PRB
June 9th, 2009, 18:53
As a Fire Control Technician (AQ), we were responsible for the weapon system avionics on the A-7E. Our shop was called IWT, which stood for Integrated Weapons Team. The A-7E had what was then a new fangled concept called an “integrated weapons system”, meaning the main computer, inertial navigation, radar, Doppler radar, and HUD were all “talking” to each other to provide accurate bombing solutions to the pilot.
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We did some silly things in those days. For example, if the pilot said the radar wasn’t transmitting, or if we suspected it wasn’t, our testing procedure was to apply power, walk out to the front of the plane, open the nose radome, and grab the radar feed horn with our hand. If it was warm, we knew it was transmitting!! :eek:
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The Doppler radar was a very useful system that provided radar altitude, ground speed, and drift angle. As a radar, of course, it provided radar altitude, but the antenna projected four beams, two fwd and two aft. The frequency shift between the fwd and aft beams, due to the Doppler effect, provided ground speed, and the antenna was mounted on a gimbal stabilized platform which would automatically rotate until the two fwd beams were each reflecting equal frequencies. This provided accurate drift angle. Very cool. But it was a pain to maintain. The stupid antenna was accessible only by sitting on the ground under the plane and removing about a hundred screws, several of which were guaranteed to be stripped, and would require an easy-out to remove. And on the carrier, they always parked the A-7s forward, over the catapult tracks. This meant we had to sit on the flight deck, on the cat tracks, which were hot as hell on account of the steam used to power them!
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The electrical fuzing system was a bit of a nightmare. Bombs could be armed with mechanical and/or electrical fuzes. A mechanical fuze was a “simple” device with a propeller to arm the weapon after it was dropped from the plane, like in WW-II. The electrical fuzes allowed the pilot to select a variety of fuzing options from the cockpit, like delay times, etc. The whole system was wired by coax cables from one central box, out to each bomb station (six of them), and was one big parallel circuit. This meant that if there was a short anywhere in the system, the entire system was shorted. And these coax cables were routed all over the damn place, and were always getting water in the connectors, meaning it was often shorted. Finding the short was the fun part! You got to be expert at splicing coax cables if you worked in the IWT shop in an A-7E squadron!
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
We did some silly things in those days. For example, if the pilot said the radar wasn’t transmitting, or if we suspected it wasn’t, our testing procedure was to apply power, walk out to the front of the plane, open the nose radome, and grab the radar feed horn with our hand. If it was warm, we knew it was transmitting!! :eek:
<o:p></o:p>
The Doppler radar was a very useful system that provided radar altitude, ground speed, and drift angle. As a radar, of course, it provided radar altitude, but the antenna projected four beams, two fwd and two aft. The frequency shift between the fwd and aft beams, due to the Doppler effect, provided ground speed, and the antenna was mounted on a gimbal stabilized platform which would automatically rotate until the two fwd beams were each reflecting equal frequencies. This provided accurate drift angle. Very cool. But it was a pain to maintain. The stupid antenna was accessible only by sitting on the ground under the plane and removing about a hundred screws, several of which were guaranteed to be stripped, and would require an easy-out to remove. And on the carrier, they always parked the A-7s forward, over the catapult tracks. This meant we had to sit on the flight deck, on the cat tracks, which were hot as hell on account of the steam used to power them!
<o:p></o:p>
The electrical fuzing system was a bit of a nightmare. Bombs could be armed with mechanical and/or electrical fuzes. A mechanical fuze was a “simple” device with a propeller to arm the weapon after it was dropped from the plane, like in WW-II. The electrical fuzes allowed the pilot to select a variety of fuzing options from the cockpit, like delay times, etc. The whole system was wired by coax cables from one central box, out to each bomb station (six of them), and was one big parallel circuit. This meant that if there was a short anywhere in the system, the entire system was shorted. And these coax cables were routed all over the damn place, and were always getting water in the connectors, meaning it was often shorted. Finding the short was the fun part! You got to be expert at splicing coax cables if you worked in the IWT shop in an A-7E squadron!