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kimuyukix

787 top speed 350kn @ FL380...how to fix?

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Hi!

My name is Keenen Davis, and I am a pilot in training for Delta Virtual Air Lines. I just got a brand new computer which runs much faster than the last one I had. On the previous computer, FSX constantly froze on landing and failed to render up-close images for seconds.  On this new computer, FSX runs like a dream, and the graphics are fantastic; however, I've run into a problem with several aircraft that I've tried to fly.

I am used to flying the A380 and the 777X at 485 knots at flight level 380, and have done so time and time again without issue...on the previous computer. On the new one, for some weird reason, the flight computer won't let me exceed 350 knots.

Before takeoff, I have my lights on, and my altitude, speed, and heading are set as told by ATC, and I have flaps configured for takeoff. The HDG/GPS toggle switch is set to GPS, and the Flight Director mode is enabled. For takeoff, I turn taxispeed off and turn autothrottle on, and then I hit the Speed button. On takeoff, I set flaps down by one increment. The first officer puts the gear up.  We takeoff smoothly at 225 knots at a climb rate of 1,200 feet per minute; at 1,000 feet, I ramp up the speed to 250 knots, and turn left or right as told by ATC while ascending to the assigned altitude.  At 10,000 feet, I ramp up the speed to 320~350 knots, and as the engines start to accelerate, I set the flaps down again by one increment.  At this point, as I ascend through FL180~FL280, I put the flaps all the way down; I should be able to accelerate further, but FSX won't let me. I ascend through FL320, and while I'm supposed to be flying at 485 knots, I am stuck at a maximum speed of 350 knots.  As I ascend through FL300, in order to maintain speed, the plane gradually starts to floor it, giving me the impression that if I ascend any higher, I may enter a stall from which I may not be able to recover.

According to Google, the 787 has a cruising speed of 487 knots at FL400. If I'm supposed to be able to reach FL400, why are my engines straining to produce thrust at FL300, and why can't I exceed 350 knots?

What the heck am I doing wrong? Maybe it's an issue regarding the files of FSX.  How can I fix this issue?

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(By the way, I forgot to mention that I am currently flying the 787 because the 777s that I have aren't fully operational.)

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@kimuyukix, far from me to tell a trainee pilot how to fly but IAS is not relevant at higher altitudes. Once you’re above FL290 you should use the Mach speed as your guide. You’ll probably find that when you level off at your cruise altitude the Mach speed is around 0.83 which would be fairly typical for such an aircraft.

Concorde flew at Mach 2.0 at 50,000ft and the IAS was around 500kts. The ground speed was 1130kts.

Im confused about your flap actions. They should be raised once you have achieved a safe climb speed. Certainly by 230kts they should be fully retracted and not touched again until below 10,000ft on approach. Extending flaps will severely affect performance and climb rate.

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Ray (Cheshire, England).
System: P3D v5.3HF2 & v3.4, Intel i7-8086K o/c to 5.0Ghz, Nvidia GTX 1080 Ti 11Gb, Samsung 970 EVO M.2 SSD, 1Tb Samsung 860 EVO SSD, Asus Prime Z370-A mobo, 32Gb G.Skill DDR4 3000Mhz RAM, Win 10 Pro 64-bit, BenQ PD3200U 32” monitor, Fulcrum One yoke.
Cheadle Hulme Weather

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Agree with Ray!  Depending on amount of fuel and runway length,  flaps should be 2 positions down for takeoff.  Takeoff speed should be around 165-175 knots max.  After a few minutes of acceleration and climb, those flaps should be fully up.


Charlie Aron

Awaiting the new Microsoft Flight Sim and the purchase of a new system.  Running a Chromebook for now! :cool:

                                     

 

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Oopsie! I completely misspoke in my frustration. Where I have said I select flaps down, I really meant to say flaps up. My mistake!

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10 hours ago, kimuyukix said:

According to Google, the 787 has a cruising speed of 487 knots at FL400

That is probably ground speed, not Indicated Air Speed.


Ray (Cheshire, England).
System: P3D v5.3HF2 & v3.4, Intel i7-8086K o/c to 5.0Ghz, Nvidia GTX 1080 Ti 11Gb, Samsung 970 EVO M.2 SSD, 1Tb Samsung 860 EVO SSD, Asus Prime Z370-A mobo, 32Gb G.Skill DDR4 3000Mhz RAM, Win 10 Pro 64-bit, BenQ PD3200U 32” monitor, Fulcrum One yoke.
Cheadle Hulme Weather

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Check your fsx settings. Perhaps in your old sim you had "airspeed, display true" and now in this one you have "airspeed, display indicated". "Indicated" is always the preferred setting.

Indicated airspeed = what instrument shows from air data on the pitot / static systems  ( what the pilot sees in cockpit, reference speeds for the aircraft are shown in indicated )
True airspeed = Indicated airspeed + outside temp, humidity adjustments.. IE air mass ( this is what a wiki / google will show for max speed )
Ground speed = True airspeed + any winds affecting flight.( GPS / FMS will display this, used for time calculations )

Edit - Using an online calculator for a standard day.
350 kts indicated @ 38000 ft yields a true airspeed of : 607 knots
Add some tailwind and you are cooking along nicely.


20AUG21_Avsim_Sig.png?dl=1  FS RTWR   SHRS F-111   JoinFS   Little Navmap 
 

 

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