Ramapriya wrote:

2. I've heard that you can let an aircraft fly itself off, so to
speak, by lifting the nose early in the takeoff roll to the desired
takeoff attitude.

The aircraft will accelerate most rapidly by keeping the wings nearly level and
keeping the nose or tail wheel off the ground, however, the plane will still
accelerate if the nose is held higher. Consequently, the pilot can raise the nose to
takeoff attitude as soon as the plane is traveling fast enough for the elevators to
work. When the plane is moving fast enough, it will lift off the ground. *If* the
pilot has held the nose at the correct attitude, it will continue to climb.

There are two reasons why this is not usually done, even with light aircraft. The
first is that the aircraft will accelerate better with the nose fairly low. The plane
will use less runway if the nose is keep down until the normal "rotation" point (the
speed at which the nose should be raised). The second is a phenomena called "ground
effect". When very close to the ground (within about 1 wingspan) an aircraft will
climb at a lower speed than it will higher up. A careless pilot who gets the nose too
high may climb well for a couple of wingspans and then find that the plane isn't
going fast enough to keep climbing. In extreme cases, planes have been known to
descend back to the runway again. This is, at best, embarrassing.

Taking off this way is used by some pilots for taking of an aircraft which has a
tailwheel when the winds are strong and blowing from one side (as "crosswind"). This
keeps the tailwheel on the runway, which helps keep the plane straight until it
leaves the ground. I personally don't like doing this.

3. Is it possible for a cruising aircraft (say at 35000 feet) to
descend and land without the pilot having to pitch the nose downward
even once? I mean, is it possible to lose altitude by just a
combination of the throttle and flaps? I know it might take a lot
longer to do it this way but is it a theoretical possibility?

Pilots usually descend by using only the throttle. Putting flaps down, however,
changes the attitude of the nose even without further pilot input. You will also
probably have to raise the nose to slow down. This can be delayed until the last
minute, but it still must be done before touchdown.

For example, I will cruise at about 120 mph. I will adjust the attitude of the nose
(this is called "trimming" the plane) until the wings are level and set the throttle
at 2600 rpm and stay that way until I want to come down. If I slow the engine down to
2400 rpm, the plane will descend at about 500 feet per minute. The wings will still
be pretty level, and my speed will still be 120 mph. This is not like a car, where
slowing the engine slows the car.

Now, let's say there's a runway in front of me and I decide to fly straight in and
land. I can descend just by slowing the engine down, but I can't touch down in my
plane at 120 mph. Lowering flaps will slow me down and raise the nose a bit, but it
also increases lift, so I have to slow the engine down even more to descend, and it
won't slow me down enough or raise the nose enough. I know from experience that I
will have to raise the nose to slow the plane enough to land safely. If I want a
smooth landing, I will either raise the nose even more in the last few feet or add a
bit of power to slow the descent (or both).

Now. In theory, a pilot could land some aircraft without touching the trim, but the
plane would touch down much faster than it is designed to do. This would abuse and
possibly blow the tires. It would also require much more runway than usual. With some
aircraft, it might also result in the nosewheel touching down first, with possibly
disastrous consequences.

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.