F35 cost goes up.

In article ,
Mary Shafer wrote:

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

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?

My original point was that the F-35 is going to have a combat range
about 50% higher than the F-18 E/F according to the specs.

If it misses its range by as much as five or ten percent, it will still
have a *much* higher unrefueled range than the F-18.

Since I've already *agreed* that it could miss by a small amount, and
since you keep *arguing* about it, that means you must disagree with
those numbers.

So pick a number. What's the *worst* you think it could be?

If it's not more than about five or ten percent, then you're arguing
with Fred on this one, not me...

--
cirby at cfl.rr.com

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

Scott Ferrin wrote:

:
: 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.

I'm sure he is, but that's simply wrong. First normalize the numbers.
Equal percentage of load, fuel, same flight profiles, etc. Next, get
some REAL numbers for the combat range of an F-35C with those sorts of
constraints, rather than all this hand waving. Then we'll talk about
how far off it has to be.

--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney

In article ,
Fred J. McCall wrote:

Scott Ferrin wrote:

: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.

I'm sure he is, but that's simply wrong.

No, that's basically what they've been using at the Navy.

First normalize the numbers.
Equal percentage of load, fuel, same flight profiles, etc.

The Navy uses a standard mission profile. It's a "high-low-high" attack
mission with a standard armament load (two 1000 pound bombs) that can
recover on the same ship it launches from (the FA-18E/F supposedly can't
recover from an abort with a max load, and has to dump some weapons or
fuel to manage a landing). The standard mission profile is what I've
been going by.

If you go with nonstandard profiles, the FA-18 E/F could have a higher
range (as much as 500 miles, with extreme fuel loads and no chance of
recovery in a short abort), but so would the F-35 (more internal fuel).

--
cirby at cfl.rr.com

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

On Tue, 30 Dec 2003 17:03:15 GMT, Fred J. McCall
wrote:

Scott Ferrin wrote:

:
: 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.

I'm sure he is, but that's simply wrong. First normalize the numbers.
Equal percentage of load, fuel, same flight profiles, etc. Next, get
some REAL numbers for the combat range of an F-35C with those sorts of
constraints, rather than all this hand waving. Then we'll talk about
how far off it has to be.


You'd think though that they'd at least have an inkling from the
prototypes on the range so they could do something about it in the
production model if it was that far off. If they haven't something is
seriously wrong with the process.

On Tue, 30 Dec 2003 16:48:31 GMT, Chad Irby wrote:

In article ,
Mary Shafer wrote:

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

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?

My original point was that the F-35 is going to have a combat range
about 50% higher than the F-18 E/F according to the specs.

If it misses its range by as much as five or ten percent, it will still
have a *much* higher unrefueled range than the F-18.

Since I've already *agreed* that it could miss by a small amount, and
since you keep *arguing* about it, that means you must disagree with
those numbers.

I'm not arguing, I'm just explaining the most common problems in
predicting drag, and, hence, range. The prediction can range from
small to large and no one has provided any meaningful information
about what the situation is. It's all speculation. You're the one
who is arguing, with what appears to be very little information but a
great deal of emotion.

I do think it's a little dishonest to compare aircraft with internal
stores to aircraft with external stores, as some of the comparisons
I've seen elsewhere do, but that's not an issue here. That's about
the only thing I'd argue about.

What's to argue about, anyway? If you know the drag, you know the
thrust you need. If you know the required thrust and you know the
engine, you know the fuel consumption. If you know that, you know the
range. What you do in flight test is find the drag and refine the
engine model. Then you hope the difference isn't so great between
what was predicted, which was enough to meet the specs, and what you
got that you can't come close enough to get a waiver. It's pretty
simple, really.

The F-35 is a nice, if odd-looking, little airplane. I have no reason
to believe it has any major problems. I hope it doesn't. If it does,
I hope they're easily fixable.

Mary


--
Mary Shafer Retired aerospace research engineer

I'm not arguing, I'm just explaining the most common problems in
predicting drag, and, hence, range. The prediction can range from
small to large and no one has provided any meaningful information
about what the situation is. It's all speculation. You're the one
who is arguing, with what appears to be very little information but a
great deal of emotion.

I do think it's a little dishonest to compare aircraft with internal
stores to aircraft with external stores, as some of the comparisons
I've seen elsewhere do, but that's not an issue here. That's about
the only thing I'd argue about.

What's to argue about, anyway? If you know the drag, you know the
thrust you need. If you know the required thrust and you know the
engine, you know the fuel consumption. If you know that, you know the
range. What you do in flight test is find the drag and refine the
engine model. Then you hope the difference isn't so great between
what was predicted, which was enough to meet the specs, and what you
got that you can't come close enough to get a waiver. It's pretty
simple, really.

The F-35 is a nice, if odd-looking, little airplane. I have no reason
to believe it has any major problems. I hope it doesn't. If it does,
I hope they're easily fixable.

Mary


Do they EVER get a *pleasant* surprise? As in "wow this sucker has
300 miles more range than we thought"? It always seems like it's
heavier than they thought or less range or lower speed or weird
aerodynamics. Seems like nothing positive ever pops up.

On Tue, 30 Dec 2003 17:56:07 GMT, Scott Ferrin
wrote:

What's to argue about, anyway? If you know the drag, you know the
thrust you need. If you know the required thrust and you know the
engine, you know the fuel consumption. If you know that, you know the
range. What you do in flight test is find the drag and refine the
engine model. Then you hope the difference isn't so great between
what was predicted, which was enough to meet the specs, and what you
got that you can't come close enough to get a waiver. It's pretty
simple, really.

Do they EVER get a *pleasant* surprise? As in "wow this sucker has
300 miles more range than we thought"? It always seems like it's
heavier than they thought or less range or lower speed or weird
aerodynamics. Seems like nothing positive ever pops up.

Yes, they occasionally do. Not usually on weight or range, though.
Aircraft always end up heavier and draggier than designed. More lift,
better HQ, more thrust is more likely, but very uncommon. Maybe
better structural dynamics, like flutter, too.

The reason it seems that only bad stuff shows up in flight test has to
do with the purchasing process. The military gives the contractor the
contract based on the contractor's promise to build an airplane that
can do at least as well as specified in the contract. There's rarely
a reward for doing better.

So, things that don't meet the specs are a problem and have to be
fixed. They get the publicity. Things that exceed the specs are not
a problem in terms of the contract, so no one hears about them. (They
could be a problem in terms of design, that the contractor made
something too good, wasting money, since the idea on the contractor's
side is to produce an airplane that's just good enough.)

Mary

--
Mary Shafer Retired aerospace research engineer

Hi!

Scott Ferrin writes:
Do they EVER get a *pleasant* surprise? As in "wow this sucker has
300 miles more range than we thought"? It always seems like it's
heavier than they thought or less range or lower speed or weird
aerodynamics. Seems like nothing positive ever pops up.

A few years ago it was reported in swedish aviation magazines that
Gripen has a little less drag then predicted during development.

Best regards,
--
Titta gärna på http://www.lysator.liu.se/~redin och kommentera min
politiska sida.
Magnus Redin, Klockaregården 6, 586 44 LINKöPING, SWEDEN
Phone: Sweden (0)70 5160046

Chad Irby wrote:

: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.

Wake up, Chad. It doesn't even have to 'miss'. What range is given
for it? Where? What load conditions? How much fuel? Any tanks?
What assumptions about flight regime? How much 'draggier' is the 'big
wing' (apparently enough to not give a range increase, if the
'handwaving' numbers are to be believed, since they don't call the C
out separately (nor the B either, for that matter)).

: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.

Your failure to understand what I'm 'assuming' is not my problem. It
is yours. Slam the thing into a carrier deck several hundred times
and put a few thousand hours on it. How much additional 'beefing up'
of structure is going to be required? What effects will it have on
fuel load, drag, etc?

Simulation is wonderful. It didn't predict the tailplane problems and
wing problems on F/A-18s of various types.

: :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.

Nonsense. So far, you're comparing apples and aardvarks. What load
is the F/A-18E/F (not just the vanilla Hornet) carrying for the range
number you're using? Any external fuel? Loaded to capacity? Same
weapon load as the F-35C and the remainder of the allowable load taken
up with fuel? What's the F-35C carrying for your example? Any
external load?

Do you get the point yet? Go find numbers that compare apples to
apples and come back and make your claims again.

: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.

And you persist in ignoring reality in favour of marketing. You've
had several chances to actually read what I'm saying and admit you
don't know enough to know if either of us is wrong, but you keep
babbling about "missing by 33%" while not admitting that you haven't a
clue what load conditions and fuel fractions go with your marketing
numbers for the F-35(generic).

Get back to me when you have real numbers with real loads on real
airplanes in real FRP trim. Those numbers exist for Hornets (of all
types). They do not exist for F-35s (of any type).

--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney

In article ,
Fred J. McCall wrote:

Wake up, Chad. It doesn't even have to 'miss'. What range is given
for it? Where? What load conditions? How much fuel? Any tanks?
What assumptions about flight regime? How much 'draggier' is the 'big
wing' (apparently enough to not give a range increase, if the
'handwaving' numbers are to be believed, since they don't call the C
out separately (nor the B either, for that matter)).

You know, I already explained the comparison. I explained where I got
the numbers.

And all you can manage is arguing against your *own* arguments.

--
cirby at cfl.rr.com

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