F35 cost goes up.

In article ,
Charles Gray writes:
On Mon, 29 Dec 2003 19:22:11 -0000, "TJ"
wrote:


"Charles Gray" wrote in message
news


Only reasonable, since you have to add stuff to an airframe to make
it carrier worthy, in addiiton to other improvements. To use it the
other way around, either all you do is take some bits off, or just
leave them as is. (I recall some German F-4's at an airshow that
still had the arresting hook.).


The hook is used for runway arrestor landings. The same way as
Luftwaffe/Marineflieger F-104s, Tornados had/are fitted with hooks.

TJ

Ah. Thank you. So, what than are the major structural differences
between a navy F-4 and an airforce design?

Wider main wheels and tires, a bulge at teh wing root to allow same to
be retracted, and a boom refuelling socket rather than a refuelling
probe.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

On Tue, 30 Dec 2003 02:21:26 GMT, Chad Irby wrote:

You don't need a few thousand hours on an airframe to figure out the
fuel usage. It's a fairly simple thing called "math."

Once you know what the drag is, sure. But predicting the drag is
fraught with error, as previous aircraft have shown. The usual
failure in prediction is trim angle of attack. It's wrong, which
means that the horizontal is set at the wrong angle, so the trim drag
is higher than predicted and the fuel usage is, too.

I'm trying to remember which airplane it was that was sweating out
something like 250 drag counts between predicted and as-flown a while
back. They were moving antennas, fidgeting with the cg to change the
trim angle, smoothing the skin--all kinds of stuff. It must have been
the F-16, I guess.

Mary
--
Mary Shafer Retired aerospace research engineer

In article ,
Fred J. McCall wrote:

Chad Irby wrote:

:But you should have a fairly concrete faith in aerodynamics, especially
:with an airframe that's already *flying*.

Final F-35C aircraft are already flying? Since when?

Early F-35 aircraft are already flying, and there's no way in hell
there's going to be enough change in the next year or so to knock 1/3
off of their range. If there was anything lke that sort of defect in
the aircraft, the more annoying Proxmire-types in Congress would be
soiling themselves in delight.

Yes, but what you CAN'T predict is what you're going to have to change
to make the thing actually work in real service. Those changes will
impact many things, including range, payload, fuel load, etc. It's a
fairly simple thing called "reality".

And, once again, you still haven't managed to mention any aircraft in
the last twenty years or so that's been off by even 20% in combat
radius, never mind the 33% you're claiming it's going to be for the
F-35. Hell, a 10% miss on any of the performance targets would be
getting headlines in Aviation Week...

To listen to you, test flight programs are totally unnecessary.
Sorry, but our present reality seems to strongly indicate otherwise.

Well, not that you've bothered to listen in the first place...

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.

In article ,
Mary Shafer wrote:

On Tue, 30 Dec 2003 02:21:26 GMT, Chad Irby wrote:

You don't need a few thousand hours on an airframe to figure out the
fuel usage. It's a fairly simple thing called "math."

Once you know what the drag is, sure. But predicting the drag is
fraught with error, as previous aircraft have shown. The usual
failure in prediction is trim angle of attack. It's wrong, which
means that the horizontal is set at the wrong angle, so the trim drag
is higher than predicted and the fuel usage is, too.

I'm trying to remember which airplane it was that was sweating out
something like 250 drag counts between predicted and as-flown a while
back. They were moving antennas, fidgeting with the cg to change the
trim angle, smoothing the skin--all kinds of stuff. It must have been
the F-16, I guess.

That difference is between the theory of a plane on the drawing board
and one in the air. They're *flying* F-35 airframes.

Those drag changes don't make for a 33% change in performance. The
problems with the F-16 were over a 5% to 10% range, and that was between
the design and the flying airframe, not between the early flying
airframe and the production model.

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.

Chad Irby wrote:

:In article ,
: Fred J. McCall wrote:
:
: Chad Irby wrote:
:
: :But you should have a fairly concrete faith in aerodynamics, especially
: :with an airframe that's already *flying*.
:
: Final F-35C aircraft are already flying? Since when?
:
:Early F-35 aircraft are already flying, and there's no way in hell
:there's going to be enough change in the next year or so to knock 1/3
ff of their range.

F-35C aircraft? What's their ACTUAL range? Have you seen it
published anywhere? What load and what profile?

:If there was anything lke that sort of defect in
:the aircraft, the more annoying Proxmire-types in Congress would be
:soiling themselves in delight.

If they were told.

: Yes, but what you CAN'T predict is what you're going to have to change
: to make the thing actually work in real service. Those changes will
: impact many things, including range, payload, fuel load, etc. It's a
: fairly simple thing called "reality".
:
:And, once again, you still haven't managed to mention any aircraft in
:the last twenty years or so that's been off by even 20% in combat
:radius, never mind the 33% you're claiming it's going to be for the
:F-35.

Pardon me, but where the hell did I claim that? What ARE you smoking?
So far, all you've put forward is a comparison between apples and
aardvarks. Handwaving predictions of ranges for the F-35C. What's
the actual range, since the data is so solid and all?

:Hell, a 10% miss on any of the performance targets would be
:getting headlines in Aviation Week...

So, what tactical radius is the F-35C demonstrating? What loads?
What flight profiles?

What? You don't have that data? Me either, which is sort of my
point. There's marketing and then there's what you can actually do
with the airplane. I'm more interested in the latter. You appear to
want to insist that the former is gospel.

: To listen to you, test flight programs are totally unnecessary.
: Sorry, but our present reality seems to strongly indicate otherwise.
:
:Well, not that you've bothered to listen in the first place...

Given your demonstrated inability to read, above, I think you've just
committed some sort of metal. Say, ironic.

--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

On Mon, 29 Dec 2003 23:55:08 -0500, (Peter
Stickney) wrote:

In article ,
Charles Gray writes:
Ah. Thank you. So, what than are the major structural differences
between a navy F-4 and an airforce design?

Wider main wheels and tires, a bulge at teh wing root to allow same to
be retracted, and a boom refuelling socket rather than a refuelling
probe.

There's more. Depending on the model, you might have two section or
three section leading edge flaps. Withe E and G you get a smaller
radar antenna and the underslung gun. With J and S you get blistered
ECM pods on the top outer corners of the intakes. There are different
radars on all versions and no stick in the R/C/P of USN airplanes.
With RF and G-eazels you get different noses. Some have slotted slabs
and some (both USAF and USN) have LES. Then there's TISEO as well.

And, more and more.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
Smithsonian Institution Press
ISBN #1-58834-103-8

On Tue, 30 Dec 2003 07:33:44 GMT, Chad Irby wrote:

In article ,
Mary Shafer wrote:

On Tue, 30 Dec 2003 02:21:26 GMT, Chad Irby wrote:

You don't need a few thousand hours on an airframe to figure out the
fuel usage. It's a fairly simple thing called "math."

Once you know what the drag is, sure. But predicting the drag is
fraught with error, as previous aircraft have shown. The usual
failure in prediction is trim angle of attack. It's wrong, which
means that the horizontal is set at the wrong angle, so the trim drag
is higher than predicted and the fuel usage is, too.

I'm trying to remember which airplane it was that was sweating out
something like 250 drag counts between predicted and as-flown a while
back. They were moving antennas, fidgeting with the cg to change the
trim angle, smoothing the skin--all kinds of stuff. It must have been
the F-16, I guess.

That difference is between the theory of a plane on the drawing board
and one in the air. They're *flying* F-35 airframes.

Well, big whoop. They're flying instrumented pre-production
airframes, not "real" F-35s, by the way. The production F-35 may
differ a fair amount from the pre-production models.

Have they done the performance points yet? They're not usually done
very early in a program. As I recall, the performance airframe is
often the fourth or fifth to go into test, because the early airframes
are dedicated to more urgent issues, like buffet and S&C and HQ.

As for the predictions, they're not from the drawing board. Rather,
they're from models, either wind tunnel or CFD. The predictions are
pretty good in general, but it is possible to miss now and then.
There are certain parameters that are disportionately sensitive to
small perturbations. Trim angle, for example.

Those drag changes don't make for a 33% change in performance. The
problems with the F-16 were over a 5% to 10% range, and that was between
the design and the flying airframe, not between the early flying
airframe and the production model.

I beg your pardon? Can you point to any place where I said that there
would be a 33% change or a difference between the pre-production model
(that's what we call "the early flying airframe") and the production
model?

The problem with 250 drag counts is that it's a hideously big amount
of drag. Really, really big. No, not enough to steal a third of the
range, but too much to meet the specs. And this was between the
predictions and the pre-production airframes, but the data from the
prototype YF-16 had been used too.

Mary

--
Mary Shafer Retired aerospace research engineer

On Mon, 29 Dec 2003 23:55:08 -0500, (Peter
Stickney) wrote:

In article ,
Charles Gray writes:

Ah. Thank you. So, what than are the major structural differences
between a navy F-4 and an airforce design?

Wider main wheels and tires, a bulge at teh wing root to allow same to
be retracted, and a boom refuelling socket rather than a refuelling
probe.

Controls in the aft cockpit, too.

Mary

--
Mary Shafer Retired aerospace research engineer

In article ,
Fred J. McCall wrote:

F-35C aircraft? What's their ACTUAL range? Have you seen it
published anywhere? What load and what profile?

You know, you keep harping on this, but you never seem to have any
justification for the extreme miss in range that you're assuming is
going to happen.

And I'm still waiting for *any* example of an aircraft that's missed by
as much as you're assuming the F-35 will.

:And, once again, you still haven't managed to mention any aircraft in
:the last twenty years or so that's been off by even 20% in combat
:radius, never mind the 33% you're claiming it's going to be for the
:F-35.

Pardon me, but where the hell did I claim that?

In every single post that you've made on this subject, by assuming that
the F-35 will miss its range target by enough to have a shorter range
than the F-18.

You've had several chances to back off and agree that you're wrong, but
you keep babbling about the "F-35C," while not admitting that the range
difference isn't going to be more than a few percent.

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.

Those drag changes don't make for a 33% change in performance. The
problems with the F-16 were over a 5% to 10% range, and that was between
the design and the flying airframe, not between the early flying
airframe and the production model.

I beg your pardon? Can you point to any place where I said that there
would be a 33% change or a difference between the pre-production model
(that's what we call "the early flying airframe") and the production
model?

I think he's referring to the comment *way* back up the thread that
suggested the F-35C wouldn't have the range of a Super Hornet and that
it's range would have to be cut by 33% to be as low as the Hornet's.