Low Level wrote:Arnulf wrote:Correct.
An aircraft can stall at any airspeed, and any attitude.
Please elaborate. I'm curious.
As requested, I will elaborate:
Stalls
An aircraft stall results from a rapid decrease in lift caused by
the separation of airflow from the wing’s surface brought on
by exceeding the critical AOA.
A stall can occur at any pitch
attitude or airspeed.
The stalling speed of a particular aircraft is not a fixed value
for all flight situations, but a given aircraft always stalls at
the same AOA regardless of airspeed, weight, load factor,
or density altitude. Each aircraft has a particular AOA where
the airflow separates from the upper surface of the wing and
the stall occurs. This critical AOA varies from 16° to 20°
depending on the aircraft’s design. But each aircraft has only
one specific AOA where the stall occurs.
There are three flight situations in which the critical AOA
can be exceeded: low speed, high speed, and turning.
The aircraft can be stalled in straight-and-level flight by flying
too slowly. As the airspeed decreases, the AOA must be
increased to retain the lift required for maintaining altitude.
The lower the airspeed becomes, the more the AOA must
be increased. Eventually, an AOA is reached which results
in the wing not producing enough lift to support the aircraft
which starts settling. If the airspeed is reduced further, the
aircraft stalls, since the AOA has exceeded the critical angle
and the airflow over the wing is disrupted.
Low speed is not necessary to produce a stall. The wing can
be brought into an excessive AOA at any speed. For example,
an aircraft is in a dive with an airspeed of 100 knots when the
pilot pulls back sharply on the elevator control.
Gravity and centrifugal force prevent an immediate alteration
of the flightpath, but the aircraft’s AOA changes abruptly
from quite low to very high. Since the flightpath of the aircraft
in relation to the oncoming air determines the direction of the
relative wind, the AOA is suddenly increased, and the aircraft
would reach the stalling angle at a speed much greater than
the normal stall speed.
The stalling speed of an aircraft is also higher in a level turn
than in straight-and-level fl ight. Centrifugal
force is added to the aircraft’s weight and the wing must
produce sufficient additional lift to counterbalance the load
imposed by the combination of centrifugal force and weight.
In a turn, the necessary additional lift is acquired by applying
back pressure to the elevator control. This increases the wing’s
AOA, and results in increased lift. The AOA must increase
as the bank angle increases to counteract the increasing load
caused by centrifugal force. If at any time during a turn the
AOA becomes excessive, the aircraft stalls.
Lack of knowledge and understanding of stalls is the main reason for accidents involving
low level steep turns, and turning downwind.
Please educate yourself on stalls. It may save your life.
, but one tends to forget it, cause I usually associate a stall with either flying too slow, or pulling too eagerly on the stick, BUT I also associated that with losing speed, therefore stall because too slow. The dive situation explains it quite well.
