They answered me too. They're looking into this, with their Beta Team of real pilots to investigate the issues.

They answered me too. They're looking into this, with their Beta Team of real pilots to investigate the issues.

That is good news!

Jip, sounds good!

We are looking into this. We just can't say much at the moment without further investigation and clarification from our sources. There is more to how this system operates than what's in the FCOM and that PDF document you guys are referencing. We have information beyond those documents that was referenced in programming our FBW model - it's a significant amount of information and input and some of it conflicts because the exact methodology used by Boeing is a trade secret. It's possible we may have misunderstood something and we'll get it clarified - if something's wrong it'll be fixed.

Great, thanks for the update.

Thx Ryan, great!

Hi Ryan,

 

Thanks to take time to investigate this.

Yes, thanks for clarification Ryan.

 

Trimming for me yesterday was a bit of a nightmare to be honest. I'm avoiding hand flying.

Martin, does the trim affect the pitch up/down motion?

 

Thanks

 

 

The thing that I don't understand is that maybe this 777 pilot didn't want his aircraft to climb, it wanted it only to get back on the glide after a downdraft, or something like that. So after he Pulled the Yoke to bring it back on the Glide, he released the pressure, let it go back to neutral, expecting the aircraft to establish once again on the previous Trimmed AirSpeed, and the aircraft will not do so, because it's now trimmed to the new speed the system interpreted was what he wanted when he did that Yoke Movement.

I think I understand now.

 

When on approach, you need to control speed with pitch and rate of descent with throttle, not the other way around. If you are below the glide because of a downdraft, you do not pitch up, as that will simply reduce your speed. You throttle up instead. Throttle back when close to the gs (remembering to premept it) and you are back on course, on speed, in trim and on track. This is as true of a Cessna as a T7.

 

I would also remind you that the T7 is not a Cessna. That means lots of things, including the facts that a) things happen slowly, and b) they happen indirectly. In a Cessna, trimming for speed makes sense. What you are actually doing is trimming the force out of the controls that are hardwired to the flight surfaces. Even if you are using a force feedback joystick, you can not feel the forces accuratly so you can not manually trim accuratly. FBW changes the rules. The controls are not hardwired so you are no longer apply force to the flight  surfaces, you move the controls to 'state your intentions' and the computers decide how to implement them. One consequence of this is that you do not need to worry about the trim. If you are at stable at 250 and you push the throttles, you will climb at 250, same as you would in a Cessna. If you push the stick forward to maintain level, your speed will increase, and if you were in a Cessna, the forces on the stick would increase until you trimmmed them out. The T7, with autotrim, will detect the forces and trim them out for you. This means that when the speed stabilises, you can release the stick and be properly trimmed.

 

I am not a T7 designer, engineer or qualified pilot, so I can not say there is definitly nothing wrong here, I can however say that I find the PMDG's offering performs pretty much as I would expect it to. Yes I am somewhat of a fanbois, but that does not necessarily mean I am wrong.

Martin, does the trim affect the pitch up/down motion?

 

Thanks

I find when I accelerate, or decelerate, and the T7 climbs or descends [as it should with speed increase] and I attempt to trim, there is no response at all for one second, sometimes not at all. Then suddenly it trims too much and too rapidly. It makes accurate trimming tricky.

 

As for the other issue mentioned, namely the weird behaviour where it's possible to auto trim with elevator input... I have no idea if this is accurate behaviour or not. It may be a yoke pressure release feature that is present in the real T7 but perhaps exaggerated in the sim.

I think I understand now.

 

When on approach, you need to control speed with pitch and rate of descent with throttle, not the other way around.

 

I would also remind you that the T7 is not a Cessna.

 

Paul, the technique you mention is usually recommended for light aircraft. So no the T7 is not a Cessna, but you are recommending a Cessna technique.

 

The technique that you have determined works for you, isn't really relevant to this discussion. What is relevant is that trimming for many of us is less than satisfactory. And in addition, the way the PMDG T7 auto trims with elevator input, and ZERO manual trimming, despite significant changes in airspeed, seems to either be exaggerated compare to the real aircraft, or not a feature of the real aircraft at all.

 

 

The T7, with autotrim, will detect the forces and trim them out for you. This means that when the speed stabilises, you can release the stick and be properly trimmed.

No Paul, that is wrong. The T7 does NOT have auto trim in regard to speed changes. It's well established that speed changes MUST be trimmed out MANUALLY.

 

The only auto trim effect is in regard to configuration changes. namely thrust increases, and flap deployment.

Awesome - thanks Ryan!

 

Best regards,

Robin.

Yes, thanks for clarification Ryan.Trimming for me yesterday was a bit of a nightmare to be honest. I'm avoiding hand flying.

Hi Martin,

 

You know what, I have that issue now as well.

With first no trim and then too much of it.

I think I needed a bit more flight to see what you mean.

 

I think it is because the system autotrims.

I feel like when you trim, the autotrim function (that should not be there in my opinion) adds its own trim value to that as soon as you let go of the yoke, and it becomes to much.

Or something like that.

I also noticed that the trim value does not change (no autotrim) as long as I keep the elevator (or any flight control for that matter) deflected.

Autotrimming seems to start as soon as I let go of the yoke at the attitude I want to be.

Like airbus.

 

You know what....that gives me an idea....maybe autotrim would stop if I keeps just a tiny bit of rudder trim in there.

I know, makes no sence but I am going to try anyway.

EDIT: Ok, forget that. total BS from my part. PMDG Autotrim will trim with or without aileron/rudder input. With deflected elevators PMDG will not trim.

 

EDIT:

I find the best way to manually fly this aircraft at the moment is by not touching the trim switches (and I am telling you that is not how the real plane works)

 

Also, as I mentioned before (above) I will try to test a few simple things on my rw flight tomorrow.

If I cant do my tests on this flight then I will try to do them on my simcheck 3 days later

(there seem to be two new guys watching over us on this flight...its called an observation flight for them.....and the idea of this is to show them normal ops, not trying stuff....still though I should be able to to some handflying and get these simple tests taken care of).

Good to hear the team is looking into this.

Martin, does the trim affect the pitch up/down motion?

 

Thanks

I have this problem on final approach. Nose is bob up and down. At first I think that AS2012 make some turbulentes, but it's the T7 by itself. If you have bad weather conditions where wind is changing rapid the hole time, the T7 is very very bad to control.

 

Other thing i have problems with Autothrottel yesterday. LNAV and VNAV was activated after takeoff, but the T7 don't speed up in AP mode and hold climb rate. The AP don't push the nose down to give the T7 a chance to accelerate. I must push Alt Hold... So the speed was extrem slow and go slower into the bad range.

 

Anybody happens this too?

 

PS: On final approach, I use only the throttle to get more or less vertical speed like a fighter pilot. The auto trim produce then this effect.