jdp@killer.UUCP (Jim Pritchett) (03/25/89)
From: gtmvax!caleb!jdp@killer.UUCP (Jim Pritchett)
Recently, there have been several postings about the F-111. Some have been
correct, while others have been repetitions of old misinformation. If I may,
I will try to clear up a few things.
[Before I begin, I should say that I was the lead F-111 performance engineer
at General Dynamics for several years in the mid 1980s. This was long after
the "controversial TFX" days, so I can't give you direct information on the
early days, except by hearsay from some of the oldtimers that I know. However,
I can provide some correct information about the current F-111s. Naturally,
General Dynamics neither knows of nor approves of any of these statements.]
First, someone made disparaging remarks about the F-111's supersonic
capability at low altitude. I know of NO fighter-bomber aircraft that comes
anywhere near the range-payload capability of an F-111 on a low altitude,
high speed mission. In fact, it is probably the only fighter-bomber with
a useful combat radius on a low altitude, supersonic mission. The above
statements include the newest aircraft of many nations and even several "paper"
aircraft. The statement that the F-111 has almost no mission radius at
supersonic speed is COMPLETELY WRONG! I can't quote numbers here because I
don't have the data any more (it is not classified.) In fact, there are VERY
few aircraft that can even fly as fast as the F-111 at low altitude.
Second, the F-111's range-payload capability on a more realistic combat mission
is unmatched by any fighter-bomber in the world. Even the USAF's vaunted F-15E
does not come close. (I have seen a marketing brochure on the F-15E that
showed comparable range. However, it overestimated the F-15E's capability
and grossly underestimated the F-111's capability. They played some marketting
games with the data. I know, I checked the data.) If you don't think the
range is important, take a look at a globe sometime. Compare the bases that
could be counted upon for our use against the places where our forces might be
required to strike. Then you will see why the USAF will continue to operate
F-111's for a long time to come.
I could go on about the many capabilities of the F-111. I could even talk
about some of it's problems. However, I doubt that there is that much interest
in a 25 year old aircraft. (If there is sufficient interest, I could provide
more information about the F-111...) I posted this mainly because this
aircraft has gotten much unfavorable press (and outright slander) over the
years. I find it amazing that 25 years after the first F-111 flew, it still
can do many things better than even the "paper" aircraft can do. (For those
who don't speak "Engineer", a "paper" aircraft is one that is still on the
drawing boards -- or computers. Also, it is, or should be, well known that
a "paper" aircraft can do almost anything. It is when you actually try to
build it that the real problems arise!)
I think that I'll close with an anecdote. As some of you may know, fighter
pilots are notorious for disobeying the rules. One day I got a call from the
USAF logistics folks. It seems that a pilot brought home his aircraft with
severely blistered paint. He had some wild story about an unusual temperature
layer that he flew through. (For the uninitiated, the paint on some aircraft
will blister if the Flight Manual speed limitations are violated.) There was
another story about 'defective paint.' The logistics folks knew that he was
probably lying, but they had to try to verify his story. (The USAF is run by
pilots...) My own theory is that we had found yet another case of a pilot
falling prey to the irresistable question: "I wonder how fast it will really
go???"
Jim Pritchett
UUCP: killer!gtmvax!dms3b1!caleb!jdphenry@zoo.toronto.edu (Henry Spencer) (03/27/89)
From: henry@zoo.toronto.edu (Henry Spencer) >... The statement that the F-111 has almost no mission radius at >supersonic speed is COMPLETELY WRONG! ... That wasn't quite the statement I made, fortunately. The statement was that for a specified mission profile (I forget the details), the low-level supersonic dash duration was specified at some substantial distance [150 miles?] but turned out to be nearly zero. I would assume that the limiting factor was fuel supply -- low-level supersonic speed is very hard on fuel. The F-111 can definitely go supersonic for reasonable distances at reasonable altitudes. It can probably go supersonic for a fair distance at low level *if* that is most of the mission, i.e. if that supersonic dash doesn't have to be at the far end of a long-range mission. (For that matter, add another constraint: if the weapons are internal. External weapons cut low-level performance drastically. The original F-111 did have an internal bay, but there is a tendency for such spaces to get filled in with electronics and such -- I don't know offhand whether this has happened to the current F-111s.) Whether all this supersonicness is particularly useful for real F-111 missions, and whether it was worth all the pain during development, are different questions. Other things being equal, one cannot fly as low over rough terrain at supersonic speed as at subsonic speed, which is one reason why the B-1 is not supersonic at low level. I certainly won't dispute that the F-111 has abilities shared by no other tactical aircraft... partly just because it's bigger than they are. One can legitimately ask, however, whether the customers would have been better off with a less ambitious aircraft that would have been easier to develop and would have been bought in much greater numbers. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu
maniac%garnet.Berkeley.EDU@ (George W. Herbert) (03/31/89)
From: maniac%garnet.Berkeley.EDU@ (George W. Herbert)
Just to make it clear, I didn't (and as far as i could tell nobody else did)
mean to complain about the F-111{A,(C),D,E,F}. They are all fine planes,
very capable, and are still (~20yrs later) at or very near the top of the heap
for strike planes. We all were bickering over the sensibility or lack thereof
of the F-111B (or, what can we do wrong in the name of 'effeciency of design
cost' to paraphrase those who criticize ex defense secretary Macnamara.)
Of course, there are ways of doing it better... but that's another story.
An upengined Tornado would be neat, though they won't and can't due to design
(what i mean is boosting it into 111's thrust class...)
george william herbert
maniac@garnet.berkeley.edu