757 v1.3 Impressions

[Guest nivenjr]

I thought you might like to see some RW performance figures for a RR-powered 757-200 (RB211-535E4). I noted these during the climb over the last few days when I got the chance, we were using a CI of 27-29 and I've noted the brake-release weights.TOW 97.5 - SL-330 21 mins, 2.7T burnFL 200 1700fpm@300kts (CLB1)FL 250 1600fpm@ "" (CLB1)FL 300 1000fpm@ "" (CLB1)FL 350 800fpm@M.078 (CLB1)TOW 91.4 - SL-370 20 mins, 2.5T burnFL 150 2400fpm@300 (CLB1)FL 200 2100fpm@"" (CLB1)FL 250 2100fpm@"" (CLB1)FL 300 1500fpm@"" (CLB1)FL 350 1300fpm@M0.79 (CLB1)It's difficult to get low level figures as it is quite busy but at 92T the 250kt climb rate today was about 2700-3000fpm, the initial climb (V2+15) rate is generally about 3000fpm at these weights.I hope this will help clear up whether the RR 757-200 performance is accurate.James Nivenps I'm a 757/767 pilot for a UK charter airline, that's how I got the information.

[zementa 0]

I have take your first One for a Test in the Sim(No Weather)97.5tfrom 200ft-33000ft in 13min 250/300/.78 with CLB1Looks a little different if you ask me!!! :-) Ralf

[philbrown 9]

Tried the second flight:PSS 757-200 RR (RB211-535E4B). FMC CI 28.TOW 91.4 - SL-370 15 mins, 2.1T burnFL 150 4250fpm@290 (CLB1)FL 200 3600fpm@"" (CLB1)FL 250 2750fpm@"" (CLB1)FL 300 1750fpm@"" (CLB1)FL 350 1150fpm@M0.79 (CLB1)250kt climb rate 4100fpmAt TO1 power, blasted through V2+15 before I could pitch to maintain it. Had to climb at 6000fpm initially to reduce the speed. Then engaged VNAV, at which time I had already passed the acceleration height and the aircraft pitched down to accelerate to 250kts.Just looking at the numbers, seems it's overpowered at low altitudes. Any thoughts from PSS?

[ghiom 2]

I fully agree with you. I ain't no real 757 pilot.However, I notice that the 757's engines tend to loose their power too quickly as altitude increases. This is not the behaviour of other sim aircraft. I barely climb at 500tf/min at full CLB at 31000ft, even at low weight when the optimal CRZ alt is FL370...Is this normal (again)Apart from that, I must admit the PSS757 is a very nice A/C to fly, especially from the very fluid VC. Too bad a few minor glitshes remain here abd there. Nice job PSS.Thank youGhiom

[Guest dmelia]

I've had the PSS 757 since it first came out. It has some irritating little glitches, but nothing earth shattering. As far as performance is concerned its pretty much bob-on. The real world RR engined kite is notoriously over powered and requires the proper calculations for derated t/o and climb - so does the PSS and if you do it right, it does it right too. As for VNAV descents, well, again, both the 757 and 767 are difficult to keep on the profile and again constant monitoring of what the aircraft is doing and compensating for it, works well for me. Stay ahead of - and in this case below - the aircraft. What you need to remember is that these aircraft are particularly slippery, and not easy to slow down when your coming "downhill". Those of you that are experiencing pitch changes on VNAV, this is probably because the aircraft is trying to keep the speed down, ALSO, its almost impossible to SLOW down and FLY down at the same time, so plan for that - its no good tipping the nose over at 315 knots, you're asking for trouble later on, and worse, lower down. Slow her up first, set a fix 5 or 6 miles shy of TOD, set a speed constraint of 280 at most, and she'll handle the VNAV much better. if shes coming down at more than 2200fpm, she wont be able to maintain the speed restriction, so either decrease the V/S or make judical - and gradual - use of the speed brakes.One point I DO agree with. some speed and altitude/height restrictions set agains waypoints don't seem to work correctly. I believe this is because the FMC calculates its TOD expecting a constant rate descent, and a height constraint - or a drastic speed constraint causing a significant change in pitch, puts a "lump" in the descent profile, and this shows up as a departure from profile as you approach and pass that waypoint, and maybe some unexpected pitch changes. The point is this. Descents are not just a matter of pushing the nose over. You've got speed restrictions to worry about, and ATC alt/height restrictions to worry about too. Get some decent charts - navigraph is fine, search the web for 767/757 material on descents, particularly constant rate descents, and when you're prgramming your route, check what constraints have been placed on the waypoints, change 'em if they don't look right. Remember the guys preparing the AIRAC files we all import, are just as prone to mistakes as the rest of us. Check, double check, recalculate, check again and ask your F/O to check it again. 757 crews often spend more time in dispatch than in the cockpit!I paid about

[FOD 23]

DMCareful

[ghiom 2]

Thanks for supporting my observation on climb at high altitude.Hope PSS will fix this.What is the small tweak you are referring to?ThanksGhiom

[FOD 23]

Up to PSS but as I said "irritating but not earth-shattering".Perhaps there are more important things.The tweak was a small change to the FDE but as I have no idea how it affects anything else, it would not be fair of me to pass it on - I only did it for my own education.John R

[ghiom 2]

I would rather see a better targeted speed hold.As already mentioned, the AP does not control the speed correctly, always a few knots below.Thanks PSSRegardsGhiom