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PavlinS

The Touchdown bug of PMDG

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Okay, let me give some examples. 

First example, this is me, touching down with static_cg_height=13.060 at PMDG 777-300ER:

As you can see severe bounce, in cockpit experiencing high speed up on touchdown, the touchdown itself was -125 fpm and G-force of 1.02. \

Second attempt, after the change, please, ignore the terrain callouts, my flight control replay program did not recorded the touchdown, so I had to use Chaseplane again as the first touchdown. 

As you can see even with high nose up the gear remained on the ground without me experiencing any touchdown problems, also the speed was going down rapidly as it is supposed to be. I am finally able to produce good landings with those planes now. 

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Where are these settings?


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5 hours ago, IanHarrison said:

Where are these settings?

The aircraft config file, but I suggest you backup the original. The setting in question is static_cg_height=13.060 for example. there is different values, sometimes is 13.240, sometimes - 13.040 or similar. 

 

Okay, time for tutorial 

 

 

gYMDDSF.png

 

This is the original PMDG 777-300ER Aircraft.cfg file. With simple search in the notepad display you can find the line static_cg_height=13.234. I suggest - keep an copy of this file before changing it, because if you decide to change the whole fleet with this you should keep the original files. 

 

VKT4k69.png

Change the value to 19.999, this is the value I use in all PMDG planes now. Check the planes after the change, give yourself one landing with each plane you changed so you can make sure this is working. 

 

When you go into the plane itself, enter PMDG menu, then options, then simulation. 

6oUEafd.png

Change the high idle on flare option to on. 

AOM1i2M.png

On the next page, turn off the A/t manual and flare idle override to never / off respectfully. 

This is it! You have a free of bounce planes! 

Edited by PavlinS

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Here's an autoland guys, so you can see the cockpit in action [ no add-on in this video]

 

 

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19 hours ago, PavlinS said:

That has to do with my settings as well, because the flare idle override is said to now and the high idle on flare is set to yes. I think, this affects the speed vector a lot more, but it is compromising variant for the touchdown. 

There is a shortcoming in P3D that significantly delays reverse thrust deployment after touch down, i.e. the reversers will take ages to deploy. High idle in flare is realistic and makes sure the engines spool up fast enough if a go around or touch and go is conducted as spooling up would take too long with the engines in ground idle. The caveat in P3D with high idle is that it delays reverse thrust deployment, so PMDG included an option to choose high or ground idle during flare and by default it's set to ground idle to allow for thrust reverse.

Perhaps this setting is affecting the speed simulation on touch down too, as you say. That might be the reason why not everyone is seeing the issue if people are using different settings for this.


Microsoft Flight Simulator | PMDG 737 for MSFS | Fenix A320 | www.united-virtual.com | www.virtual-aal.com | Ryzen 9 7950X3D | Kingston Fury Renegade 32 GB | RTX 3090 MSI Suprim X | Windows 11 Pro | HP Reverb G2 VR HMD

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7 minutes ago, Nixoq said:

High idle in flare is realistic and makes sure the engines spool up fast enough if a go around or touch and go is conducted as spooling up would take too long with the engines in ground idle.

That is very good, because most long haulers land with auto thrust on. 

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1 minute ago, PavlinS said:

That is very good, because most long haulers land with auto thrust on. 

High idle is active during flare regardless of whether the autothrottle is used though.


Microsoft Flight Simulator | PMDG 737 for MSFS | Fenix A320 | www.united-virtual.com | www.virtual-aal.com | Ryzen 9 7950X3D | Kingston Fury Renegade 32 GB | RTX 3090 MSI Suprim X | Windows 11 Pro | HP Reverb G2 VR HMD

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Just now, Nixoq said:

High idle is active during flare regardless of whether the autothrottle is used though.

Not completely understand what you mean, can you elaborate?

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1 minute ago, PavlinS said:

Not completely understand what you mean, can you elaborate?

High idle is commanded by the FADEC (full authority digital engine control) system to keep the engines above ground idle during flare to facilitate faster spool up times in case of a late aborted landing, but this happens regardless of whether the autothrottle is engaged or disengaged. Even if disengaged, the FADEC will keep the engines at high idle.

In real aircraft this still allows rapid reverse thrust deployment, but in P3D it delays reverse thrust significantly. Did you select idle reverse in the autoland video yourself? Because the engines never went past idle reverse.


Microsoft Flight Simulator | PMDG 737 for MSFS | Fenix A320 | www.united-virtual.com | www.virtual-aal.com | Ryzen 9 7950X3D | Kingston Fury Renegade 32 GB | RTX 3090 MSI Suprim X | Windows 11 Pro | HP Reverb G2 VR HMD

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No, I just deployed the thrust reversers, in Autoland the speed is A/t controlled, so no intervene from me will affect it. 

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2 minutes ago, PavlinS said:

No, I just deployed the thrust reversers, in Autoland the speed is A/t controlled, so no intervene from me will affect it. 

You still need to manually select reverse thrust during an autoland, which will also disconnect the autothrottle. Did you command idle or full reverse? My guess is in the video with high idle set to on prevented thrust reverse deployment past idle (P3D issue).


Microsoft Flight Simulator | PMDG 737 for MSFS | Fenix A320 | www.united-virtual.com | www.virtual-aal.com | Ryzen 9 7950X3D | Kingston Fury Renegade 32 GB | RTX 3090 MSI Suprim X | Windows 11 Pro | HP Reverb G2 VR HMD

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Just now, Nixoq said:

You still need to manually select reverse thrust during an autoland, which will also disconnect the autothrottle. Did you command idle or full reverse? My guess is in the video with high idle set to on prevented thrust reverse deployment past idle (P3D issue).

I always use full reverse. I click on F2 for that. 

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1 minute ago, PavlinS said:

I always use full reverse. I click on F2 for that. 

Wouldn't that be F1 to go full reverse? In any case, that's the downside with the high idle option set to on. Thrust reverse simulation suffers.


Microsoft Flight Simulator | PMDG 737 for MSFS | Fenix A320 | www.united-virtual.com | www.virtual-aal.com | Ryzen 9 7950X3D | Kingston Fury Renegade 32 GB | RTX 3090 MSI Suprim X | Windows 11 Pro | HP Reverb G2 VR HMD

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11 minutes ago, PavlinS said:

I have autobrakes, speedbrakes for that. 

Sure, of course idle reverse isn't unrealistic. Just pointing out the problem with the high/low idle in P3D.


Microsoft Flight Simulator | PMDG 737 for MSFS | Fenix A320 | www.united-virtual.com | www.virtual-aal.com | Ryzen 9 7950X3D | Kingston Fury Renegade 32 GB | RTX 3090 MSI Suprim X | Windows 11 Pro | HP Reverb G2 VR HMD

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