NGX and Idle throttle on touchdown

[Windh]

Hi Pete,

 

Now I've got my CH yoke and throttlequad setup and I'm able to calibrate/assign in FSUIPC.

 

After hours of tweaking, and not getting the reverse thrust to work with the "below detent" position of the throttles, I decided to assign reverse thrust to a separate lever. That works too, -when on the ground.

 

 

Obviously, the throttle must be idle in order to apply reverse thrust, however, for some reason the throttle of the NGX "creeps" up to about 42% N1, whenever I try to put it in idle before, during, and just after landing. It takes a good deal of braking before the throttles reacts normally, and REALLY goes idle, enabling reverse thrust to be applied. And by the time that occurs, the whole point of reverse thrust is gone, as would the aircraft be on a wet and short runway.

 

 

I have disabled the reverser option in my throttles page, and calibrated them to be "idle" a bit above the physical stop of the lever, just to be sure. 

 

But still I get this creeping throttle when airborn and landing.

 

 

Maybe this is an NGX issue?

 

 

Anyways, any help is much appreciated!

 

 

Regards

 

Johan

[Pete Dowson]

... for some reason the throttle of the NGX "creeps" up to about 42% N1, whenever I try to put it in idle before, during, and just after landing. It takes a good deal of braking before the throttles reacts normally,

 

Could your throttle levers be doing that?  Or maybe you have conflicting assignments?

 

Try using the axis logging in FSUIPC (loggng tab in the options) to see whast is happening. The LOG file is placed in the Modules folder, but it may be more useful if you did a test with FS in Windowed mode and enabled the console logging option so that the logging occurs on screen in real time, beside the FSX screen.

 

Regards

Pete

 

[Windh]

OK Pete, I'll check that out..

 

However, it seems a bit strange, since it goes to idle with no problem when on the ground.

[Pete Dowson]

However, it seems a bit strange, since it goes to idle with no problem when on the ground.

 

Maybe it's interlinked with the speedbrake which if armed should auto-engage on touchdown? A bit weird if it is. Any other reports on the NGX forum? It can't really be specifically FSUIPC because FSUIPC doesn't care about touch down. Axes are left to their own devices, literally in fact!

 

Could it be to do with VNAV and/or just AutoThrottle? I would presume you disconnected the A/T on final approach or earlier?

 

Pete

[Windh]

Hi Pete,

 

Yes, perhaps speedbrake related...  I've assigned an axis to that, but it's not been working 100% yet.. Maybe that is inhibiting idle thrust.. I haven't been able to reach the PMDG forum, as Avsim seems to be having server problems at the moment.

 

I'll continue testing and get back. Thank you.

 

/Johan

[Windh]

Looking more into the issue, tried without any external controllers active either thropugh FSX or FSUIPC. it seems that this "creeping" of the idle thrust is just a correct modelling on PMPGs part. Flight idle should be around 34% N1, (which is the case, not 40% that I wrote earlier).

 

So, my question is... Why is it not possible to engage the reverse thrust (by pulling that lever) until the aircraft has slowed down enough to allow a lower N1 percentage?

 

Is this anything withing FSUIPC, or is it all PMDG?

 

 

/Johan

[Pete Dowson]

Looking more into the issue, tried without any external controllers active either thropugh FSX or FSUIPC. it seems that this "creeping" of the idle thrust is just a correct modelling on PMPGs part. Flight idle should be around 34% N1, (which is the case, not 40% that I wrote earlier).

 

Yes, but you are confused between engine rotation speeds (N1/N2) and throttle control settings. The throttle control is not directly linked to the N1 or N2 values, the latter are a result of the throttle inputs, they are not a copy of the throttle control value!

 

The idle N1 of 34% is obtained by a control input from the throttle of zero (0) when the THROTTLEn_SET controls are used, or -16384 when the normal FS AXIS_THROTTLEn_SET controls are used. The latter have no reverse range at all. FSUIPC can only provide a reverse axis control with the THROTTLEn_SET controls which have the idle at 0 and every negative value, down to -4096 (by default) as reverse thrust (the -4096 is when the AIRCRAFT.CFG defines the max reverse as 25%, 25% of 16384, full thrust, is 4096).

 

Naturally the throttle value cannot be negative before being zero.

 

So, my question is... Why is it not possible to engage the reverse thrust (by pulling that lever) until the aircraft has slowed down enough to allow a lower N1 percentage?

 

Is should be possible as far as I know, though it may be some "realistic" implementation by PMDG -- you'd have to ask them. Try it on the default 738, for example.  But as far as FS and FSUIPC are concerned, It is nothing to do with N1 or N2. It is simply the throttle input value that matters, not the current N1 or N2, or anything else to do with the engine simluation.

 

BTW surely your engines are pretty much idling by the time you touch down? Before the flare you should have pulled the power right back already. Landing is just a stall at the right height for a soft "crash".

 

Regards

Pete

[Windh]

Ok Pete. Well the input values are correct, I believe. I get good numbers on calibration and my Quad is pretty accurate, I'd say..

 

 

Perhaps I should try once more to make reverse thrust work as it has been in FS9, with the throttles being pulled down below the detent to apply reverese thrust...

 

 

When I tried this, I first changed in CH Manager so that the detent values are 240 instead of 255.

 

 

In FSUIPC it now looks like this:

 

 

 

I've calibrated Idle to be a bit over the detent and reverse at the physical end of the lever movement.

 

 

This does result in reverse thrust being activated, but only Idle...

 

 

What do you think about these settings Pete?

 

[Pete Dowson]

This does result in reverse thrust being activated, but only Idle...

 

Sorry, can you re-phrase that as it seems not to make sense.

 

What do you think about these settings Pete?

 

I have no thoughts on them at all really. if they are the results of correctly calibrating to the positions you want, and work with the aircraft you use, then they are fine. I don't have your hardware or your aircraft, so I've no comparisons to make.

 

Did you never bother to do the axis logging as I suggested, so you could see what was making your throttles drift? Or was that drift just a misunderstanding of what an Idle engine does?

 

Regards

Pete

[Windh]

Sorry, can you re-phrase that as it seems not to make sense.

 

 

I have no thoughts on them at all really. if they are the results of correctly calibrating to the positions you want, and work with the aircraft you use, then they are fine. I don't have your hardware or your aircraft, so I've no comparisons to make.

 

Did you never bother to do the axis logging as I suggested, so you could see what was making your throttles drift? Or was that drift just a misunderstanding of what an Idle engine does?

 

Regards

Pete

 

 

Yes I did bother. Hmm.. I'm not allowed to attach text files. Do you want me to paste all the text in a post?

 

Until I get stuff working the way I want to, I'll assign a pushbutton to the "decrease throttle quickly" command.

[Pete Dowson]

Yes I did bother. Hmm.. I'm not allowed to attach text files. Do you want me to paste all the text in a post?

 

Not really -- it was for your information, not mine. If there's anything you don't understand then paste in a fragment and i'll explain what it means.

 

Until I get stuff working the way I want to, I'll assign a pushbutton to the "decrease throttle quickly" command.

 

Does that stop the throttle drifting forward to foerward thrust?  Or was all that about throttle drift actually only referring to the N1 figure, not to the throttle values at all? If the latter, then the logging isn't relevant.

 

Regards

Pete

[Windh]

Sorry, yes it was an N1 issue only, the throttle remained at idle. Strange why the Reverse-lever didn't work then..!