Greg Billigen hated the cockpit.
“It was cramped. Everything was packed in there pretty good. The ejection seat was hard as a rock. It wasn’t pressurized. You pretty much wore the plane on your back and it was miserable.”
The OV-1A Mohawk was designed specifically for photography. The B model added side-looking airborne radar capability. The C model also used infrared technology. By the end of the Vietnam War, all three models were under operational control of field commanders. U.S. Army photo
Former Spc. 5 Billigen, 65, was a TO, or technical observer, on the Grumman OV-1 Mohawk, a unique U.S. Army combat aircraft of the Vietnam War. The Mohawk was built to carry weapons, and until it was disarmed in an inter-service squabble it was exactly the kind of light attack aircraft being considered for widespread use today.
The insect-like canopy that interrupts the smooth lines of the Mohawk is deceptive: The cockpit is less roomy than it appears. Despite the discomfort, pilots and TOs, who occupied the left and right seats respectively, loved the airplane. “It was a really sweet-flying airplane,” said Billigen of the only fixed-wing aircraft ever developed expressly to meet Army Aviation requirements.
“It was a really sweet-flying airplane.”
Mohawk Origins
First flown on April 14, 1959, and conceived for joint use by the Army and Marine Corps before the Marines dropped out of the program, the bug-eyed, twin turboprop, triple-tail, mid-wing Mohawk was known as the AO-1 until the military designation system was changed on Oct. 1, 1962 to make it the OV-1. The Vietnam-era Army flew these versions:
- OV-1A for armed photoreconnaissance
- OV-1B for side-looking airborne radar (SLAR) surveillance
- OV-1C for infrared (IR) surveillance
- OV-1D for all three missions
The Marine version that was never built would have been dubbed the OF-1.
An OV-1C Mohawk in South Vietnam. This aircraft wore Army colors from 1962 to 1988 and after retirement became a maintenance trainer at Fort Huachuca, Ariz. Robert F. Dorr Collection
The Mohawk drew its power from two Lycoming T-53 turboprop engines. Improved versions were introduced throughout the lifetime of the OV-1, culminating in the 1,160-shp T53-L-701.
As American soldiers learned in Southeast Asia, on a typical mission a Mohawk could conduct surveillance and intelligence gathering out to a distance of 1,100 miles (1,770 km) or to a radius of 500 miles (805 km) at an initial takeoff weight of 10,915 pounds (4,590 kilograms). Pilot and TO sat side-by-side in Martin Baker J5 ejection seats beneath the bubble-like braced canopy which, tight as it was, afforded excellent visibility.
The unit began with two OV-1As armed with .50-caliber (12.7-mm) machine guns and 2.75-inch rocket pods, contrary to objections by the Air Force, which argued that fixed-wing warplanes were its purview.
The OV-1 began operations in South Vietnam with the 23rd Special Warfare Aviation Detachment (SWAD), “The Warriors,” under Maj. William J. Morris in October 1962, initially at Nha Trang. The unit began with two OV-1As armed with .50-caliber (12.7-mm) machine guns and 2.75-inch rocket pods, contrary to objections by the Air Force, which argued that fixed-wing warplanes were its purview.
Mohawk Models
The OV-1A (plus a handful of slightly modified JOV-1A versions) carried a reconnaissance system built around a KA-30 film camera in a bay in the lower rear fuselage. The camera could pivot from horizon to horizon and could be set to shoot vertically; 15 degrees off the centerline; or 30 degrees off the centerline. Boxy photoflash flare pods could be fitted above the wing roots to provide 52 flares, which were ejected upward to ensure that the flash was above the camera and out of the crew’s field of view. The flares fired upward at a 90-degree angle, but because the pod was mounted on the sloped trailing edge of the wing, they went up at about 10 degrees to the rear relative to the aircraft. This flare arrangement proved dangerous and caused the loss of at least one Mohawk before being replaced by a strobe light system on later models.
A U.S. Army OV-1A Mohawk takes off. The OV-1A was the armed version of the Mohawk. U.S. Army photo
The “A” model was the only version of the Mohawk with dual flight controls, which were later deemed unnecessary.
The OV-1B (originally, AO-1B), delivered in April 1961, carried AN/ASP-94 side-looking airborne radar (SLAR) in a rounded, 18-foot pod beneath the right side of the fuselage. The B model and the D, which came later with a different SLAR unit, benefited from a 6 foot (1.86-meter) increase in wingspan as compared to the A and C versions.
In addition to marking targets, the Mohawk often gathered intelligence that reached ground commanders far more rapidly than the “take” from Air Force reconnaissance aircraft.
The OV-1C (née AO-1C), delivered in October 1961, introduced the UAS-4 IR mapping sensor mounted in the central fuselage, and was powered by T53-L-15s. Israel received two OV-1Cs (the only overseas purchaser, although the Mohawk was evaluated by France, Germany, Pakistan and the Philippines) that were eventually returned to U.S. Army inventory.
The definitive Mohawk for battlefield surveillance and target-acquisition duties was the OV-1D, introduced belatedly in Vietnam in 1970. Thirty-seven “D” models were built new, and 111 earlier Mohawks were upgraded to this standard. The OV-1D’s sensors included an AN/APD-7 radar surveillance system, AN/AAS-24 IR scanners, and KS-60 cameras.
Four OV-1A Mohawks fly in echelon formation. U.S. Army photo
After their combat debut with the 23rd SWAD, Mohawks went on to serve in South Vietnam with the 73rd, 131st, 225th, 244th and 245th Aviation Companies.
Billigen, the Mohawk TO quoted above, flew his last mission Jan. 5, 1970, identifying naval gunfire targets for the battleship USS New Jersey. He recalls finding a target that showed up as “black dots” on the SLAR scope. He said that in addition to marking targets, the Mohawk often gathered intelligence that reached ground commanders far more rapidly than the “take” from Air Force reconnaissance aircraft.
And despite the cramped cockpit, the Mohawk, he said, “was a real performer and a super ship to fly.
“But don’t let me tell you that,” Billigen suggested. “You ought to ask a pilot.”
Grumman OV-1 Mohawk
Type: Two-seat surveillance, observation and light attack aircraft
Powerplant: Two 1,150-eshp Lycoming T53-L7 free-turbine turboprop engines (1,100 shp plus 124 pounds (53.60 kg) of residual thrust (T-53-L3 on OV-1A; T53-L15 on OV-1C; T53-L-701 on OV-1D)
Performance: Maximum speed 308 miles per hour (496 km/h) at 5,000 ft (1520 m); maximum cruising speed 297 miles per hour (478 km/h); service ceiling 30,000 feet (9150 m); range 441 miles (710 km)
Weights: Empty 10,370 pounds (4704 kg); loaded in “clean” configuration, 13,040 pounds (5915 kg); loaded with two 150 US gallon external tanks, 15,399 pounds (6985 kg)
Dimensions: Wingspan 42 feet (12.80 m) on OV-1A and OV-1C; 48 feet (14.86 m) on OV-1B and OV-1D; length 41 feet (12.50 m); height 12 feet 8 inches (3.86 m); wing area 330 square feet (30.65 sq m)
First flight: April 14, 1959 (YAO-1A)