FS XXI Maneuvering Flight and
Power Management
C Co. 1-212 Aviation Regiment
Lowe Army Airfield
SPUD
Terminal Learning Objective: At the completion of
this lesson the student will be able to discuss and apply
the concepts of maneuvering flight and power
management.
Condition: As a UH-60 student pilot.
Standard: In accordance with TC 1-237 Aircrew
Training Manual Utility Helicopter H-60 Series and 1-212
Aviation Regiment Handbook for Combat Maneuvering
Flight and Power Management.
Safety Requirements: None
Environmental Considerations: None
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References
• TC 1-237 Aircrew Training Manual Utility Helicopter H-60 Series
• 1-212 Aviation Regiment Handbook for Combat Maneuvering Flight
and Power Management
• FM 3-04.203 Fundamentals of Flight
• TM 1-1520-237-10 Operator’s Manual for UH-60A, UH-60L, and
EH-60A Helicopters
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Topics Covered
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Basic maneuvering flight aerodynamics
Relationship of maneuvering flight versus power available
Transient torque
Mushing
Retreating blade stall
Conservation of angular momentum
Aerodynamics ECU/DEC relationship
High bank angle turns
Maneuvering flight rules of thumb
UH-60 performance characteristics
Maneuvering flight tasks
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Basic Maneuvering Flight
Aerodynamics
Just as rotor performance is affected by the aircraft being in or out
of ground effect, there are several aerodynamic characteristics
that aviators must be aware of to successfully perform combat
maneuvers.
• Transient torque
• Mushing
• Conservation of Angular Momentum
• Retreating blade stall
• High bank angle turns
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Relationship of Maneuvering Flight To
Power Available
Power Available is the amount of excess power (maximum torque
available or transmission limit) available above that required for
straight-and-level flight. It is one of the limiting factors in
maneuvering flight. As the power available margin decreases,
maneuvering flight capability is decreased.
1000
24
60
0
100
42
106
156
106
89
760
Maximum Torque Available:
100 KIAS Cruise Torque:
Power Available:
Max Angle:
193
110
24
80
76
6000
104
112
84
88
32
53
81
32
100
52
635
106
116
82
840
100%
42%
58%
60°
Maximum Torque Available:
100 KIAS Cruise Torque:
Power Available:
Max Angle:
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184
84
46
80
84
78
86
89
81
775
81%
52%
29%
53°
Transient Torque
Transient torque is a phenomenon occurring when lateral cyclic is
applied and is caused by aerodynamic forces. When the cyclic is
displaced laterally to the left, induced drag is increased causing a
temporary increase in torque. When the cyclic is displaced to the
right, a reduction in induced drag causes an increase in %RMR R
resulting in a temporary decrease in torque.
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Transient Torque
Five factors affect how much torque change occurs during transient
torque:
• Torque transients are proportional with the amount of power
applied.
• Rate of movement of the cyclic. The faster the rate of movement
the higher resultant torque increase.
• Magnitude of cyclic displacement directly affects the torque
transient.
• Drag is increased or decreased by the factor of velocity squared.
Thus, the higher the forward airspeed, the higher the torque transient
results.
• High aircraft weight increases coning, which will make transient
torque more pronounced.
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Mushing
Mushing is a temporary stall condition occurring in helicopters
when rapid aft cyclic is applied at high forward airspeeds. Airflow
changes result in a decrease of total lift area and rotor disc coning.
Instead of induced flow downward through the rotor system, an
upward flow is produced resulting in a stall condition on portions of
the entire rotor system. Conditions conducive to mushing include:
• High forward airspeeds
• High gross weight
• High density altitude
• Severity of maneuver
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Retreating Blade Stall
In forward flight, decreasing velocity of airflow on the retreating
blade requires a higher angle of attack (AOA) to generate the
same lift as the advancing blade. When forward airspeed
increases, the no-lift areas of the retreating blade grow larger,
placing an even greater demand for production of lift on the
progressively smaller section of lift-producing area until the tip of
the blade (area of highest AOA) stalls. Maximum angles of bank
less than 60° on the PPC indicate the onset of blade stall if
exceeded.
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Conservation of Angular Momentum
The value of angular momentum of a rotating body will not
change unless external forces are applied. Simply put, a rotating
body will continue to rotate with the same rotational velocity until
some external force is applied to change the speed of rotation.
Velocity can be changed by placing the mass of the rotating
body closer to or further from the axis of rotation. An excellent
example of this law is the figure skater.
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Aerodynamics ECU/DEC Relationship
Application of lateral or aft cyclic causes the center of
gravity to move inboard causing %RPM R to increase.
%RPM R Increases
An Increase of %RPM R is monitored by the ECU/DEC. The ECU/DEC
schedules fuel to lower %RPM 1 & 2 causing a reduction in %RPM R.
Total aerodynamic force is also forward of the lift vector causing an
increase of %RPM R.
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Aerodynamics ECU/DEC Relationship
Application of forward cyclic causes the center of gravity
to move outboard causing %RPM R to decrease.
%RPM R Decreases
A decrease of %RPM R is monitored by the ECU/DEC. An increase of
collective will further decrease %RMR R depending on rate of collective
movement. Total aerodynamic force is also aft of the lift vector causing a
decrease of %RPM R.
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High Bank Angle Turns
If adequate excess engine power is available, increasing
collective pitch will enable continued flight while maintaining
airspeed and altitude. If sufficient excess power is not available,
the result is altitude loss unless airspeed is traded (aft cyclic) to
maintain altitude or altitude is traded to maintain airspeed.
Bank
Angle
Increase
in %TQ
Load/G
Factor
0°
--
1.0
15°
3.6
1.054
30°
15.4
1.154
45°
41.4
1.414
60°
100.0
2.0
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UH-60 Performance Characteristics
To minimize transient rotor droop, avoid situations which result in
rapid rotor loading from low Ng SPEED and %TRQ conditions.
Initiate maneuvers with collective inputs leading or simultaneous to
cyclic inputs. During approach and landing, maintain at least
15% - 20% TRQ and transient droop will be minimal as hover
power is applied.
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Maneuvering Flight Rules of Thumb
• Every aviator that employs these techniques at the wrong place
and time endangers our ability to continue this critical training.
• Only train maneuvers that have a combat application.
• Taking unnecessary risks when carrying a load of combat equipped
infantry soldiers can be equated to a Commercial Airline Pilot
showing off when carrying athletes to the Olympics.
• There is no excuse - do what the mission requires.
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Maneuvering Flight Tasks
3005 Demonstrate/Perform Flight Characteristics at Vh-IAS
3006 Perform Maximum Bank Angle
3007 Perform Maximum Pitch Angle
3008 Perform Decelerating Turn
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Demonstrate/Perform Flight
Characteristics at Vh IAS
1. Maintain entry altitude/airspeed 1000 MSL and 100 KIAS.
2. Increase collective to maintain maximum torque available
or transmission limit +0 to -5%.
3. Establish and maintain Vh KIAS ± 5 KIAS.
4. Maintain Vh KIAS for a minimum of 30 seconds.
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Demonstrate/Perform Maximum Bank
Angle
1. Maintain entry altitude/airspeed 1000 MSL
and 100 KIAS.
2. Maintain maximum bank angle +0 to -5°.
3. Apply cyclic in direction of turn until
maximum angle is achieved followed
immediately by applying cyclic in opposite
direction to maximum bank angle.
4. Observe torque increase in left turn and
torque decrease in right turn.
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60° AOB
60° AOB
Demonstrate/Perform Maximum Bank
Angle
Altitude with Cyclic
1. Maintain entry altitude/airspeed
1000 MSL and 100 KIAS.
2. Maintain maximum bank angle
+0 to -5°.
3. Maintain the maximum bank angle
without adjusting collective position.
4. Maintain maximum bank angle
throughout a minimum of 270°.
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60° AOB
270°
Demonstrate/Perform Maximum Bank
Angle
Constant Altitude and Airspeed
1. Maintain entry altitude/airspeed 1000
MSL and 100 KIAS.
2. Maintain maximum bank angle +0 to -5°.
3. Adjust collective and cyclic as necessary
to maintain entry altitude and airspeed.
4. Maintain the maximum bank angle
throughout a minimum of 270 degrees.
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60° AOB
270°
Demonstrate/Perform Maximum Pitch
Angle
30° Pitch
70 KIAS
1. Maintain entry altitude/airspeed 400 AGL and 100 KIAS.
2. Maintain maximum pitch angle +0 to -5°.
3. Smoothly apply aft cyclic until the maximum pitch up angle is
achieved.
4. Maintain the maximum pitch up angle until the airspeed decreases
to 70 KIAS.
5. Adjust cyclic as necessary to level the aircraft and return to 100
KIAS.
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Demonstrate/Perform Maximum Pitch
Angle
30° Pitch
130 KIAS
1. Maintain entry altitude/airspeed 2000 MSL and 100 KIAS.
2. Reduce collective until torque is 5% below cruise then apply
forward cyclic until the maximum pitch down angle is achieved.
3. Maintain the maximum pitch down angle until airspeed increases
to 130 KIAS.
4. Apply collective to cruise power no later than 1000 MSL.
5. Apply aft cyclic to level the aircraft to prevent rotor droop. Level the
aircraft and return to 100 KIAS without descending below 400 feet
AGL.
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Perform Decelerating Turn
1. Maintain terrain flight altitude and no lower
than 50 feet AHO at cruise airspeed.
2. On downwind abeam or beyond the
abeam point of the intended point of
termination initiate the maneuver.
3. Apply lateral and aft cyclic until the
desirable bank angle and decelerative
attitude is achieved.
4. Progressively decelerate while intercepting
an approach angle clear of all obstacles to
the point of termination.
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Review
•
•
•
•
•
•
•
•
•
•
•
Basic maneuvering flight aerodynamics
Relationship of maneuvering flight versus power available
Transient torque
Mushing
Retreating blade stall
Conservation of angular momentum
Aerodynamics ECU/DEC relationship
High bank angle turns
Maneuvering flight rules of thumb
UH-60 performance characteristics
Maneuvering flight tasks
SPUD
Questions?
C Co. 1-212 Aviation Regiment
Lowe Army Airfield
SPUD