posted 08-11-2008 12:53 PM               

Most put the height of the Saturn V as 363 feet, but they do not add the 3.5" of the Q-ball as it goes in as the air pressure goes up, so sometimes it's 363 feet, sometimes it a bit more to a max of 363.3 feet in height.

posted 08-12-2008 09:42 AM               

-001:10 Public Affairs Officer: "This is Apollo Saturn Launch Control. T minus 1 hour, 10 minutes, 58 seconds and counting. At the 1 hour and 13 minute mark, scheduled with a Q-ball simulated command, this command goes to the Q-ball and is read out in the spacecraft by the spacecraft commander. The Q-ball is an angle of attack sphere perched above the launch escape system, and it's used to give the spacecraft commander and the crew any signals which would indicate an out of tolerance condition during the early stages of flight. The countdown [is] moving along well at this time. T minus 1 hour, 10 minutes, 25 seconds and counting. This is Kennedy Launch Control."

[The Q-ball is not unlike a pitot tube on an aircraft that measures airspeed. It consists of eight openings at the top of the Launch Escape Tower. These openings lead to instruments which gauge air pressure. As well as providing dynamic pressure (known as "Q") information during powered flight, they help determine the angle of incidence of the tower during an abort event. The Q-ball design works at almost all air-speeds, unlike the pitot-static instruments used on most aircraft. A similar type of Q-ball was fitted to NASA's hypersonic X-15 research aircraft made, like the CSM, by North American in Downey, California. The Q-ball is covered until shortly before launch, to prevent blockage of the holes.]

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Originally posted by jasonelam:
For those interested, it can mainly be seen in Apollo 15 televised launch coverage.

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The Q-ball cover was split in half vertically and held together by a 2-inch (51 mm) rubber band. A razor blade was positioned behind the rubber band, pinched between the halves of the cover. A wire rope was connected to the top and bottom of the razor blade and to both halves of the cover. The wire rope was routed through a pulley on the hammerhead crane at the top of the launch umbilical tower (LUT) down to a tube on the right side of the 360-foot (110 m) level of the LUT. The wire rope was connected to a cylindrical weight inside a tube. The weight rested on a lever controlled by a pneumatic solenoid valve. When the valve was actuated from the Launch Control Center (LCC), the pneumatic pressure of 600 PSI GN2 (nitrogen gas) rotated the lever down allowing the weight to drop down the tube. The dropping weight pulled the wire rope, which pulled the blade cutting the rubber band, and the wire rope pulled the halves of the Q-Ball away from the launch vehicle. The apparent overengineering of this simple system was due to the fact that the launch escape system, which depended on the Q-ball data, was armed 5 minutes before launch, so retraction of the Q-ball cover was a life-critical part of a possible pad abort.