Three more newbie Qs, if you don't mind :)

Hi all,

I'm encouraged by your non-disparaging response to my first posting
here yesterday. I have a few more Qs that will look utterly idiotic to
you guys -- but remember that I'm not a pilot

1. Is there a way of mathematically justifying the dictum that a
successful takeoff is guaranteed if you develop 70% of the desired
thrust in half the runway length? And is this dictum kind of set in
stone or are there riders?

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. To a non-pilot like me, it's intriguing how this can
be possible. I know that plane manufacturers prescribe takeoff flap
settings, which means that there's gotta be some predetermined angle
of the wing with reference to the horizontal that'll give the aircraft
an optimal kind of lift at some speed enough to make it afloat and
keep it afloat. How then would increasing this wing angle, which is
what would happen by an early nose-lift, help? If at all, I feel it'll
get the craft airborne without enough speed to sustain itself,
whereupon it should start descending before too long... I could be
completely wrong in the way I'm thinking here but would love to hear
how this principle works.

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?


You may be stifling laughs by now at these but I hope to get better in
the days to come through such Qs... not wrong to hope, is it?

Cheers,

Ramapriya