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Guest wake2rbulence

I'm Having a problem with Take offs

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i was wondering why i'm having a problem during take offs i'm stalling! I have set my V speeds before taking of and sundenly my airspeed instead of speeding up it slows down and even if i turn off the auto pilot and have it full throttle the plane is not reacting and I end up stalling and then crashed!help!

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Hi,When you set the V2 speed in the MPC (e.g. 136 kts), and you engage the autopilot, the MPC wil put V2 + 20kts in the MPC-speed window. When that happens you have to manualy put 250 kts in the speed window to keep the plane from stalling. When you don't and you use the autothrottle, the autopilot wil climb whilst trying to maintain 156 kts which is impossible, and the plane will stall...RudiPS. Fly Timothy Metzingers tutorial, asuming you are flying the 737NG!

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"i was wondering why i'm having a problem during take offs i'm stalling! I have set my V speeds before taking of and sundenly my airspeed instead of speeding up it slows down and even if i turn off the auto pilot and have it full throttle the plane is not reacting and I end up stalling and then crashed!help!"Dear Mr "Help!"Are your hydraulics switched on? Are your generators switched on? Is your horizontal stabilizer trimmed correctly? Are your flaps in the correct position? Are you overweight?What do you mean by the plane not reacting? Is the nose not pitching down and following the FD commands? (when the A/P is engaged). Are the thrust levers not responding to (TOGA) A/T commands? Is the plane not responding to manual stick and throttle inputs also (when you disengage A/T and A/P)?Can you post a screenshot of what is happening here?Thanks.Cheers.Ian.

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"When you set the V2 speed in the MPC (e.g. 136 kts), and you engage the autopilot, the MPC will put V2 + 20kts in the MPC-speed window. When that happens you have to manually put 250 kts in the speed window to keep the plane from stalling."Why should it stall, Rudi? (Unless you retract the flaps before selecting a higher MCP speed). "When you don't and you use the autothrottle, the autopilot will climb whilst trying to maintain 156 kts which is impossible, and the plane will stall..."When you don't do what? (Don't) Set V2 speed and engage the autopilot? If you don't engage the A/P, the autopilot will not try to climb (it won't do anything if you don't engage it ;-)). The FD mode will remain in takeoff mode and the FD bars will provide V2+20 guidance, so if you manually control the pitch to follow the FD bars, you shouldn't stall...unless you (again) retract your flaps without increasing speed).Can you clarify what you are saying?Thanks.Cheers.Ian.

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Hey Tim,Why can't we set the MCP to 250 kts before takeoff instead of the V2 speed of 136 kts or what ever it may be at that time? When I am flying and the auto pilot automatically sets it to V2+20 I still have a hard time trying to follow the box in the HSI because it seems that I will be trying to climb at around 20 degrees nose up and then set the MCP window to 250. When I tried it by setting the MCP to 250 kts before takeoff it seems to go much smoother. Is it that it is just more realistic to do it the other way? Thanks,Sean Campbell

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>Why should it stall, Rudi? (Unless you retract the flaps>before selecting a higher MCP speed). I had the same thing (stalling plane) happening to me after take off... I am not a rated pilot ;-) and I am learning as I get along, so I just shared my thoughts... This is what I do:I set the V2 speed - 136 kts - flaps 5Use TO/GA to take off...After positive climb I retract the gear...At 500 ft I engage the AP and start retracting the flaps...>When you don't do what? When you forget to put 250 kts in the MPC the plane will use maximum climb at 156 kts which (I think) is not enough... and the plane stalls.>Don't Set V2 speed and engage the>autopilot? If you don't engage the A/P, the autopilot will not>try to climb (it won't do anything if you don't engage it>;-)). The FD mode will remain in takeoff mode and the FD bars>will provide V2+20 guidance, so if you manually control the>pitch to follow the FD bars, you shouldn't stall...unless you>again retract your flaps without increasing speed).Right... ;-) I relly too much on the AP. So sue me...Taken from Timothy Metzingers manual:TakeoffAdvance the throttles and ensure that both engines come uptogether. Once sure that we

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I know exactly what you are talking about. Every now and then, the V2+20 does not kick in for some reason (procedures problem) which leaves the V2 set which is not enough speed to fly and climb so you start sinking and decelerating like a rock.Not sure what I muff up to cause it, but it is definitely a procedures thing. You are not alone in this problem, but it is not anything wrong with the aircraft, it is something we do.Ray

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>I know exactly what you are talking about. Every now and>then, the V2+20 does not kick in for some reason (procedures>problem) which leaves the V2 set which is not enough speed to>fly and climb so you start sinking and decelerating like a>rock.>>Not sure what I muff up to cause it, but it is definitely a>procedures thing. You are not alone in this problem, but it is>not anything wrong with the aircraft, it is something we do.>>RayHi Ray,You're right. In my case I engaged the AP right after take off and forgot to put 250 kts in the MPC ;-( [duh]Once (before landing) I was told to go around because I forgot to lower my landing gear ...People make mistakes... Computers just crach with no reason ;-)

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There seems to be plenty of misinformation around here... including in the above tutorial.How to take off, having set the bug speeds correctly, MCP to V2, flaps 5:Set 40% N1.Press TOGA. Monitor setting of T/O thrust.At V1 take your hand off the thrust levers.At Vr smoothly rotate to about +17 to +20 deg, at 2.5 to 3 degs / sec.The FD will help you fly at V2+20. Follow it!!At 400' (all heights are AAL) select LNAV.At 1000' select A/P to command A.At 1500' monitor the a/c selecting N1 mode (it will pitch down a couple of degrees to hold speed at the reduced thrust).At 3000' set MCP speed to clean speed (the UP bug on the speed tape). The aircraft will now lower pitch to about +10 deg.When accelerating select flaps to 1.When speed passes the "1" marker on the speed tape, select flaps up.When the flap indicator shows up and the warning lights are out, say to yourself "flaps up, no lights" and then select the gear lever to off and autobrake to off (PMDG actually has the sim do this).Now select VNAV and the aircraft will accelerate to 250, or (and this is a poor way of flying and not actually done, press level change, speed 250). VNAV is better because it allows you to program speeds into the SID (for sharp turns) and it remembers to accelerate above FL100.Turn the start switches off, release the cabin crew, and do some checks.Drink coffee.Mr Help:At the moment everything "goes wrong", press P and if you can get a screen shot we'll work out what's wrong.Others:A pitch up of around 20 deg is normal.Do NOT select 250 knots before flaps up - firstly you may damage the flaps and secondly you have no useful indication of your V2 which you'll need if an engine stops. Also you will not fly the correct and safe terrain clearance and noise abatement profile - you could just do a shallow noisy departure into an obstacle! Your passengers would not appreciate that, even if their tickets were very cheap.The obstacle might have something to say about it too.Andrew

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"Every now and then, the V2+20 does not kick in for some reason (procedures problem) which leaves the V2 set which is not enough speed to fly and climb so you start sinking and decelerating like a rock."There is no logical reason for the aircraft to start sinking and decelerating, Ray. The aircraft should climb very well with V2 selected (after all, isn't V2 the engine-out climb speed?). Having a slower airspeed (forward motion) allows the aircraft (for a given thrust) to convert the surplus thrust/energy into vertical speed (climb)The slower the speed (down to V2), the faster the aircraft should climb (in the initial climb phase). You need a good initial climb rate so that if you hit a downdraft, you don't go crashing back into the runway. V2 + 20, however, provides a better all-round speed (you are further away from stall speed).The only drawback is that at slower speeds, you won't be able to retract your flaps. Flaps = Drag, so you won't be able to accelerate as fast as a "cleaner" (less/no flap) aircraft. Ultimately, this leads to a degradation in climb speed.... not good if you want to avoid that mountain a few miles beyond the end of the runway. That is why you select higher speeds once you are well clear of the runway. i.e. as Andrew says, the Flap UP speed, then automatically 250kts with VNAV (below 10,000')Hope this makes sense.Cheers.Ian.

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