Boeing Climb Thrust!!!!!!!

[ktroemer]

Hi Folks!

Have to add a few lines here coz i still have the same problem with the clim thrust and maybe someone here can help me now.
I work with FS9 and all the lates PM software as well latesr FSUIPC.
But my problem is the climb thrust. Whatever i do and what kind of settings i use, my 737 always runs into overspeed!!!
I can remember times where the clim automatically limited to 272 kts but even when i reduce the speed in the CLB page the plane follows full thrust set and dont reduce even when it comes to overspeed. when i enter 272 kts in the CLB page ...no effect.
I have also tried the different speed protecion settings and a roll back to a former MCP or CDU build but no effect.....
I think i have some mistage in my planning or i have forgotten to switch on something...
Does anybody have or had the same problem and how can i solv it???

Many thanks to you guys.....appreciate it much..!!

All the best to you all fellow simmers and thank you for your help

Regards

Klaus

[Geremy Britton]

as far as i know the 737 will run into overspeed unless you reduce the throttle after takeoff a little. you should only have full power or relative full thrust when on the ground when airborne reduce thrust a little so it doesn't go into overspeed. were you refering to under 10,000 ft overspeed (ie. over 250knots) or overspeed in the aircraft 320 ish.

either way as far as i know this cannot be solved apart from the obvious solution of just setting the autopilot speed to less than the maximum speed so it can be maintained by the aircraft automatically.

hope that helps a little in your question.

[JonathanRichardson]

Hi

If your flight model is reasonably good and you follow the correct procedures, and also have set your weight and balance correctly you should not get an over speed condition.

Make a TOGA take-off (this is never going to be full power - if you have full power set I would immediately be suspicious of what is going on)
At V2, rotate initial to 10degrees and then once you have a positive rate (after approx 1 to 2seconds [you have to be quick]) maintain climb to 15+ degrees pitch up or what the FD commands to maintain the V2+20 speed (this is dependent on GW etc). Gear Up select FLCH. Set in an acceleration speed (maybe initial 185kts [or whatever you want / cleared] to) up to 250kts retract flaps pre schedule to clean. If you are 'overspeeding' in this condition or before it, yet following the FD command pitch, then something is wrong - some performance factor or perhaps weights are not properly set in the config files.

Note that with incorrect W&B or power setting and also even with slow response to FD cues the 737 in manual flight can easily get into an overspeed condition in TOGA, the AT may be too slow to correct, the pitch is key to maintaining speed. Much of this is due to Flight Models, but you must follow the correct procedures to find out where the problems lies, i.e. with your own flying or with the flight model or perhaps some error in the pre-flight or type.txt CDU files re weights.


Regards
Jonathan Richardson

[Geremy Britton]

duh, totally forgot about TOGA, i just never use it thats all:roll:. Yes i was wondering this when you posted you neveractually set "full power" as in the throttles wide open forward (even though it might be good for the buttkicker:)) this is not nessessary and you only need around 90% N1 to takoff successfully without stalling. Maybe this is where you are going wrong.

To cut a long story short, set the autopilot to your cruising altitude and set the vertical speed of around say 500 ft p.m. Then your speed of around 245 knots (not over 250) (then if you have a flight plan loaded press/ click nav and do this after takeoff later). tTe autopilot is now tuned. Takeoff, put the gear up maintain steady takeoff of around 15 degrees then retract flaps incrementally. Finally engage the autopilot this is all done pretty fast and by the time the autopilot is engaged it will control the speed for you and keep you out of the "overspeed" area. the aircraft itself wont have enough time after you engage takeoff power ontil it manages to go overspeed because then the autopilot is controlling speed.

finally when you do engage the autopilot dont forget to get the autothrottle so the autopilot has permission (from you) that it can can control power. just in case you didn' know the autothrottle is the white switch at the near left of the autopilot module.

Hopefully no more overspeeds will be coming your way:)

Gez

(If the going gets tough...... eject - oh, no you can't do that on a 737 can you:roll::D)

[NicD]

737Gez - this thread is about PM software, is that what you are describing? Doesn't sound like it. If you are engaging TOGA (which is standard 737 takeoff procedure) then you would already have A/T armed. As soon as you hit TOGA the A/T is engaged on the ground and fully managed by the AFDS from then on, but restricted by MCP speed settings until VNAV (for example) is selected

And Like Jonathon explained you should engage a pitch mode immediately after rotation (LVL CHG), and a roll mode is usually preselected before takeoff on the 737 (such as LNAV). Then going through acceleration height (usually around 1000ft), select 'bug-up' speed on the MCP (usually around 210 kts), reduce flaps on schedule, then when flaps are fully up either bug-up to 250kts (below 10000) or select VNAV as your pitch mode. Autopilot is usually engaged somewhere between that action and reaching 10000 feet.

[Michael Carter]

I'm glad I just have to just push the throttles forward after FL100. ;)

[ktroemer]

Thanks folks...i think i will make some test flights and maybe check my W&B and flightmodel.
And good recommendations for a good flightmodel and where to download the files?
Wanted to use the PMDG but the Mod. never worked......
Anyways....thanks you really so much for your help....appreciate it very very much......

Many greetings from cold LOWW

Klaus

[Thunder175]

And Like Jonathon explained you should engage a pitch mode immediately after rotation (LVL CHG), and a roll mode is usually preselected before takeoff on the 737 (such as LNAV).


Just a question of proper procedure here, but should LVL CHG be used or is it "permissibile" to go straight to VNAV after rotation and initial climb out? I've been going straight to VNAV with no apparent issues but I was curious as to if I am doing it right. VNAV will command the Vref+20 but will then select 250kts and the aircraft will flatten out on climb out to let the airspeed increase, leading to a few GPWS warnings right after takeoff.

[NicD]

I think the LVL CHG thing is just a PM work-around for now. We have to do that to get a pitch mode that works reliably just ater takeoff. Shouldn't be a requirement once PM gets the VNAV issues fixed.

[Thunder175]

Got it. Right now I just use SPD INTV as a work around for the descent issues we all know about. Thanks for the info!

[michelmvd]

Hi Thunder 175

VNAV is a rather complex mode item and not working all the same in the different Boeing aircraft. The "system" is working differently in the "older concept" B737 than in the more modern B747/777 type of auto-flight management. This makes it even more difficult for PM to implement it correctly in their software.

I can't speak for a B737, but as a good exemple how autoflights are working in real, this is how VNAV should work for the B744 / B777.

According SOP, VNAV must be armed on the ground (together with LNAV)

Command Speed VREF+20 after rotation

VNAV becomes active at 400ft RA

At the moment LNAV/VNAV becomes active, the TOGA modes end (which is a F/D mode only).

VNAV will command a pitch down at the preset altitude of the FLAP/ACCEL.HT in the TAKEOFF REF page of the CDU and command a VREF+100 speed. (On heavier T/O weights this can be higher than 250)

(exemple : 10/1500 : aircraft speed will be set to VREF+100 and will pitch at 1500 Ft to start the flap retraction scheme.

VNAV will command CLB speed (or CLB+1,2) at the moment the preset factor in the THR REDUCTION (TakeOff page) is reached.

'exemple : FLAPS5 CLB1 : aircraft will come in CLB1 speed mode at the moment FLAPS5 are set. TO thrust mode (or TO1/2) ends at that moment.

All this must happen with or without A/P on. (F/D mode - bars command) In most SOP, for T/O in complex airport SIDS situations / noise procedures, A/P is on after 500ft.

This is how it works in the real B744, VNAV behavior in PM for B744 is unfortunately totally unrealistic. I suppose for the B737 is it futher developped, as actually these days, the PM software is more focussed on the B737. I heard from the real life pilots, there isn't such a high degree of automatisation in the little boeing.

To have a good behavior, it is also very important to use a proper airfile, as it all depends on good airspeeds/ climb pitches performances etc at the correct altitudes. That is also the reason some guys has problems with it and others not. Airliners are flown by the numbers and their behavior can be very different if these are not correctly followed or set.

B. Rgds
Michel

[Thunder175]

Thanks for the awesome reply! I'm mostly flying the 738 so its probably a good thing PM is geared toward the 737 series! :p Course I am using a panel-less PMDG 737 at the moment so I don't know how much better the flight dynamics can be. I'm anxious to try out the new POSKY 747 v4 with the v9.7 FDE files.

[michelmvd]

Well Thunder175, it is of course good for the B737 fans, but a pitty for all others as the original idea of PM was to develop a cockpitsystem for a lot more types ;) What the B744 concerns, a lot is done, but some major differences still need to be adressed in the VNAV and MCP/CDU operation matters.
Via PMSystem we can do a lot of the logic ourselfs, but not all.

If you have good results concerning the new Posky B744 FDE, pls inform us here.

See you

Michel