THE NORTH AMERICAN OV-10 ‘BRONCO’
submitted by: Alva Leon Matheson
It was a fun airplane to fly. It was responsive, fully acrobatic, had great visibility and good fuel economy. For those of us right out of pilot training, it was a slug compared to the T-38 but boy, was it nimble. You could turn on a dime and make change. The power response was fast compared to the windup time of a jet. And, unlike the other FAC aircraft, it had an ejection seat. Although I was young and invincible when I flew the OV-10 in Vietnam, knowing that the ejection seat was there gave me a feeling of reassurance.
It would be stretching the truth to describe this airplane in terms of power and grace. In my own humble opinion, then and now, it was underpowered for the configuration we flew it in over Laos. Powered by two 715 Shaft Horsepower Garrett AirResearch T-76 turbo- prop engines with counter rotating propellers, it was a solid aircraft to fly. The fact that the props counter rotated made for a much easier transition for those of us who had little or no twin-engine prop experience. It eliminated the torque effects and made it a lot easier to fly.
When flown without external stores it was adequately powered. Even though it would not run away from much of anything, it was fun to fly. Flown clean it could cruise at about 180 – 200 KIAS. The normal cruise or recon speed for the airplane with an external load was between 120 – 150 KIAS. To the best of my recollection take-off speed was 100 – 110 KIAS and final approach speed was 100 KIAS.
Top speed in the Dash One was a whopping 350 Knots, however, the only way to get close to that was in a clean aircraft. On a maintenance check flight where this speed check was required, you climbed to some ridiculous altitude, maybe 10,000 MSL, and rolled it over into a vertical dive. Initially with full power and lots of nose down trim, it would accelerate rapidly, but as the speed increased above 250 KIAS you had to keep an eye on the torque gages to keep from over torquing the engines. At 350 KIAS, you were supposed to pull out using five Gs. My own personal experience was that I normally blacked myself out during the pull out and had to rely on the G meter (accelerometer) to see if I had gotten close to five. We didn’t have anti-G suits in Vietnam.
However, when the aircraft was flown with four rocket pods, four fully armed M60 machine guns, plus the 230-gallon centerline tank and a full load of internal fuel, it was, in my opinion, somewhat underpowered. Even with a long runway it seemed prudent to have minimum expected torque for the conditions. The other thing you had to understand was that it had no single engine takeoff capability. If you lost an engine on the ground, you were staying on the ground, regardless if there was runway in front of you or not. Airborne, just after takeoff, if you lost an engine and jettisoned the external stores quickly enough and got the landing gear retracted, you could fly it on one engine back to a landing. Failure to do any of the right things in a timely manner could result in loss of control and not even that neat ejection seat could save you if you were too close to the ground in the resulting unusual attitude.
Although it was really noisy, I didn’t notice that as much as I did the lack of ventilation. You were sitting in a greenhouse flying in the humid climate of Southeast Asia. On the ground you could use a touch of reverse on the props to push air forward to help out a little, but once you closed the canopy you were at the mercy of the built in vent system. It consisted of a canopy vent/air scoop in each cockpit and the ram air scoop at the base of the windscreen that was not all that big. Both of these were totally dependent on forward motion and outside air temperature. Until you got to altitude, where the outside air temp would compensate for the size of the openings, you just got hot. That was, of course, unless it was raining. Then you got wet and then hot and then cold because the airplane leaked.
The back seat was a place that I avoided at all costs. It lacked all but the most basic flight instrumentation, had no radio control heads, its flight controls were without any trim capability, you could lower the gear but not raise it, had no armament controls, the rudder pedals were placed ridiculously far apart and high for comfortable flying, and last but not least, it was just in front of the prop arc, so it was noisy as hell. And if the props were out of sync, the backseater took the brunt of that punishment, too. Plus, you seemed to be more prone to air sickness back there than in the front. I accumulated little more than the required fifty hours in the back seat in Southeast Asia, but later in life while checking out new maintenance pilots, I logged more time in the back seat than I ever wanted. By then, though, I had lots of time in back of the T-38 and it didn’t seem so bad.
Bottom line evaluation of the OV-10 as a FAC aircraft is that overall it was the right airplane for the job. Although I only flew daylight interdiction missions over the Ho Chi Minh Trail and don’t have any real first hand knowledge of ground force support and troops in contact situations, I believe that it was an excellent platform for all aspects of the forward air control mission, with the notable exception of night interdiction. No one ever really worked out a way to keep interior lighting reflections from interfering with a starlight scope in the back seat.
Much like your first true love, your first assignment out of flight school can never be replaced. Mine was the OV-10 Bronco and for all its faults, it was a great airplane and a great mission.
By Brad Wright, Covey 251, 1970-71.
SPECIFICATIONS
First flight: July 16, 1965.
Wing Span: 40 ft, 0 in.
Length: 41 ft, 7 in.
Height: 15 ft, 2 in.
Weight Empty: 7,190 pounds.
Maximum take-off weight: 14,444 pounds.
Maximum speed at sea level: 244 knots.
Range: 700 nm with internal fuel. 1,200 nm with
150-gallon drop tank.
Fuel: Five self-sealing fuel tanks in wing: 252 gallon capacity. 150 or 230 gallon external tanks.
Crew: One pilot and one observer (removable rear seat).
Armament: Centerline station for 20 mm gun pod, or stores; four 7.62 mm M60C machine guns in sponsons; four sponson stations for rockets, miniguns or stores; two wing stations for rockets or missiles.
Equipment: Zero-speed, zero-altitude escape seats.
“G” Limits: +6.5 (Positive) and -1.0 (Negative) in the clean configuration.