From:	"Paul J. Adam" <shadowtk@********.DEMON.CO.UK>
Subject:	Re: Arrow
Date:	Fri, 6 Mar 1998 00:36:17 +0000

In message <3.0.3.16.19980305153153.3817bc70@****.fbiz.com>, Erik
Jameson <erikj@****.COM> writes
>At 10:23 PM 3/5/98 +0000, you wrote:
>>Politics and money.
>>
>Mind elaborating a bit on this point? Was it simply too expensive and
>politically unpopular, or was there something more?

The US saw it as a threat. On paper (the only judgement available) it
was superior to anything the US had. For instance, had the Arrow been
available to NATO, Lockheed would have sold many fewer Starfighters, and
the RAF might have chosen the Commonwealth CF-105 over the US F-4.
Considerable political pressure was exerted to cause Canada to drop the
project. The F-101 sale was pushed hard as being cheaper and less risky.

There are similar claims about the TSR-2 being seen as a threat to the
TFX program and the F-111; when TSR-2 was cancelled, the UK nearly
bought the F-111K, before joining Panavia to develop the Tornado.

>>Gets around some of the inlet problems you run into at very high speeds.
>>
>Erm, so? Again, mind going into a bit more depth on this? I'm highly
>non-technical (drives my Dad absolutely bonkers), so please keep it to
>layman's terms.

I'm not totally sure myself, so be gentle :) Basically, above Mach 1
flow regimes change quite dramatically, and you get shock waves forming
off every projection. The SR-71's engines work damn hard to keep the
shockwave from the inlet cone from popping out of the duct, because that
dumps the airflow and stalls the engine.

One reason 1960s aircraft like the F-4 could pull Mach 2.2, while
today's F/A-18 Hornet can only manage Mach 1.8, is because the inlets on
the newer aircraft are not optimised for high-speed flight but for
subsonic manoevering: high-Mach flight is so rare that the cost and
weight penalty of variable inlets isn't worthwhile.


As the speed rises, the shockwaves become more and more acute and the
problems of intake design for steady flow become greater. By going to a
pulse-detonation engine - one which takes a "gulp" of air and fuel and
then expels it - you can tolerate variations in airflow into the engine
better than a steady-flow system. It gives you a noisy engine and one
with a very "bumpy" thrust profile, though.