Flanker vs F-15

I'm no aerodynamicist but I've been running some numbers and noticed some
interesting things.
The SU-27 is credited with being more manueverable than F-15 and yet F-15
has a higher TTW number (except at gross) and a lower wing loading by a
large margin (again except at gross). The SU should develope more body lift
than Eagle, but at best it looks like a wash at low altitudes, with Eagle
turning better than SU at altitude.
Any thoughts? Am I missing something large here? The Su's lerx's and higher
aspect wing should make a positive differance at low level and low speeds
but I dont think it would make up for the other numbers. Eagle should have a
20% better wing loading and about a 14% better TTW number.

--



Curiosity killed the cat, and I'm gonna find out why!

"Boomer" wrote in message
...
I'm no aerodynamicist but I've been running some numbers and noticed some
interesting things.
The SU-27 is credited with being more manueverable than F-15 and yet F-15
has a higher TTW number (except at gross) and a lower wing loading by a
large margin (again except at gross). The SU should develope more body
lift
than Eagle, but at best it looks like a wash at low altitudes, with Eagle
turning better than SU at altitude.
Any thoughts? Am I missing something large here? The Su's lerx's and
higher
aspect wing should make a positive differance at low level and low speeds
but I dont think it would make up for the other numbers. Eagle should have
a
20% better wing loading and about a 14% better TTW number.

The Su has a pull-through fuction on the fbw ISTR. Might be a factor?

John

John Mullen wrote:

The Su has a pull-through fuction on the fbw ISTR. Might be a factor?

Probably not since the the F-15C isn't FBW and only has an overload
warning function. You can over G a F-15C.

Michael Kelly, Bone Maintainer


John

yes Flankers have a switch which over rides the FBW limits, that's the only
way they can do the "Cobra" manuever. As I recall F-15s started out with
hydro controls with FBW as back up, then later models went fully fly by
wire.

--



Curiosity killed the cat, and I'm gonna find out why!
"Michael Kelly" wrote in message
m...

John Mullen wrote:

The Su has a pull-through fuction on the fbw ISTR. Might be a factor?

Probably not since the the F-15C isn't FBW and only has an overload
warning function. You can over G a F-15C.

Michael Kelly, Bone Maintainer


John

"Michael Kelly" wrote in message
m...

John Mullen wrote:

The Su has a pull-through fuction on the fbw ISTR. Might be a factor?

Probably not since the the F-15C isn't FBW and only has an overload
warning function. You can over G a F-15C.

Michael Kelly, Bone Maintainer

Actually fly-by-wire aircraft can be over-Gd -- it happens to F-16s all the
time.

The F-15, while not "fully" fly-by-wire, has a primary flight control system
that is FBW (called the CAS, or Control Augmentation System) and a
hydromechanical backup system.

R Haskin wrote:
Actually fly-by-wire aircraft can be over-Gd -- it happens to F-16s all
the
time.

Yabbut, isn't that a case of a Lawn Dart pulling max G and
then hitting turbulence, etc.?


Jeff

On Thu, 25 Mar 2004 02:44:04 -0600, "Boomer"
wrote:

yes Flankers have a switch which over rides the FBW limits, that's the only
way they can do the "Cobra" manuever. As I recall F-15s started out with
hydro controls with FBW as back up, then later models went fully fly by
wire.

The F-15 started as conventional with conventional backup and an
analog FCS. It eventually went to a digital FCS, but not to FBW.

The E might be FBW, but the A-D aren't.

Mary

--
Mary Shafer Retired aerospace research engineer

There are two really important questions:

1. What are the other odds? (AWACS, support aircraft, SAM defenses, range to
bases, numbers on each side, etc.)

2. Who are the pilots?

Both of these are quite critical to the equation.

DEP

R Haskin wrote:
Actually fly-by-wire aircraft can be over-Gd -- it happens to F-16s all the
time.

Agreed. The Bone is a 2 channel FBW on one side with a hydromechanical
stability augmented system on the other side. There are no limiters on
the FBW or stability aug so over G's happen all the time. Limiters on
the 16 make it harder to over G but not impossible.

The F-15, while not "fully" fly-by-wire, has a primary flight control system
that is FBW (called the CAS, or Control Augmentation System) and a
hydromechanical backup system.

IIRC my F-15 test pilot former colleague described the F-15C as fully
hydromechanical and the Echo's as you did. BTW saw you the other day on
the history channel. Good interview.

Cheers,
Michael Kelly, Bone Maintainer

Jeff Crowell wrote:

Yabbut, isn't that a case of a Lawn Dart pulling max G and
then hitting turbulence, etc.?

I could see too high of an onset rate, or pulling a turn as you
decelerated through the sound barrier. The latter case would be a very
good candidate if pulling a turn close to the limiter because of the
forward shift in the aerodynamic center going from supersonic to subsonic.


Jeff

Michael Kelly, Bone Maintainer