TOW CABLES AND ASSOCIATED EQUIPMENT

Steel cables used in target towing are manufactured specifically for that purpose. Three of the several types of cables used are discussed here: the 3/32-inch, 7 by 7 cable; the 1/8-inch, 7 by 19 cable; and the 1/8-inch, 1 by 19 armored cable.

Figure 8-5.-Mk 1 target leader.

The 3/32-inch cable comes in 10,000-foot spools, has a minimum breaking strength of 920 pounds when new, and is 7 by 7 in construction. It consists of seven strands; each strand has seven wires, and is commonly referred to as 7 by 7. This cable weighs 1.5 pounds per 100 feet.

The 1/8-inch cable is shipped in either 11,500-to 12,500-foot spools or 7,000-to 7,500-foot spools. It has a minimum breaking strength of 2,000 pounds when new. It is 7 by 19 in construction (7 strands, 19 wires per strand) and weighs 2.9 pounds per 100 feet.

The 1/8-inch armored cable is shipped in spools. It has a minimum breaking strength of 2,160 pounds. It is constructed of one strand of 19 wires, with a flat armoring wire swaged spirally around the strand with a minimum of 6 turns per inch. The armored cable weighs 4 pounds per 100 feet. Cross-sectional views of these three cables are shown in figure 8-4.

These cables are not lubricated. The use of grease, oil, paraffin, or other lubricants on the cable is a fire hazard. An explosive vapor is created in the towing aircraft as the cable is reeled out at high speeds. Since the cables are not lubricated, they must be stored in a dry place, or cleaned and coated with corrosion-preventive compound according to instructions.

Continual use of a cable reduces its strength. Target towing subjects the cable to severe stress in addition to the damage caused by gunfire. You need to inspect _{cables frequently.} The cable should be repaired or replaced if there are indications of fraying (broken wires), birdcaging (partial unwinding of the strands along the cable), or snarling (unwinding of the strands and wires at the end of the cable). Running a cloth along the cable will help you locate broken wires, as they will catch in the cloth. Never run your bare hand along the cable because the broken wires will catch in the flesh. Also, you should never use a knot to attach a target, since the knot weakens the cable by 50 percent or more. An eye splice is recommended for this purpose.

Mk 1 Target Leader

The Mk 1 target leader (fig. 8-5) is used to attach targets and target-release messengers to the release ring. In turn, the target ring is held by the Mk 7 Mod 4 target release. When the target is dropped, the leader and ring drop with it.

The leader is a 34-inch length of 5/32-inch diameter 7 by 19 steel cable swaged into a yoke at one end with an eye at the other end. To use the leader, you attach the bridle eye of the target to the yoke of the leader. Then, secure the eye end of the leader with a shackle to the release ring or snarl catcher that slides along the tow cable.

Mk 8 Target Release Ring

The Mk 8 target release ring (fig. 8-6) is made of case-hardened alloy steel and is about 3 inches long. The smaller eye is 1/2 inch in diameter, while the larger eye is 1 1/2 inches in diameter. You should attach the target leader to the smaller eye (securing eye). The larger loop (hole) slides along the cable, and is held by the target release when the target is towed with a reel.

Figure 8-6.-Mk 8 target release ring.

Release rings are also used in drag takeoffs and _{container launchings.} In container launchings, you should attach the ring directly to the towline, and then to the target-release device of the aircraft.

Klein "Chicago" Grip

The Klein "Chicago" grip (fig. 8-7) provides a means of transferring the target drag load from the reel to a structural member of the towing aircraft. This procedure is used to take the strain off the reel while the target is streamed.

The grip is a standard commercial item. It is about 10 inches long and composed of a series of spring-loaded linkages and a shackle. The jaws are opened by compressing the entire grip in line with the extended shackle. It will grip bare wires, solid or stranded, from 0.081 to 0.162 inch in diameter.

Figure 8-7.-Klein "Chicago" grip.

The grip is first secured by a cable to the aircraft's internal structure. Then, it is attached to the tow cable near the outrigger sheave. Slightly unwinding the reel transfers the load from the reel to the grip. The greater the drag load, the tighter the jaws grip the cable.

CAUTION

Do NOT apply loads greater than 1,500 pounds to the grip. It will accept cable with a much greater breaking strength than that of the grip itself. As a safety measure, set the reel brake while the grip is in use, keep the clutch in the IN position, and keep the slack in the tow cable between the grip and reel at a minimum.