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HoratioWondersocks

POSKY 737-800 NG cruise speed question

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Hello Folks

When I fly this particular aircraft I nearly always select a cruising altitude in the range FL320-FL340 I select Mach 80 as my cruising speed (I know there are a range of factors that affect airspeeds ) however at this speed and especially if I try 81-82 I always get overspeed warnings at some point in the flight. I have a number of vistaliner 800s and don't get the same problem with this model.

Allowing for all factors involved in a flight is MACH 80 at FL320-FL340 an acceptable cruising speed for this aircraft and If this is generally acceptable , is there something in the Aircraft CFG of the Posky 737/800ng that I can alter to make it less likely to get the pretty much guaranteed overspeed warnings in my flights.

cheers Andy

 

PS If i do get an overspeed warning I use the air brakes to reduce my speed .is this correct procedure ?Its certainly quicker than just reducing my mach number.

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Good heavens!

No one?

I wouldn't have thought this was the most difficult FS query ever asked .

Don't let me down chaps.

 

Hello Horatio old boy seems that the cruise speed at your usual fl320-340 is .....

 

 

Cruising speed

Mach 0.785 (937 km/h) So that would explain my overspeed warnings.

Ok H

OK thanks H

 

Now about those air brakes.

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The settings are in the airfile. Open with AirEd. And the aircraft.cfg file

 

AirEd - section: 316

 

Aircraft cfg =

 

[Reference Speeds]

flaps_up_stall_speed = 142.000

full_flaps_stall_speed = 113.000

cruise_speed = 452.160 <-------------------------------------------------change this to suit-----------

max_mach = 0.82 <-------------------------------------------------change this to suit-----------

max_indicated_speed = 340 //Red line (KIAS)

 

 

Airbrake effect settings also in Airfile; section 1011

 

Mel

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The settings are in the airfile. Open with AirEd. And the aircraft.cfg file

 

AirEd - section: 316

 

Aircraft cfg =

 

[Reference Speeds]

flaps_up_stall_speed = 142.000

full_flaps_stall_speed = 113.000

cruise_speed = 452.160 <-------------------------------------------------change this to suit-----------

max_mach = 0.82 <-------------------------------------------------change this to suit-----------

max_indicated_speed = 340 //Red line (KIAS)

 

 

Airbrake effect settings also in Airfile; section 1011

 

Mel

 

 

Thanks Mel

I will note your reply for possible future use. it does seem in the case of Posky 737/800 (my orig query) I am simply choosing an incorrect cruising speed (so its pilot error on my part)

 

As to the use of AIR/SPEED Brakes (get a little confused as to which is what) to reduce speed if an overspeed warning is given ,it seems that a reduction in mach/airspeed (throttle back ) is the correct procedure NOT the use of A/S brakes.

Thanks for replying to my query.

Andy

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In straight and level flight or climbing reduction of power will slow the aircraft. If using the MCP with AT, reducing the mach speed in the AT setting will slow the aircraft by reducing power.

 

In cruise if you are maintaining altitude as power is reduced the aircraft will increase pitch to increase lift to maintain altitude as the increased drag slows the aircraft. This applies also to AT reduced power to slow the aircraft.

 

Air brakes do have maximum extension speeds. Plan ahead to to adjust power/AT as needed such as anticipating the effects of reduced pitch for a descent which will increase the speed of the aircraft. In pilot evaluation for certain flight phases they can be penalized for using the air brakes unnecessarily when power and pitch control can appropriately slow the aircraft.

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