amazon. There are many good joysticks that really aren expensive. 20-30$... they are fine. And you can at least fly. Or you wait a bit and go for the Honeycomb when it‘s released. Looks like a great yoke.

he  has  said  previously  he  had  disconnected  his  joystick   from  his  pc  and  had  the  issue   so  cant  be  his  joystick at  fault  if  its  disconnected  and  still has  the  issues

[Ephedrin 418]

19 minutes ago, pete_auau said:

he  has  said  previously  he  had  disconnected  his  joystick   from  his  pc  and  had  the  issue   so  cant  be  his  joystick at  fault  if  its  disconnected  and  still has  the  issues

Okay I missed that. There are several possibilities, such as other hardware being assigned accidentally (virtual mouse axes for example), misconfigured FSUIPC, bad weather program or.. but I don‘t believe it... a bug of the 747. but as he‘s the only one here I bet it‘s an axis. My mouse has axes in the P3D control settings that aren‘t there physically. But they get assigned and without even touching the mouse they constantly send values. 

But I honestly think after the check with the controller a ticket with reference to this thread would be helpful. We can‘t do much.

[JRBarrett 3,128]

44 minutes ago, pete_auau said:

he  has  said  previously  he  had  disconnected  his  joystick   from  his  pc  and  had  the  issue   so  cant  be  his  joystick at  fault  if  its  disconnected  and  still has  the  issues

I don’t think he disconnected his joystick completely - just the wiring that provides the return-to center function.

[pete_auau 1,168]

1 minute ago, JRBarrett said:

I don’t think he disconnected his joystick completely - just the wiring that provides the return-to center function.

well  than  he  should  try  it to make  sure  if  its  his joystick  or  not, be a simple  and  quick  test

Edited October 9, 2018 by pete_auau