Sunday, August 24, 2014

Turns in the skyye

For precision in manoeuvres in the skyye, aircraft turns are classified in terms of the speed and angle of bank at which the turns are made.

Rate-1 turns require you to turn the aircraft 360 deg in two minutes (or 3 deg per second) and Rate-2 turns 360 deg in one minute, the latter obviously being at twice the speed. 

90 deg in 30 secs, and 360 deg in 2 mins = Rate-1 turn
Lesser bank

For aircraft holding purposes, the International Civil Aviation Organisation (ICAO) mandates that all turns should be made, "at a bank angle of 25° or at a rate of 3° per second, whichever requires the lesser bank."

By the above formula, a rate one turn at a TAS (True Air Speed) greater than 180 knots would require a bank angle of more than 25 degrees. Therefore faster aircraft just use 25 degrees for their turns. Our Flight School aircraft cruise at 90 - 110 kts, so a Rate-1 turn would apply to us.

Medium Turns

A Medium turn is defined as a turn using up to 30 deg angle of bank. When taking off or landing one shouldn't use more than 15 deg angle of bank as the stall speed of the aircraft increases with an increased angle of bank and during landings and take-offs the speed of the aircraft is at its lowest and already closest to stall speed. 

This article explains how you enter, maintain and exit a medium turn:
(Click on the link for the full article) - the following is an extract only)

In the Turn

At 30 degrees angle of bank – which should be recognised by reference to the attitude and confirmed by instruments – a slight check of aileron will be required and rudder pressure reduced to maintain balance.
Maintaining the turn involves using the LAI scan.
In a scan, look out to the left (port) and scan 20 degrees for 2 seconds from left to right, passing over the nose of the aeroplane. Emphasise looking into the turn.
Ensure the attitude for 30 degrees angle of bank and level flight is correct relative to the horizon and, more importantly, constant. When the outside scan is complete, scan inside.
Are scanned to confirm accurate flight (height – bank – ball).
Angle of bank is controlled with aileron – altitude with elevator.
During the turn, scan only those instruments relevant to the manoeuvre and do not trim the aeroplane.

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