Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!ukma!tut.cis.ohio-state.edu!att!cbnews!henry@zoo.toronto.edu
From: henry@zoo.toronto.edu (Henry Spencer)
Newsgroups: sci.military
Subject: Re: B1A vs. B1B
Message-ID: <6255@cbnews.ATT.COM>
Date: 5 May 89 00:34:48 GMT
Sender: military@cbnews.ATT.COM
Lines: 47
Approved: military@att.att.com



From: henry@zoo.toronto.edu (Henry Spencer)
>My question is how big a difference is there between the A and B? I
>know the A was supersonic and the B subsonic, but how about payload,
>range etc. What were the technical reasons for changing the B to
>subsonic (or was it all just political/money)? ...

The differences are mostly modest improvements of one kind and another.
For example, lower radar cross-section.  The loss of supersonic capability
is really pretty unimportant, since it wasn't very useful in the first
place.  (It was available only at high altitude.)  The B-1 would probably
have been better off without the original supersonic requirement, actually.
I think they just found it inconvenient to retain supersonic speed and
said "oh, to hell with it".  I don't think payload and range have changed
much, although they may have reshuffled the payload-bay layout a bit for
bigger cruise missiles.

>To stretch things even farther, how different is the B1A from the
>original XB-70 (range, payload, speed)?

Very.  Much.  Extremely.  Range and payload probably vaguely similar,
but the difference between cruising speeds of 600 mph and 2000 mph is not
trivial!  The XB-70 was built for blazing speed at very high altitude, the
B-1A was built for modest speed at very low altitude.

> Were any of the results from the
>B-70 program used in the B1, or was all that lost?

Some of the more fundamental technology may have been relevant, but there
is so little resemblance between the aircraft that I'd be surprised if
there was much overlap.

> Why was the B-70
>cancelled (I remember a crahs but assume the cancellation was politics)....

The crash was in fact post-cancellation, I think.  The B-70 had three big
problems:  it arrived at a time when ICBMs were increasingly looking better
than manned bombers for the strategic-nuclear role, it arrived at a time
when flying slower but lower was increasingly thought to be better than
flying fast and high, and it was extremely expensive at a time when the
ICBM programs were also spending money like water.  The hardware pretty
much worked, although with delays and cost overruns, but the political
and strategic issues killed it.

                                     Henry Spencer at U of Toronto Zoology
                                 uunet!attcan!utzoo!henry henry@zoo.toronto.edu