Sprint (missile)

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Sprint
Sprint-i-box.jpg
Sprint missile in flight
Type Anti-ballistic missile
Place of origin United States
Service history
In service 1972
Production history
Manufacturer Martin Marietta
Specifications
Weight 3500 kg
Length 8.20 m
Diameter 1.35 m
Warhead W66 nuclear low kt

Engine 1st Stage: Hercules X-265 (2,900 kN (650,000 lbf));
2nd Stage: Hercules X-271
Operational
range
40 km
Flight ceiling 30 km
Speed Mach 10 (7,500 mph)
Guidance
system
Radio command
Launch
platform
Silo

The Sprint was a two-stage, solid-fuel anti-ballistic missile, armed with a W66 enhanced radiation thermonuclear warhead. It was designed as the short-range high-speed counterpart to the longer-range LIM-49 Spartan as part of the Sentinel program. Sentinel never became operational, but the technology was deployed briefly in a downsized version called the Safeguard program. The Sprint, like the Spartan, was in operational service for only a few months in the Safeguard program, from October 1975 to early 1976. Congressional opposition and high costs linked to its questionable economics and efficacy against the then emerging MIRV warheads of the Soviet Union, resulted in a very short operational period.

The Sprint accelerated at 100 g, reaching a speed of Mach 10 in 5 seconds.[1][2] It was designed for close-in defense against incoming nuclear weapons. As the last line of defense it was to intercept the reentry vehicles that had not been destroyed by the Spartan, with which it was deployed.

The conical Sprint was stored in and launched from a silo. To make the launch as quick as possible, the cover was blown off the silo by explosive charges, then the missile was ejected by an explosive-driven piston. As the missile cleared the silo, the first stage fired and the missile was tilted toward its target. The first stage was exhausted after only 1.2 seconds, but produced 2,900 kN (650,000 lbf) of thrust. The second stage fired within 1 – 2 seconds of launch. Interception at an altitude of 1,500 m to 30,000 m took at most 15 seconds.

The Sprint was controlled by ground-based radio command, which tracked the incoming reentry vehicles with phased-array radar and guided the missile to its target.

The Sprint was armed with an enhanced radiation nuclear warhead with a yield reportedly of a few kilotons, though the exact number has not been declassified. The warhead was intended to destroy the incoming reentry vehicle primarily by neutron flux.

Comparisons[edit]

The still in service USSR/Russian 53T6 Gazelle (missile) of the A-135 anti-ballistic missile system system is similar in being neutron warhead tipped and therefore fills the same general lower-tier ABM role that the Sprint was designed for. However the Gazelle's greater missile length and launch mass results in a flight ceiling that is 80 km, which outperforms the Sprint in range, though its acceleration performance is "inferior", for comparison the "53T6 Gazelle peaks at 200 G and the Sprint at 100+ G". Similarly the 2014 Israeli IAI Arrow 2 ABM has an apogee of 50 km, and range of 90 km, with a launch mass of 3,500 kg, therefore the latter more closely resembles the performance of the Sprint ABM in range.[3]

Design predecessors[edit]

See also: Nike Zeus
HIBEX rocket

The "HIBEX" (HIgh Boost EXperiment) missile is considered to be somewhat of a design predecessor and competitor to the Sprint missile, as it was a similar high acceleration missile in the early 1960s, with a technological transfer from that program to the Sprint development program occurring.[4] Both were tested at the White Sands Launch Complex 38. Although HIBEX's initial acceleration rate in G's was higher at near 400 G, its role was to intercept reentry vehicles at a much lower altitude than Sprint, 6,100 m, and it is considered to be a last ditch ABM missile "in a similar vein to Sprint".[5]

The small "Thunderbird" rocket of 1947 produced an acceleration of 100 G with a polysulfide composite propellant, star-grained cross section solid rocket motor.[6]

Engines & Propellant[edit]

The first stage, Hercules X-265 engine, is believed to have contained alternating layers of zirconium "staples" embedded in nitrocellulose powder, followed by gelatinizing with nitroglycerine, thus forming a higher thrust double-base powder.[7][8]

Guidance & attitude control[edit]

Survivors[edit]

See also[edit]

References[edit]

External links[edit]