what the heck is lift?

Roger Long wrote:
Lift in a fully developed spin or steady sinking mush is also exactly
the same as in level flight.

Not according to the Jepp Private Pilot's Manual.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

"George Patterson" wrote in message
news:_8kUe.739$626.593@trndny08...
Roger Long wrote:
Lift in a fully developed spin or steady sinking mush is also exactly the
same as in level flight.

Not according to the Jepp Private Pilot's Manual.

Are you relying on the part of that manual that you quoted elsewhere?

You'll note that the quote you provided does not include the word "only".
It's incorrect to infer from the statement that lift equals weight in
straight and level flight, that when not straight and level lift does not
equal weight.

The statement you quoted is not inconsistent with Roger's post.

Pete

Peter Duniho wrote:

Are you relying on the part of that manual that you quoted elsewhere?

No. In a spin, at least one wing is at least partially stalled. According to
Jepp, this "results in a loss of lift in the area of the wing where it is taking
place."

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

"George Patterson" wrote in message
news:bWkUe.743$626.107@trndny08...
No. In a spin, at least one wing is at least partially stalled. According
to Jepp, this "results in a loss of lift in the area of the wing where it
is
taking place."

That still does not contradict Roger's post.

IMHO, by "lift" Roger clearly meant "the force acting against gravity".
This is a fairly common (though not aerodynamically correct) definition of
"lift", and in fact is the one the Jepp training book uses (assuming it
hasn't changed much in the 15 years since I used it). That is, they have
the classic "lift, weight, thrust, drag" picture with the two pairs of
opposing arrows.

If Roger had meant by "lift", the "aerodynamic force created by the wing as
a result of relative wind" (or something similar), then he would have been
incorrect. But given that that definition makes his post incorrect, and
given that there's another widely accepted definition that does not, it
seems fair to give him the benefit of the doubt and assume he was using the
definition that's consistent with his post.

Now, granted, this *is* Usenet after all, and everyone seems to think it's
their job to point out why everyone else is wrong. So maybe I'm all wet in
my thinking. But that's my thinking, nonetheless.

Pete

Stall is not loss of lift but loss of stability in the airstream.
Stability is the ability to reach a steady state. A fully stalled
wing will develop just as much lift as an unstalled one but will seek
an angle of attack that will result in a steady state by sinking
faster. This makes most aircraft head nose first for the ground which
feels like loss of lift.

For a more complete explanation:

http://www.avweb.com/news/airman/184307-1.html

--

Roger Long

George Patterson wrote:

Not according to the Jepp Private Pilot's Manual.

Which is the authoritative physics textbook ;-)

Stefan