Sunday, August 16, 2009

Chapter 18: Night Owl

Night had long been a cloak of invisibility for military movements on land, sea or air. Radar had its limitations, especially as the radar transmissions acted as a beacon for any enemy missiles to follow. A partial answer was found in the use of night vision goggles which could amplify available starlight. Goggles in turn had their limitations, however. For use in the inky blackness of a moonless night under an overcast, various types of Forward-Looking Infra-Red (FLIR) systems were developed. FLIR was passive and did not radiate signals as did radar.

I had flown a daylight mission to assess a FLIR in the unique and strange-looking ASTTA aircraft, a twin-turboprop transport fitted with a radar and FLIR. The acronym ASTTA stood for the Avionics Systems Test Training aircraft, modified from a Convair 580 transport. The ASTTA was a one-off research aircraft and was flown from a fighter-type cockpit back in the cabin, with a safety pilot up-front in the standard cockpit. Fitted with a fly-by-wire flight control system, the transport had been modified to fly like a fighter. The FLIR had proved useful during the flight, but of course I only had to look out of the window to see the target in the eighty-mile visibility of the high desert out at Edwards AFB.

Shortly afterwards came an opportunity to fly a real FLIR mission at night with the US Marine Corps. At that time, in the mid-eighties, the Marines at Camp Pendleton in California flew a mix of OV-10As and OV-10Ds for Forward Air Control. I had previously flown a tactical mission with the OV-10A in daylight, so was familiar with the capabilities of this twin-boom turboprop.

Prepared for battle. The writer preparing to embark on a daylight tactical mission in an OV-10A out of Camp Pendleton. With a pair of 715HP turboprops and a relatively small airframe, the Bronco was fast, maneuverable and heavily armed.

The North American Rockwell OV-10A was designed as a counter-insurgency aircraft. Airesearch T-76 turboprops of 715 HP each good good acceleration on takeoff. When this was combined with the lift improvement given by the double-slotted flap system, a spectacular takeoff roll of under eight hundred feet was possible. Counter-rotating propellers eliminated the normal swing on takeoff, and reversing propellers gave a remarkably short ground run on landing. A long-stroke trailing link tricycle landing gear mopped up any bumps and permitted the Marines to operate their Broncos from roads and primitive airstrips.

A pair of OV-10As from VMO-2 embarking on a Forward Air Control mission. Capable of 240 knots on the deck, and with a better endurance than jets, improved further by the use of under-fuselage fuel tanks, the OV-10s served in Vietnam and the Gulf War.

In flight the bulged canopy gave good visibility. The cockpit was spacious and rugged. Reversals and steep turns during tactical maneuvering confirmed the OV-10s ability to turn on a sixpence, invaluable in the battlefield environment. Even at low speeds the combination of ailerons and spoilers on the upper surface of the wing gave a good roll rate. The Bronco packed a considerable punch. Fixed armament was a quartet of 7.62mm guns mounted in the sponsons under the cockpit. For the normal Forward Air Control task, Zuni rockets or 2.75 inch rockets could be carried for target-marking. The Marine pilots of VMO-2 swore by their Broncos.

The OV-10A was operated by the USMC in the Forward Air Control Mode. Normally armed with guns and rockets for daytime operations, it was to have an expanded capability in the more powerful OV-10D version with a nose-turret with FLIR and laser sytems for night operations.

The OV-10D was modified for the night surveillance mission. It was distinguished by infra-red suppressors on the exhausts and larger engines of 1040 SHP each, driving new fibreglass propellers. An extended nose was fitted with a slewable chin turret which mounted a combined FLIR and laser. This system provided automatic target tracking together with laser target designation and ranging. The laser could be used to direct laser-guided munitions such as the Paveway Laser Guided Bomb and the Hellfire missile.
VMO-2 naturally used the night observation capability of the OV-10D as an extension of its daytime capability. For example, the squadron had monitored aircraft suspected of drug smuggling coming up from Mexico. The pilots of VMO-2 were tight-lipped about this, but said that very little could outrun the turboprop Bronco.

At low level under normal starlight conditions, they had found that the best results came when the pilot used night vision goggles for terrain avoidance and pilot navigation, with the back-seater using the FLIR for target identification.

I was briefed on the aircraft FLIR system by Major Russ Looney of VMO-2. Sitting in the rear cockpit of our OV-10D on the ground I found the rear cockpit similar to that of the OV-10A. There were some additions. The FLIR display was a nine-inch screen up on the left glareshield. A smaller repeater unit was provided in the front cockpit for the pilot. The electrical load of the FLIR was such that a third inverter had been added. Until the engines were running, the power to activate the FLIR was provided by a ground power unit, sitting on the ramp beside the Bronco, and connected to the fuselage by a thick electrical umbilical. The FLIR display, together with a radar warning display on the right side of my instrument panel cut down on the excellent visibility I had noted from the OV-10A.

I went carefully through the sequence of switching necessary to activate the FLIR, firing up the FLIR and then selecting the various modes, while the ground power unit howled away, providing the power to run the FLIR. The display gave a black and white infra-red picture, similar to a TV. I practised tracking other Broncos and helicopters moving about the ramp. While the aircraft appeared as various shades of gray, the hotter engine exhausts were white.Using a hand controller on the right hand side of the cockpit I could swivel the FLIR, while the laser tracker also mounted in the turret was activated from a hand controller on the left hand panel. As this required the back-seaters hands to be fully occupied, a floor-mounted intercom button could be operated with his left foot while a radio transmit button was operated by his right foot

As the sun went down over the Pacific, we briefed for the mission. Our night mission, piloted by Lieutenant-Colonel Don Persky, Commanding Officer of VMO-2, would take us initially round the populated local area to give me some familiarisation with the FLIR system. We would then head east towards the Mountainours area around Mount Palomar and Lake Henshaw to practise using the system against various targets. The desert of the Borrego valley would be an ideal place to carry out simulated diving gun attacks before heading back to the coast to look for any maritime targets.

Just after sunset we walked out to our olive-drab aircraft, silhouetted menacingly against a western sky glowing eerily with multi-colored swatches and curlicues of light, the aftermath of a satellite launch from Vandenberg. We strapped into our ejection seats and carried out our respective pre-start checks. The night air was cooling fast and I lost no time in closing down the large transparencies flanking my seat. The instrument panel sprang to life. Once both engines were running I pushed in the inverter control to power up the system and then switched the FLIR to standby mode. This started the automatic sequence to cool down the sensors. In a couple of minutes my FLIR display started to brighten up, so that by the time we were ready to taxi, my system was fully operative. Switiching the FLIR to the manual tracking mode I practised using the hand controller to slew the nose turret in elevation and azimuth to track a pair of unsuspecting seagulls flying past in the twilight.

We taxied out to the runway. With power levers forward and brakes released, the combined 2,080 HP of the T-76s smartly accelerated us to our 110 knots lift-off speed. During a lazy left-hand orbit after takeoff I practised slewing the seeker with the hand controller, easily picking out roads and houses.

We initially headed east to the mountains. By now it was pitch dark, although the moon was rising in the east. Looking over the side I could just make out the hazy blur of the ground, but no details could be seen. Overhead Lake Henshaw, I looked with the FLIR to see if any boat traffic was visible. In fact I confirmed that all the boats had been beached for the night. The display was amazingly clear, so much so that I was surprised to see even the image of the mountains reflected in the lake.

A flashing strobe light at our ten o'clock provided an opprtunity for tracking an air-to-air target. Slewing the turret to our nine o'clock, in a wide-angle scan, I found the white dot of the target at the appropriate bearing, westbound on a reciprocal course to us. Switching to a higher magnification revealed that the target was an unsuspecting Piper Cherokee heading for Oceanside airport. Any Bronco pilot would become a night-fighter ace with no trouble at all.

Further east over the unlit desert we identified a rectangular pattern of solar collectors on the ground. While I kept the turret slewed to this target using the hand controller, then pressed the trigger to lock it on the target, we initially flew away from the target until it was way behind my right shoulder. We then turned through 180 degrees back towards the target for an attack. Despite this maneuvering the FLIR stayed locked on the target. Range to the target, displayed on the bottom of the screen, started counting down. When the target was at our twelve o'clock I locked the system to the boresight mode. Lt. Col Persky, using his FLIR repeater display, entered a simulated ten degree dive gun attack.

Weapons attacks at night are never routine. Diving into the inky blackness of the Borrego desert with mountainous terrain around is always going to gain your attention. However with the target displayed on the screen, together with its range, it became a much more civilised affair. On the display the target expanded as we dived until a 4g pullout pushed me down in my seat and got us heading back upstairs.

I reset the FLIR in manual tracking mode, searching for more targets in the desert. Initially my attempts at locking onto smaller targets were unsuccessful. I found the trick was to fine-tune the size of a small rectangular box on the display which had to overlay the target. Choosing the right size was important in achieving lock. My success rate improved as I reduced the size of the box to just encompass the target. In a few minutes I could even lock onto cars driving down the desert roads.

Cruising at 160 knots and 8,700 feet we turned westbound to return to the coast. Locking the FLIR into the boresight mode I took control of the OV-10D for a few minutes to try a few tracking maneuvers using only the FLIR for reference. The OV-10 had fairly light control forces and was quite responsive. I used my FLIR display, offset on the left hand side of the cockpit, for reference. Despite the offset it was easy enough to pick a ground target and fly the aircraft until the cursor crosshairs overlaid the target in a simulated gun-aiming situation.

While still some miles inland and scanning seaward with the FLIR again, I could clearly see a power station complex on the coast. Anchored some way offshore was a large supertanker, stern on to us. I obtained a good lock on this ship. We flew out over the sea while I practised locking-on in various modes. The target was an attack pilot's dream.

We turned inland again and flew back towards Camp Pendleton. Runways and hangars came up clearly on the display, As we ran in to an overhead break I practised locking-on to an aircraft on the runway. Even as we entered the break, and headed downwind the system maintained lock on this other aircraft as it took off.

We landed, taxying back while using the FLIR in a surveillance mode, demonstrating that it would be possible to steer the Bronco around the taxiways and between other aircraft to our parking space even if the field were to be blacked out. Our ground crew were clearly visible on the display as they marshalled us into our parking spot.

I was mightily impressed. The FLIR system was similar to that used by the Coast Guard to combat contraband smuggling. It was a powerful tool, could see through darkness, haze or smoke, and multiplied the capability of the Bronco immensely. The Bronco was a handy aircraft. It was apparent that an experienced crew could use the FLIR and laser systems to good effect to carry out observation and ordnance delivery at night. Technology and teamwork combined to give this Night Owl a devastating punch.

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