Flying the OV-10 Bronco
by Jim Richmond
Long before I ever saw the OV-10, I had read several articles concerning its development as a tri-service counterinsurgency aircraft. I had also seen artists’ conceptions of the airplane as well as early pictures of it in Aviation Week. I first actually saw the Bronco, it was during a stopover at McClellan Air Force Base where it was perched on the ramp with the visage of a giant prehistoric bird. The airplane sat high on its spindly looking main gear, while its short wings and twin booms combined to give it the appearance of being ready to leap into the air. The oversize unusual-shaped canopy was undoubtedly this bird’s eye on the world. One approached the Bronco almost cautiously. Unlike other forward air controller (FAC) aircraft, there was no doubt that the OV-10 was a warbird, and its four sponson mounted machine guns and weapons hard points gave it an air of authority.
Notification that it was my turn to go to Southeast Asia in a combat position came soon after my first physical encounter with the OV-10, so with a favorable impression in my mind, I asked for and was given an assignment to fly the OV-10. It was still another year before I was actually to fly the OV-10 and fall in love with it. Training in the OV-10 and the fine art of of being a FAC was conducted at Hurlburt Field, Florida. After a few hours of classroom instruction and study, I was ready to fly the airplane. The combination of the airplane and the mission stirred a “kick the tires, light the fires” image in me, and I developed a habit of kicking the tires during every exterior inspection – not that kicking the tires really told me much! There really wasn’t much to the exterior inspection anyway; the pilot had to check the fuel level in the exterior tank, make sure the armament was installed properly, check the general condition of the aircraft, and – in Southeast Asia – make sure there were no bird nests in the exhaust stacks. I never did find a bird nest there, by the way.
Getting into the aircraft was unlike any other FAC aircraft. The OV-10 had an ejection seat, but unlike other ejection seat aircraft I had flown, it didn’t require lugging an unwieldy parachute out to the aircraft since the parachute was integrated into the seat. It was a real pleasure to walk out to the aircraft wearing only the ejection harness, but there the pleasure stopped. Getting into the Bronco was almost impossible for the novice and never mastered gracefully by anyone. Perhaps North American planned it that way to get the pilot in the right frame of mind for the demanding mission. To enter the cockpit, the pilot unfolded a small step on the right side of the aircraft, mounted via the step, and climbed in through the right side canopy, which folded upward like the gullwing doors on a Mercedes 300SL coupe. After getting situated in the seat, the pilot needed help attaching the shoulder harnesses, which were also the parachute risers. Attaching the shoulder harness solo wasn’t impossible, but it required considerable contortions and took a lot of time.
Once in the cockpit and strapped in, the pilot could at last get on with the business of getting the OV-10 airborne. The interior preflight was easy and followed a logical sequence and could be completed in approximately one minute – provided the pilot didn’t get hung up on cranking the rudder pedals in or out. Starting the engines was also easy; they had a smooth, continuous wind-up that was typical of a turboprop. Since the airplane was intended for use in forward areas where ground power might not be available, it was designed to start on the battery power only, but it was seldom started on battery only. Battery starts were slower, were hard on the batteries and engines, and had to be accomplished without full engine instrumentation. The engines were started with the propellers “on the locks”, which was in a flat pitch position. Getting the propellers on the locks required moving the throttles momentarily into the reverse range in order to get the props off the locks prior to taxiing.
Taxiing the OV-10 was easy but a little tricky, and it was an operation that was closely scrutinized and invariably criticized by almost every instructor pilot. Turns could be made by use of differential thrust, braking or the nosewheel steering system or any combination of the three. Using differential braking was usually frowned upon unless it was necessary for very tight turns; nosewheel steering was used only for turns requiring more turning power than available from differential power. Differential power was normally used for small turns and to keep the airplane going straight. When to use which system was a judgment call and easily open for instructor criticism.
Reaching the end of the runway, the OV-10 ready for takeoff without any run-up, but as with any aircraft with external ordnance, an end-of-the-runway inspection and weapons arming was required. In daytime, this was a quick operation, but at night we had to shut down the engines to ensure the crewmembers safety. Pilots were told that this was because an armorer had been seriously injured when struck by a spinning propeller at night when he inadvertently moved into its invisible arc. After being armed and collecting the safety pins from the armorer, the OV-10 was ready for takeoff.
Taking the runway, the power levers were advanced to the takeoff and land position, the throttles were advanced to 100%, and we were underway as the engine instruments were given a quick check to ensure the engines were operating properly. Originally designed as a short takeoff and land (STOL) aircraft, the OV-10 could lift off at 73 knots in some 700 feet on a standard day at sea level. That was impressive to most of us reading the Airplane flight Manual (AFM). After all, most of us were transplanted bomber, transport or fighter pilots used to much longer takeoff rolls and higher liftoff speeds, However, we were soon to learn that the STOL liftoff speed was lower than the minimum safe single engine speed and that at least one pilot had crashed after losing an engine on a STOL takeoff. We were, therefore, restricted to using a higher rotation speed – one that got us airborne after the safe single engine speed.
We were in for yet another surprise regarding takeoffs, particularly those of us destined for Thailand where we carried a 300 gallon centerline fuel tank. The fully loaded tank levied both a weight and drag penalty that lengthened the takeoff roll and decreased climb performance. If an engine were lost immediately after takeoff, the airplane would be too heavy to fly with a combat load, and it would be necessary to jettison the external stores or put the airplane back on the ground. Despite these problems, the Bronco always seemed to get airborne with little difficulty. In fact, I I recall ever having to abort a takeoff for any serious problem. Low torque seemed to be the main cause of aborted takeoffs, but that was usually evident before the brakes were ever released.
Once in the air the OV-10 performed well with a training load at Hurlburt but was more sluggish with a full combat load in Southeast Asia. Nevertheless, for me and most of the pilots I knew, flying the OV-10 was a welcome interlude between bomber, tanker or transport assignments. Almost without fail, the first thing that impressed pilots flying the Bronco were its turning performance and visibility. Old timers frequently said that it would turn on a dime and give you five cents change. I don’t know about that, but the turning performance was spectacular and a particular plus for a FAC because one could stay over a target and easily observe activity below because of the turning performance and visibility. As for speed, most pilots were not impressed, but there were few grumbles either about the fairly low top speed. After reading the flight manual and seeing 350 knots as the top speed, I had rather expected to be able to attain 350 knots easily. That was not the case. The Bronco was power limited and could attain only about 210 knots clean and 170 knots with a combat load at 5,000 feet. Many Broncos could not even do that. I did get the Bronco up to 350 knots a couple of times but found that it was a difficult task requiring a steep dive angle and full power.
Nearly all Air Force pilots liked an acrobatic airplane, and the Bronco was fully aerobatic. The two booms with twin rudders gave the airplane plenty of directional control, and the large elevator was effective well below stall speed. The ailerons were assisted by a set of spoilers on the top of each wing which combined to give the OV-10 a good roll rate at all airspeeds. The flight controls were so effective that the airplane could literally be flown out of a spin. The engines were the only limitation on its acrobatic performance. After a few over the top maneuvers, one would have to sop and climb back to a good starting altitude for the next maneuver. When the airplane was heavy, a 60° bank couldn’t even be maintained. Even with these problems, the airplane was still a little fighter, and I couldn’t resist the urge to try out some aerial combat maneuvers on a willing friend.
I had heard that some pilots who flew the aircraft but never in combat felt the Air Force should not have bought the OV-10, but I doubt those critics considered that alternatives – the O-2 and O-1. All of the OV-10 pilots I knew in Southeast Asia thought the OV-10 did an excellent job as a FAC aircraft. Its superb visibility, tight turning radius, relatively large ordnance load, and long loiter time over target (especially with the 300 gallon centerline tank) made the Bronco an unequaled aircraft for its mission. The Navy and Marines also used it as a light attack aircraft. The Air Force also armed it for some light attack for the Prairie Fire mission. The OV-10 could accept several different combat configurations on its five external stations. On the centerline station the Air Force birds usually carried a jettisonable fuel tank, and the four sponson stations carried the ordnance. The sponsons were two small winglike protuberances on the bottom of the fuselage that appeared to be an afterthought. The normal ordnance load carried by FAC aircraft were pods of 2.75 inch folding fin smoke rockets for daylight target marking or canisters of flares or ground marks for night target marking. In addition to the external ordnance, the OV-10 could carry four internal M-60 machine guns – two in each sponson. The machine guns, however, were normally used only for special missions, such as Prairie Fire, where the guns could support troops in contact. Starlight scopes were also mounted in some airplanes for night missions, and in 1971, as few Broncos were modified to accept a laser designator to guide the recently developed smart bombs accurately to their targets.
The FAC’s job was to perform visual reconnaissance, direct air strikes, and assess the damage after air strikes. In Vietnam where the plane could work as low as 1,500 feet above the ground, reconnaissance could be performed with the naked eye, but along the Ho Chi Minh trail in Laos where FACS were required to fly at 6,500 feet above the terrain because of antiaircraft fire, binoculars were required to do the job. The wide expanse of Plexiglas in the OV-10 made this an easy job whether working with the unaided eye or binoculars. Initially, trying to watch the ground below with binoculars while flying the airplane was not easy, but after a while a pilot got used to doing both jobs simultaneously.
Once a target was located and the fighter bombers were on scene and ready to work, the FAC had to mark the target and direct the air strike. Marking a target with the OV-10 was an easy job but took some skill because of the varying dive angles we used. Firing rockets or guns and dropping ordnance could only be done from the front seat. Instructor pilots, however, prided themselves with being able to line up on a target from the rear seat and direct the pilot in the front seat to fire a rocket with greater accuracy than the pilot in the front seat could using his gun sight. Marking a target at night with flares and ground marks was done from level flight with the help of a navigator FAC in the back seat. After an air strike was completed, the FAC assessed the damage to the target and reported to the strike flight and the airborne controller, who was miles away in another airplane.
Radio coordination was a big job for the FAC since it required listening to two or three radios simultaneously. The FAC was constantly on the radio requesting air strikes, directing air strikes or making reports. The OV-10 was well equipped for this portion of the job, but it seemed not a great amount of thought was given to human factors in the design. There was one of each type of radio used by U.S. military aircraft, but switching from one radio to another, talking on the radio and flying the airplane would have made a third hand useful. Somehow we managed but never with the greatest of ease.
Range was of little importance to the FAC, but endurance was. With the 300 gallon drop tank the pilots thought that, if anything, the Bronco had too much endurance. Normal missions were four and a half to 5 hours long – an awfully long time to be sitting immobile, strapped into the ejection seat of an airplane. And the seats weren’t comfortable, either! We put down five and a half hours as the endurance on our mission sign out sheets, but I once flew a five and three quarters hour mission and still returned to base before reaching the prescribed bingo fuel state.
Returning from a mission, the standard approach for an OV-10 was a 360 overhead pattern, and that was what the pilots liked best. However, at most bases we couldn’t fly a 360 overhead pattern with any ordnance on board, and it was seldom that we returned from a mission without a few rockets left over from the day’s mission. Therefore, our pattern usually had to be a large box pattern flown outside the base perimeter. At least, that was the way it was at Nakhon Phanom in Thailand. At Nakhon Phanom most Bronco pilots liked to announce their return by making a high airspeed, steep bank turn onto the outside downwind leg of the traffic pattern just opposite the quarters area and near the busiest portion of the base. The Doppler effect took care of the arrival announcement by driving the roar of the engine right into the quarters area. There was even a small competition, particularly among the lieutenants, to see who could arrive with the loudest roar. After announcing our arrival, the controllable pitch of the propellers made a steep glide slope to landing possible and spot landings easy. Once on the ground, the combination of reverse thrust and wheel brakes gave the Bronco a short landing roll.
Once the ideas incorporated into the Bronco as a tri-service counterinsurgency aircraft was its multi mission capability. Provisions had to be made for paratroops, but to the best of my knowledge, troops never bailed out of the OV-10. That was something reserved primarily for the pilot and extra crewmember in the tandem seats. Fortunately, the OV-10 had one of the best and most reliable ejection systems around. I was a particular fan of its ejection system because I had to use it on one occasion after my plane was hit by antiaircraft fire. The seat was rocket launched right through the canopy of the airplane. The ejection itself was rather soft by most standards. No one I knew who ejected from the OV-10 suffered any after effects more than a little soreness and some singed hair on the back of one’s calves from the rocket blast. The ejection sequence could be initiated at any speed or altitude within the envelope of the aircraft with an almost sure expectation of success. One inexperienced back seater even punched out successfully while the aircraft was parked when his arming pin streamer became entangled with the ejection D-ring and he ejected himself accidentally. The seat worked just as advertised, and he walked away from the experience somewhat shaken by his sudden unplanned departure from the aircraft but otherwise okay.
As in any flying organization, talking about our missions and the airplanes we flew occupied a great deal of our off-duty time. Using those discussions as an indicator of how the FAC pilots felt about the OV-10, I would say that there were few who didn’t love the airplane. It wasn’t fast, it wasn’t very powerful, it wasn’t aerodynamically beautiful, but it had a place all its own among Air Force aircraft.
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