F16 max speed without using afterburners (naked)

[Fortos]

Hello,

What is the max speed a F16 can flight without using its afterburners ?

Regards

F

[Typhoon502]

Post by Fortos
Hello,
What is the max speed a F16 can flight without using its afterburners ?

Let's narrow down the parameters. Clean, F-16C, with the strongest
engine option. Would it supercruise?

[Kurt R. Todoroff]

Post by Typhoon502

Post by Fortos
Hello,
What is the max speed a F16 can flight without using its afterburners ?

Let's narrow down the parameters. Clean, F-16C, with the strongest
engine option. Would it supercruise?

Supercruise is defined as "supersonic persistence without the use of
afterburner". Here's the rub: different definitions AND uses of the
word "supersonic". The simple aeronautical definition of supersonic is
velocity above the "transonic range". i.e. generally speaking (but not
absolutely since it varies with aircraft type) approximately Mach 1.1.
No flame zone here, since I said "approximately".

We've all read postings in this newsgroup about this or that fighter
flying Mach 1.1 in Mil power. This is NOT supercruise in my way of
thinking. The USAF and Lockheed define supercruise as Mach 1.5
persistence without afterburner. Those who manufacturer the slower
latest generation fighters consider supercruise to be the supersonic
velocity that their aircraft can attain (which is much less than Mach
1.5) in Mil power.

I am confident that the clean F-16C with the General Electric
F110-GE-132 engine can exceed Mach 1.0 in Mil power. This is not
supercruise. It can probably attain Mach 1.1 in Mil power. Is this
supercruise? Maybe. Maybe not. The thrust requirements at Mach 1.5
are exponentially greater than at Mach 1.1.

Does supercruise occur at 1.2, 1.3, 1.4, or only at and above Mach 1.5?
I don't know. Can the F-16C / F110-GE-132 supercruise? I doubt it.

[bbrought]

Post by Kurt R. Todoroff
Supercruise is defined as "supersonic persistence without the use of
afterburner". Here's the rub: different definitions AND uses of the
word "supersonic". The simple aeronautical definition of supersonic is
velocity above the "transonic range". i.e. generally speaking (but not
absolutely since it varies with aircraft type) approximately Mach 1.1.
No flame zone here, since I said "approximately".

Kurt, that is not true. You can pick up any engineering aerodynamics
text book and it will tell you supersonic is when the Mach number is
more than 1.0. Sonic is when it is exactly 1.0 (such as in the throat
of a nozzle). Subsonic is less than 1.0. There is no ambiguity here.

For an aircraft, Mach number is defined as the true airspeed of the
aircraft, divided by the local speed of sound (the speed of sound at
that altitude/temperature). Therefore, if an aircraft is flying at a
TAS of 300.00000001 m/s, and the local speed of sound is 300.0 m/s,
then it is supersonic.

Transonic is a term that we came up with in aerodynamics to describe a
region where there is a significant amount of mixed flow around an
object (in other words, there are significant amounts of subsonic and
supersonic flow regions around the body). The key word is
"significant", because even at Mach 2 you will find local areas of
subsonic flows (for instance inside boundary layers close to the
surface and behind bluff bodies such as antennas and other
protrusions). Transonic flow is quite difficult to analyse and has to
be treated differently compared to "pure" supersonic or subsonic flow,
therefore the seperate term to describe transonic flow problems.
Hypersonic has similar issues, but although an aircraft traveling at
Mach 7 may be in the "hypersonic flow regime" it is still traveling
supersonic (i.e. the aircraft itself is traveling through the air
faster than the local speed of sound).

The definition that LM uses for supercruise is a marketing term that
they seem to have come up with by themselves. If what they mean is what
you stated in the beginning: "supersonic persistence without the use of
afterburner", and they use the correct definition of supersonic
(aircraft TAS / speed of sound at local ambient conditions), then an
aircraft that can cruise at M=1.000001 is supercruising. It seems what
they mean with "supercruise" is: "the aircraft Mach number as well as
the majority of the flow around the aircraft is supersonic". As you can
see, that is a very arbitrary definition.

[John Carrier]

SNIP

Post by bbrought
Kurt, that is not true. You can pick up any engineering aerodynamics
text book and it will tell you supersonic is when the Mach number is
more than 1.0. Sonic is when it is exactly 1.0 (such as in the throat
of a nozzle). Subsonic is less than 1.0. There is no ambiguity here.

True, but the word being analyzed is "supercruise." "We" didn't have that
in any of the aero texts. So the definition is open to debate. I suspect
104 drivers doing 1.05 or so in basic engine back in the late fifties would
have talked up supercruise if they gave a ****.

Post by bbrought
Transonic is a term that we came up with in aerodynamics to describe a
region where there is a significant amount of mixed flow around an
object (in other words, there are significant amounts of subsonic and
supersonic flow regions around the body). The key word is
"significant", because even at Mach 2 you will find local areas of
subsonic flows (for instance inside boundary layers close to the
surface and behind bluff bodies such as antennas and other
protrusions). Transonic flow is quite difficult to analyse and has to
be treated differently compared to "pure" supersonic or subsonic flow,
therefore the seperate term to describe transonic flow problems.

Exactly. And once the significant effects go away (and Cd resolves itself
to a supersonic number), you can talk about pure supersonic flow.

R / John

[RAP Flashnet]

Great discussion and you all have hit it on the head - different definitions
of super cruise.
But from the pilot standpoint I think the more F-22 approach of a solid Mach
1.2 to say 1.5 in mil power is really doing it, despite the aero text book
definitions which usually date back to the 60's and then just squeeking past
Mach and staying there was a true measure of something. Even the F-4N could
do it if it was clean around 27,000 feet or better in A/B to about 1.2 and
then back to military for a level ride at 1.1 for as long as you did not
touch the stick. Perhaps the only advantage was making 10 miles a minute,
not bad and better then 8 or 9 for the same gas.

[Kurt R. Todoroff]

Post by bbrought

Post by Kurt R. Todoroff
Supercruise is defined as "supersonic persistence without the use of
afterburner". Here's the rub: different definitions AND uses of the
word "supersonic". The simple aeronautical definition of supersonic is
velocity above the "transonic range". i.e. generally speaking (but not
absolutely since it varies with aircraft type) approximately Mach 1.1.
No flame zone here, since I said "approximately".

Kurt, that is not true. You can pick up any engineering aerodynamics
text book and it will tell you supersonic is when the Mach number is
more than 1.0. Sonic is when it is exactly 1.0 (such as in the throat
of a nozzle). Subsonic is less than 1.0. There is no ambiguity here.
For an aircraft, Mach number is defined as the true airspeed of the
aircraft, divided by the local speed of sound (the speed of sound at
that altitude/temperature). Therefore, if an aircraft is flying at a
TAS of 300.00000001 m/s, and the local speed of sound is 300.0 m/s,
then it is supersonic.
Transonic is a term that we came up with in aerodynamics to describe a
region where there is a significant amount of mixed flow around an
object (in other words, there are significant amounts of subsonic and
supersonic flow regions around the body). The key word is
"significant", because even at Mach 2 you will find local areas of
subsonic flows (for instance inside boundary layers close to the
surface and behind bluff bodies such as antennas and other
protrusions). Transonic flow is quite difficult to analyse and has to
be treated differently compared to "pure" supersonic or subsonic flow,
therefore the seperate term to describe transonic flow problems.
Hypersonic has similar issues, but although an aircraft traveling at
Mach 7 may be in the "hypersonic flow regime" it is still traveling
supersonic (i.e. the aircraft itself is traveling through the air
faster than the local speed of sound).
The definition that LM uses for supercruise is a marketing term that
they seem to have come up with by themselves. If what they mean is what
you stated in the beginning: "supersonic persistence without the use of
afterburner", and they use the correct definition of supersonic
(aircraft TAS / speed of sound at local ambient conditions), then an
aircraft that can cruise at M=1.000001 is supercruising. It seems what
they mean with "supercruise" is: "the aircraft Mach number as well as
the majority of the flow around the aircraft is supersonic". As you can
see, that is a very arbitrary definition.

Hi bbrought,

The aeronautical engineering textbooks that USAFA issued to me for my
aero major didn't say that. Let's leave the lay domain for a bit and
talk technical.

The wing critical Mach number is the free stream Mach number at which
sonic flow first appears on the wing.
 
The aircraft critical Mach number is the free stream Mach number at
which sonic flow first appears on the aircraft.  The formation of sonic
flow can occur at the wing, the fuselage, the canopy, or other location
on the aircraft.  The critical Mach number marks the exit of the
subsonic regime and the entrance into the transonic regime.  When local
regions of subsonic flow disappear, that is, the flow exceeds sonic
velocities everywhere, this marks the exit of the transonic regime and
the entrance into the supersonic regime.

A simpler lay explanation is:

subsonic - all local flow is less than sonic

transonic - a mixture where some local flow is less than sonic
and some local flow is equal to or greater than sonic

supersonic - all local flow is greater than sonic

hypersonic - freestream velocity exceeds Mach 5

When I flew my F-111 above Mach 0.92, I had entered the aircraft's
transonic regime. When the Mach tape exceeded 1.0, we would "claim"
that we flew supersonic, when in fact this was not always true. There
is technical talk and there is casual talk. I don't know what the upper
limit of the F-111 transonic regime was. For this discussion, let's
establish Mach 1.1 as that value. If I flew at Mach 1.05, then
technically I wasn't flying supersonic yet. Once I exceeded Mach 1.1,
then I could claim to be flying supersonic. Back in the squadron, I
would claim that I flew supersonic if the Mach tape indicated 1.05.
This is the difference between casual pilot talk and technical
engineering talk.

By the way, LM did not conceive the term supercruise. The USAF first
employed it over two decades ago before any of the primes ever submitted
a proposal for the Advanced Tactical Fighter.

[bbrought]

Post by Kurt R. Todoroff

Post by bbrought

Post by Kurt R. Todoroff
Supercruise is defined as "supersonic persistence without the use of
afterburner". Here's the rub: different definitions AND uses of the
word "supersonic". The simple aeronautical definition of supersonic is
velocity above the "transonic range". i.e. generally speaking (but not
absolutely since it varies with aircraft type) approximately Mach 1.1.
No flame zone here, since I said "approximately".

Kurt, that is not true. You can pick up any engineering aerodynamics
text book and it will tell you supersonic is when the Mach number is
more than 1.0. Sonic is when it is exactly 1.0 (such as in the throat
of a nozzle). Subsonic is less than 1.0. There is no ambiguity here.
For an aircraft, Mach number is defined as the true airspeed of the
aircraft, divided by the local speed of sound (the speed of sound at
that altitude/temperature). Therefore, if an aircraft is flying at a
TAS of 300.00000001 m/s, and the local speed of sound is 300.0 m/s,
then it is supersonic.
Transonic is a term that we came up with in aerodynamics to describe a
region where there is a significant amount of mixed flow around an
object (in other words, there are significant amounts of subsonic and
supersonic flow regions around the body). The key word is
"significant", because even at Mach 2 you will find local areas of
subsonic flows (for instance inside boundary layers close to the
surface and behind bluff bodies such as antennas and other
protrusions). Transonic flow is quite difficult to analyse and has to
be treated differently compared to "pure" supersonic or subsonic flow,
therefore the seperate term to describe transonic flow problems.
Hypersonic has similar issues, but although an aircraft traveling at
Mach 7 may be in the "hypersonic flow regime" it is still traveling
supersonic (i.e. the aircraft itself is traveling through the air
faster than the local speed of sound).
The definition that LM uses for supercruise is a marketing term that
they seem to have come up with by themselves. If what they mean is what
you stated in the beginning: "supersonic persistence without the use of
afterburner", and they use the correct definition of supersonic
(aircraft TAS / speed of sound at local ambient conditions), then an
aircraft that can cruise at M=1.000001 is supercruising. It seems what
they mean with "supercruise" is: "the aircraft Mach number as well as
the majority of the flow around the aircraft is supersonic". As you can
see, that is a very arbitrary definition.

Hi bbrought,
The aeronautical engineering textbooks that USAFA issued to me for my
aero major didn't say that. Let's leave the lay domain for a bit and
talk technical.

I am curious, what exactly did they say? Every aerodynamics text book I
have define subsonic and supersonic as Mach number less than 1.0 and
Mach number greater than 1.0 respectively.
http://roland.lerc.nasa.gov/~dglover/dictionary/
"supersonic: Of or pertaining to, or dealing with, speeds greater than
the acoustic velocity."

Post by Kurt R. Todoroff
The wing critical Mach number is the free stream Mach number at which
sonic flow first appears on the wing.

Indeed. On parts of the wing the FLOW is supersonic, but your aircraft
is still moving at a Mach number of less than 1, and therefore your
aircraft is subsonic, regardless of what happens locally on parts of
the wing.

Post by Kurt R. Todoroff
The aircraft critical Mach number is the free stream Mach number at
which sonic flow first appears on the aircraft. The formation of sonic
flow can occur at the wing, the fuselage, the canopy, or other location
on the aircraft. The critical Mach number marks the exit of the
subsonic regime and the entrance into the transonic regime. When local
regions of subsonic flow disappear, that is, the flow exceeds sonic
velocities everywhere, this marks the exit of the transonic regime and
the entrance into the supersonic regime.

You see, that is the problem - the local regions of subsonic flow never
disappears. Directly at the surface of the aircraft, the flow is
stationary relative to the aircraft. Just off the surface, it
transitions from zero speed relative to the aircraft, to the airspeed
just outside the boundary layer. Inside the boundary layer there will
always be some subsonic flow, no matter how fast you are flying. The
word transonic refers to that regime where there are "significant"
amounts of both subsonic and supersonic flow around the object. Note
the use again of "subsonic" and "supersonic" flow in what I wrote -
there is no ambiguity again about what constitutes local subsonic flow
and local supersonic flow. Any place where the flow is less than Mach
one, it is subsonic. Any place where the flow is greater than Mach one,
it is supersonic. Since you find significant amounts of both types of
flow in around the object, we say it is operating in the transonic
regime. But it is still either subsonic or supersonic.

Again, what you and I talk about above, is what happens locally in the
flow. The aircraft Mach number is based on the airspeed of the aircraft
relative to the speed of sound at that altitude and ambient
temperature. Therefore, if the aircraft is flying at a Mach number just
under one, it is subsonic. Just over one, it is supersonic. Yes, we
might say it operates in the transonic regime due to the mixed flow,
but as soon as it goes faster than Mach one, it is supersonic.

Again from the NASA aerospace dictionary:
"transonic flow
In aerodynamics, flow of a fluid over a body in the range just above
and just below the acoustic velocity. Transonic flow presents a special
problem in aerodynamics in that neither the equations describing
subsonic flow nor the equations describing supersonic flow can be
applied in the transonic range."

and also:

"transonic speed
The speed of a body relative to the surrounding fluid at which the flow
is in some places on the body subsonic and in other places supersonic."

I would have added "significant", as explained earlier. Notice that
what actually constitutes subsonic and supersonic doesn't change, these
two terms are still well defined.

I know what the "lay" explanations are and that people tend to divide
it into the four airspeed categories. Also, when I do analysis or
design work, I use different methods when I am working with airspeeds
around Mach 1 and I sure use the term "transonic" for those types of
flows. However, if you follow the textbook definition of what
supersonic means when refering to an aircraft, then supersonic should
refer to anything moving faster than the speed of sound.

Post by Kurt R. Todoroff
By the way, LM did not conceive the term supercruise. The USAF first
employed it over two decades ago before any of the primes ever submitted
a proposal for the Advanced Tactical Fighter.

Indeed, and now LM uses their own definition instead, saying
supercruise only refers to aircraft that flies faster than what they
regard as the transonic regime. It is arbitrary, because as mentioned
before there is no unambiguous definition of where the transonic regime
ends.

As an aside, if supersonic refers only to an aircraft flying faster
than what is regarded as the "transonic" regime, do you know when the
first "supersonic" flight occured?

[Kurt R. Todoroff]

Post by bbrought

Post by Kurt R. Todoroff

Post by bbrought

Post by Kurt R. Todoroff
Supercruise is defined as "supersonic persistence without the use of
afterburner". Here's the rub: different definitions AND uses of the
word "supersonic". The simple aeronautical definition of supersonic is
velocity above the "transonic range". i.e. generally speaking (but not
absolutely since it varies with aircraft type) approximately Mach 1.1.
No flame zone here, since I said "approximately".

Kurt, that is not true. You can pick up any engineering aerodynamics
text book and it will tell you supersonic is when the Mach number is
more than 1.0. Sonic is when it is exactly 1.0 (such as in the throat
of a nozzle). Subsonic is less than 1.0. There is no ambiguity here.
For an aircraft, Mach number is defined as the true airspeed of the
aircraft, divided by the local speed of sound (the speed of sound at
that altitude/temperature). Therefore, if an aircraft is flying at a
TAS of 300.00000001 m/s, and the local speed of sound is 300.0 m/s,
then it is supersonic.
Transonic is a term that we came up with in aerodynamics to describe a
region where there is a significant amount of mixed flow around an
object (in other words, there are significant amounts of subsonic and
supersonic flow regions around the body). The key word is
"significant", because even at Mach 2 you will find local areas of
subsonic flows (for instance inside boundary layers close to the
surface and behind bluff bodies such as antennas and other
protrusions). Transonic flow is quite difficult to analyse and has to
be treated differently compared to "pure" supersonic or subsonic flow,
therefore the seperate term to describe transonic flow problems.
Hypersonic has similar issues, but although an aircraft traveling at
Mach 7 may be in the "hypersonic flow regime" it is still traveling
supersonic (i.e. the aircraft itself is traveling through the air
faster than the local speed of sound).
The definition that LM uses for supercruise is a marketing term that
they seem to have come up with by themselves. If what they mean is what
you stated in the beginning: "supersonic persistence without the use of
afterburner", and they use the correct definition of supersonic
(aircraft TAS / speed of sound at local ambient conditions), then an
aircraft that can cruise at M=1.000001 is supercruising. It seems what
they mean with "supercruise" is: "the aircraft Mach number as well as
the majority of the flow around the aircraft is supersonic". As you can
see, that is a very arbitrary definition.

Hi bbrought,
The aeronautical engineering textbooks that USAFA issued to me for my
aero major didn't say that. Let's leave the lay domain for a bit and
talk technical.

I am curious, what exactly did they say? Every aerodynamics text book I
have define subsonic and supersonic as Mach number less than 1.0 and
Mach number greater than 1.0 respectively.
http://roland.lerc.nasa.gov/~dglover/dictionary/
"supersonic: Of or pertaining to, or dealing with, speeds greater than
the acoustic velocity."

Post by Kurt R. Todoroff
The wing critical Mach number is the free stream Mach number at which
sonic flow first appears on the wing.

Indeed. On parts of the wing the FLOW is supersonic, but your aircraft
is still moving at a Mach number of less than 1, and therefore your
aircraft is subsonic, regardless of what happens locally on parts of
the wing.

Yes, this is what I said.

Post by bbrought

Post by Kurt R. Todoroff
The aircraft critical Mach number is the free stream Mach number at
which sonic flow first appears on the aircraft. The formation of sonic
flow can occur at the wing, the fuselage, the canopy, or other location
on the aircraft. The critical Mach number marks the exit of the
subsonic regime and the entrance into the transonic regime. When local
regions of subsonic flow disappear, that is, the flow exceeds sonic
velocities everywhere, this marks the exit of the transonic regime and
the entrance into the supersonic regime.

You see, that is the problem - the local regions of subsonic flow never
disappears. Directly at the surface of the aircraft, the flow is
stationary relative to the aircraft. Just off the surface, it
transitions from zero speed relative to the aircraft, to the airspeed
just outside the boundary layer. Inside the boundary layer there will
always be some subsonic flow, no matter how fast you are flying. The
word transonic refers to that regime where there are "significant"
amounts of both subsonic and supersonic flow around the object. Note
the use again of "subsonic" and "supersonic" flow in what I wrote -
there is no ambiguity again about what constitutes local subsonic flow
and local supersonic flow. Any place where the flow is less than Mach
one, it is subsonic. Any place where the flow is greater than Mach one,
it is supersonic. Since you find significant amounts of both types of
flow in around the object, we say it is operating in the transonic
regime. But it is still either subsonic or supersonic.

You use the terms "subsonic" and "supersonic" identically in dissimilar
contexts. It is appropriate to use the terms subsonic and supersonic as
they apply to fluid flow about the wing, but it is not accurate to use
these terms in describing the aircraft's velocity due to its complexity.
We can describe the local fluid velocity over a wing station as subsonic
or supersonic when it is less than or greater than the speed of sound
since the wing is essentially an uncomplicated article unencumbered by
attachments, and since we are referring only to a local velocity.
However, I refrain from describing the aircraft velocity as supersonic,
when its freestream velocity exceeds the speed of sound, unless said
velocity is above the upper threshhold of the transonic range.

Post by bbrought
Again, what you and I talk about above, is what happens locally in the
flow. The aircraft Mach number is based on the airspeed of the aircraft
relative to the speed of sound at that altitude and ambient
temperature. Therefore, if the aircraft is flying at a Mach number just
under one, it is subsonic. Just over one, it is supersonic. Yes, we
might say it operates in the transonic regime due to the mixed flow,
but as soon as it goes faster than Mach one, it is supersonic.

The speed of sound is not a function of altitude, only temperature.

a = sqrt( Gamma * R * T )

The aircraft is not flying supersonic the moment it exceeds the speed of
sound or Mach one. It is flying transonic. There is a substantial
difference between supersonic flow and supersonic objects. The
distinction is not subtle.

Post by bbrought
"transonic flow
In aerodynamics, flow of a fluid over a body in the range just above
and just below the acoustic velocity. Transonic flow presents a special
problem in aerodynamics in that neither the equations describing
subsonic flow nor the equations describing supersonic flow can be
applied in the transonic range."
"transonic speed
The speed of a body relative to the surrounding fluid at which the flow
is in some places on the body subsonic and in other places supersonic."
I would have added "significant", as explained earlier. Notice that
what actually constitutes subsonic and supersonic doesn't change, these
two terms are still well defined.
I know what the "lay" explanations are and that people tend to divide
it into the four airspeed categories. Also, when I do analysis or
design work, I use different methods when I am working with airspeeds
around Mach 1 and I sure use the term "transonic" for those types of
flows. However, if you follow the textbook definition of what
supersonic means when refering to an aircraft, then supersonic should
refer to anything moving faster than the speed of sound.

Post by Kurt R. Todoroff
By the way, LM did not conceive the term supercruise. The USAF first
employed it over two decades ago before any of the primes ever submitted
a proposal for the Advanced Tactical Fighter.

Indeed, and now LM uses their own definition instead, saying
supercruise only refers to aircraft that flies faster than what they
regard as the transonic regime. It is arbitrary, because as mentioned
before there is no unambiguous definition of where the transonic regime
ends.
As an aside, if supersonic refers only to an aircraft flying faster
than what is regarded as the "transonic" regime, do you know when the
first "supersonic" flight occured?

Most of the text that I have read, either technical or historical,
describes Yeager as breaking the "sound barrier". Only a few
descriptions inaccurately credit him with flying supersonic on October
14, 1947. Whether or not he flew supersonic that day (he didn't), he
still broke the sound barrier which means that he exceeded Mach one.
The application or mis-application of words do not diminish the
monumental accomplishment of that remarkable team of persons. When was
the first supersonic flight recorded? I don't know. What was the upper
transonic limit of the X-1, and when was it exceeded? That would be a
great piece of research.

[bbrought]

Post by Kurt R. Todoroff

Post by bbrought
You see, that is the problem - the local regions of subsonic flow never
disappears. Directly at the surface of the aircraft, the flow is
stationary relative to the aircraft. Just off the surface, it
transitions from zero speed relative to the aircraft, to the airspeed
just outside the boundary layer. Inside the boundary layer there will
always be some subsonic flow, no matter how fast you are flying. The
word transonic refers to that regime where there are "significant"
amounts of both subsonic and supersonic flow around the object. Note
the use again of "subsonic" and "supersonic" flow in what I wrote -
there is no ambiguity again about what constitutes local subsonic flow
and local supersonic flow. Any place where the flow is less than Mach
one, it is subsonic. Any place where the flow is greater than Mach one,
it is supersonic. Since you find significant amounts of both types of
flow in around the object, we say it is operating in the transonic
regime. But it is still either subsonic or supersonic.

You use the terms "subsonic" and "supersonic" identically in dissimilar
contexts. It is appropriate to use the terms subsonic and supersonic as
they apply to fluid flow about the wing, but it is not accurate to use
these terms in describing the aircraft's velocity due to its complexity.
We can describe the local fluid velocity over a wing station as subsonic
or supersonic when it is less than or greater than the speed of sound
since the wing is essentially an uncomplicated article unencumbered by
attachments, and since we are referring only to a local velocity.
However, I refrain from describing the aircraft velocity as supersonic,
when its freestream velocity exceeds the speed of sound, unless said
velocity is above the upper threshhold of the transonic range.

Of course I use the terms identically in more than one context - it is
a clearly defined definition. You are welcome of course to refrain from
calling an aircraft flying faster than Mach 1 but still in the
transonic regime as flying transonic. However, I repeat my earlier

Post by Kurt R. Todoroff

Post by bbrought
http://roland.lerc.nasa.gov/~dglover/dictionary/
"supersonic: Of or pertaining to, or dealing with, speeds greater than
the acoustic velocity."

That is a very simple, non-ambiguous definition. That is the one that I
prefer to use. For analysis purposes I do divide flow into the four
regions mentioned here, but in terms of correctness and strictly
following the definition of supersonic, I contend anything moving
faster than the local speed of sound is supersonic.

You also mentioned "hypersonic" in one of your posts, and that it
starts at Mach 5. Again, that Mach number is very arbitrary - again
most text books will state that this number is arbitrary, and many of
them use Mach numbers other than 5.

Post by Kurt R. Todoroff

Post by bbrought
Again, what you and I talk about above, is what happens locally in the
flow. The aircraft Mach number is based on the airspeed of the aircraft
relative to the speed of sound at that altitude and ambient
temperature. Therefore, if the aircraft is flying at a Mach number just
under one, it is subsonic. Just over one, it is supersonic. Yes, we
might say it operates in the transonic regime due to the mixed flow,
but as soon as it goes faster than Mach one, it is supersonic.

The speed of sound is not a function of altitude, only temperature.
a = sqrt( Gamma * R * T )

And temperature is a function of altitude, no? When you do analysis and
don't know the actual ambient temperature, you use a standard
atmospheric table and look up the average temperature for the altitude
you are working with - and use this to calculate the local speed of
sound. When you do flight testing, you can measure the actual ambient
temperature and then of course you use that directly.

Post by Kurt R. Todoroff

Post by bbrought
As an aside, if supersonic refers only to an aircraft flying faster
than what is regarded as the "transonic" regime, do you know when the
first "supersonic" flight occured?

Most of the text that I have read, either technical or historical,
describes Yeager as breaking the "sound barrier". Only a few
descriptions inaccurately credit him with flying supersonic on October
14, 1947. Whether or not he flew supersonic that day (he didn't), he
still broke the sound barrier which means that he exceeded Mach one.
The application or mis-application of words do not diminish the
monumental accomplishment of that remarkable team of persons. When was
the first supersonic flight recorded? I don't know. What was the upper
transonic limit of the X-1, and when was it exceeded? That would be a
great piece of research.

Again, the problem is there is not a very clear definition for
transonic. As I mentioned several times now, there is always some
subsonic flow in the boundary layer, so if we follow the definition of
"no subsonic flow anywhere", then you can never truly go supersonic.
The boundaries of what constitutes transonic flow or transonic flight
are very smeared.

Subsonic and supersonic, on the other hand, are very clearly defined.

This morning back in the office I had a chance to discuss this with
some of my fellow aerodynamicists, and I have yet to find one that says
supersonic flight only starts once you leave the transonic regime. All
of them agree the definition of subsonic and supersonic for an object
is clear and unambiguous, namely that M = V/a > 1.

To get back to the historical context, type in "first supersonic
flight" in google. There sure are a lot of sites and books getting it
wrong, and they refer not only to the Bell X-1, but also to the first
supersonic flights of several more contemporary aircraft. Look at this
one for instance:
http://www.boeing.com/news/releases/1998/news_release_981012n.htm
Mach 1.1 - not really supersonic according to your definition, right?

[bbrought]

Post by bbrought
Of course I use the terms identically in more than one context - it is
a clearly defined definition. You are welcome of course to refrain from
calling an aircraft flying faster than Mach 1 but still in the
transonic regime as flying transonic.

Second "transonic" in the last sentence should of course read
"supersonic"...

[John Carrier]

SNIP ALL

In my course lecture (Aero for Poets), I differentiate by referring to
vehicle speed (Supersonic = 1.0+) and flow characteristics:

Subsonic -- <.75 - .85 (varies with aircraft)

Transonic -- . 75/.85 - 1.20 range (give or take, varies with aircraft)

Supersonic -- 1.20+ (varies with aircraft)

Technically transonic occurs when localized supersonic flow first occurs
(wing upper surface, canopy, assorted blisters, antennae, etc) and continues
until all flow (less boundary layer) is supersonic. This is usually delayed
to some mach number in the range of 1.2 (give or take) because of localized
flow stagnation, significant heat generation and large drag penalties. The
magic number is typically where the bow wave attaches to the wing leading
edge (less a molecule or two) and the stagnation area is eliminated.

R / John

[Ed Rasimus]

Post by John Carrier
SNIP ALL
In my course lecture (Aero for Poets), I differentiate by referring to
Subsonic -- <.75 - .85 (varies with aircraft)
Transonic -- . 75/.85 - 1.20 range (give or take, varies with aircraft)
Supersonic -- 1.20+ (varies with aircraft)
Technically transonic occurs when localized supersonic flow first occurs
(wing upper surface, canopy, assorted blisters, antennae, etc) and continues
until all flow (less boundary layer) is supersonic. This is usually delayed
to some mach number in the range of 1.2 (give or take) because of localized
flow stagnation, significant heat generation and large drag penalties. The
magic number is typically where the bow wave attaches to the wing leading
edge (less a molecule or two) and the stagnation area is eliminated.
R / John

I love it when you talk dirty!

That sounds like engineer talk for my operator experience. Transonic
occurs when drag increases rapidly and portions of the airframe begin
to generate a normal shock wave. Curved surfaces such as you listed
cause the normal shock wave as airflow is accelerated (contrary to the
previous post's emphasis on some portions of airflow being delayed in
achieving supersonic flow because of boundary layer effects.)

And, supersonic was pretty much recognized by that characteristic
hang-up then pop through the M .99 to M 1.2. Dunno that anybody could
ever fly at a stable 1.05 or 1.1? You were either subsonic in the
range of .96 or super at 1.2. The "aero for dummies" course simplified
it to be the point where the shock wave has refined to the bow and
trailing attachments and absence of "normal" or perpendicular shock
waves.

It seems to me, as a part of this discussion that what is going on
within the intakes is pretty much irrelevant as far as discussion of
whether or not the airframe is supersonic or transonic. The engine
cares, but the airframe doesn't.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[John Carrier]

SNIP

Post by Ed Rasimus
It seems to me, as a part of this discussion that what is going on
within the intakes is pretty much irrelevant as far as discussion of
whether or not the airframe is supersonic or transonic. The engine
cares, but the airframe doesn't.

The engine cares all right. A good inlet design minimizes losses and can
increase thrust over static. A bad design generates a huge differential
normal shock and seriously effects performance.

R / John

[John Carrier]

Post by Kurt R. Todoroff
subsonic - all local flow is less than sonic
transonic - a mixture where some local flow is less than sonic
and some local flow is equal to or greater than sonic
supersonic - all local flow is greater than sonic
hypersonic - freestream velocity exceeds Mach 5

As a further amplification of the practical employment of such info, the F-4
had a pretty significant transonic drag rise. To minimize its effects and
maximize performance in a climb/accelleration to maximum energy state, one
would hold (approx) .9 IMN until 27,000' and then nose over at low G
(slightly greater than zero G to avoid oil press issues) mimimizing
trim/induced drag until 1.2 was reached. Then resume nose up attitude to
accellerate AND climb to max energy state (north of 2.0 IMN and 40,000
feet).

Transonic effects are interesting and numerous. In addition to a large drag
increase which may exceed the available thrust (and cannot be overcome in
level flight), flight controls may lose some of their effectiveness, a heavy
wing may develop, a/c longitudinal trim may be dramatically altered, flight
control flutter and buzz may cause damage to the airframe, etc. Taking a
subsonic airframe into supersonic flight (typically in a steep dive from
high altitude) can be a cheap thrill.

I teach the intro to T-45 aero course in the USN strike training curriculum.
I spend the first lecture discussing the (interesting) flying qualities of
the airframe in the transonic range, one which it can barely reach in level
flight. .8 Mcrit, .85 Force Divergent Mach No. .83 max level flight speed.
1.04 maximum speed EVER achieved in a dive. By comparison, every aircraft I
flew operationally (F-8, F-4, F-14; I don't count training aircraft and
incidental machinery) treated 1.0 as just a number on the dial. The lowest
performing of these, the F-8, was faster than the F-18, a similar size
aircraft with twice the installed thrust. (OTOH, it couldn't come close to
the F-18's maneuvering capabilities.)

R / John

[Ed Rasimus]

Post by John Carrier

Post by Kurt R. Todoroff
subsonic - all local flow is less than sonic
transonic - a mixture where some local flow is less than sonic
and some local flow is equal to or greater than sonic
supersonic - all local flow is greater than sonic
hypersonic - freestream velocity exceeds Mach 5

As a further amplification of the practical employment of such info, the F-4
had a pretty significant transonic drag rise. To minimize its effects and
maximize performance in a climb/accelleration to maximum energy state, one
would hold (approx) .9 IMN until 27,000' and then nose over at low G
(slightly greater than zero G to avoid oil press issues) mimimizing
trim/induced drag until 1.2 was reached. Then resume nose up attitude to
accellerate AND climb to max energy state (north of 2.0 IMN and 40,000
feet).

What was the name of the guy that the profile was named after?
Radowsky? Ratofsky? Ratkowski? Something like that. It was known as
the quickest route to M2.

I say that only from hear-say, since I never did the M2 thing.

Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[John Carrier]

Post by Ed Rasimus

Post by John Carrier

Post by Kurt R. Todoroff
subsonic - all local flow is less than sonic
transonic - a mixture where some local flow is less than sonic
and some local flow is equal to or greater than sonic
supersonic - all local flow is greater than sonic
hypersonic - freestream velocity exceeds Mach 5

As a further amplification of the practical employment of such info, the F-4
had a pretty significant transonic drag rise. To minimize its effects and
maximize performance in a climb/accelleration to maximum energy state, one
would hold (approx) .9 IMN until 27,000' and then nose over at low G
(slightly greater than zero G to avoid oil press issues) mimimizing
trim/induced drag until 1.2 was reached. Then resume nose up attitude to
accellerate AND climb to max energy state (north of 2.0 IMN and 40,000
feet).

What was the name of the guy that the profile was named after?
Radowsky? Ratofsky? Ratkowski? Something like that. It was known as
the quickest route to M2.
I say that only from hear-say, since I never did the M2 thing.

Rukowski IIRC. Phantoms and Thuds and never Mach 2? Well, if you flew the
soft-wing Phantom it was unlikely. But I thought a Thud on a maintenance
check flight would have 2.0+ as a given. OTOH, I imagine the Thud showed
you 800KIAS plus at some time in your life.

R / John

[Leadfoot]

Post by John Carrier

Post by Ed Rasimus

Post by John Carrier

Post by Kurt R. Todoroff
subsonic - all local flow is less than sonic
transonic - a mixture where some local flow is less than sonic
and some local flow is equal to or greater than sonic
supersonic - all local flow is greater than sonic
hypersonic - freestream velocity exceeds Mach 5

As a further amplification of the practical employment of such info, the F-4
had a pretty significant transonic drag rise. To minimize its effects and
maximize performance in a climb/accelleration to maximum energy state, one
would hold (approx) .9 IMN until 27,000' and then nose over at low G
(slightly greater than zero G to avoid oil press issues) mimimizing
trim/induced drag until 1.2 was reached. Then resume nose up attitude to
accellerate AND climb to max energy state (north of 2.0 IMN and 40,000
feet).

What was the name of the guy that the profile was named after?
Radowsky? Ratofsky? Ratkowski? Something like that. It was known as
the quickest route to M2.
I say that only from hear-say, since I never did the M2 thing.

Rukowski IIRC. Phantoms and Thuds and never Mach 2? Well, if you flew
the soft-wing Phantom it was unlikely. But I thought a Thud on a
maintenance check flight would have 2.0+ as a given. OTOH, I imagine the
Thud showed you 800KIAS plus at some time in your life.
R / John

[Baruch Kantor]

Routovski (My performance software flies his trajectory automatically).

And by the way, I thoght pilots should think simple !

Supersonic = Aircraft airspeed is well above local speed of sound. It has
NOTHIHG to do with local flow speed.
As far as I know current (Clean) F16 can cruise supersonic in MIL power.

Baruch
______________________
Aircraft Performance and Flight Dynamics.
http://www.newbyte.co.il/

Post by John Carrier

Post by Ed Rasimus

Post by John Carrier

Post by Kurt R. Todoroff
subsonic - all local flow is less than sonic
transonic - a mixture where some local flow is less than sonic
and some local flow is equal to or greater than sonic
supersonic - all local flow is greater than sonic
hypersonic - freestream velocity exceeds Mach 5

As a further amplification of the practical employment of such info, the F-4
had a pretty significant transonic drag rise. To minimize its effects and
maximize performance in a climb/accelleration to maximum energy state, one
would hold (approx) .9 IMN until 27,000' and then nose over at low G
(slightly greater than zero G to avoid oil press issues) mimimizing
trim/induced drag until 1.2 was reached. Then resume nose up attitude to
accellerate AND climb to max energy state (north of 2.0 IMN and 40,000
feet).

What was the name of the guy that the profile was named after?
Radowsky? Ratofsky? Ratkowski? Something like that. It was known as
the quickest route to M2.
I say that only from hear-say, since I never did the M2 thing.

Rukowski IIRC. Phantoms and Thuds and never Mach 2? Well, if you flew
the soft-wing Phantom it was unlikely. But I thought a Thud on a
maintenance check flight would have 2.0+ as a given. OTOH, I imagine the
Thud showed you 800KIAS plus at some time in your life.
R / John

[RAP Flashnet]

The clean F-16 of all models has a neat switch in the leading edge flaps
going transonic, they twist up to enhance the ability to maintain the best
camber for cruise. But in general the Falcon is carrying so much crap nobody
gets to see clean flying anymore or just tooling around in supercruise

Post by Baruch Kantor
Routovski (My performance software flies his trajectory automatically).
And by the way, I thoght pilots should think simple !
Supersonic = Aircraft airspeed is well above local speed of sound. It has
NOTHIHG to do with local flow speed.
As far as I know current (Clean) F16 can cruise supersonic in MIL power.
Baruch
______________________
Aircraft Performance and Flight Dynamics.
http://www.newbyte.co.il/

Post by John Carrier

Post by Ed Rasimus

Post by John Carrier

Post by Kurt R. Todoroff
subsonic - all local flow is less than sonic
transonic - a mixture where some local flow is less than sonic
and some local flow is equal to or greater than sonic
supersonic - all local flow is greater than sonic
hypersonic - freestream velocity exceeds Mach 5

As a further amplification of the practical employment of such info, the F-4
had a pretty significant transonic drag rise. To minimize its effects and
maximize performance in a climb/accelleration to maximum energy state, one
would hold (approx) .9 IMN until 27,000' and then nose over at low G
(slightly greater than zero G to avoid oil press issues) mimimizing
trim/induced drag until 1.2 was reached. Then resume nose up attitude to
accellerate AND climb to max energy state (north of 2.0 IMN and 40,000
feet).

What was the name of the guy that the profile was named after?
Radowsky? Ratofsky? Ratkowski? Something like that. It was known as
the quickest route to M2.
I say that only from hear-say, since I never did the M2 thing.

Rukowski IIRC. Phantoms and Thuds and never Mach 2? Well, if you flew
the soft-wing Phantom it was unlikely. But I thought a Thud on a
maintenance check flight would have 2.0+ as a given. OTOH, I imagine
the Thud showed you 800KIAS plus at some time in your life.
R / John

[Leadfoot]

Post by John Carrier
Rukowski IIRC. Phantoms and Thuds and never Mach 2?

Somewhere there is a story in a USAF Flight Safety magazine written by an
F-4 Maintenance check pilot who after checking whatever write up he was
checking decided to try this maneuver although I think he called it the
dipsy-doodle because thats how it's referred to when the SR-71 does it. As
I recall a lot of conditions had to be met before you can even think about
doing it in an F-4 and this guy got "lucky" by having a flight that met
those conditions. Any way the pilot damn near killed himself trying to do
it.

Maybe Ed or WaltBJ can find the article. It was over the Atlantic off the
carolina coast as I recall

I do have a sneaking suspicion that for Ed it wass more fun to fly the plane
as fast as you can as close to the ground than at 40,000 feet




Well, if you flew the

Post by John Carrier
soft-wing Phantom it was unlikely. But I thought a Thud on a maintenance
check flight would have 2.0+ as a given. OTOH, I imagine the Thud showed
you 800KIAS plus at some time in your life.
R / John

[Ed Rasimus]

Post by John Carrier

Post by Ed Rasimus

Post by John Carrier
As a further amplification of the practical employment of such info, the F-4
had a pretty significant transonic drag rise. To minimize its effects and
maximize performance in a climb/accelleration to maximum energy state, one
would hold (approx) .9 IMN until 27,000' and then nose over at low G
(slightly greater than zero G to avoid oil press issues) mimimizing
trim/induced drag until 1.2 was reached. Then resume nose up attitude to
accellerate AND climb to max energy state (north of 2.0 IMN and 40,000
feet).

What was the name of the guy that the profile was named after?
Radowsky? Ratofsky? Ratkowski? Something like that. It was known as
the quickest route to M2.
I say that only from hear-say, since I never did the M2 thing.

Rukowski IIRC. Phantoms and Thuds and never Mach 2? Well, if you flew the
soft-wing Phantom it was unlikely. But I thought a Thud on a maintenance
check flight would have 2.0+ as a given. OTOH, I imagine the Thud showed
you 800KIAS plus at some time in your life.
R / John

In the F-105 syllabus there was a "Gee Whiz" sortie scheduled to run
it out to M2, but due to maintenance problems when I was in training,
it got cancelled for all students. The outcome was that in my entire
time in the A/C I never took off with a clean airplane. I brought
several back clean, but never started a flight that way. Fastest I
ever saw on the clock was in the 750 KIAS region.

All of my F-4 time was hard-wing, but I didn't ever get into the FCF
(maint. check flight) business. Also never had a sortie dedicated to
M2. Fastest I ever went in the F-4 was a C-model with three bags on it
that got me up to around M1.6. Did fly the Phantom clean quite a bit
and always enjoyed the opportunity to take the birds to Incirlik and
drop the tanks for a week or two of ACM.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[Dan]

Ed Rasimus wrote:
<snip>

Post by Ed Rasimus
All of my F-4 time was hard-wing, but I didn't ever get into the FCF
(maint. check flight) business.

<snip>

Functional check flight if memory serves.

Dan, U.S. Air Force, retired

[Ed Rasimus]

Post by Dan
<snip>

Post by Ed Rasimus
All of my F-4 time was hard-wing, but I didn't ever get into the FCF
(maint. check flight) business.

<snip>
Functional check flight if memory serves.
Dan, U.S. Air Force, retired

Correctamundo! But, I was translating for the Navy.

Lots of guys liked to get on FCF orders for the opportunity to do max
climbouts and high speed runs in a clean jet. But, the downside was
that you had to be "on call" at weird times when a bird came ready.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[John Carrier]

Post by Ed Rasimus

Post by Dan
<snip>

Post by Ed Rasimus
All of my F-4 time was hard-wing, but I didn't ever get into the FCF
(maint. check flight) business.

<snip>
Functional check flight if memory serves.
Dan, U.S. Air Force, retired

Correctamundo! But, I was translating for the Navy.
Lots of guys liked to get on FCF orders for the opportunity to do max
climbouts and high speed runs in a clean jet. But, the downside was
that you had to be "on call" at weird times when a bird came ready.

FCF or PMCF (post maintenance check flight) are terms with which I am
familiar. Picked up about half a dozen F-4's from rework ... clean except
for the inboard pylons. Acceptance flights: 2.05 out of a J, and 1.9
accelerating when the master caution came on. I saw 750 clean at Nellis
when exiting a fight with the 64th.

Did F-14 post rework check for 3 years. All A/C would make 1.88 placard
limit easily (the airframe made 2.41 in flight test with a dedicated sortie
and a ramp programmer in the back seat), given the room. Lost a canopy seal
around 1.8 or so. Never did a max Q effort with the clean airplane, but it
was pretty quick. 750 with Phoenix rails. The B's and D's have less top
end mach but much better mid-range and can easily bust 800.

As a contemporary of the Hun, the F-8 was pretty quick. 1.75 or so. The
D's and H's were quickest. Great maneuvering wing with pilot selectable
leading edge maneuvering droop. A bit unforgiving at the blunt end of the
boat.

R / John

[RAP Flashnet]

John

The F-4 got real quick in full A/B after about 600 knots didn't it. And see
750 or better exiting the ranges at Nellis, almost a necessary calling card
for getting a beer in town. Did see 800 and did damage the machine, turkey
feathers and doors lost with sway-bolts on the stab broke. Had to one-time
it to North Island gear down for scrap.

Post by John Carrier

Post by Ed Rasimus

Post by Dan
<snip>

Post by Ed Rasimus
All of my F-4 time was hard-wing, but I didn't ever get into the FCF
(maint. check flight) business.

<snip>
Functional check flight if memory serves.
Dan, U.S. Air Force, retired

Correctamundo! But, I was translating for the Navy.
Lots of guys liked to get on FCF orders for the opportunity to do max
climbouts and high speed runs in a clean jet. But, the downside was
that you had to be "on call" at weird times when a bird came ready.

FCF or PMCF (post maintenance check flight) are terms with which I am
familiar. Picked up about half a dozen F-4's from rework ... clean except
for the inboard pylons. Acceptance flights: 2.05 out of a J, and 1.9
accelerating when the master caution came on. I saw 750 clean at Nellis
when exiting a fight with the 64th.
Did F-14 post rework check for 3 years. All A/C would make 1.88 placard
limit easily (the airframe made 2.41 in flight test with a dedicated
sortie and a ramp programmer in the back seat), given the room. Lost a
canopy seal around 1.8 or so. Never did a max Q effort with the clean
airplane, but it was pretty quick. 750 with Phoenix rails. The B's and
D's have less top end mach but much better mid-range and can easily bust
800.
As a contemporary of the Hun, the F-8 was pretty quick. 1.75 or so. The
D's and H's were quickest. Great maneuvering wing with pilot selectable
leading edge maneuvering droop. A bit unforgiving at the blunt end of the
boat.
R / John

[Ed Rasimus]

Post by RAP Flashnet
John
The F-4 got real quick in full A/B after about 600 knots didn't it. And see
750 or better exiting the ranges at Nellis, almost a necessary calling card
for getting a beer in town. Did see 800 and did damage the machine, turkey
feathers and doors lost with sway-bolts on the stab broke. Had to one-time
it to North Island gear down for scrap.

The old line was "the faster you go the faster you go faster".

Could really notice it on takeoff when you held it down and left it in
max reheat. About 500 KIAS you really began to get a push.
Unfortunately there aren't many place left in the world that let you
get away with that anymore.

I suspect that the Sandbox offers some opportunities though.

Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[Dan]

Post by Ed Rasimus

Post by Dan
<snip>

Post by Ed Rasimus
All of my F-4 time was hard-wing, but I didn't ever get into the FCF
(maint. check flight) business.

<snip>
Functional check flight if memory serves.
Dan, U.S. Air Force, retired

Correctamundo! But, I was translating for the Navy.
Lots of guys liked to get on FCF orders for the opportunity to do max
climbouts and high speed runs in a clean jet. But, the downside was
that you had to be "on call" at weird times when a bird came ready.
Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

One of these days I'd like to find an Navy to English dictionary.
They got all bent out of shape when I went to sea on their boats and
used terms like door, wall, ceiling..etc.

Dan, U.S. Air Force, retired

[Ed Rasimus]

Post by Dan

Post by Ed Rasimus

Post by Dan
<snip>

Post by Ed Rasimus
All of my F-4 time was hard-wing, but I didn't ever get into the FCF
(maint. check flight) business.

<snip>
Functional check flight if memory serves.
Dan, U.S. Air Force, retired

Correctamundo! But, I was translating for the Navy.
Lots of guys liked to get on FCF orders for the opportunity to do max
climbouts and high speed runs in a clean jet. But, the downside was
that you had to be "on call" at weird times when a bird came ready.
Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

One of these days I'd like to find an Navy to English dictionary.
They got all bent out of shape when I went to sea on their boats and
used terms like door, wall, ceiling..etc.
Dan, U.S. Air Force, retired

Air Force and Navy is a lot like Americans and Brits--two peoples
separated by a common language.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[Ken S. Tucker]

Post by Kurt R. Todoroff

Post by Typhoon502

Post by Fortos
Hello,
What is the max speed a F16 can flight without using its afterburners ?

Let's narrow down the parameters. Clean, F-16C, with the strongest
engine option. Would it supercruise?

Supercruise is defined as "supersonic persistence without the use of
afterburner". Here's the rub: different definitions AND uses of the
word "supersonic". The simple aeronautical definition of supersonic is
velocity above the "transonic range". i.e. generally speaking (but not
absolutely since it varies with aircraft type) approximately Mach 1.1.
No flame zone here, since I said "approximately".
We've all read postings in this newsgroup about this or that fighter
flying Mach 1.1 in Mil power. This is NOT supercruise in my way of
thinking. The USAF and Lockheed define supercruise as Mach 1.5
persistence without afterburner. Those who manufacturer the slower
latest generation fighters consider supercruise to be the supersonic
velocity that their aircraft can attain (which is much less than Mach
1.5) in Mil power.
I am confident that the clean F-16C with the General Electric
F110-GE-132 engine can exceed Mach 1.0 in Mil power. This is not
supercruise. It can probably attain Mach 1.1 in Mil power. Is this
supercruise? Maybe. Maybe not. The thrust requirements at Mach 1.5
are exponentially greater than at Mach 1.1.
Does supercruise occur at 1.2, 1.3, 1.4, or only at and above Mach 1.5?
I don't know. Can the F-16C / F110-GE-132 supercruise? I doubt it.
Kurt Todoroff

Agreed, the F-16 was (IIRC) designed for sub-sonic
transonic combat economically, meaning the intake
geometry is not variable, that I know of.
The Cd (Coefficient of drag) is not optimized for
supersonic, due to the wing sweep, but perhaps
most important is the Cd geometry of the intake.
Ken

http://en.wikipedia.org/wiki/F-16

[Diamond Jim]

Post by Typhoon502

Post by Fortos
Hello,
What is the max speed a F16 can flight without using its afterburners ?

Let's narrow down the parameters. Clean, F-16C, with the strongest
engine option. Would it supercruise?

Lets narrow it down farther. Climbing? Level flight? Diving? Falling out of
the sky?

[RAP Flashnet]

In layman's terms - This is a great question because it hits upon the whole
field of fighter performance.
The jet engine at full power ("dry power" / "military power" / full rated
power / etc.) with out after burner is just that and the speed would be
relatively a function of the thrust-to-weight adjusted for the drag at some
density altitude. Technically you could go supersonic in dry power but it is
rarely achieved simply because their is not enough thrust to get the Mach up
to sonic proportions in dry powered machines - but that does not mean it
could not be done. The afterburner, or "wet", or "maximum power" is supposed
to give you a jump in acceleration and the extra push to get you going.

Now the higher you are the less dense the air is and the Mach goes up
accordingly, so a U-2 at 120 knots calibrated at 60,000 feet may be almost
supersonic, say over 600 knots True. So an afterburning fighter at altitude
can step right out there. But at low altitude where the air is dense and
the jet has to work harder the dynamic pressure and forces built up on the
airframe could actually hurt you, the engine, or the airframe, and a term
used to represent the dynamic pressure "Q" demonstrates that some fighters
can go faster then they are structurally capable of sustaining.

A fan also is less efficient in afterburner then a pure turbo-jet because
the fan suddenly becomes frontal area generating drag when you get moving
along and the fan takes work to spool up so the jet engine works harder to
generate thrust on a fan-jet thenin a pure turbo.

Now the F-16 has a fascinating historical data base. The first prototypes
were very clean and around 30% smaller then the C models of today and
definately a whole lot lighter, under 18,000 pounds where today they get
above 40,000 lbs. So the early prototypes could fly from Edwards to
Washington DC nonstop and still clean, and that was under 6,000 pounds of
fuel. In fact Neil Anderson, God Bless him, just deceased, showed the world
this many times. From its conception the basic F-16 has gained around 1.5
pounds a day all during its existence. But - because of the enormous
strides in jet power it was gaining on the average of around 2 pounds a day
of thrust or close to those numbers. But a big F-16 of today with greater
thrust to weight of the first A models flies like a heavier aircraft and
essentially is not as agile as the first aircraft, so when you pull up close
to the ground you have to consider the "sink rate" as you transition the
nose from down to up.

There was at one time when the F-5G (later to become the F-20) an F-16 that
had a J-79 engine put into it taken out of an F-4 Phantom. This F-16/79 was
about 5000 heavier than a basic F-16A (Block 15) and had around 6,000 pounds
less maximum thrust - but the J-79 was a pure turbo jet. This remarkable
aircraft proved the F-16 aerodynamics because the F-16/79 had some
performance advantages over the Pratt powered F-16A with a fan engine. The
turbo F-16/79 cruised at sea level at mil power (dry power) close to 0.9
Mach, the fan powered F-16A with more thrust could not keep up with it, and
to do sowould have to tap burner every once in a while. Now if the F-16/79
was cruising at the slower F-16A's optimal cruise speed the F-16A would
almost double the range of the F-16/79 - so guess why the fan engines were
introduced.

Now at altitude, the turbojet J-79 would get hotter and faster as speed
increased enabling the F-16/79 to go beyond 2.1 Mach and it had to be
stopped at that becauee the flight control laws for the electronic flight
control system were not computed. On the other had the F-16A could barely
push 1.9 and newer F-16's are worse.

But both F-16's had the same instantaneous turn capability but the fan
powered with more thrust could sustain G longer. There is a feeling that
Joe Bill Dryden, another great test pilot and person, (and God Bless him
too) may have miscalculated flying the heavier Block 50 after spending a
month fling the F-16A's in Belgium, so on the test flight he was on, he had
completed his runs, throttled back to write up some comments, and thought he
was still level at enough altitude to execute a slpit-S down to reverse
heading to RTB. The heavier C model in fact in idle was sinking ever so
slightly and when he was called to go home he just rolled and pulled
thinking he was still up at altitude having not double checked his
instruments. He caught it but was very nose low so ejected and it got him
out but he did not survive. The differences in the two machines.

So many time the older test beds are much more agile the the productio
machines, but now with the great leaps in power as seen with the F-14D and
the upgraded F-15E, there is a point where a whole lot of thrust beats
anything

Post by Typhoon502

Post by Fortos
Hello,
What is the max speed a F16 can flight without using its afterburners ?

Let's narrow down the parameters. Clean, F-16C, with the strongest
engine option. Would it supercruise?

[John Carrier]

Post by RAP Flashnet
Now the higher you are the less dense the air is and the Mach goes up
accordingly, so a U-2 at 120 knots calibrated at 60,000 feet may be almost
supersonic, say over 600 knots True. So an afterburning fighter at
altitude can step right out there. But at low altitude where the air is
dense and the jet has to work harder the dynamic pressure and forces built
up on the airframe could actually hurt you, the engine, or the airframe,
and a term used to represent the dynamic pressure "Q" demonstrates that
some fighters can go faster then they are structurally capable of
sustaining.

Mach number is the ratio between true airspeed and the speed of sound (which
is a function of temperature only). Meanwhile indicated airspeed is a
function of density. So 1.0 IMN would be around 667 KTAS and 667 KIAS at
sea level and perhaps 570 KTAS and less than 300 KIAS at the tropopause and
far less KIAS at U-2 cruise altitudes. The U-2 while operating at its max
altitude had a range of 2-3 knots between mach buffet (something less than
.9 for that airframe) and stall.

If you look at the other side of the envelope, aircraft that were generally
fast but subsonic (F-86, F-4D, etc ... they could dive to supersonic at
altitude) generated their speed records at low altitudes (salton sea was a
favorite) where they could fly below 0' MSL and in very high temperatures,
thus allowing them higher TAS before running into their drag limit
(somewhere past force divergent mach number in the heart of the transonic
drag rise region).

R / John

[WaltBJ]

Slightly off topic but an airplane that can exceed m 1.0 in
non-afterburning power has a very definite fuel advantage in that less
powerful aircraft must use afterburner to combat them, and thus use
fuel about 4x faster. Low altitude supersonic speeds raise internal
engine pressures to the point where failure can occur. The J79 engine
had a computer discharge pressure limiter to prevent this.
Walt BJ

[Baruch Kantor]

AFAIK Supersonic in MIL is not possible in low altitude, only at 30-40 kft
(?)

Baruch
______________________
Aircraft Performance and Flight Dynamics.
http://www.newbyte.co.il/

Post by WaltBJ
Slightly off topic but an airplane that can exceed m 1.0 in
non-afterburning power has a very definite fuel advantage in that less
powerful aircraft must use afterburner to combat them, and thus use
fuel about 4x faster. Low altitude supersonic speeds raise internal
engine pressures to the point where failure can occur. The J79 engine
had a computer discharge pressure limiter to prevent this.
Walt BJ

[Ed Rasimus]

On Sun, 15 Oct 2006 00:33:56 +0200, "Baruch Kantor"

Post by Baruch Kantor
AFAIK Supersonic in MIL is not possible in low altitude, only at 30-40 kft
(?)
Baruch
______________________
Aircraft Performance and Flight Dynamics.
http://www.newbyte.co.il/

I'll try not to mention that to a lot of F-105 drivers I know. A clean
airplane and a lot of adrenaline will get you going pretty fast,
pretty low, and 750 on the clock in mil wasn't at all uncommon.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[WaltBJ]

The F104A/J79-19 would accelerate from .95 to at least 1.05 in level
flight at 25000 feet. Never tried to do that at zero feet, but an
indicated .97 was easy. Never tried to peg the Mach meter, either, but
I was a husband and father by then. Did make a Mach 2 cruise at FL 730,
though. Exhilirating. After flying that brand of Zipper the F4 was sort
of sluggish.
I did a lot of F4E FCFs in my last several years in the USAF. Reaching
2.0 wa. s difficult since we were runing straight away from home and
fuel was the limiting factor. I suspect the inboard pylons, 'soft
wings' and the usual peacetime engine-sparing minimum fuel control trim
settings were responsible. The F4s at Da Nang were obviiusly trimmed at
the max limit. With a center line tank, MERs, TERs, 2 AIM7, 2AIM9B, the
ones I flew would do 745KIAS at 4000 in full AB getting out of 'Dodge
City', where Charlie had 7 sites all interlocking (to begin with) so
loitering wasn't a sane option. We got 5; I think Ubon got the other 2,
the rascals poaching in our preserve.
Walt BJ

[WaltBJ]

The F104A/J79-19 would accelerate from .95 to at least 1.05 in level
flight at 25000 feet. Never tried to do that at zero feet, but an
indicated .97 was easy. Never tried to peg the Mach meter, either, but
I was a husband and father by then. Did make a Mach 2 cruise at FL 730,
though. Exhilirating. After flying that brand of Zipper the F4 was sort
of sluggish.
I did a lot of F4E FCFs in my last several years in the USAF. Reaching
2.0 wa. s difficult since we were runing straight away from home and
fuel was the limiting factor. I suspect the inboard pylons, 'soft
wings' and the usual peacetime engine-sparing minimum fuel control trim
settings were responsible. The F4s at Da Nang were obviiusly trimmed at
the max limit. With a center line tank, MERs, TERs, 2 AIM7, 2AIM9B, the
ones I flew would do 745KIAS at 4000 in full AB getting out of 'Dodge
City', where Charlie had 7 sites all interlocking (to begin with) so
loitering wasn't a sane option. We got 5; I think Ubon got the other 2,
the rascals poaching in our preserve.
Walt BJ

[Andy Bush]

I don't think I ever saw more than 550 or so in the F-4...but 800 in the 104
wasn't unusual if someone wanted to push it that hard. Other than burn a lot
of gas, it wasn't worth much other than bragging rights at the club.

Post by WaltBJ
The F104A/J79-19 would accelerate from .95 to at least 1.05 in level
flight at 25000 feet. Never tried to do that at zero feet, but an
indicated .97 was easy. Never tried to peg the Mach meter, either, but
I was a husband and father by then. Did make a Mach 2 cruise at FL 730,
though. Exhilirating. After flying that brand of Zipper the F4 was sort
of sluggish.
I did a lot of F4E FCFs in my last several years in the USAF. Reaching
2.0 wa. s difficult since we were runing straight away from home and
fuel was the limiting factor. I suspect the inboard pylons, 'soft
wings' and the usual peacetime engine-sparing minimum fuel control trim
settings were responsible. The F4s at Da Nang were obviiusly trimmed at
the max limit. With a center line tank, MERs, TERs, 2 AIM7, 2AIM9B, the
ones I flew would do 745KIAS at 4000 in full AB getting out of 'Dodge
City', where Charlie had 7 sites all interlocking (to begin with) so
loitering wasn't a sane option. We got 5; I think Ubon got the other 2,
the rascals poaching in our preserve.
Walt BJ

[Paul Hirose]

Post by RAP Flashnet
Now the higher you are the less dense the air is and the Mach goes
up accordingly, so a U-2 at 120 knots calibrated at 60,000 feet may
be almost supersonic, say over 600 knots True.

Those numbers are very inaccurate. According to my CR-2 whiz wheel,
120 KCAS at 60,000 ft PA equals .65 Mach and 375 KTAS.

[Baruch Kantor]

When my site will return to live, you'll be able to download my performance
software.
There you can draw a performance chart (H vs Mach) with KCAS reference
lines.
60kft, 120 KCAS > Mach = 0.64987 KTAS = 372.745 (ISA)

Baruch
________________________________
http://www.newbyte.co.il/
Aircraft Performance and Flight Dynamics.

Post by RAP Flashnet
Now the higher you are the less dense the air is and the Mach goes
up accordingly, so a U-2 at 120 knots calibrated at 60,000 feet may
be almost supersonic, say over 600 knots True.

Those numbers are very inaccurate. According to my CR-2 whiz wheel, 120
KCAS at 60,000 ft PA equals .65 Mach and 375 KTAS.
--
To reply by email remove INVALID

[Lynn Coffelt]

Ubon Airfield, mid 1960's, F-4C's on 100th mission or after a Mig kill got a
"victory pass" over the field. Usually a high speed, low level pass, with a
vertical climb out of sight. (sometimes with a sonic "boom" dive) There was
obvious, visual to us mechanics, pitch and roll instability during the low
level pass, and I understool that if not for "stab aug" (computer stability
augmentation) such low level, Mach ?? passes were not good practice. Do you
"Zoomies" have any words that can help our fading memories? Oh, Lord, those
were the days!

Old Chief Lynn

[Ed Rasimus]

On Tue, 17 Oct 2006 00:12:25 -0700, "Lynn Coffelt"

Post by Lynn Coffelt
Ubon Airfield, mid 1960's, F-4C's on 100th mission or after a Mig kill got a
"victory pass" over the field. Usually a high speed, low level pass, with a
vertical climb out of sight. (sometimes with a sonic "boom" dive) There was
obvious, visual to us mechanics, pitch and roll instability during the low
level pass, and I understool that if not for "stab aug" (computer stability
augmentation) such low level, Mach ?? passes were not good practice. Do you
"Zoomies" have any words that can help our fading memories? Oh, Lord, those
were the days!
Old Chief Lynn

High speed at low level is a high concentration task. Different
airplanes have made it a different experience. Modern jets with
multi-axis stability augmentation systems (stab-aug) can reduce the
pilot load considerably.

In the F-105, which was optimized for the high speed/low alt mission,
there was a huge jack-screw in the pitch control system called the
mechanical advantage (MA) shifter. As your indicated airspeed
increased the jack screw would reduce the stick effectiveness for slab
command. The result was that there was no appreciable sensitivity
increase as you got fast. Made for a nice comfy ride at 600 plus knots
in the weeds.

The F-4 didn't have that sort of advantage. The stick got quite
sensitive at high indicated airspeed and required a very conscious
effort to minimize pitch changes and not get out of cycle chasing a
correction (pilot-induced oscillation--PIO--often referred to as a JC
maneuver.)

What really created a problem was the fact that the engines were
canted slightly downward off the aircraft's plumb line. Lighting off
the ABs at high airspeed/low altitude would give you a sudden downward
pitch change. The corrective action had to be smooth and tender to
avoid some serious oscillations. Was better technique to get into
reheat before getting really low.

Best end-of-tour passes were if you saved internal wing fuel after an
RTB tanker hit, so that you could hit the dump switch on the fly-by
and get a "Thunderbird"-style smoke off both wings.

At Korat, we got an end-of-tour flyby and pull-up. But, you could only
do rolls for a MiG kill.

Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[John Carrier]

Post by Ed Rasimus
On Tue, 17 Oct 2006 00:12:25 -0700, "Lynn Coffelt"

Post by Lynn Coffelt
Ubon Airfield, mid 1960's, F-4C's on 100th mission or after a Mig kill got a
"victory pass" over the field. Usually a high speed, low level pass, with a
vertical climb out of sight. (sometimes with a sonic "boom" dive) There was
obvious, visual to us mechanics, pitch and roll instability during the low
level pass, and I understool that if not for "stab aug" (computer stability
augmentation) such low level, Mach ?? passes were not good practice. Do you
"Zoomies" have any words that can help our fading memories? Oh, Lord, those
were the days!
Old Chief Lynn

High speed at low level is a high concentration task. Different
airplanes have made it a different experience. Modern jets with
multi-axis stability augmentation systems (stab-aug) can reduce the
pilot load considerably.
In the F-105, which was optimized for the high speed/low alt mission,
there was a huge jack-screw in the pitch control system called the
mechanical advantage (MA) shifter. As your indicated airspeed
increased the jack screw would reduce the stick effectiveness for slab
command. The result was that there was no appreciable sensitivity
increase as you got fast. Made for a nice comfy ride at 600 plus knots
in the weeds.
The F-4 didn't have that sort of advantage. The stick got quite
sensitive at high indicated airspeed and required a very conscious
effort to minimize pitch changes and not get out of cycle chasing a
correction (pilot-induced oscillation--PIO--often referred to as a JC
maneuver.)
What really created a problem was the fact that the engines were
canted slightly downward off the aircraft's plumb line. Lighting off
the ABs at high airspeed/low altitude would give you a sudden downward
pitch change. The corrective action had to be smooth and tender to
avoid some serious oscillations. Was better technique to get into
reheat before getting really low.
Best end-of-tour passes were if you saved internal wing fuel after an
RTB tanker hit, so that you could hit the dump switch on the fly-by
and get a "Thunderbird"-style smoke off both wings.
At Korat, we got an end-of-tour flyby and pull-up. But, you could only
do rolls for a MiG kill.

The F-4 had a bellows system which used dynamic pressure to increase stick
forces at high Q. Generally pretty effective, but it failed on the first
Sageburner attempt with catastrophic effect (Also provided proof that bare
J-79's were faster than the airframe in which the were installed).

R / John

[Ed Rasimus]

Post by John Carrier

Post by Ed Rasimus
High speed at low level is a high concentration task. Different
airplanes have made it a different experience. Modern jets with
multi-axis stability augmentation systems (stab-aug) can reduce the
pilot load considerably.
In the F-105, which was optimized for the high speed/low alt mission,
there was a huge jack-screw in the pitch control system called the
mechanical advantage (MA) shifter. As your indicated airspeed
increased the jack screw would reduce the stick effectiveness for slab
command. The result was that there was no appreciable sensitivity
increase as you got fast. Made for a nice comfy ride at 600 plus knots
in the weeds.
The F-4 didn't have that sort of advantage. The stick got quite
sensitive at high indicated airspeed and required a very conscious
effort to minimize pitch changes and not get out of cycle chasing a
correction (pilot-induced oscillation--PIO--often referred to as a JC
maneuver.)
What really created a problem was the fact that the engines were
canted slightly downward off the aircraft's plumb line. Lighting off
the ABs at high airspeed/low altitude would give you a sudden downward
pitch change. The corrective action had to be smooth and tender to
avoid some serious oscillations. Was better technique to get into
reheat before getting really low.
Best end-of-tour passes were if you saved internal wing fuel after an
RTB tanker hit, so that you could hit the dump switch on the fly-by
and get a "Thunderbird"-style smoke off both wings.
At Korat, we got an end-of-tour flyby and pull-up. But, you could only
do rolls for a MiG kill.

The F-4 had a bellows system which used dynamic pressure to increase stick
forces at high Q. Generally pretty effective, but it failed on the first
Sageburner attempt with catastrophic effect (Also provided proof that bare
J-79's were faster than the airframe in which the were installed).
R / John

IIRC, the Sageburner accident was due to a known inop pitch stab aug
system. The driver made the decision to press on regardless and didn't
quite have the hands to pull it off.

Various aircraft have dealt with pitch instability differently. I
remember in the F-105 that an overly aggressive dive pullout would
usually pop the stab aug off. And, I also recall using two hands on
the stick with some degree of regularity.

The F-4 three-axis aug system was weird too. Part of the "fence check"
as well as part of the pre-engagement ACM/BFM check was to disengage
the roll axis of the stab aug, since its aileron/rudder interaction
caused you to fly polygons instead of rolls. There was also the issue
with the old C-models we had at Torrejon of mis-matched CSD's
(Constant Speed Drives) for the generators that would cause a
generator to drop off line when pulling G. Simple solution for BFM was
to turn off one generator prior and let a single generator run the
system.

The T-38 had a bob-weight on the stick to give it some feel. Early
aircraft had a three pound weight which turned out to be overly
sensitive. Later jets replaced it with a five pound weight.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com