Article 11836 of rec.aviation.military:
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From: jfb@usgp1.ih.att.com (Joe Baugher)
Subject: New Fighter Series--McDonnell Douglas F-15 Eagle (5 of 26)
Message-ID: <D3787t.1MA@ssbunews.ih.att.com>
Summary: Armament of F-15A/B/C/D
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Organization: AT&T
Date: Mon, 30 Jan 1995 03:26:17 GMT
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There are three components to the Eagle's armament--the AIM-7 Sparrow 
(later the AIM-120 AMRAAM) for BVR encounters, and AIM-9 Sidewinder 
missiles and an internal cannon for short-range encounters.  

Sparrow:  

In the F-15, The AIM-7 Sparrow semi-active radar homing missile is 
carried on attachment points mounted on the lower outer edges of the 
air intake trunks, two on each side.  The first Eagles to enter 
service with the USAF carried the AIM-7F version of the Sparrow, which 
introduced solid-state electronics as substitutes for the miniature 
vacuum tubes of the earlier versions.  This miniaturization enabled 
the warhead to be moved forward of the wings, with the aft part of the 
missile being devoted almost entirely to the rocket motor.  The extra 
space that was made available by the introduction of solid-state 
miniaturization made it possible to introduce a dual-thrust 
booster/sustainer rocket motor that enabled the effective range of the 
Sparrow to be essentially doubled (up to 28-30 miles) in a head-on 
engagement.  The AIM-7L had fewer tubes and more solid state features.  
The AIM-7M introduced in 1982 featured a inverse-processed digital 
monopulse seeker which was more difficult to detect and jam and 
provided better look-down, shoot-down capability.  The AIM-7P was 
fitted with improved guidance electronics, including an on-board 
computer based on VLSIC technology.  It is intended to have better 
capability against small targets such as cruise missiles and 
sea-skimming antiship missiles.  

The AIM-7M is 12 feet long and has a launch weight of about 500 
pounds.  The missile carries a 85-pound high-explosive blast 
fragmentation warhead.  It has two sets of delta-shaped fins--a set of 
fixed fins at the rear of the missile and a set of movable fins at the 
middle of the missile for steering.  

AIM-120 AMRAAM:  

From 1991 onward, the Sparrow has been replaced aboard most Eagles 
with the Hughes AIM-120 AMRAAM (Advanced Medium Range Air-to-Air 
Missile), which is a "fire and forget" weapon.  The Sparrow AAM had a 
semi-active radar guidance system which required that the target be 
continuously illuminated throughout the entire duration of the 
engagement.  

The AMRAAM is guided to the vicinity of its target by a inertial 
guidance unit, which can be updated if necessary by a datalink from 
the launching aircraft.  For the final approach to the target, the 
AMRAAM switches over to its own high-PRF (pulse repetition frequency) 
active seeker and homes in on the target.  Since the seeker in the 
nose of the AMRAAM uses active radar homing, the missile does not 
require that the launching aircraft illuminate the target or continue 
to track it after launch.  If the target tries to protect itself by 
jamming, the AMRAAM can switch over to a medium-PRF home-on-jam mode.  
Although the AIM-120 handles its own terminal homing onto the target, 
it usually still requires radar illumination from the fighter for a 
portion of its initial run-in to the target.  

The AMRAAM is 11.97 feet long, has a wingspan of 20.7 inches, and a 
diameter of 7 inches.  The AMRAAM is considerably lighter than the 
Sparrow, weighing about 350 pounds at launch.  It carries a 48-pound 
high-explosive directed-fragmentation warhead.  Maximum speed is about 
Mach 4, and the maximum range is of the order of 35-45 miles.  

Test firings of the AMRAAM began in 1981, with initial deployment 
being scheduled for the mid-1980s.  However, the development of the 
AMRAAM turned out to be much more difficult than expected, and 
numerous problems turned up which required time-consuming and 
expensive fixes.  The schedules began to slip and costs began to rise.  
Congress became so dissatisfied with AMRAAM that in 1986 they 
seriously threatened to cancel the whole program unless the original 
specification could be met at a unit cost of no more than $440,000.  
Deployment slipped into the early 1990s.  A few AMRAAMs were rushed 
into service in the final stages of the Gulf War, but none were fired 
in actual combat.  However, the AMRAAM has been fired in combat 
incidents following the Gulf War with highly successful results, 
although one of these involved a "friendly-fire" incident in which a 
pair of Blackhawk helicopters were shot down by mistake.  

Sidewinder:  

Four AIM-9 Sidewinders (today AIM-9M) are carried on the underwing 
pylons of the F-15, two on each side.  Attachment points for 
Sidewinder missiles are provided on each side of the underwing pylons, 
enabling a drop tank or a bomb ejector rack to be carried underneath 
the pylons at the same time as the Sidewinders.  

The Sidewinder infrared homing missile dates back to 1956, but the 
missile has been continuously upgraded over the years.  Early F-15As 
carried the AIM-9J, which was the first major post-Vietnam improvement 
of the Sidewinder missile.  The J model had an expanded 
target-engagement cone which enabled it to be launched at any spot in 
the rear half of a target aircraft rather than merely at its exhaust.  
Compared with the Vietnam-era AIM-9G, it had a more powerful motor and 
an improved warhead.  The AIM-9J introduced the Sidewinder Expanded 
Acquisition Mode (SEAM), which slaved the seeker head of the missile 
to the radar when in "dogfight" mode, which enabled the AIM-9J seeker 
head to be uncaged, slewed toward a specific target by the aircraft 
radar, and made to track that particular target only.  The AIM-9H 
introduced some minor improvements.  The AIM-9L introduced in 1979 was 
"all-aspect", and was no longer limited to engaging an enemy aircraft 
from the rear.  The seeker head was more sensitive and was able to 
pick up heat from the friction off the leading edges of an aircraft's 
wing and was able to distinguish between aircraft and decoy flares.  
The AIM-9L also uses a higher-impulse rocket motor, a more powerful 
warhead, and a proximity fuse rigged to blow outward toward the target 
in order to ensure better probability of a kill.  The AIM-9M 
introduced in 1982 had better capability to distinguish between 
aircraft and decoy flares, and has a low-smoke rocket motor so that it 
is less likely to be seen by its prey.  The number of vacuum tubes was 
reduced to two.  

The AIM-9 Sidewinder is 9.4 feet long, has a wingspan of 25 inches and 
a diameter of 5 inches.  The missile has four tail fins on the rear, 
with a "rolleron" at the tip of each fin.  These "rollerons" are spun 
at high speed by the slipstream in order to provide roll stability.  
The missile is steered by four canard fins mounted in the forward part 
of the missile just behind the infrared seeker head.  The Sidewinder 
missile has a launch weight of about 180 pounds, and a maximum 
effective range of about 10 miles.  The blast-fragmentation warhead 
weighs 21 pounds.  Despite the advanced age of the basic design, the 
all-aspect Sidewinder remains a potent threat, exceeded in 
effectiveness perhaps only by the Russian-built Molniya/Vympel R-73 
(known in the West as the AA-11 *Archer*) which combines aerodynamic 
and thrust-vectoring control systems.  

Cannon:  

For the very closest air-to-air encounters, the F-15 carries a 20-mm 
M61A1 cannon installed in the starboard wing leading edge lip, just 
outboard of the upper air intake.  The gun is fed by ammunition drum 
containing 940 rounds located inside the central fuselage just below 
the hinge of the large dorsal air brake.  The lip on the port side of 
the aircraft is taken up by a receptacle for midair refuelling by the 
boom/receptacle method.  

The Eagle was originally intended to have been armed with a 25-mm 
Ford-Philco GAU-7 cannon that fired caseless ammunition.  Caseless 
ammunition offers the advantage of a higher round velocity with a 
flatter trajectory.  In addition, it has the advantage that there are 
no spent casings that need to be handled.  However, the feed system of 
the GAU-7 never did work properly, which meant that the gun could not 
be fired at high rates lest it jam.  In addition, caseless ammunition 
is much more difficult to handle than conventional ammunition, and 
there is always the danger of it "cooking off" inside the gun, so 
every part of the gun system (including the ammunition drum) had to be 
lined with armor, adding to the weight.  Consequently, it was decided 
to opt instead for the 20-mm M61A1 Vulcan cannon, since it was by that 
time a fully-proven weapon 

Bombs:  

Although primarily an air superiority fighter, the F-15 Eagle has a 
secondary air-to-ground capability.  Up to 16,000 pounds of bombs, 
fuel tanks, and missiles can be carried, although the F-15A/B/C/D
very rarely functions in a ground-attack role.  

The underwing pylons can each accommodate a multiple ejector rack which 
can carry six 500-pound bombs.  The bomb racks can be installed on the 
underwing pylons without disrupting the normal carriage of Sidewinder 
missiles.  

Air-to-ground stores can also be carried on the underfuselage 
centerline.  

A typical load consists of 18 500-pound bombs, carried 6 each on 
underwing and centerline ejector racks.  

The F-15A/B/C/D can carry and deliver laser-guided bombs such as the 
GBU-10E/B Paveway II or the GBU-12D/B Paveway II.  However, it does 
not have the capability of guiding these weapons by itself, and must 
rely on laser designators carried by other aircraft or by personnel on 
the ground.  




