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Maximum Sustained Turn Rate?



 
 
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  #1  
Old May 10th 04, 03:49 PM
Emilio
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Default Maximum Sustained Turn Rate?

Is it correct to say that maximum sustained turn rate of an aircraft is
equivalent to steepest bank angle aircraft can sustain in a turn?

Emilio


  #2  
Old May 10th 04, 04:02 PM
Andy Bush
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Possibly.

Energy maneuvering (EM) diagrams that show turn rates usually assume a level
flight condition (no altitude gain or loss). The sustained turn rate is
defined as a line that starts at the left hand boundary ("stall" line) and
goes across the chart to the right until it meets the max airspeed line.
This line, known as the "zero Ps" line, goes up and down as a function of
speed and "g".

The peak of the zero Ps line is the max sustained turn rate and is defined
as the intersection of a turn rate and airspeed value. In most cases, this
point is below the max attainable turn rate point. All EM diagrams must
specify a weight, altitude, power setting, and configuration...therefore
there is no such thing as one max sustainable speed.

Bank angle enters the picture as a function of available g and the need to
maintain level flight. If an aircraft can pull additional g while
maintaining level flight, then it is not at its max zero Ps point.

The absolute max turn rate for a given weight and altitude would be with the
aircraft inverted and pulling max available g...the additional one g of
gravity would increase the turn rate as long as the lift vector was oriented
below the horizon.
"Emilio" wrote in message
...
Is it correct to say that maximum sustained turn rate of an aircraft is
equivalent to steepest bank angle aircraft can sustain in a turn?

Emilio




  #3  
Old May 10th 04, 04:50 PM
Emilio
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Posts: n/a
Default

All EM diagrams must specify a weight, altitude, power setting, and
configuration...

I was trying to relate the diagrams to real situation. As you put it, too
much factors come in to play as far as performance is concerned. The bank
angle and whether your opponent is sustaining level turn is one thing you
can see in ACM.

The absolute max turn rate for a given weight and altitude would be with

the aircraft inverted and pulling max available g...

That is the tactical egg right? If that is the case, Split S maneuver to
reverse flight direction beats max turn rate to turn 180 degrees?

Emilio.

"Andy Bush" wrote in message
...
Possibly.

Energy maneuvering (EM) diagrams that show turn rates usually assume a

level
flight condition (no altitude gain or loss). The sustained turn rate is
defined as a line that starts at the left hand boundary ("stall" line) and
goes across the chart to the right until it meets the max airspeed line.
This line, known as the "zero Ps" line, goes up and down as a function of
speed and "g".

The peak of the zero Ps line is the max sustained turn rate and is defined
as the intersection of a turn rate and airspeed value. In most cases, this
point is below the max attainable turn rate point. All EM diagrams must
specify a weight, altitude, power setting, and configuration...therefore
there is no such thing as one max sustainable speed.

Bank angle enters the picture as a function of available g and the need to
maintain level flight. If an aircraft can pull additional g while
maintaining level flight, then it is not at its max zero Ps point.

The absolute max turn rate for a given weight and altitude would be with

the
aircraft inverted and pulling max available g...the additional one g of
gravity would increase the turn rate as long as the lift vector was

oriented
below the horizon.
"Emilio" wrote in message
...
Is it correct to say that maximum sustained turn rate of an aircraft is
equivalent to steepest bank angle aircraft can sustain in a turn?

Emilio






  #4  
Old May 10th 04, 05:10 PM
Ed Rasimus
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Default

On Mon, 10 May 2004 10:50:50 -0500, "Emilio"
wrote:

I was trying to relate the diagrams to real situation. As you put it, too
much factors come in to play as far as performance is concerned. The bank
angle and whether your opponent is sustaining level turn is one thing you
can see in ACM.


Frankly, in ACM, you don't really care about sustaining a level turn.
What you care about is the ability to maneuver to a weapons employment
solution.

That being said, we can find simplicity in "Eddie's Three Rules of
BFM"---these are for 1-v-1, forward firing, low-aspect ratio kill
solutions. In other words, classic gun tracking or boresight IR shots.

Rule 1:--maneuver to reduce angles.
This means reduce both aspect angle and angle off. Get to a
position behind your adversary and align your fuselage with his.
(Defensively it reverses--maneuver to increase angles. Move your
adversary to high crossing angle and forward on your wingline.)

Rule 2:--maintain positive delta energy.
This means get a superior total energy situation over your
adversary. Total energy is the combination of kinetic and potential
(speed and altitude). Never exchange energy for a net loss. Don't
dissipate energy without gaining signficantly in position--think
"don't cobra!"

Rule 3:--unless taking up the slack in the trigger, always maneuver
outside of the enemy's plane of motion.
This means don't tail chase. If he turn level, you turn vertical.
Predict where he is going and employ cut-off. Maneuver in three
dimensions relative to his two dimension turn.

The absolute max turn rate for a given weight and altitude would be with

the aircraft inverted and pulling max available g...

That is the tactical egg right? If that is the case, Split S maneuver to
reverse flight direction beats max turn rate to turn 180 degrees?


Actually the best rate reversal depends upon own speed relative to
corner velocity. (Corner is the min speed to pull max allowable G). If
above corner, pitch-back--a nose high 45 degree banked reversal. If
below corner, slice back--a nose low 135 degree bank reversal. The
nose high controls loss of airspeed better while minimizing the loss
of G in a pure vertical climbing turn. The nose low maximizes airspeed
gain while reducing altitude loss yet still giving a good component of
god's G to turn rate.

Nobody gives a damn about bank angle.



Emilio.

"Andy Bush" wrote in message
...
Possibly.

Energy maneuvering (EM) diagrams that show turn rates usually assume a

level
flight condition (no altitude gain or loss). The sustained turn rate is
defined as a line that starts at the left hand boundary ("stall" line) and
goes across the chart to the right until it meets the max airspeed line.
This line, known as the "zero Ps" line, goes up and down as a function of
speed and "g".

The peak of the zero Ps line is the max sustained turn rate and is defined
as the intersection of a turn rate and airspeed value. In most cases, this
point is below the max attainable turn rate point. All EM diagrams must
specify a weight, altitude, power setting, and configuration...therefore
there is no such thing as one max sustainable speed.

Bank angle enters the picture as a function of available g and the need to
maintain level flight. If an aircraft can pull additional g while
maintaining level flight, then it is not at its max zero Ps point.

The absolute max turn rate for a given weight and altitude would be with

the
aircraft inverted and pulling max available g...the additional one g of
gravity would increase the turn rate as long as the lift vector was

oriented
below the horizon.
"Emilio" wrote in message
...
Is it correct to say that maximum sustained turn rate of an aircraft is
equivalent to steepest bank angle aircraft can sustain in a turn?

Emilio






Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
Smithsonian Institution Press
ISBN #1-58834-103-8
  #5  
Old May 11th 04, 02:39 AM
Jim Thomas
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Posts: n/a
Default

"Emilio" wrote in message ...
Is it correct to say that maximum sustained turn rate of an aircraft is
equivalent to steepest bank angle aircraft can sustain in a turn?

Emilio


The simple answer is this: yes, the maximum sustained "level" turn
rate is equivalent to steepest bank angle aircraft can sustain in a
"level" turn under given conditions of airspeed and altitude. Although
this may not have tactical significance, this level turn performance
has historically been a contract requirement for fighter aircraft. It
is also the flight test that defines the zero specific excess power
(Ps) condition.

Jim Thomas
  #6  
Old May 11th 04, 03:12 AM
Andy Bush
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Posts: n/a
Default

A Split S is not going to be the quickest way to reverse direction. Ed has
described the pitchback and sliceback, both of which can be thought of as
the most practical way of turning around in the least amount of time,
depending on entry airspeed.

Your original question can be seen as an academic query...or as a basis for
a tactics discussion. As you said, when taking an academic point of view,
parameters such as sustained flight conditions, turn rate, specific energy
curves, etc, all depend on a set of predetermined conditions.

If we switch to tactics, then much of this EM stuff is left in the
classroom...because what is "smart" in an engagement may have little to do
with academic theories. One of the best examples of this is the corner speed
value. Few would ever advise cruising at this speed simply because it
represents a high turn rate value.
"Emilio" wrote in message
...
All EM diagrams must specify a weight, altitude, power setting, and

configuration...

I was trying to relate the diagrams to real situation. As you put it, too
much factors come in to play as far as performance is concerned. The bank
angle and whether your opponent is sustaining level turn is one thing you
can see in ACM.

The absolute max turn rate for a given weight and altitude would be with

the aircraft inverted and pulling max available g...

That is the tactical egg right? If that is the case, Split S maneuver to
reverse flight direction beats max turn rate to turn 180 degrees?

Emilio.

"Andy Bush" wrote in message
...
Possibly.

Energy maneuvering (EM) diagrams that show turn rates usually assume a

level
flight condition (no altitude gain or loss). The sustained turn rate is
defined as a line that starts at the left hand boundary ("stall" line)

and
goes across the chart to the right until it meets the max airspeed line.
This line, known as the "zero Ps" line, goes up and down as a function

of
speed and "g".

The peak of the zero Ps line is the max sustained turn rate and is

defined
as the intersection of a turn rate and airspeed value. In most cases,

this
point is below the max attainable turn rate point. All EM diagrams must
specify a weight, altitude, power setting, and configuration...therefore
there is no such thing as one max sustainable speed.

Bank angle enters the picture as a function of available g and the need

to
maintain level flight. If an aircraft can pull additional g while
maintaining level flight, then it is not at its max zero Ps point.

The absolute max turn rate for a given weight and altitude would be with

the
aircraft inverted and pulling max available g...the additional one g of
gravity would increase the turn rate as long as the lift vector was

oriented
below the horizon.
"Emilio" wrote in message
...
Is it correct to say that maximum sustained turn rate of an aircraft

is
equivalent to steepest bank angle aircraft can sustain in a turn?

Emilio








 




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