What is minimum cruise speed for F-15 & F-16 ?

I'm not sure I understand the concept of "minimum cruising speed." The two
speeds of concern to most tactical aviators are maximum endurance (flown at
L/D max, an optimum AOA clean) and maximum range (best mpg or usually mpp,
typically a given mach number).

R / John

Post by Elmo von Thud
Virtual greets.
I searched for this info through Google but am having some trouble
finding it as most sources only supply max speeds.
Can some kind person please tell me what are the approximate minimum
cruising speeds for the F-15 C and F-16 assuming that they are
carrying minimum loads.
Thanks in advance for your help.
Elmo

Elmo von Thud

2006-08-27 02:24:55 UTC

Post by John Carrier
I'm not sure I understand the concept of "minimum cruising speed." The two
speeds of concern to most tactical aviators are maximum endurance (flown at
L/D max, an optimum AOA clean) and maximum range (best mpg or usually mpp,
typically a given mach number).
R / John

Hi John.

I mean the minimum speed that these planes can fly at without losing
altitude (horizontal flight).

Cheers,

Elmo

Peter Stickney

2006-08-27 03:20:13 UTC

Post by John Carrier
I'm not sure I understand the concept of "minimum cruising speed." The
two speeds of concern to most tactical aviators are maximum endurance
(flown at L/D max, an optimum AOA clean) and maximum range (best mpg or
usually mpp, typically a given mach number).
R / John

Hi John.
I mean the minimum speed that these planes can fly at without losing
altitude (horizontal flight).
Cheers,
Elmo

That's one of those "That Depends" questions.
As in, "What's the current weight of the airplane?"
"What's the state of the high lift devices?" (Slats, flaps, that sort of
thing)
"What's the power setting?" A modern jet fighter can fly very slowly at
high Angles of Attack at high power settings - the angle of the thrust line
reduces the weight the wings have to carry.
"How high are you, and what's the temperature?" These have big effects on
air density, and thus how much lift is available at a given speed.
"When was the last time it was washed, and how many bugs did I fly through
to get here?" Surface condition of the airplane has a big effect.

--
Pete Stickney
Without data, all you have is an opinion

vlado

2006-08-27 04:34:44 UTC

Post by Peter Stickney

Post by John Carrier
I'm not sure I understand the concept of "minimum cruising speed." The
two speeds of concern to most tactical aviators are maximum endurance
(flown at L/D max, an optimum AOA clean) and maximum range (best mpg or
usually mpp, typically a given mach number).
R / John

Hi John.
I mean the minimum speed that these planes can fly at without losing
altitude (horizontal flight).
Cheers,
Elmo

Just a wide approximate number (because it depends) try using 120 knots
below 15,000 feet for your needs. If you need a number, here it is.
VL

John Carrier

2006-08-27 11:41:15 UTC

Hi John.
I mean the minimum speed that these planes can fly at without losing
altitude (horizontal flight).

A function of altitude (which effects available thrust) and weight. The
blue angels do a high alpha pass (approx 25-30 degrees AOA, not the a/c's
maximum) at show altitude and they're indicating approx 100 knots, this at
military thrust. Figure a couple knots slower in afterburner (only a few as
induced drag builds up rapidly). The same maneuver at 15,000 would result
in a significant altitude loss. The maneuvering devices (leading and
trailing edge) will auto-deploy in this configuration. As slow speed is the
F-18's forte, I'd suspect the F-15 and F-16 speeds would be somewhat higher.

This is not "cruise" and nobody's interested in the specifics of this
performance parameter. If you're in a scissors or similar slow speed
dogfighting environment, it's literally relative ... turn radius, rate
compared to the other guy. Descent rate compared to the other guy.

R / John

Mike Dennis

2006-08-27 14:27:47 UTC

Hi John.
I mean the minimum speed that these planes can fly at without losing
altitude (horizontal flight).

A function of altitude (which effects available thrust) and weight. The
blue angels do a high alpha pass (approx 25-30 degrees AOA, not the a/c's
maximum) at show altitude and they're indicating approx 100 knots, this at
military thrust. Figure a couple knots slower in afterburner (only a few
as induced drag builds up rapidly). The same maneuver at 15,000 would
result in a significant altitude loss. The maneuvering devices (leading
and trailing edge) will auto-deploy in this configuration. As slow speed
is the F-18's forte, I'd suspect the F-15 and F-16 speeds would be
somewhat higher.
This is not "cruise" and nobody's interested in the specifics of this
performance parameter. If you're in a scissors or similar slow speed
dogfighting environment, it's literally relative ... turn radius, rate
compared to the other guy. Descent rate compared to the other guy.
R / John

The F-22 is zero (or very near zero) KIAS. But I wouldn't call that
cruising... Maybe he's really just looking for the minimum TOW stall speed?

WaltBJ

2006-08-28 03:32:33 UTC

Minmum speed in level flight? I cannot conceive of an operational use
for this unless you're trying to read tail numbers or otherwise
communicate to some civilian prop-driven aircraft. We did have to do
this when intercepting unkowns or aircraft who missed their ADIZ
penetration time. (at night out over the ocean on a blacked-out P2V at
say 500-1000ASL this gave rise to thought) Minimum control speed is
useful if and only if you're playing with a friend in another aircraft,
or doing performance demonstrations, or landing on a very dubious
runway. Max L/D is useful in that it gives you least fuel burn amd thus
max imum time aloft Max range speed, obvious. FWIW here's an example
of a minimum level flight speed number of no use except Gee Whiz - 115
KIAS in level flight in an F102 in full afterburner using fuel at about
750 pounds a minute. Any slower and it began to sink. And to accelerate
from 115 required lowering the nose because the AOA was so high (ca 35
degrees) the total drag precluded acceleration. Oh, yes, any airplane
with a thrust to weight greater than 1:1 can attain a ground speed of
zero by going straight up. Harrier is an obvious example. All airplanes
can do that going straight down - for a limited time, that is.
Walt BJ

Tony Whitaker

2006-08-29 11:22:59 UTC

Post by WaltBJ
Minmum speed in level flight? I cannot conceive of an operational use
for this unless you're trying to read tail numbers or otherwise
communicate to some civilian prop-driven aircraft.

I don't know what the OP wanted to know, but I'm just curious to know how
slow a jet fighter can fly comfortably. I mean, NOT with the nose pointed
toward the moon and the afterburner blasting out the back side. What would
be, roughly, the minimum speed without afterburner, full control, and the
nose reasonably near the horizon? Would this speed correspond to lowest fuel
consumption?

John Carrier

2006-08-29 11:50:47 UTC

Post by Tony Whitaker

I would say so. Max endurance at L/D max (jet aircraft). A function of
AOA, although it can be approximated with airspeed. Varies with the
airframe quite a bit. Some century series were quite high, approaching 300
KIAS. Certainly, the aircraft can be flown much slower, but only at the
cost of additional fuel flow and sloppy handling.

R / John

John Banister

2006-08-29 15:27:13 UTC

Tony, using the F-4 as a example, one could fly it in level flight, clean
with no flaps/slats at around 180-200 kts calibrated. However, this was not
"comfortable" as the controls were mushy and anything over 45 deg of bank
required lots of attention and plenty of extra power. Probably similar to
flying a Cessna 150 on final but much less forgiving.

Up the speed to the 240 kt range, and things got more comfortable but one
had to watch the bird pretty carefully and limit maneuvering. We regularly
refueled from a KC-97 with three bags full at 230 kts and afterburner was
sometimes needed. It was not fun, but it could be done.

Up the speed to 300 kts and the bird was comfortable in all but the harder
maneuvers.

As to fuel consumption, the answer to your question would probably be, "No."
One would have to speed up a bit. However, it is important to know what you
mean by lowest fuel consumption. If you mean the least fuel for a given
amount of flying time (i.e. max endurance) then 240 kts is a good
approximation. If you mean least fuel for a given distance flown (i.e. max
cruise) then 300-310 kts is the figure. All for the F-4.

-John

"Tony Whitaker" <***@_____mindspring.com> wrote in message
news:nsVIg.15117

Post by Tony Whitaker
I don't know what the OP wanted to know, but I'm just curious to know how
slow a jet fighter can fly comfortably. I mean, NOT with the nose pointed
toward the moon and the afterburner blasting out the back side. What would
be, roughly, the minimum speed without afterburner, full control, and the
nose reasonably near the horizon? Would this speed correspond to lowest
fuel consumption?

John Carrier

2006-08-28 11:47:07 UTC

Post by Mike Dennis