747 v3 idle simulation options

[fabristunt 25]

Hi there,

I've been watching Kyle's video review of the Queen, where he nicely explains all the configuration options that we will be able to choose.

It's all clear, apart from two of the simulation options, mentioned around the 44min mark in the video.

 

-A/T flare Idle override

 

-High idle on flare

 

I only have the NGX, which doesn't have them. No triple 7 for me, so if it's in there as well, that's why I'm not familiar with it.

My question is, what do these options do?

They are not company options, as they are in the simulation "group" in the fmc. From what I understand their goal is to overcome some shortcomings of the sim regarding the various possible idles (ground idle, flight idle, gear down or up idle and so on, as kyle explains) that the sim itself can't handle, but why put them as an option then? Why would I want to have it do something wrong?

 

I'm assuming that the second one keeps high idle during the flare, without letting it switch to what exactly? And why wouldn't I want it to do that? What option should one choose to more closely mimic the real aircraft?

 

What about the A/T flare idle override then? Is it the same thing as above, but when using the A/T till touchdown?

 

Regards,

Fabrizio

[Meekg 86]

From the PMDG 777 manual:
 

A/T FLARE IDLE OVERRIDE: This option allows the physical throttle to override the autothrottle’s retard to idle during the flare sequence. This may be useful to some users who feel their thrust reversers are not engaging fast enough. In the real airplane pilots often manually pull the thrust levers to idle manually quickly during the flare in order to get the reversers activated right as the main landing gear touch down.

 

 

 

Not sure about high idle on flare: it's not present in the T7.

[fabristunt 25]

Thanks Mike, so it's like the ovverride in HOLD/ARM mode (which the 737 also has), but extended to work during the flare mode too. Might come in handy.

 

What about High idle on flare then? Does anyone of the beta testers know it? Maybe Kyle could shed some light on it  :smile: 

 

Cheers,

Fabrizio

[77west 139]

I would think keeping the engines spooled up a bit more on final would allow a quicker acceleration to full power for a go-around, but then, I thought this logic was baked in to the FADEC anyhow, flight idle vs ground idle..

[G550flyer 1,013]

As 77west mentioned, it could be engine accel. The FAA cert is based around going from idle to Go Around in 8 seconds. It's not uncommon. When I flew DC10s, the flight idle(45%) was controlled by the ground sensing mechanism on the nose gear. Kept 45% N1 until the nose strut compressed. The Gulfstreams I fly will enter high idle when flaps go to the landing. It holds high idle for 10 seconds after landing to ensure go around and fast spool for reverse thrust.

[Qavion 19]

The Gulfstreams I fly will enter high idle when flaps go to the landing. It holds high idle for 10 seconds after landing to ensure go around and fast spool for reverse thrust.

 

 

It's similar on the -400. For example, on RB211-powered aircraft, with the inboard TE flaps at greater than 20 units in flight, the engine will go into high (approach) idle and remain in high idle for 5 seconds after touchdown. If the reversers are deployed fast enough, the engines will remain in high idle.

 

If you have a flap problem and the inboard flaps won't extend, you have to use alternative methods to get the engines into high/approach idle.

 

Cheers

John H Watson

[G550flyer 1,013]

All about keeping those big fans spooled for power when needed during landing

[fabristunt 25]

remain in high idle for 5 seconds after touchdown

 

Got it, thanks.

 

But why is it a simulation option then? If the real deal keeps high idle even after the flare, why shouldn't the 747 v3 want to do it?

[fabristunt 25]

*Bump*

 

Come on guys, how come no beta tester know what this is about? How did you test it then?

Please take 2 mins of your time and help me understand this "high idle on flare" thing

[PinkPony 171]

*Bump*

Come on guys, how come no beta tester know what this is about? How did you test it then?

Please take 2 mins of your time and help me understand this "high idle on flare" thing

It's fairly simple. By design, approach idle remains until 5 seconds after touchdown. PMDG is giving us the option to disable it in the flare already. Why would some users want to disable this? Most likely a way for unique hardware/throttle combinations to further override the limited FSX/P3D throttle input.

 

If you want it like it is in the real aircraft, you leave it enabled

 

I can't wait for the Queen!

[downscc 1,327]

What Leo said.

 

This is not an aircraft option, but a simulation option that applies to all of your B744 fleet.

 

If you are not used to it, it is guaranteed to mess with your pretty landings haha.  Keep it on and learn to deal with it.

[fabristunt 25]

Thanks Leo! That's whst I was looking for.

 

Keep it on and learn to deal with it.

 

That's the plan, Dan

 

This is not an aircraft option, but a simulation option that applies to all of your B744 fleet.

 

Yeah, I figured out this much, see my first post.

 

Thanks for your help guys, I'm really looking forward to fly her

[Tabs 2,790]

These options are mainly there to deal with problems people have reported with the NGX and 777 where reverse thrust couldn't be selected immediately upon MLG touchdown. If you experience that issue you'll want to try these.

[rsrandazzo 6,353]

Gents,

 

As Leo pointed out, on nearly all Boeing airplanes, you have a ground idle and a flght idle power setting.  The selection of this setting is run by the airplane and helps to keep the engines from unspooling to a degree that is undesirable in the event you need to conduct a go-around.

 

We have the engine control logic handling this difference realistically- but this puts the sim into conflict with itself because FSX and Prepar3D have some hard coded limitations within the simulators themselves that create problems for highly detailed add-ons such as ours.

 

In this particular case, the approach idle power setting is picked up by FSX/Prepar3D as a signal that says "the throttles are not at idle power" and thus FSX refuses to allow the selection of reverse thrust.

 

High Idle on the 747 lasts for 5 seconds after the airplane circuitry confirms that the airplane is on the ground.  In the REAL 747, you can select reverse thrust during this period of time.  In FSX/Prepar3D you cannot, unless we "under-rule" the high-idle immediately.

 

So... we give you the opportunity to select this ON (in which case you lose reverse thrust immediately on landing, but you CAN select it after the 5 seconds expire) or OFF (in which case you can select reverse thrust instantly upon landing...)

 

Operationally and performance wise, you will be unable to tell the difference, but for simulation value we put this option in there to allow users to decide which approach they prefer.

[fabristunt 25]

Thanks for the explanation Mr. Randazzo. Thank you too Ryan. It's all clear now, I'll experiment with the settings and see what suits me best.

 

I didn't expect a developer to answer my question, let alone two! How's that for costumer care?

PMDG for the win!

 

Regards,

Fabrizio