Rate of Turn
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Jets typically go too fast for standard rate turns. Everything in TERPs and PANS-OPS is pretty much predicated on a 25 degree bank (achieved) for terminal area turns.
From Aerodynamics for Naval Aviations (a long-time reference source):
TURNING PERFORMANCE.
The horizontal component of lift will equal the centrifugal force of steady, turning flight. This fact allows development of the following relationships of turning performance:
turn radius
V2
r = -------------
11.26 tan f
where
r = turn radius, ft
V = velocity, knots (TAS)
f = bank angle, degrees
turn rate
1,091 tan f
ROT = -------------
V
where
ROT = rate of turn, degrees per second
f = bank angle, degrees
V = velocity, knots, TAS
These relationships define the turn radius, r, and rate of turn, ROT, as functions of the two principal variables: bank angle, f, and velocity, V (TAS). Thus, when the airplane is flown in the steady, coordinated turn at specific values of bank angle and velocity, the turn rate and turn radius are fixed and independent of the airplane type. As an example, an airplane in a steady, coordinated turn at a bank angle of 45° and a velocity of 250 knots (TAS) would have the following turn performance:
(250)2
r = --------------- (tan 45° = 1.000)
(11.26) (1.000)
= 5,550 ft
and
(1,091)(1.000)
ROT = --------------
250
= 4.37 degrees per second
If the airplane were to hold the same angle of bank at 500 knots (TAS), the turn radius would quadruple (r = 22,200 feet) and the turn rate would be one-half the original value (ROT = 2.19 degrees per second).
Values of turn radius and turn rate versus velocity are shown in Figure 2.29 for various angles of bank and the corresponding load factors. The conditions are for the steady, coordinated turn at constant altitude but the results are applicable for climbing or descending flight when the angle of climb or descent is relatively small. While the effect of altitude on turning performance is not immediately apparent from these curves, the principal effect must be appreciated as an increased true airspeed (TAS) for a given equivalent airspeed (EAS).
From Aerodynamics for Naval Aviations (a long-time reference source):
TURNING PERFORMANCE.
The horizontal component of lift will equal the centrifugal force of steady, turning flight. This fact allows development of the following relationships of turning performance:
turn radius
V2
r = -------------
11.26 tan f
where
r = turn radius, ft
V = velocity, knots (TAS)
f = bank angle, degrees
turn rate
1,091 tan f
ROT = -------------
V
where
ROT = rate of turn, degrees per second
f = bank angle, degrees
V = velocity, knots, TAS
These relationships define the turn radius, r, and rate of turn, ROT, as functions of the two principal variables: bank angle, f, and velocity, V (TAS). Thus, when the airplane is flown in the steady, coordinated turn at specific values of bank angle and velocity, the turn rate and turn radius are fixed and independent of the airplane type. As an example, an airplane in a steady, coordinated turn at a bank angle of 45° and a velocity of 250 knots (TAS) would have the following turn performance:
(250)2
r = --------------- (tan 45° = 1.000)
(11.26) (1.000)
= 5,550 ft
and
(1,091)(1.000)
ROT = --------------
250
= 4.37 degrees per second
If the airplane were to hold the same angle of bank at 500 knots (TAS), the turn radius would quadruple (r = 22,200 feet) and the turn rate would be one-half the original value (ROT = 2.19 degrees per second).
Values of turn radius and turn rate versus velocity are shown in Figure 2.29 for various angles of bank and the corresponding load factors. The conditions are for the steady, coordinated turn at constant altitude but the results are applicable for climbing or descending flight when the angle of climb or descent is relatively small. While the effect of altitude on turning performance is not immediately apparent from these curves, the principal effect must be appreciated as an increased true airspeed (TAS) for a given equivalent airspeed (EAS).
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At 180 kt (GS) with the rule of thumb you already need a 25º bank angle. Many jets fly faster than that during approach procedures. They cannot maintain rate one turns without exceeding 30º bank angles.
In a holding pattern, for instance, a jet rarely makes the turn in a minute.
For turn performance, I use a rule of thumb that I derived from the turn of radius formula. It is approximate, of course:
I find my GS in NM per minute, (always approximately, for instance, for a GS of 264, I use 4 nmpm), I calculate the square of that (in the example 16) then divide by 10 (1,6NM) here.
This would be approximately the radius of turn for a 25º-30º bank angle turn. It works very well for me.
In a holding pattern, for instance, a jet rarely makes the turn in a minute.
For turn performance, I use a rule of thumb that I derived from the turn of radius formula. It is approximate, of course:
I find my GS in NM per minute, (always approximately, for instance, for a GS of 264, I use 4 nmpm), I calculate the square of that (in the example 16) then divide by 10 (1,6NM) here.
This would be approximately the radius of turn for a 25º-30º bank angle turn. It works very well for me.
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What the AIM says about bank angle for holding patterns:
Make all turns during entry and while holding at:
(1) 3 degrees per second; or
(2) 30 degree bank angle; or
(3) 25 degree bank provided a flight director system is used.
NOTE-
Use whichever requires the least bank angle.
Make all turns during entry and while holding at:
(1) 3 degrees per second; or
(2) 30 degree bank angle; or
(3) 25 degree bank provided a flight director system is used.
NOTE-
Use whichever requires the least bank angle.
