Paul Austin wrote:

"Scott Ferrin" wrote

Some
improvement in range is possible. Much higher is questionable.
ASRAAM
and Python have much larger motors for the same generation seeker
technology (same seeker in ASRAAMs case) indicating that designers
not
tied to a large stock of existing ordnance feel that more impulse
can
be usefully employed exploiting the seeker's performance.

IIRC all the rest of the entries for which the -9x as-is was
selected
had bigger motors too.

Yep, they did. The USAF perhaps feels less need for a long range IR
missile since AIM-120 fills that range bin.

Exactly right. That, and they had a lot of AIM-9s (at least half of the
24,000 in stock) available to convert. FWIW, here's some data from the
Air International article "Battle of the Missiles" by John Fricker in the
Feb. 1997 issue:

"Two Sidewinder-derived reduced airframe drag configurations were
proposed by the Pentagon in April 1993, as AIM-9X options. From the USAF
came the wingless Box Office concept, using very small (28cm/11 in span)
all-moving tail-mounted fin controls, with no foreplanes, plus digital
autopilot stabilisation, while the Naval Weapons Center's relaxed
stability Boa project employed a clipped canard and fin configuration
(40.64cm/16 in. span each), with a similar autopilot."

"In broad terms, Box Office was expected to halve the drag of the current
AIM-9M8/9 and double its 8km (4.3nm) range. A speed increase of up to
Mach 1.3 over the original Mach 2.5 was also sought, with doubled
g-limits. Boa has higher drag and hence a reduced range and maximum
speed, but it has less speed loss in turns. . . ."

"AIM-9X seeker performance targets included increasing clear sky target
acquisition range to 13-16km (7 - 8 3/4 nm) and 6.6km (3 1/2 nm) in
ground clutter. . . ."

He then goes on to give descriptions of the Iris-T, ASRAAM, P4 and Magic
2 and their variants on offer, and says why each was rejected. The
design eventually selected was a Hughes version called Box Office 2 Plus,
although it seems to have the clipped canard/fins Fricker attributes to
Boa.

Guy