Yak 18T Flight Operations Manual
Page 49 of 82
Disclaimer: This manual is to be used as a reference only, it is based on translated Yak 18T Flight Operations
Manuals and has not been approved by the Yakovlev Design Bureau or any other authority.
• The IAS during the half-loop recovery must be 140km/h. If the speed at the time of
the half-roll is NOT 140km/h, then the half-roll is NOT ALLOWED to be performed.
TERMINATE the manoeuvre WITHOUT making the second half-loop
8.14 Aircraft Behaviour at Large Angles of Attack and Stall
• Pilots are warned about the fact that the aircraft is approaching a STALL by an
AUDIBLE signal in the headset and LIGHT signals (indication DANGEROUS SPEED on
the annunciator panel) approximately 15 SECONDS prior to the stall
• The character of the Yak 18T can be remarkably DIFFERENT to that of a C172. For
example, a C172 experiences a relatively sharp nose drop after the stall has occurred.
The 18T has been known to produce a negative VSI upon stall without any other visible
or audible signals so DO NOT RELY on receiving a stall signal for the awareness of the
aircraft stall. A good instrument SCAN and attitudinal awareness will help to highlight an
imminent stall and UNEXPECTED negative VSI reading
• The warning detector is SET to the response indicated speed of 130km/h. The warning
indicator is cut-in by a toggle switch on the switchboard
• The aircraft controls retain their operational effectiveness at low flight speeds, up to the
POINT of the actual stall
• Other symptoms at the point of stall include a nose down attitude with rolling either to
the left or to the right side and a small shaking or buffeting
• By pushing the yoke FORWARD, the aircraft attitude will transition from the angle of
incidence to one that is below the stall, but only once the speed INCREASES
• The indicated stalling speeds with n
y
=1.0 are as follows –
• in the cruise configuration at the engine conditions IDLING 120-123km/h
• in the cruise configuration at the engine conditions NOMINAL I 102-105km/h
• in the landing configuration at the engine conditions IDLING 112-114km/h
• in the landing configuration at the engine conditions TAKE-OFF 97km/h
• Large speed values correspond to the aircraft's weight of 1,650 kg, small ones to the
aircraft's weight of 1,500kg
• At NOMINAL I engine conditions, with a full pulling of the yoke after the stall, the
aircraft will ROLL either to the left or to the right with a greater VIGOUR than at
IDLING conditions
• During 360° banked turns and spirals, while pulling the yoke BACKWARDS, the aircraft
vigorously DROPS the nose with a simultaneous rising of the IAS an INCREASE in roll
will also take place
• An even greater INCREASE will occur if dropping the nose at the time of stall, and more
so, the higher the speed during the turn-spiral. In moving the yoke FORWARD, the
aircraft makes a quick transition to a sub-critical angle-of-attack
• In this case, pre-stall warning of shaking or buffeting is NOT felt. However, at the time
of the actual stall, a slight shaking or buffeting APPEARS
• The turn-spiral stalls with different engine conditions and c.g. positions DO NOT differ in
their nature
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