FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1960
1960 - 1174.PDF
148 FLIGHT, 29 July 1%, 1957 On September 27 the first "boilerplate" dummy was hunched at Hunters Point during Operation Peashooter POLARIS . . . initiated under Project Skyhook (a land-based project) was thatthe missile should be tethered by steel cables passed over rollers carried atop triangulated tower structures on either side of thelaunch tube. Towards apogee the missile would pull the cables taut, deceleration then being assisted by a snubbing device. Bycontrolling the loads on the cables the missile would then be allowed to fall back but prevented from hitting the ground. Inthe event, however, Skyhook was superseded by Skycatch, which became a reality towards the end of 1958. Located at San FranciscoNavy Yard, the system involves the use of that dockyard's largest travelling crane. To the top of its structure were attachedhydraulic snubbing units modified from carrier arresting installa- tions. Unpowered test vehicles were fired from a launch tube,while tethered by cables to these arresting units. As the missile rose into the air the cables were reeled in so that the missii •eventually came to rest high above the ground; the missile w; . then lowered gently and recovered. By this means structural;representative and fully instrumented airframes were evaluate during the actual departure from the tube. In order to conduct similar tests during underwater launchinga rig had to be designed and built from scratch. The US Nav • Yard at Long Beach built a barge 100ft square, on which WEmounted a crane derrick towering 186ft above the water an; 100ft out from the barge gunwale. The cable from the barge waattached to the test vehicle through a detachable nosecap in :; manner which did not affect the hydrodynamic behaviour of thomissile, the actual anchorage being made through a shock-absorb- ing mechanism. Under the code-name of Fishhook, the rig wasstationed at San Clemente Island and went into operation on April 24, 1959. As in the Skycatch programme, the cable attachedto the rising missile was reeled in by a hydraulic ram and multiply- ing cable system. During the summer of 1958 Lockheed began to deliver flyabletest vehicles almost indistinguishable from the operational Polaris, and incorporating all the airborne components which had beendeveloped up to that time. The first series were designated AX-1, AX-2, et seq. Each was instrumented to yield information inparticular areas, and although the series was fired in approximately numerical order, the sequence was sometimes upset by suddenrequirements for a particular set of test results which could best be obtained by a particular member of the AX family. Static testing of the AX vehicles began at Santa Cruz, California,and AX-1 was fired from Cape Canaveral in September 1958. In the words of Admiral Raborn, "We expected more problems inthis phase than we had experienced in development of the missile sub-systems. We knew, however, that basic design of the individualsub-systems had been proven, and that any problems unearthed would be susceptible to straightforward engineering solutions." In fact, no particularly serious difficulty was encountered. Thefirst flights were concerned with first-stage ignition, thrust and flight control, second-stage ignition, inter-stage and re-entry bodyseparation, re-entry confirmation, and operation of the guidance system in a flight environment. Dramatic proof of the quality ofthe airborne components was obtained during the flight of AX-12, fired on July 15, 1959. One of the primary purposes of AX-12 wasto test the airborne guidance computer. On take-off the missile lost part of a jetevator—something which had never previouslyhappened—and the subsequent aerobatic behaviour established test conditions well outside the design limits. The performance ofthe airborne guidance system in this highly adverse environment was so outstanding that its remaining development schedule wasforeshortened. While the flight-test programme proved the flyable portions ofthe FBM system, the immense navigational problems were tackled with the aid of USS Compass Island (EAG-153), an 18,000-toncargo ship rebuilt for this purpose and recornmissioned in November 1956. The conversion included the installation of thecomplete ship's inertial navigation system, and Compass Island has now completed three years at sea in the perfection of all thenon-airborne navigational equipment. A sister ship, USS Observation Island (EAG-154) has been equipped with most ofthe shipborne portions of the weapon system, including a launch tube projecting through the main deck near the starboard quarter.On August 14, 1959, an AX was successfully launched from Cape Canaveral Pad 25B (the ship simulator) under conditions repre- 1958 Early in the year "Polaris jg" test vehicles were being launched at Cape Canaveral (left); on September 24 there was launched from the same complex the first vehicle of Polaris configuration (AX-1, middle picture); and the third photograph, taken on November 72, shows a launching under Operation Skycatch, with a structurally representative airframe nearing apogee after launching
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
