Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!oliveb!apple!rutgers!att!cbnews!henry@zoo.toronto.edu
From: henry@zoo.toronto.edu (Henry Spencer)
Newsgroups: sci.military
Subject: Re: F-111
Message-ID: <5139@cbnews.ATT.COM>
Date: 27 Mar 89 02:18:28 GMT
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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