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Langley Contributions
to Missiles
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Background |
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In support of the
Department of Defense (DOD), Langley Research Center
is frequently requested to assist in the assessment
and development of missiles. Langley provides support
in the areas of aerodynamics, stability, and control
for the isolated missile configuration, as well
as in areas that might be affected by the carriage
and release of the missile (aircraft performance,
spin recovery, and flutter).
Langley became involved in the development of
missile systems in the early 1950’s, when
a detachment of Langley researchers formed the
core of what would become the NASA Wallops Flight
Facility. These pioneering researchers used booster
rockets to assess the aerodynamic characteristics
of evolving air-to-air military missiles.
When large-scale supersonic wind tunnels were
put into operation at Langley, special tests and
test techniques were developed and validated for
basic research for specific missile programs. Langley’s
leader in these early efforts was M. Leroy Spearman,
who maintained a close working relationship with
DOD and other agencies. In the 1960’s and
1970’s, Charles M. Jackson and Wallace C.
Sawyer led the Langley missile program, which focused
on a number of technical issues that were within
the interests of the NASA program. The program
included an expansion of the database for missile
design (led by Jerry M. Allen and Adolphus B. Blair,
Jr.), the development and validation of computational
codes for missile aerodynamics (led by David S.
Miller and Richard M. Wood), store carriage and
separation (led by Robert L. Stallings, Jr.), and
experimental techniques (led by William Corlett).
The vast majority of work in the Langley missile
program involved research on representative missile
shapes; however, very significant contributions
were made to specific missile programs.
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AIM-9 Sidewinder |
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In 1953, the Naval
Ordnance Test Section requested assistance from
Langley in the development of a short range, guided
air-to-air missile for close-in combat. Known as
the Sidewinder, the missile was to be heat seeking—that
is, able to lock on to a target’s heat producing
sources, and featured forward canards for improved
control.
At Wallops Island, Langley researchers conducted
flight tests to improve the roll characteristics
at supersonic speeds of the Sidewinder. During
the tests, the missile was mounted atop a rocket
test section. Langley developed special dampers,
known as rollerons, for the rear control surfaces
of the missile, which eliminated undesirable oscillatory
roll tendencies. In 1956, Langley researchers studied
how fighter aircraft would perform at supersonic
speeds with various numbers of Sidewinder missiles
stored in underwing locations and wingtip hard
points. These studies were conducted in the Langley
4- by 4-Foot Supersonic Pressure Tunnel. The tests
helped to establish limits on the external store
capability of aircraft destined to carry the missile.
Through the years, programs have improved the
maneuverability and range of the Sidewinder missile,
and Langley has conducted numerous wind-tunnel
test programs in the Langley Unitary Plan Wind
Tunnel in cooperation with the Naval Weapons Center,
China Lake, California. The most recent efforts
in 1990, led by Blair and Allen, were conducted
in the Unitary Plan Wind Tunnel and focused on
the potential benefits of reduced tail span for
enhanced supersonic maneuverability. The Langley
and Navy team also examined a long range Sidewinder
configuration, which incorporated an increased
body diameter for more booster fuel.
Air Force crew loads a Sidewinder.
Sidewinder missile research model
in the Langley Unitary Plan Tunnel.
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AIM-7 Sparrow |
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In August 1948,
Langley assisted the Navy and its contractors,
the Sperry Corporation and the Douglas Corporation,
in the development of the nation’s first
medium range guided air-to-air missile system.
Langley constructed two uninstrumented development
models of the missile, the XAAM-N-2 Sparrow I.
The models were flown at the rocket range at Wallops
to solve early booster problems. Refinements to
the nose and fin sections of the missile were completed
through subsonic and supersonic tests in Langley
wind tunnels during the early 1950’s.
Once the aerodynamics of the Sparrow configuration
had been proven, the launching characteristics
from positions under the wings, on the wingtips,
and under the fuselage of the aircraft had to be
determined for factors that might hinder aircraft
and missile performance. With scale models, realistic
simulations of missile launches were conducted
during the mid-1950’s in the Langley 7- by
10-Foot High-Speed Tunnel. Various fighter designs
with the missiles carried externally (including
the F-4) were tested at supersonic speeds in the
Langley Unitary Plan Wind Tunnel to determine the
aerodynamic loads on the missiles, as well as other
external stores. Reliable and extremely accurate,
the Sparrow later became the medium range workhorse
for the Navy and Air Force.
Updates of the Sparrow missile system, such as
the Sparrow III, also were tested in Langley wind
tunnels. Initial tests of the advanced version
began with an examination of the aerodynamic characteristics
of the missile at supersonic speeds in the Unitary
Plan Wind Tunnel in 1977. During the early to mid-1980’s,
further studies of the separation characteristics
from simulated aircraft were conducted again in
the Unitary Plan Wind Tunnel at speeds in excess
of a Mach number of 2.
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AIM-120 AMRAAM |
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By the mid-1980’s,
the military hoped to gradually replace the air-to-air
medium range guided missile mainstay, the AIM-7
Sparrow with a more advanced weapons delivery system
that would be carried by the next generation of
fighters with supersonic cruise capability. The
new missile, produced by McDonnell Douglas was
designated the AIM-120 Advanced Medium Range Air-to-Air
Missile (AMRAAM).
Initial aerodynamic studies of the AMRAAM at
Langley focused on the missile itself, with scale
models studied on a weapons palette. Extensive
studies were conducted at supersonic speeds in
the Langley Unitary Plan Wind Tunnel, first on
a generic wing-body configuration and later on
an advanced fighter configuration to determine
the optimum external carriage locations. Researchers
examined such factors as the amount of drag produced
by missile arrangements and the amount of space
required between missiles for effective weapons
launch.
Today, the AMRAAM dominates the active radar
missile field. Export orders for the AMRAAM totaled
more than 7000, which is more than ten times the
orders of its competitors combined.
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Impact on Aircraft
Characteristics |
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Since Langley is
usually requested to support the development of
high-performance aircraft, the Center is in an
excellent position to assess the impact of missiles
and other external stores on characteristics of
the aircraft. Thus, assessments of the impact of
missile configurations are normally included in
performance evaluations in transonic and supersonic
wind tunnels, studies of spin recovery characteristics
in the Langley 20-Foot Vertical Spin Tunnel, and
flutter clearance tests in Langley 16-Foot Transonic
Dynamics Tunnel.
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