what isthe effeect of altitude on the maxmimum and minimum speeds of airplane?

Answer 1

Depends on the source of thrust. To maintain altitude an airplane needs lift. For propeller driven aircraft, lift will decrease with thinner air (higher altitude) because less air is hitting the wing and less air is hitting the prop blades (less thrust).

Also if you look at the Bernoulli principle (which several scientists list as one of the reasons why aircraft fly) the thinner the air is, the less effect the wing will have at creating a pressure differential for any aircraft. In addition, the thinner the air the less effective jet engines become, because combustion is less efficient in low oxygen environments. At the highest altitudes, jets will actually loose engine power.

So, unless the source of thrust is liquid oxygen (as used in spacecraft) the higher you go, the slower you can propell yourself.

As for the guy above me, friction is the least important of the forces acting on the plane. In fact, friction on the bottom of the wing is actually good for keeping the plane up, which is why the wing will be titled just a small amount.

Answer 2

At higher altitudes, the air is thinner, thus objects can pass through it easier. As a plane gets higher and higher in altitude, it's resistance lessens and it will be able to fly faster. Thus Higher Altitude = Faster Maximum Speed.