What was the whirl tower used for?

Matt the Mystery Man:

In Imperial County, not too far from NAS El Centro, is a "whirl tower" rising above the fields and dust. This tower has become a ghost of its former self over the last 20 years but still stands as an imposing landmark. One desert rat claims the Navy used the tower to spin bombs around and then throw them into the desert. Another says it was used to test ejection seats by throwing them. One sputtering old man claims that it whirled targets for machine gunners to practice shooting at low-altitude aircraft. Who constructed this tower? When? What was it used for?

-- Not Believing Any of It, the desert

Let me first say the thing looks like a run-down, one-story stucco house with a three-story oil derrick on top of it. A boom is mounted at the top of the derrick, and a cable hangs from one end of the boom. A whirl tower is most often used to test helicopter rotors and other plane parts. The one north of the town of Seeley (on Wheeler Road, west of Huff Road) is a defunct parachute tester. The building houses the remains of the old machinery that drove the whirler. The Navy built it in the 1960s and abandoned it soon after, when the thing didn't work properly. It's under the jurisdiction of the Navy base at China Lake.