deuzx

Hello everybody!

To make it clear! I am not an airline pilot, but playing NGX simulation software for FSX. If you want to fire, just come with it : )

The NGX has high realism, but I just wonder if I found a bug in the software. When flying an approach and near sealevel the flight idle thrust for an 737 800 should be aprox 30% N1. What happends sometime is, when I am trying to reduce the speed fast from 170 IAS to lets say 140 as my REF SPEED, the thrust leavers sometimes glides some cm away from mechanically IDLE point and therafter the N1 increases from 30% N1 to aprox 40%. I have to manually hold the thrust leavers down towards idle to come down at speed fast enought.

This problem applys when flying steep approaches like 3 degrees ILS`es and 15-20 knots too high at speed and I try to dramatic reduce the speed in a hurry. It seems that either the real a/c has some form of protection agains a low speed condition or otherways the NGX simulation has a program bug. I belive the last, I am just interested in checking out what is the true here.


Does anybody like to give me a tips; is this real 737 NG behaviour or should the thrust leavers in ANY circumstances NOT be moved by A/T without A/T is on?

To make it clear; when this happends A/T is off! The switch is DOWN, and NO annonciation for A/T in FMA.

If A/T is engaged (as normal) A/T has no problems with commanding flight idle and thats around 30% N1 as seen in the picture below:

STBYRUD

For the record: N1 below 40% below 1000ft is a criterion for an unstabilized approach in our outfit Anyway, if the A/T is off, the servos are inhibited (even if the thing is is on and in ARM), there can be no motion of the thrust levers. However that does not mean that the idle N1 does not change:
The EEC will command approach idle when landing flaps are set, TAI is in use or when the EECs cannot receive signals about flaps or TAI below 1500ft. N1 and N2 will increase but the thrust levers will not move, and you have no way of going back to flight idle manually. Perhaps PMDG cheated a bit and simply bumped the thrust levers forward to simulate this? No clue.

deuzx

Thank you for anwering!


I know, N1 below 1000 feet is an non-stabilized situation. So are excessiv sink rate also, I use to take this into consideration also.

I will check what happend in the NGX when turning on TAI or extending landing gear and watch N1 indications closely. Some of the most hard core simmers who also really care about problems like this, told me it could be an FSX limitation, which leads to mandatory thrust leaver movement by the AP for simulating new ground idle. It would be strange if this really is necesary but I really dont know the limitations of the program codes.


By the way, 60 tonns, flap 40, approach speed at VREF+5 lead to 59 % N1 for maintaining speed and 2.5 degrees g/p! I think the engines and model is awesome modelled, something totally other than the old PMDG, which many pilots know about : )

STBYRUD

I want to try it out, sucks that I don't have a gutsy system to run it on at the moment... Anyhow, why should I fly the thing in my precious time off anyway - 59% N1 sound a bit low actually in that situation

deuzx

Hehe, If you fly the 737 maybe flying it in sim shouldn`t be the most interesting thing, but maybe. Give it a try if you allreaddy have FSX innstalled. It is really amazing what it simulates: In air right before some clouds and showers I turned on anti ice and start switches cont. Then the message "TAI ON ABOVE 10 DEGREES" was shown in the sq.pd. It was 11 degrees C outside, very nice that they take every small tiny element included. "SINGLE FMC OPERATIONS" "DUAL FMC OPERATIONS RESTORED" "EXCESS MOVEMENT". It simulates a lot.

59% was maybe too less. Maybe I sneezed and pushed the yoke and a/c -3 degrees and the A/T followed on ; ) Seen 60+ N1 at finale with flap 40.

Cap. PiSkiS

Had the same question regarding the throttles, I guess is the way that Boeing/PMDG managed APP IDLE power, on Airbus as soon you select flaps 1, you get and increased thrust on the instruments only, as the throttles are not mechanical driven, I figured out that when selecting flaps 15 and/or Ldg down you get that increment from the throttles, I put the PMDG on a hold a 10,000 ft over the water, and then push FL Change down to 3000 ft with A/T on (or off is the same) and manage the speed toward flaps 15 and between flaps 10 & flaps 15 you would see that throttle increment, same with gear up and down, hope you can see the same.

best rgds.

5420N

With all the support that PMDG provides, I would recommend asking on their forums.....

Are you sure it's not an interface problem (Joystick?)

Cheerio

deuzx

I can see the same. The a/c is behaviouring like that A/T is on, even it is turned off. This has nothing to do with the joystick. In NGX A/T is programmed to override any joystick input, whatever the thrust at the joystick is set on. This is an option in the PMDG NGX menu. I also tried to disable the joystick, and the problem still exists.

Thank you for clarifying! I will take this with PMDG from now, I know the thrust leavers does not move without A/T on