Question about autopilot

[Macgyva]

Im somewhat new to flight sims and flying in general and have noticed something thats really been annoying me lately.  when I am using autopilot to fly there is always 5-10 degrees nose up (while holding altitude).  The flaps are set to 0 and the speedbrake is off.  If i turn autopilot off and try to fly straight and level I lose altitude. Is this normal? is there something I am missing? I have been flying the 737, a321 and the 747 and its doing it in all 3 so its either something I am missing or its just normal.

[Alejandro Rhodes]

,do you mean when your in cruise altitude?? I think is normal also this depends in your speed & altitude , If you are holding an airbus 340 at FL350 all the aircraft wont be absolutely flat ,they will  hold a little inclination ,as I said depends on the speed, altitude, 5 degree is normal in any altitude in any passenger plane ,specially when they are on their limits of altitude.

the plane will goes faster and the angle of attach at this level of the wings will be forced to remained this inclination because the air is thiner in high altitudes

anyway let's hear of some real pilots of this site

Alex  

[Macgyva]

I have tried holding FL150, FL250, and FL350 and in the 737 it has about a 7 degree nose up and the 747 is about 10 degree nose up.  Speed is about 250 in the 37 and 280 in the 47

[BAW0343]

,do you mean when your in cruise altitude?? I think is normal also this depends in your speed & altitude , If you are holding an airbus 340 at FL350 all the aircraft wont be absolutely flat ,they will  hold a little inclination ,as I said depends on the speed, altitude, 5 degree is normal in any altitude in any passenger plane ,specially when they are on their limits of altitude.

the plane will goes faster and the angle of attach at this level of the wings will be forced to remained this inclination because the air is thiner in high altitudes

anyway let's hear of some real pilots of this site

Alex  

We don't need the real pilots to pitch in as you got the point exactly.  ;D

As you gain altitude the air gets thin, the aircraft must keep a slightly nose high pitch to stay at its altitude.

[Macgyva]

I understand that it has to keep some nose up but isnt 10degrees way too much?

[Alejandro Rhodes]

We don't need the real pilots to pitch in as you got the point exactly.  ;D

As you gain altitude the air gets thin, the aircraft must keep a slightly nose high pitch to stay at its altitude.

It ij my henglishi is so badly ,thay sometimesi don't trust myself in my explanatoriations

Thanks BAW

[RxZ]

I understand that it has to keep some nose up but isnt 10degrees way too much?

No

It all depends on your forward speed.  For example, next time you drive anywhere, see what happens when you stick your hand out of the window and rotate it with respect to the way you are driving (forward I hope).  As you rotate your hand, it will want to go up or down depending on how the air is hitting your hand.  It is the exact same with the wings on an airplane.  The curvature of the wing gives it lift, but sometimes not enough.  That's when the whole plane has to angle up so that the wings can "catch" more air and deflect it downwards to create more lift (and drag, but thats a different story for some more knowledgeable people).

[Macgyva]

So if i up the speed to say 340 or so the nose will come down some?

[Deviant]

[quote]Im somewhat new to flight sims and flying in general and have noticed something thats really been annoying me lately.

[Sovien]

So if i up the speed to say 340 or so the nose will come down some?

Correct, that's the basic idea. The opposite would occur by slowing down. It's all due to lift. As the speed increase you increasing lift, as it decreases there is less lift produced by the wings.

The effect is seen more dramatically in a 747 then, say, a cessna because the 747 weigh more.