PSS 757 - a series of question about its future

[ghiom 2]

HiI really love the 757-200 Virtual Cockpit. It is too bad that this plane were to be abandoned...Has someone recover the source file for the gauge programming and VC design?Among the things which I am sure could be fixed easily:1. MCP speed target hold (always a few knots below during climb)2. VNAV descent (maybe?)3. Star insertionNow a question:I was taking off from KCLT, Empty weight was 180,000Lbs and 14,000 lbs of fuel and a CoG at 20. With TO-2/60

[FOD 23]

Hi Ghiom,Firstly, if you read the posts here you will see that no one knows what is happening to PSS and the 757. At the moment,all we can do is wait. To your second point:"With this, I would have stalled right after V2...Not sure why; who was flying the aircraft? I have just flown this profile in both PW and RR versions and saw no tendency to stall. If you could you explain in more detail exactly how you fly the TO and initial climb, I will try and help.RegardsJohn R

[ghiom 2]

>Hi Ghiom,>>Firstly, if you read the posts here you will see that no one>knows what is happening to PSS and the 757. At the moment,all>we can do is wait. Yes, that is what it seems.I thought maybe you guys may know better.>To your second point:>>"With this, I would have stalled right after V2...>>Not sure why; who was flying the aircraft? I have just flown>this profile in both PW and RR versions and saw no tendency to>stall. If you could you explain in more detail exactly how>you fly the TO and initial climb, I will try and help.With the weight and conditions mentioned before, I set the trim at 5.5 (and not 7.5 as advised by the FMC. The load tool advised my CoG was at 20%). The TO rate was TO2-60 with some 15

[FOD 23]

Ghiom,Try this little exercise for me:1. Same ZFW and fuel weight. Us the PW variant {less power; easier to control}.2. Normal TO using derate 2 as before but leave the gear and 15 flap down. Climb to a safe height say 2000 ft and level off.3. Reduce speed in level flight to VR trimming all the time to reduce the load on the stick.4. When you are stable at VR and 2000 ft trimmed hands off; note the trim position.5. What do you see? We can then compare.John R

[ghiom 2]

180,000 lbs + 20,000 of fuelHere are the results:I am on A/P, flaps 15, gear down,at Vr (142 knots)Trim at 6.8-7.0 compared to 7.25 proposed by FMC after entering a CoG at 21%.Is this what it should be?Note that during take-off, speed reduced down to 130 knots after rotation, although I pushed the stick to try and maintain a pitch attitude compatible with V2+10...Thank you for your help, againRegards, Ghiom

[FOD 23]

Hi,You did not need to be in AP as we are looking at manual flying. However, the trim figure is about right for the configuration.I believe that the gauge is programmed to select a desired trim so that the aircraft is trimmed out on take off for the V Rotate speed. This ensures the best pitch control at the most critical point of the take off in order to achieve rotation using the correct technique. If a different trim is set you have the following:1. Nose down say in this case 5.0. It will be more difficult to rotate the aircraft at the correct speed and it will tend to stay on the ground.2. Nose up say 8.0+. The aircraft will tend to rotate too early / fast and will tend to lurch into the air.Now, if you use the trim setting from the CDU, as you lift off and the aircraft accelerates you will either have to hold forward pressure on the stick to stop the nose rising too fast or you must trim nose forward. If you do neither and leave the aircraft to its own devices, the nose will slowly rise and the speed will begin to reduce. All this is straightforward aerodynamics.So when you take off now, anticipate the nose rise and gently push forward, trimming forward as necessary, to control the pitch attitude to maintain V2+10. I do not select the AP until the gear is up and I have started raising the flaps.The 757 has plenty of pitch authority and there is no problem maintaining the attitude that YOU want; not perhaps the one the aircraft thinks that you want.One final point, I assume that you are using the standard FDE and a joystck for control?Good LuckJohn R

[ghiom 2]

Yes, I am using the std FDE and a joystick for controlBy the way, I can achieve good t/o control with the PW and flaps 15.Maybe the overpowered RR is too tricky for me...In any case, I will follow your advice as best as I can.For your info, I don't have such issues with other addons...For me, the 757 PSS is the best addon for descent control (decelerates easily) and worst for climb, without mentioning the target speed maintain issue.Thank youRegardsghiom

[FOD 23]

The RR is the one that many people have problems with {you will recall the comments from RW 757 pilots on the original Boeing forum}But as long as you realise the excess power at low AUW, you can handle it. The key is to anticipate and fly the ADI itself because the FD can lag and lead into a diverging PIO type situation.And of course do not expect to get it right first time "practice makes perfect"Happy LandingsJohn

[Guest brianshepherd]

Hi everyone. Interesting topic.I've just started flying PSS 757 RR.I've noticed that just at VR the nose lifts without any assistance. My ZFW was 166.6 with 27000lbs in fuel,128 passengers Front cargo 4000lbs and rear 5000Lbs.My trim was 7.5 with CG at 20%. According the load editor that comes with v1.3.Is this normal for this type of aircraft, It also seems to accelerate very quickly when airborne and I can get behind the aircraft especially with flap speed, what is the typical angle of attack for climbing. Should I be adjusting the trim in climb out ?? nosing forward increases the speedAppreciate any pointers tips that you have, RegardsBrian

[aentwis 61]

I am learning fast from reading about real world operations with the 757, and the Rolls Royce powered variants, that the aircraft has been given masses of power. It is very seldom that full takeoff power is used, with normal operations involving some derating of T/O and CLB power...Climbs of up to 6000ft/min are possible at low TOW, so it is a common practice to derate: dial in an assumed temp higher than the current ambient, in order to derate the engines... it is also good practice in real life, prolonging engine life...Now, calculating the assumed temp is a bit of a dark art it seems, being based on several factors. In particular, it is often airport specific, depending on TORA, air temps, pressure alts and so on...Check on the Net for 757 derated takeoff or similar... but you can play trial and error in the sim to see what figures work best for you at airports of your choice...Andrew

[FOD 23]

Brian, Sorry I missed your post earlier. What you are seeing is correct. Try this little exercise.Using the same configuration, take off normally with auto throttle but leave the gear down and 15 flap. Level off at a couple of thousand feet and engage the AP selecting alt hold, speed and your VR speed {about 134?} on the speed selector.Let the aircraft stabilise {use airbrakes if necessary to reduce the speed more quickly}. Once you are straight and level with the speed stabilised, check the trim setting. It will be the value calculated by the FMC and you will have a pitch attitude of about 8 degrees.So, on take off, as the aircraft accelerates towards VR with the pilot