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Guest pierre974

PSS 777 issues

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First of all, this is not a post aiming at criticizing PSS, but a review of annoying issues after version 2.1.Good points - remarks :-VNAV seems to be rock solid now, but FL CHANGE is leading to weird vertical behavior.-LNAV is acceptable, but there is a problem again with pronounced turns - unlike other add-ons, tough turns are not smooth and anticipated, and you often find yourself overshooting the intersection.-No more problem with overflying the destination airport (circle to land) - end of route is no longer displayed and you can pursue the approach.-No more CTD freezing problem (on my PC) - congratulations PSS.-Fix page can now be used.Bad points :-Odd trim settings given from the CG determined by the load editor - from the exterior view the trim position is weird and you can feel the problem on take-off.-The major problem is a landing issue that is known since the airbus series - you have to cut the throttle very soon (above the DA/DH - which is quite unrealistic) if you don't want to float over the runway upon flaring. Your speed is dangerously diving below your VREF but the aircraft is not stalling (unrealistic again). If you decide to cut the throttle as it should normally be cut (say between 50 and 30 feet radio) then you condemn your aircraft to a long floating journey over the runway before touching down far from the piano keys...-The "woopwoop" warning sound has changed but is still there.There are other unsignificant issues, but the above are the major ones from my point of view. Considering those oddities and strange behavior, my 777 is like a broken toy and is parked to its hangar.

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Pierre,I wasnt able to match a purchase against your name. Trim settings, certainly on the 772LR, match the load sheets I have here. Floating - Triple7 made a very good post a few weeks ago about floating.

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Pierre, I have not experienced the 777 floating. Was this a problem before SP2, just curious because I have not yet installed SP2? The PSS 777PRO is a good addon, though I have experienced a few pesty bugs, over all it is not a bad product and I NOT parked my T7. Thanks to all at PSS for your hard work in bringing to life my favorite aircraft.John Urry

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"The major problem is a landing issue that is known since the airbus series - you have to cut the throttle very soon (above the DA/DH - which is quite unrealistic) if you don't want to float over the runway upon flaring. Your speed is dangerously diving below your VREF but the aircraft is not stalling (unrealistic again). If you decide to cut the throttle as it should normally be cut (say between 50 and 30 feet radio) then you condemn your aircraft to a long floating journey over the runway before touching down far from the piano keys..."i agree with every word you said.

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The 777 is not perfect by any means, but post patch 1.1 flies pretty well for a FS9 add-on.Note, Vref is not the stall speed, it is 30% above that. So if for example Vref is 143 knots, Vstall is 110 knots. So in this example you are going to have to lose 33 knots before stalling (you should hear the stall warning long before this of course, just before you enter the buffet region on the speed tape). Clearly as you flare, speed decays to below Vref. In fact you should be at the threshold at something like Vref+5 to allow for this, depending on wind allowances, etc. If you flare too much or too fast you will float.I haven't verified where the stall warning and stall speed are in landing config yet as it's not a problem I've noticed, but I'll look closer at it when I get time. I've never seen the landing problems you describe on any of the PSS add-ons I have (and I have most of them). I can land them in the TDZ without too much trouble, but I don't expect too much fidelity from FS9's ground effects and stall modelling. You simply can't expect exact "as aircraft" landing behaviour in a FS9 sim. It will be closer in a full flight simulator with proper data, but still not exact.The only generic problem I see with PSS sims is that for whatever reason, they are prepared to accept FS9 limitations, whereas the likes of PMDG and Level-D have found ways to get around them.Kevin

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>Pierre,>>I wasnt able to match a purchase against your name. >Are you accusing me of piracy ?That is ridiculous ! I've paid for the 777 as soon as it was available and I still have access to the exe. download in the members/my files page...Disappointed regards.

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>Are you accusing me of piracy ?No, I am not. What I am saying, is that based from your name I couldnt find a purchase - nothing more sinister!I hope that Kevin's post above (and the one by Triple7 I mentioned) were able to answer your query however.

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Another issue that I forgot to mention is the taxi behavior with a light loaded aircraft. As soon as you release the parking brake, the aircraft starts accelerating even without applying any thrust (throttle is on idle position).You have to apply brakes during taxi if you don't want to reach the taxi speed limit. Maybe not a major issue, but an oddity for sure...

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Pierre,In FS (certainly as far as version 9 is concerned) there is a delicate balance between too much / not enough power between the ground and the air. Make the aircraft more slow (or sticky I guess) on the ground and this will have an adverse affect on its air performance. The opposite is then also true.

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I had a closer look at the 777 landing performance tonight. Flare and touchdown look about right to me (not that I'm a 777 pilot, but it does what I'd expect), as long as you don't overdo the flare. Just pull enough to slow down the descent rate, as aircraft. Then it will touch down on the numbers at about Vref. No worries.There is a problem with stall warning and stall speed though. As I said, Vref is 1.3 Vs. On the PFD the bricks should start at Vs. The buffet speed (amber), also where stall warning will occur, should be at about 1.2 Vs. On the PSS 777, the buffet boundary starts at what should be Vs, with the bricks a few knots lower. If you let speed bleed off, you won't get a stall warning until this buffet boundary speed is reached. In fact the stall warning should sound at about 1.2 Vs, giving you plenty of advance warning.In my example above (Vref = 143), Vs was 110 so stall warning should occur at 1.2 times 110 = 132 kts. What you get is a warning at 110 kts, with stall very soon after. Stall speed is a few knots low as a result of this mistake. Of course if you fly properly you never get anywhere near this point, but it still looks very wrong on the PFD. The amber box should extend up two thirds of the way from the bricks to Vref.To summarise:...........Aircraft.......PSSVref........143.........143Vsw........132.........110Vs..........110.........105 (ish)I've called the buffet/stall warning speed Vsw for the sake of brevity, not sure what the real nomenclature should be.This is greatly simplified, but the fact remains stall warning is set too low, and the stall speed is slightly too low as a result. Obviously I've only checked one configuration, but I expect everything is affected. For a quick fix, leave the stall speeds as they are and get the stall warning speeds/buffet boundary correct.Kevin

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Clayton,I have had that behaviour too during my 3 "test flights" I've done with the SP2 but I assumed it was due to the 772LR being more similar in its "gliding" ability (due to better aerodynamics) to the airbuses (which also speed up and glide and I've read from experienced flightsimmers and Airbus pilots too that it is NOT unusual to use the spoilers when approaching to reduce speed). So I just assumed that I just had to get used to handling the 772 which I've flown very little due to that annoying CDU freeze and have never flown online on VATSIM. I have flown mostly the 744 and the 737-700 by PMDG recently, both of which really "sink" if your N1 % is anything less than about 60% whereas the 772LR needs a much lower N1 (roughly around 45-55% on final) to reduce its speed as required all the way down to VREF (or VREF+5 which I use to leave an extra safety margin against stalls).So I'm with you about going below the VREF and not stalling-I did notice that. But for gliding and going too fast, I think, we have to slow it down with the spoilers. I also use the technique of simply deploying flaps sooner than indicated on the flap retraction schedule (on the HSI) which helps greatly to reduce speed.John

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John,I wouldn't like to say how accurate the PSS 777 drag model is, but it is well known that the 777 is a very slippery shape. Therefore the same engine N1 numbers that work for a 737 or a 744 will not necessarily work for a 777. It would not be surprising if less N1 might be required to maintain vertical speed for the 777.As for Vref, it is not the stall speed, so drifting below it will not cause a stall, until you get right down to Vs. If Vref was the stall speed, you would not be able to manoeuvre.My personal feeling is that over-emphasis on flying to the numbers (especially engine settings) will not get the best out of the sim. It's FS9 after all, a compromise and only an approximation to the real thing. It is perfectly possible to flare and land the PSS 777 in a representative way, even if N1 might not be quite right. If you get near to stall you didn't fly it right, it's not the sim's fault. You cannot expect to be able to use the same landing technique as you use for the PMDG 747 and 737 sims. It has to be said that this applies to real world flying too.Slowing down with speedbrake on approach is to be avoided. I was in the jump seat for a 747-200 approach once, and the pilot managed the deceleration entirely using well timed flap and gear extension. No speedbrake and with constant thrust lever position down to the threshold. Lovely to watch a professional at work.Kevin

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Thanks Kevin for the info.Actually, I know Vref is not the stall speed, just a fear I have of going too slow in case of the sims inaccuracy, it's better to be a little fast than a little slow because once you stall at or below 500' AGL, you're pretty much done for...I am aware you don't fly the 737 or the 747 like the 777 or the A330/A320/A340 Airbuses, and that was what I was pointing out actually. But it's good you confirmed the "slipperiness" of the 777, so my info on that was correct.Interesting about the 742 captain using flaps for that's what I've found works the best. Do you remember by any chance if he deployed them DIFFERENTLY than what the flap retraction schedule would have been? (as the 742 does not have an automatic/LCD HSI but manually set "bugs" for the speeds - knowledge I owe in whole part to Ready for Pushback's great model!) In other words, did he use flaps to slow down even if it was BEFORE the flap retraction schedule (as long as he was below the max. speed for that flap setting)?I'd like to know that, out of sheer curiosity.Thanks again,John

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