7 Stalling
Stalling 7
Key Facts 1
Self Study
The following four pages contain a revision aid to encourage students to become familiar with any new terminology, together with the key elements of “stalling”.
Insert the missing words in these statements, using the foregoing paragraphs for reference.
Stalling involves loss of ________ and loss of _________.
A pilot must be able to clearly and unmistakably ___________ a stall.
A stall is caused by airflow _____________.
Separation can occur when either the boundary layer has insufficient _________ energy or the
_________ ___________ gradient becomes too great.
Adverse pressure gradient increases with increase in angle of ________.
Alternative names for the angle of attack at which stall occurs are the _______ angle and the
__________ angle of attack.
The coefficient of lift at which a stall occurs is ________.
A stall can occur at any ___________ or flight ___________.
A typical stalling angle is approximately ____°.
To recover from a stall the angle of ________ must be ___________.
Maximum power is applied during stall recovery to minimize _________ loss.
On small aircraft, the _________ should be used to prevent wing _______ at the stall.
On swept wing aircraft, the _______ should be used to prevent wing _____ at the stall.
Recover height lost during stall recovery with moderate _______ pressure on the _________
control.
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The first indications of a stall may be _____________ flight controls, stall _________ device or aerodynamic ________.
At speeds close to the stall, __________ must be used with caution to ______ a dropping wing.
Acceptable indications of a stall are:
(1)a nose ______ pitch that can not be readily arrested.
(2)severe ___________.
(3)pitch control reaching _____ stop and no further increase in _______ attitude occurs.
Reference stall speed (VSR ) is a CAS defined by the ________ ___________.
VSR may not be _____ than a ____ stall speed.
When a device that abruptly pushes the _____ _____ at a selected angle of ______ is installed, VSR may not be _____ than ___ knots or ___ %, whichever is ______, above the speed at which the ________ operates.
Stall warning with sufficient _______ to prevent inadvertent stalling must be ______ and
______________ to the pilot in straight and turning flight.
Acceptable stall warning may consist of the inherent ____________ qualities of the aeroplane or by a ___________ that will give clearly distinguishable indications under expected conditions of flight.
Stall warning must begin at a speed exceeding the stall speed by not less than __ knots or __ % CAS, whichever is the greater.
Artificial stall warning on a small aircraft is usually given by a ______ or ________.
Artificial stall warning on a large aircraft is usually given by a _______ shaker, in conjunction with ________ and a noisemaker.
An artificial stall warning device can be activated by a _________ switch, an angle of ________
vane or an angle of attack _______.
Most angle of attack sensors compute the ______ of change of angle of attack to give _________
warning in the case of accelerated rates of stall approach.
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7 Stalling
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EASA required stall characteristics, up to the time the aeroplane is stalled, are:
a.It must be possible to produce and correct ____ by unreversed use of the ________ and
________.
b.No abnormal nose-up ________ may occur.
c.Longitudinal control force must be ________.
d.It must be possible to promptly prevent ________ and recover from a stall by normal use of the ________.
e.There should be no excessive ____ between the stall and completion of recovery.
f.For turning flight stalls, the action of the aeroplane after the stall may not be so
_______ or _______ as to make it difficult, with normal piloting _____, to effect prompt
_________ and to regain _______ of the aeroplane.
An aerofoil section with a small leading edge ______ will stall at a _______ angle of attack and the stall will be more ______.
An aerofoil section with a large thickness-chord ratio will stall at a ______ angle of attack and will stall more ______.
An aerofoil section with camber near the ________ ______ will stall at a higher angle of attack.
A rectangular wing planform will tend to stall at the ____ first.
A rectangular wing planform usually has ideal stall characteristics; these are:
a.Aileron _____________ at the stall.
b.Nose _____ at the stall.
c.Aerodynamic _______ at the stall.
d.Absence of violent wing _____ at the stall.
To give a wing with a tapered planform the desired stall characteristics, the following devices can be included in the design:
a.________ (decreasing incidence from root to tip).
b.An aerofoil section with ________ thickness and camber at the tip.
c.Leading edge ______ at the tip.
d.Stall _______ fitted to the wing inboard leading edge.
e._______ generators which re-energize the _________ layer at the tip.
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A swept-back wing has an increased tendency to tip stall due to the spanwise flow of boundary layer from root to tip on the wing top surface. Methods of delaying tip stall on a swept wing planform are:
a.Wing _______, thin metal fences which generally extend from the leading edge to the trailing edge on the wing top surface.
b._________, also thin metal fences, but smaller and are situated on the underside of the wing leading edge.
c.Saw _____ leading edge, generates vortices over wing top surface at high angles of
attack.
d.Engine _______ of pod mounted wing engines also act as vortilons.
e._______ generators are also used to delay tip stall on a swept wing.
Tip stall on a swept wing planform gives a tendency for the aircraft to _____-___ at the stall. This is due to the ___ moving forwards when the wing tips stall ______.
KEY FACTS 1, WITH WORD INSERTS CAN BE FOUND ON page 201.
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