In the mid-1950s the US Army and US Marine Corps published a post-Korean War assessment discussing the vulnerabilities of their existing light observation aircraft, namely the L-19/OE Bird Dog, during that conflict. With this in mind, on behalf of the US Navy the two services initiated the TS-145 requirement for a two-seat, twin-turboprop light observation aircraft to operate from small, unimproved airfields under all weather conditions. The observation aircraft specified by TS-145 had to be faster and utilize greater firepower and heavier armor than the Bird Dog in order to address the vulnerabilities that the Bird Dog had faced during the Korean War.
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| Three-view drawing of the Northrop N-180 from the Northrop company documents. |
Northrop's proposal for the TS-145 requirement was designated N-180 by the company. It was a twin turboprop design measuring 46 feet 1 in (14.05 meters) long with a wingspan of 44 feet 6 in (13.56 meters), and it featured a large cockpit placed ahead of the propeller arcs whereby the pilot and observer sat side-by-side. Power was provided by two General Electric T58-GE-4 turboprops each generating 1,020 shp (750 kW) (the Lycoming T53 was investigated as an alternate engine option for the N-180). The engine nacelles were mounted on the lower surface of the gull wing at the break where the wings levelled out. Missions to be carried out by the N-180 included day and night observation, artillery spotting, forward-position resupply with wing-mounted 750-lb packs, and liaison duties. The N-180 would have a service ceiling of 38,200 feet (11,643 meters) and a top speed of 299 mph (481 km/h) at an altitude of 5,000 feet (1,524 meters), and 150-gallon drop tanks and up to four smoke rockets for target marking would be carried below three hardpoints under each outer wing section.
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| The OV-1 Mohawk, the winner of the TS-152 competition. |
In November 1956, Northrop submitted the N-180 design, but it lost the TS-145 competition to the rival Grumman G-134 design. The winning G-134 design became the AO-1/OV-1 Mohawk, and even though the Navy withdrew from the OV-1 program, the Army pressed ahead with it. The Mohawk would go on to have a long and very useful career, especially during the Vietnam War.
