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AGM-78 Standard ARM



Overview


AGM-78 Standard ARM

An AGM-78 Standard ARM on display alongside a F-4G Wild Weasel at the National Museum of the U.S. Air Force in 2009.
Source: US Air Force - © Public domain

Origin
United States
Type
Anti-radiation missile
Entered service
1968
Status
Out of service
Development
1966 - 1967
Developer
United States - General Dynamics
Production
1967 - 1976
Producer
United States - General Dynamics
Unit cost
Expensive compared to AGM-45
Number produced
At least 700
Reportedly over 3.000
Designations
STARM / Standard ARM
Notable users
United States
Israel

Description


Introduction

The AGM-78 Standard ARM is a mid Cold War era anti-radiation missile of US origin. The AMG-78 was developed on behalf of the US Navy as a longer range alternative to the AGM-45 Shrike. It was the first American anti-radiation missile to feature a flexible seeker head. The AGM-78 proved successful, but was also deemed very expensive, heavy and had a rathe low flight speed. The AGM-88 HARM was subsequently developed to remedy all these drawbacks while retaining flexibility and range.

Design

The Standard ARM uses the missile body and rocket motor of the SM-1MR naval surface to air missile. The seeker head is replaced by a passive radar seeker and a blast fragmentation warhead is fitted. Over time the design was improved with more reliable electronics, target identification smoke markers, an improved rocket motor and improved warhead. The large body provides a much longer effective range, but comes at the cost of high weight and production cost.

Guidance

The AGM-78A was introduced with the seeker head of the AGM-45 Shrike as an interim solution. This was quickly replaced by the Maxson broadband seeker, which is also gimballed. This provides flexibility to engage a wide range of radar systems without the need to physically change seeker heads. Furthermore, the gimballed seeker does not require the launch aircraft to continuously fly towards the enemy air defenses when plotting a firing solution. AGM-78 introduced two novel features. The first was that it would fly towards the last known location of an emitter in case it stopped emitting. Earlier missiles were easily defeated by briefly turning a radar system off. The second novel feature is the ability to reconfigure the target bandwidth in flight based on in flight detection of radar emissions using the AN/APS-118 system.

Firepower

The effective flight speed and range differ significantly per source. Most common are a maximum theoretical range of 90 km and a practical range of 55 km. Both are significantly beyond the maximum and practical ranges of the AGM-45 Shrike. The 100 kg blast fragmentation warhead has a larger lethal radius than the 66 kg warhead of the AGM-45.

Platforms

The AGM-78 was carried by the US Air Force EF-105F and F-105G Thunderchief and F-4G Phantom II in the Wild Weasel role. In the US Navy the A-6B and A-6E Intruder was armed with the AGM-78. There are several photos of F-106A Delta Dart with AGM-78, possibly only for testing purposes of the later cancelled XAIM-97 Seekbat. A unique application is the Israeli Keres ground based truck mounted launcher. These have been used to loft the Standard ARM in a high angle towards enemy SAM sites.

Users

The primary user of the AGM-78 Standard ARM was the United States. Both the US Air Force and the US Navy operated the AGM-78. About 300 missiles were exported to Israel and used on aircraft and the Keres truck mounted launcher. Often reported sales to South Korea do not concern the AGM-78, but the very similar RGM-66 surface launched anti-ship missile.

Variants


AGM-78 Standard ARM

An AGM-78 Standard ARM on display at the Point Magu Missile Park, California.
Source: www.marvellouswings.com - © Copyright lies with original owner

List of Standard ARM variants

AGM-78A-1
First operational variant of the Standard ARM, introduced in 1968. Early model using the seeker head of the older AGM-45. Known by the US Navy as Standard ARM Mod 1. Subvariant AGM-78A-2 features a read phosphorus target market. AGM-78A-4 are rebuilt to AGM-78B standard.
AGM-78B
First AGM-78 to feature the Maxson broadband seeker head, introduced in 1969. A memory chip retains last known target coordinates and flies the missile towards last known radar location. Known by the US Navy as Standard ARM Mod 1.
AGM-78C
Air force program to reduce production cost and improve reliability. Similar performance to AGM-78B, but features a white phosphorus target marker instead of red.
AGM-78D
Final variant of the Standard ARM. A new rocket motor provides increased flight speed, reducing time for the target to take evasive measures. AGM-78D-2 has an improved blast fragmentation warhead with optical proximity fuse.

Details


Facts AGM-78A-2 AGM-78B AGM-78D-2
General
Origin
United States
Type
Anti-radiation missile
Dimensions
Length
4.5 m
Diameter
0.34 m
Wingspan
1.08 m
Weight
Over 600 kg
Guidance
Guidance mode
Passive radar homing
Seeker model
AGM-45A-3A seeker
Narrow seeker band
Bandwith
Reconfigurable on the ground by replacing seeker head
Warhead
Type
Blast-fragmentation warhead
Weight
97 kg
Fuse
Proximity fuse
Marker
Red phosphorus target marker
Propulsion
Type
Dual-thrust solid propellant rocket motor
Model
Aerojet Mk 27 Mod 4
Engagement envelope
Speed
Mach 2.5
Range
90 km maximum
55 km practical
10 km minimum
Launch speed
Up to Mach 2

Media


Related articles


AGM-45 Shrike

The Standard ARM was developed as a more flexible, longer range and more lethal alternative to the earlier AGM-45 Shrike.

AGM-88 HARM

The AGM-88 is a dedicated ARM design that replaced the AGM-78 Standard ARM.