<text id=00he2006><title>Special Weapons for the Trail</title>
<history>US Air Force: Events History</history>
<article><hdr>Special Weapons for the Trail</hdr><body>
<p>Several other special systems were developed, deployed and evaluated in combat on the Trail. One of these was the Martin B-57G, planned as a self-contained night attack aircraft for solo missions, detecting and destroying targets in total darkness. The standard Martin B-57 airframe was modified by the addition of several sensors, including a forward-looking radar with a moving-target indicator sensitive enough to track slow-moving trucks 10 miles (16 km) off; a low-light-level television (LLLTV) system; a forward-looking infra-red (FLIR) detector; and a laser rangefinder. In its belly the B-57G carried a 20-mm gun turret.
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<p>About a dozen of these planes were built, one of which was lost during factory tests, and a second was shot down in Laos in December 1970, soon after the squadron had become operational. The combat evaluation showed that the planes killed only 2.3 trucks on each sortie, a figure only about one-quarter as good as the gunship kill rate.
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<p>Another surprising weapon developed for night war on the Trail was a pair of modified Fairchild C-123 transports. Designated NC-123K, these two planes were equipped with a group of special sensors, including night-vision types, and their bellies were modified to carry dispensers for anti-personnel mines. The usual short nose of the standard aircraft was lengthened by a radome, probably housing a forward-looking radar for nighttime trail navigation. Both planes were equipped with auxiliary wing tanks on short pylons and two auxiliary jet engines on longer pylons just outboard of the two piston engines that were the main powerplant. Standard night camouflage finish was used.
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<p>Most of the ordnance used with the Igloo White system was wide-area, rather than precision, type. There were too many variables in the system to result in a small CEP. Typical dive-bombing CEP values were around 400 ft (120 m), which is a large miss distance for a small target like a truck. Consequently, wide-area munitions and fragmentation bombs were the bulk of the ordnance dropped on the Trail. Among the specific weapons were these:
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<list style=aflst>
<item>• <hi format=bold>BLU-31 land mine</hi>, a 750-lb (340-kg) blunt-nosed weapon designed to penetrate the ground for only a short distance. Its fuze was capable of detecting movement of heavy targets such as tanks.
<item>• <hi format=bold>BLU-52 riot control gas bomb</hi>, a standard napalm bomb case filled instead with 270 lb (120-kg) of either CS-1 or CS-2 riot-control agent. The weapon produces nausea, choking and copious weeping; CS-1 effects last three to five days in an area; CS-2, up to 45 days.
<item>• <hi format=bold>CBU-24 fragmentation anti-truck munition</hi>, a combination of the BLU-26/B bomblet and the SUU-30/B clamshell dispenser. It was one of the most effective, and therefore most widely used, munitions against trucks. Its fragments perforated fuel tanks, tires, radiators and drivers equally well.
<item>• <hi format=bold>CBU-28 anti-personnel mine</hi>, called Dragontooth. These were carried in canisters and dropped from a dispenser.
<item>• <hi format=bold>CBU-33 anti-vehicular land mine</hi>, which was designed to destroy tanks. It weighed about 20 lb (9 kg). Only about 600 were built; they saw minimum use in the theater because of the limited use of armor by the NVA.
<item>• <hi format=bold>CBU-34 wide-area anti-personnel mine (WAAPM)</hi>, using a dispenser and canisters containing the bomblets.
<item>• <hi format=bold>CBU-42 WAAPM munition</hi>, developed by the DCPG specifically for the conditions of the Trail. It had a longer life than the -34 before it destroyed itself in a time-fuzed explosion.
<item>• <hi format=bold>CBU-49 fragmentation anti-truck munition</hi>, the same basic weapon as the CBU-24 except that the -49 had a random-delay time fuse.
<item>• <hi format=bold>EOGB/Electro-Optical Guided Bomb)</hi>, a standard 2,000-lb general-purpose bomb equipped with an electro-optical guidance head. It was a self-contained weapon, not needing other aircraft to illuminate the target as in the case of the laser-guided bomb. However, it did need daylight with good visual conditions, and a degree of contrast between the target and its background, something not always attainable.
<item>• <hi format=bold>Gravel anti-personnel mine</hi>, basically an area denial munition. It was strewn from an SUU-41 dispenser.
<item>• <hi format=bold>LGB (Laser-Guided Bomb)</hi>, a 2,000-lb GP bomb with an attached laser guidance head and oversized fins to counter the destabilizing effect of the head. CEP was about 30 ft (9 m) with this precision weapon.
<item>• <hi format=bold>M-36 incendiary cluster of 182 M-126 incendiary bombs</hi> developed for World War II. The cluster, weighing about 800 lb (360 kg), was carried externally on the A-1 and the A-26, internally on the B-57. It was very effective against trucks.
<item>• <hi format=bold>Mk-36 destructor</hi>, a retarded GP bomb with a special fuze that sensed the seismic disturbance caused by a moving target.
<item>• <hi format=bold>Pave Pat I fuel-air explosive munition</hi>, built into a commercial propane tank. Only 52 were built, and they were dropped from A-1Es during the autumn of 1968 in a combat evaluation that showed them to be rather unsuccessful.
<item>• <hi format=bold>Pave Pat II fuel-air explosive bomb</hi> weighing 2,500 lb, and designed for high-speed aircraft. Three could be carried on a Phantom.
