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Chapstick

Could someone help me understand the gear/throttle relationship?

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When the landing gear is up, flight idle is about 30% N1 When I lower the landing gear, the throttles move and increase thrust to 39% N1. My CH yoke complies with this new idle position. However, if I press F1 I can bring the throttles back to the physical idle position. But as soon as I let go of F1 they go forward again. Is this how the real NG works? I can't find anything in the manuals about the throttles physically moving to produce the approach idle thrust.

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With the gear down, the idle thrust is increased automatically to counter the drag. This is how the real NG works.

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With the gear down, the idle thrust is increased automatically to counter the drag. This is how the real NG works.
Bingo. Also helps spool up time for go arounds and missed approaches.

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Yes yes, I understand that. My question is with specific regard to the throttles actually moving on their own to produce the thrust. I assume it's correct, I just can't find any info on it in the manuals.

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This the so called flight and then approach idle. In reality you will not see movement because the fuel flow is adjusted by the EEC internally. In FSX unfortunately while numbers can be manufactured for display the desired "thrust" effect can only be achived thru the native engine.... Ergo push the throttles a little forward... C' est la vie. Same since NG1, then 744, then MD11 and now this. One does what one can do.

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With the gear down, the idle thrust is increased automatically to counter the drag. This is how the real NG works.
Idle N1 is increased, but the throttle does not move accordingly. Only the minimum N1 which it can command is affected. Kevin Hall

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Yes yes, I understand that. My question is with specific regard to the throttles actually moving on their own to produce the thrust. I assume it's correct, I just can't find any info on it in the manuals.
In the real aircraft the throttles move by themselves (as directed by the auto-throttle) and you should be seeing this happen in the VC. If you add a throttle quadrant on your desktop that had motors in it (like some people do with expensive home cockpits) you would be seeing them move too!

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In the real aircraft the throttles move by themselves (as directed by the auto-throttle) and you should be seeing this happen in the VC. If you add a throttle quadrant on your desktop that had motors in it (like some people do with expensive home cockpits) you would be seeing them move too!
The real throttles don't move when the EEC's command approach idle thrust. As stated by Dr. Vaos in the quote above, they move in the NGX only to get around FSX's limitations.

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Idle N1 is increased, but the throttle does not move accordingly. Only the minimum N1 which it can command is affected. Kevin Hall
Yes, I misread where he was asking about the physical movement of the throttles and thought he was only talking about the increase of the idle N1.

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This what I can find the about the Flight IDLE and Approach IDLE in the 737 NG Training manual. I quote: During flight, the EEC controls engine idle to satisfy idle speed requirements.The EEC software maintains flight idle at 72%. The EEC goes to the approach idle mode (72 - 79% N2) when the airplane is in flight and one of these conditions occur: - Cowl thermal anti-ice switch is in the on position for engine 1 or engine 2- Below 15,500 feet and the left or right main gear is down and locked- Below 15,500 feet and the left or right flaps are equal to or more than 15 The Throttles are at IDLE position. If the Throttles move they are commanded by the A/T computer to maintain Approach speed.

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Ah! Does this mean that if we have selected A/T OFF and still seas the thrust leavers moves slightly forward to aprox 40% N1, even you are low level (maybe 2000 feet) this is A/T which overrides your descision of idle thrust at that situation? If YES; the PMDG is modelled in a fantastic way. I thought it was a bug, and I have moderate to good knowledge about the 737 NG : )

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NO !!! When the A/T is OFF the Thrust lever's stays at IDLE when you move the thrust levers to IDLE. What you ask is what you get at 737NG !!!!. (IT's NO AIRBUS).Only when the A/T is ON, During approach the A/T system is in the MCP SPD mode. When the A/T notice that the airspeed is lower than the MCP speed, the A/T computer commands the Thrust levers to give more power to the engine's to maintain the commanded MCP speed.

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As you (ajacied551) tell, so I thought it was! The post above was confusing me! PMDG NGX is actually adjusting the thrust leavers at approach if your speed is falling rapidly (in example if you are high and hot and try to reduce your speed by adding drag and setting idle thrust). I just checked it and I see the thrust leavers moves a tiny bit and adjusts the thrust from 30% N1 to aprox 40% I underline: The A/T is _OFF_! Any developers? Or pilots? Anyone who knows the correct answer? It is correct that the thrust is automaticly adjusted (with A/T OFF) or should it remain completely still? If so, the NGX has a little bug here! : )Otherwise: I love this product! Very good made with many of the real NG features on!!

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I've found that if the idle thrust is increased on e.g. gear extension, it does not automatically restore to a lower idle on gear retraction. Best regards,Robin.

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I've found that if the idle thrust is increased on e.g. gear extension, it does not automatically restore to a lower idle on gear retraction. Best regards,Robin.
It does but make sure your physical throttle (joystick) is at idle. Has to be less than new lower minimum. It diid not on the old NG, the 744 and the MD.

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This could also be connected to a setting: "OVERRIDE IN ARM MODE". I have this mode selected in the option meny (in CDU). Then it is most like the real plane for my opinion. Still, it is not clear if the real a/c does command the thrust leavers even if the A/T Is off or not! So it is in the PMDG and I try to find a answer on this. A pilot on ppRune told me that the A/T will NOT command any thrust leavers movement unless A/T is armed or in an active mode! THerefor, this CAN be a bug!

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Okay! So how I understand it; the EEC commands higher N1 (approach idle) when gear is selected down. How to get this in FSX is to make the thrust leavers physically glides forward. So therefor the NGX is correct modelled also here! You will have 30% N1 with gear up and almost 40% N1 with gear down (approach idle)?I will ask some pilots and do some more testing in NGX when flying around at my scheduled legs : )NB! This is not for trying find some bugs, this is just for interest and wondering if I do something wrong or the program is modelled slightly from the real behaviour of the 737. FSX limitations heard realistic to me : )

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To Clearify how the real A/C work's, When A/T system is OFF the thrust levers will not move automaticely. When the A/C is in air the EEC (Electronic Engine Control) will calculate the engine to flight IDLE (72 N2) when the thrust levers are at IDLE and it will not move, When the A/C goes to approach mode (gear down etc.) again the EEC will calculate the engine to approach IDLE (72 - 79 N2) and still the thrust levers are at IDLE and it will not move.

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During flight, the EEC controls engine idle to satisfy idle speed requirements.The EEC software maintains flight idle at 72%. The EEC goes to the approach idle mode (72 - 79% N2) when the airplane is in flight and one of these conditions occur:
Just FYI, the NGX doesn't do that. A reason could be, well just increase thrust manually to 72% N2, this might result in rather large thrust setting so maybe it's a limitation in order not to overpower the aircraft under these conditions.
I've found that if the idle thrust is increased on e.g. gear extension, it does not automatically restore to a lower idle on gear retraction.
I've found the same and reported it to Ryan about a week ago.
It does but make sure your physical throttle (joystick) is at idle. Has to be less than new lower minimum. It diid not on the old NG, the 744 and the MD.
Sorry Dr Vaos, it does not, at least not for me. I asked Ryan about this, let me quote from my inquiry quick:
[...] the engines won't go back to flight idle. They seem to "forget" about the hardware joystick throttle position in that very moment. You could for example flick the hardware throttle forth and back quickly to get them back to flight idle. Would there be a possiblity to momantarily "check" the hardware throttle, once approach idle conditions are no longer met, in order to get the engines back to flight idle automatically (assuming the HW throttle is actually at its physical idle stop)? [...]
When you say it should do it, is this something it does in the background? Well as I said, I don't currently see it working here, but I'd certainly like to know. My hardware throttle was definately at its physical aft stop during testing. Thanks, sig.gif

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Etienne, I coded in this particular thing so I know what it does. Make sure your throttle is well calibrated though.

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I coded in this particular thing so I know what it does. Make sure your throttle is well calibrated though.
Ah ok - didn't mean you didn't know what it did LMAO.gif, so it in fact DOES check for HW position once flight idle conditions aren't met anymore?Not sure what to calibrate with my joystick though, I've had this MS SideWinder FF2 for years, just plug in and go. Never messed around with it in any way. Throttle seems rather precise at least. Will see what I can do. sig.gif

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Press F1, slam back. The panel must read hardware throttle less than new minimum.

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