Theory Q: Cold Air, Lower Fuel Consumption?

john smith wrote:

During Winter in the colder climes, do you use less fuel when you fly
because the air is more dense?

First, lift is proportional to mass-air flow over a curved surface.
Cold air is denser so at a give speed, you'll get more lift from cold
air. Now, if you choose to, you can throttle back a bit to get better
fuel economy.

Then, the engine power is controlled by the fuel/air mixture. To burn
X fuel molecules you need Y air molecules. Cold air will supply the X
molecules of air easily.
--Bill

Stubby writes:

First, lift is proportional to mass-air flow over a curved surface.

A curved surface has nothing to do with lift.

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On Feb 4, 12:00 pm, Mxsmanic wrote:
Stubby writes:
First, lift is proportional to mass-air flow over a curved surface.

A curved surface has nothing to do with lift.

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Of course it does, the propeller produces more thrust when the air is
colder ( A propeller is a curved surface )

Now, back to the orginal question, if the engine is maintained at a
constant rpm at a some cold and hot temperatures, it will burn more
fuel at the colder temperature, but it will also produce more thrust.
So to get the same thrust, you would throttle back and almost the same
fuel burn with less rpm.

writes:

Of course it does, the propeller produces more thrust when the air is
colder ( A propeller is a curved surface )

A propeller is an airfoil. That's why it produces lift. A flat board
presented at a slight angle to a stream of air also produces lift and
is also an airfoil, even though it is not curved.

The curved cross-section of most airfoils increases the critical angle
of attack for stalls and reduces drag, but it does not improve lift
and is not necessary to produce it.

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On Feb 5, 7:00 am, Mxsmanic wrote:
Stubby writes:
First, lift is proportional to mass-air flow over a curved surface.

A curved surface has nothing to do with lift.


Riiiight.
NACA sections are just to make the wing look pretty

george writes:

Riiiight.
NACA sections are just to make the wing look pretty

No, they reduce drag and increase the range of angles of attack
through which lift is produced. The curves are not necessary for
lift.

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