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Orange Harvest

From Alfawiki
Orange Harvest
Company typeElectronic support measures system
IndustryMilitary electronics
Founded1961
ProductsRadar warning receiver

Front half of a Shackleton aircraft. The Orange Harvest antenna appears as a ribbed white cylinder on top of the fuselage.
WR977 'B – Basil' displayed at Newark Air Museum. The Orange Harvest "spark-plug" antenna is visible atop the fuselage, just left of the outer propeller tips.

Orange Harvest was an ESM system installed on marine patrol Avro Shackleton aircraft during the Cold War era.

This device functioned as an S band and X band radar warning receiver, capable of determining the directional bearing of surface vessels or submarines emitting radar signals. While it lacked the pinpoint accuracy of the Shackleton's primary ASV.21 search radar, Orange Harvest offered an extended detection range,[1][2] provided the target was actively transmitting. Being a passive receiver, it also ensured the aircraft remained undetected by its target. It has been regarded as "arguably the most underrated and underutilised equipment onboard".[2]

A key focus was detecting radars such as the I band[lower-roman 1] RLK-101 Albatros (NATO codename Snoop Tray) and MRK-50 Snoop Pair systems used by early Soviet nuclear submarines. These submarines could operate fully submerged without snorkelling, making them harder to locate using previous techniques like Autolycus or search radar.

The system comprised two electrically distinct components: wide-band and narrow-band receivers, both housed within a common external antenna enclosure. The wide-band unit was manufactured by Rank in Plymouth. Its antenna featured four "windows" arranged at 90-degree intervals, positioned between the aerial's flanges. The narrow-band antenna was an omni-directional element mounted at the very top beneath a black cover. Integral heating prevented ice accumulation on the antenna assembly. The narrow-band receiver evolved from an early ELINT device named 'Breton', originally developed for use in Comet aircraft by 51 Squadron.

File:Orange Harvest antenna, Avro Shackleton (4867396007).jpg
External Orange Harvest antenna fitted to XF708 at Duxford

The distinctive white dielectric 'spark plug' antenna mounted atop the Shackleton served as Orange Harvest’s external aerial.[3][2] This 'spark plug' is frequently mistaken for an insulator supporting a HF long-wire antenna extending to the tail. In reality, it is a self-contained unit operating at wavelengths much shorter than those requiring long wires. The Shackleton did carry separate HF antennas supported by two small metal masts positioned just forward of Orange Harvest's installation. Structurally, Orange Harvest was mounted on a metal plinth integrated into the fuselage roughly where the dorsal turret had previously been located. The large antenna was secured to this base. Two different antennas existed—one for each frequency band—with changes between bands necessitating replacement of both the aerial and some narrow-band line-replaceable units (LRUs). Because this large antenna generated considerable drag, it was sometimes removed, leaving only the mounting plinth visible.[4] This practice was more prevalent during the 1960s anti-submarine warfare phase than in later airborne early warning operations.

View inside Shackleton cabin looking forward along port side operator desks
Interior view showing operator stations inside the Shackleton; Orange Harvest display is at far left

Inside, Orange Harvest’s output was presented on a 3-inch cathode ray tube located before the C operator,[5] which could occasionally prove distracting.[2]

Orange Harvest was introduced with the Shackleton MR.3 Phase II variant in 1961.[6] After the Shackleton was superseded by the Nimrod MR.1 in anti-submarine warfare duties, Orange Harvest remained in service aboard Shackleton AEW.2 aircraft operated by 8 Squadron RAF from 1972 until 1991.[7][5]

File:Memorial on Maodal - geograph.org.uk - 832568.jpg
Memorial cairn incorporating AEW.2 WR965's Orange Harvest antenna on the Isle of Harris

The Orange Harvest antenna from AEW.2 WR965 Dylan is incorporated into a memorial cairn commemorating the 1990 Isle of Harris crash.

See also

References

  1. ↑ The NATO I band partially overlaps with the lower frequencies of the IEEE-defined X band.
  1. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  2. ↑ 2.0 2.1 2.2 2.3 Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  3. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  4. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  5. ↑ 5.0 5.1 Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  6. ↑ Gibson (2015), p. 87.
  7. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).

External links

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