AIM-7麻雀飛彈

began work on the semi-active radar homing version of Sparrow family of missiles, the AAM-N-6 Sparrow III. The first of these weapons entered US Navy service in 1958.

The AAM-N-6a was similar to the -6, but used a new Thiokol liquid-fuel rocket engine for improved performance. It also included changes to the guidance electronics to make it effective at higher closing speeds. The -6a was also selected to arm the Air Force's F-110A Spectre (F-4 Phantom) fighters in 1962, known to them as the AIM-101. It entered production in 1959, eventually being built to about 7500 examples.

Another upgrade switched back to a Rocketdyne solid-fuel motor for the AAM-N-6b, which started production in 1963. The new motor significantly increased range, which was up to 35 km for head-on attacks.

During this year the Navy and Air Force agreed on a standardized naming for their missiles, the Sparrows becoming the AIM-7 series. The original Sparrow I and aborted Sparrow II became the AIM-7A and AIM-7B, even though both were long gone from the inventory. The -6, -6a and -6B became the AIM-7C, AIM-7D and AIM-7E respectively.

25,000 AIM-7E's were produced, and saw extensive use during the Vietnam War, where its performance was generally considered disappointing. The mixed results were a combination of reliability problems (exacerbated by the tropical climate), limited pilot training in fighter-to-fighter combat, and restrictive rules of engagement that generally prohibited BVR (beyond visual range) engagements. The P_k (kill probability) of the AIM-7E was less than 10%.

In 1969 an improved version, the E-2, was introduced with clipped wings and various changes to the fusing. It was intended to be used at shorter ranges where the missile was still travelling at high speeds, making it much more useful in the visual limitations imposed on the engagements. An E-3 included additional changes to the fusing, and an E-4 featured a modified seeker for use with the F-14 Tomcat.

Improved versions of the AIM-7 were developed in the 1970s in an attempt to address the weapon's limitations. The AIM-7F, which entered service in 1976, had a dual-stage rocket motor for longer range, solid-state electronics for greatly improved reliability, and a larger warhead. Even this version had room for improvement, leading British Aerospace and the Italian firm Selenia to develop advanced versions of Sparrow with better performance and improved electronics as the Skyflash and Selenia Aspide, respectively.

The most common version of the Sparrow today, the AIM-7M, entered service in 1982 and featured a new inverse monopulse seeker (matching the capabilities of Skyflash), active radar fuse, digital controls, improved ECM resistance, and better low-altitude performance. It was used to good advantage in the 1991 Gulf War, where it scored many USAF air-to-air kills.

The AIM-7P is similar in most ways to the M versions, and was primarily an upgrade program for existing M-series missiles. The main changes were to the software, improving low-level performance. A follow-on Block II upgrade added a new rear receiver allowing the missile to receive mid-course correction from the launching aircraft. Plans initially called for all M versions to be upgraded, but currently P's are being issued as required to replace M's lost or removed from the inventory.

The final version of the missile was to have been the AIM-7R, which added an infrared seeker to an otherwise unchanged AIM-7P Block II. A general wind-down of the budget led to it being cancelled in 1997.

Sparrow is now being phased out with the availability of the active-radar AIM-120 AMRAAM, but is likely to remain in service for a number of years.

In the early 1990s, the Shanghai 2nd Mechanical-Electronics Bureau was tasked to produce a better medium-range AAM. They succeeded by merging the domestic HQ-61C missile with the Aspide's mono-pulse semi-active radar-homing seeker. The new missile was given the desgination PL-11. Some western observers mistakenly confuse the PL-10, which is based on the older HQ-61 technology. [2]

己知的PL-11版本包括:

• PL-11 - MRAAM based on HQ-61C & Aspide (AIM-7M) technology. First tested from a J-8B fighter in 1992, limited service in mid-1990s for testing and evaluation. Promoted for export as the FD-60. [[3]]

• PL-11A - Improved PL-11 with better range, warhead, and seeker. The new seeker only requires fire-control radar guidance during the terminal stage.

• PL-11B - Also known as PL-11 AMR, improved PL-11 with AMR-1 active radar-homing seeker developed by the 607 Institute. Did not enter service as PLAAF opted for other missiles (PL-12/SD-10).

• LY-60 - "Chinese Sea Sparrow", PL-11 adopted for navy ships for air-defense. Sold to Pakistan but did not enter service with the PLAN. VLS-launch version is rumored to be under development. [4]

The launching aircraft will illuminate the target with its radar. In radars of the 1950's these were single target tracking devices using a nutating horn as part of its antenna. This caused the beam to be swept in a small cone. Signal processing would be applied to determine the direction of maximum illumination and so develop a signal to steer the antenna toward the target. The missile detects the reflected signal from the target with a high gain antenna in a similar fashion and steers the entire missile toward closure with the target. The missile guidance also samples a portion of the illuminating signal via rearward pointing waveguides. The comparison of these two signals enabled logic circuits to determine the true target reflection signal, even if the target were to eject radar-reflecting chaff.