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kevinh

757 and 777 engine out too problems

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Normally I don't bother much with inflight engine shutdowns, but I thought I'd try one out on the 757. When I shut an engine down there was no sideslip and hardly any asymmetry, even if the other engine was at full power. The sim just rolls a little into the failed engine. I checked this on the 777 and it's the same.Autopilot was off, FS9 auto-rudder was not selected. I tried yaw damper on and off but this made no difference to the 757. The 777 yaws more with Y/D off. Even with Y/D on, the aircraft should enter a tightening spiral unless controlled with rudder (disregarding the automatic thrust asymmetry system on the 777 which is not simulated by PSS).I know FS9 is weak when it comes to lateral aerodynamics, but I would hope to see a bit more yaw given such high thrust asymmetry.Kevin

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Kevin,I personally never tried assymetric flight with the 757 but do recall hearing on the 777 that in real life the pilot wont know much difference (performance aside) since the systems autocorrect everything anyway.I will bow to others with more knowledge on this than me though!

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Kevin, Oddly enough, I tried the same thing a few days ago just to see what it's like. Well, it didn't go so well for me. I was yawing all over the place. So yes, the asymmetry did occur for me. I'll tell you what, I have a much greater appreciation for pilots when an engine fails/is shut down. I don't know how they control it. The slightest adjustment to thrust and whammo, more yaw. I was able to get it controlled enough for a landing...after one go-around. Not a graceful landing by far but, I did land on the runway and my descent rate was ~200fps. When I did have to go-around the first time, application of max thrust required almost full rudder deflection to stay straight, so I know the asymmetry is modeled. I am using CH yoke/rudder pedals which makes it easier. Anyway, what model/airline were you flying? I used UPS 757F PW engines. Also, what hardware do you use? After simulating an engine shutdown, verify that you are still flying straight and jump to the spot view just to be sure that the A/C isn't being auto-trimmed in some way. If the rudder is deflected, you know that the A/C is compensating in some way. Check all FS9 settings. Make sure all realism sliders are at max and (I know you already checked) that auto-rudder is indeed off. I have noticed that FS sometimes has an annoying tendency to revert to previous settings. This goes way back at least to FS98. Anyway, I hope some of this helps. I'm sure this is easily resolvable.-adam

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AdamI'll try again and double check the settings. FS9 does do strange things, thats for sure.For asymmetry the trick is too keep power settings as constant as possible, that keeps the trimming to a minimum. Go around will be an exciting ride of course. In the real aircraft you get a load more cues, so it can actually be easier.Norman,You are right, it is a non event in the 777 aircraft, as long as the auto rudder trim is working. Sadly PSS didn't implement that...Kevin

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Double checked and all the realism sliders are at max, autorudder is off. Still get very little lateral asymmetry. I tried the default Beech Baron, and that responded in a more realistic manner. I also tried the PMDG 744 and the LDS 767 and they also show the thrust asymmetry problem on my set-up. Anyone any ideas what might be causing this with add-on aircraft?Kevin

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Kevin:I have tried engine out with the 777 several times with no noticeable yaw, including approaches and landings. The yaw damper was activated, which probably handles the idiosyncracies of FS.The real 777 has a Thrust Asymmetry Compensation System which automatically applies correct trim rudder so the pilot can basically fly "feet on the floor". I have seen demonstrations of this system (in the full simulator) and it operates flawlessly, even at V2 at full gross weight.Steve Weixler

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Steve,If you read my first post, you'll see I was aware of the 777 thrust asymmetry compensation system. I've had the opportunity to try the TAC in a 777 FFS and as you say it works perfectly, almost completely countering thrust asymmetry. Just like selecting auto-rudder in FS9 in fact. :)Yaw damper should not have much effect on engine out yaw, but it does in MSFS. The yaw damper has limited authority and is intended mainly to damp out dutch roll oscillations.It seems lack of thrust asymmetry is a weakness of most FS9 add-ons, but strangely the default aircraft respond more realistically. Not sure why this should be. Only the FS9 FDE gurus could answer. Perhaps they think the default aircraft are too sensitive directionally?Kevin

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