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Guest mukesh

Cruising altitude in PMDG 747

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Guest mukesh

I never rich my cruising altitude in 747 which is FL330.either it stall or never get there at that altitude.how can i solve this problem.i don't have this problem in default (FS9.1) 747-400. Thanks, Mukesh

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Mukesh,Just a guess, but you're probably trying to climb with full fuel. Real 747's cannot climb straight to high altitudes totally full of fuel - you need to reduce your gross weight by removing some fuel prior to takeoff, or else step climb your way up to altitude if it's a long flight that requires that much fuel.


Ryan Maziarz
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Beginners often try to use vertical speed mode (which has no speed protection) for climb.I recommend following one of the tutorials from start to finish.This is as real as it gets.... the default planes are toys ;)Cheers.Q>

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Guest dt1951

Ah yes, the eternal problem for developers. The double edged sword here. The good thing is that they develop very realistic aircraft with many of the aircraft systems modeled. The bad thing is that they develop very realistic aircraft with many of the aircraft systems modeled. When the aircraft in FS behaves like the real aircraft you get yelled at because they didn't really want it to do that. But do what they want it to do...

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Guest M-Sauce

You need to look at you OPT/MAX altitude readout on your FMC. If you look at your VNAV Criuse page (Page 2), you will find those figures next to LSK 6R (Bottom right). As an example, on the 400F when we cross the Pacific after taking off at 395T (Close to MTOW), we can only get up to 280 or 290 initially. As the flight progresses and we burn off that weight of fuel, we step climb higher and higher to burn the least amount of fuel. You might start the flight with 125T of fuel and land at your destination with 10T, so that is a pretty big weight loss, hence the difference in your initial criuse altituse with your final TOD altitude.I never like to get closer than 1000 feet to my MAX altitude readout, and that is only if I know I won't encounter mod or greater turbulence up there. The 747-400 is actually limited by its wing aerodynamics, not the thrust of the engine. So you will actually stall before you can't climb anymore. The danger of hovering close to your MAX altitude is that your coffin corner gets pretty small. You don't have a lot of room between your max and min speeds, so the red army (that black and red portion of the speed tape) is right above and below your current speed. This means that any increase in speed puts you in airflow separation territory due to the airflow over the wing nearing supersonic (Mach tuck, but that will take another paragraph to explain). Any decrease in speed puts you in a stall due to low speed airflow separation. That is why sitting in this regime during strong turbulence (Ie, speed excursions) is not a good idea. Some guys call it flying on the tip of a needle. From what I hear, the MD-11 is normally operated right on the tip of the needle quite frequently, but that is a whole different beast that I've never set foot in.Another thing I don't like about being close to the MAX alt is that you have very little time to deal with an engine failure before you have to start drifting down. In today's 1000 foot separation RVSM airspace things can get hairy very quickly.So ATC and Weather permitting, try to stay within 1000 feet of you OPT altitude. That will roughly give you the best economy for your flights. And the hairs in the back of your neck should perk up when you get close to MAX alt.

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