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ghiom

Autothrottle response time

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HiI am still a big fan of the 737NG.Old but good.However, I don't like the response time of the A/T. It takes too long (especially at x4 simulation rate) to decrease, when descending. It often result in overspeed.I was wondering whether the ACS.ini could be tweaked (or some other file) to have quicker A/T response?Also, the NG is difficult to descend below 10,000ft. With LVCH and 250knots, it goes down clean at 1200 ft/min. It is normal?Because of the ATC control (using RDC4), I need much quicker descents. What could I do to allow this, with compromise on realism, if necessary?I was thinking of reducing engine idle thrust. How to do that?Thank you.PMDG: don't let the NG down. It is still the best and must remain so.RegardsGhiom

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Ghiom,>However, I don't like the response time of the A/T. It takes>too long (especially at x4 simulation rate) to decrease, when>descending. It often result in overspeed.It is probably the engine response you are questioning. A gas turbine response will lag after a throttle change. Besides I don't think the NG is certified for x4 simulation rate (or even x2). >I was wondering whether the ACS.ini could be tweaked (or some>other file) to have quicker A/T response?You may do that on your own risk. But be aware that the PMDG NG characteristics are very true to what you would see in a real NG.>Also, the NG is difficult to descend below 10,000ft. With LVCH>and 250knots, it goes down clean at 1200 ft/min. It is>normal?Yes. Planning ahead is crucial if you are descending manually (without VNAV).>Because of the ATC control (using RDC4), I need much quicker>descents. What could I do to allow this, with compromise on>realism, if necessary?>I was thinking of reducing engine idle thrust. How to do>that?Without compromising realism you might deploy spoilers to add drag, even some early flaps and even gear to slow down if you are high and hot. But as stated above you are best to plan ahead so you are aware were the aircraft will be at a future point. Hope it helps,


Mats Johansson
PMDG Flight Test Dept
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| Asus Z270-A | Intel i5-7600K @ 4.8 GHz OC/H2O | nVidia Geforce GTX 1070 8GB OC/O2|

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Thank you for your reply.The 737NG works well at x2 and x4.For those who have little time to spend. It is nice to have this facility for long range cruise.Can you tell whether the gas turbine response time can be lowered, even if against realism?Thank youGhiom

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Ghiom,>Can you tell whether the gas turbine response time can be>lowered, even if against realism?I could, but then I'd have to kill you. :-) Seriously. I've never changed anything regarding flight characteristics so you're on your own there.Hope it helps,


Mats Johansson
PMDG Flight Test Dept
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| Asus Z270-A | Intel i5-7600K @ 4.8 GHz OC/H2O | nVidia Geforce GTX 1070 8GB OC/O2|

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<I have found that I can achieve descent rates in excess of 200ft/nm by slowing down to (for example) 230 KIAS below 10,000. Remember, it is not only your vertical speed (Vft/min) but ground speed (Hft/min) that affects descent rate (Vft/Hft). The easiest solution to high decent rate requirements below 10,000 is to not use VNAV. It seems to hold you above 10,000 as long as possible or longer before the decent for final approach, then asks for drag to go down the profile it has in mind. I usually start down much earlier than the VNAV profile and when done well will see 800 fpm all the way to the final approach fix.


Dan Downs KCRP

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