Grumman panther

Flight Journal, Oct 2002 by Meyer, Corwin H

Test pilot Corky Meyer flies the F9F

In the late '40s, Grumman's first jet fighter, the F9F-2 Panther, was the last in a line of jetfighter development relative to the Chance Vought F6U-1 Pirate, the McDonnell F2H-1 Banshee and the North American F2J-1 Fury. Like the Grumman WW II Hellcat, however, the Panther also had two reliable engines available to fulfill Grumman's long-standing policy of never equipping a new fighter with a new engine. That policy paid off not only in timely output but also in providing the most reliable Navy carrier jet fighter in the Korean War. Eight Panthers from VF-51 on the CV-45, the USS Valley Forge, made the first strike on the Pyongyang airfield only eight days after the "police action" was declared by President Truman. Before the truce at the 38th Parallel was signed two and a half years later, 26 Naval and 16 Marine squadrons had used the Panther in combat-not bad for the last Navy jet fighter to have a coming-out party.

I previously described the Panther's preliminary design and first flight problems in "Blowing a Panther's Nose" (October 1997 Flight Journal), so now I will relate several tales of the unexpected, unwanted and all-too-frequent embarrassing episodes that happened during its early test-flight escapades.

FLAMEOUT FIASCO

My first "escapade" happened during an early Panther test flight-before we had much understanding of jet engine fuel systems. Pratt & Whitney, which was producing the RollsRoyce-designed J-42 Nene jet engine for the Panther, asked us to check out engine operations during full-throttle switchovers from the normal to the emergency fuel systems.

I started the tests at 5,000 feet. The switchovers were normal until I got to 25,000 feet. Then, when I switched from normal to emergency, the engine began to growl and the tail pipe temperature rose somewhat, but not over the limit. At 30,000 feet, the switch-over showed the engine to have louder aches and pains. The growl now shook the aircraft, and the tailpipe temperatures went to the limit. I should have stopped at this point of the test, but I had been assured by the Pratt and Rolls engineers that I would have no trouble with air-starting the engine-none whatsoever!

During the next switchover at 33,000 feet, there was a series of explosions, the tailpipe temperature went rapidly over the limit, and the engine flamed out before I could yank the throttle back. I was now riding in a very quiet, heavy and descending "glider," whose cabin pressurization was disappearing rapidly. I went through the air-start procedure at the correct windmilling rpm of 10 percent, but nothing happened; silence! The Rolls representative had told me that air starts would be immediate at below 25,000 feet, so I waited. It didn't start at 25,000, 20,000, or 15,000, so I frantically tried 1,000-foot intervals, while getting more apprehensive with each failure. I tried slightly differing engine windmilling speeds, but to no avail.

Before the flight, I had decided that if an engine-off landing was required, I would use a two-mile-long potato field just north of the Grumman airport in preference to Grumman's 5,000-foot runway that had housing developments at either end.

At 3,300 feet, I gave up all starting efforts on that uncooperative Rolls-Royce Nene engine and concentrated on a 360-- degree flameout-landing pattern for a wheels-up landing on the potatoes. Without any cockpit help from me, all of a sudden, a great blast of energy shot out of the engine, the tailpipe temperature soared way over the limit, and engine rpm increased rapidly to about 30 percent thrust. Fortunately, it stopped where I had left the throttle after my last air-start attempt. After "things" (mainly me) had settled down, I noted that the engine seemed to be running smoothly enough and with sufficient power for a landing at Grumman. With wheels and flaps down, I made a much less dramatic landing at the Grumman airport than I had planned at the potato field.

After I had shut down the engine, mechanics looked into the tailpipe and found that the two spark-plug-like air-start igniters had been burnt to a crisp and were also so twisted and warped that they could not be removed or tested. They also told me that they had seen the flames, more than 100 yards long, shoot out of my tailpipe when the engine had overcome my vain efforts and had mercifully started on its own.

During our debriefing, the Pratt representatives gave me the usual down-the-nose look implying "pilot error." They couldn't find any "engineering" justification for my near catastrophe. Their inspection report also stated that there was no possibility that the igniters could have started the engine because they had been damaged beyond use. Because of the excessive temperatures generated during the air-start attempts, the engine was removed and returned to Pratt for a complete teardown and inspection. I was later advised that Pratt judged Grumman test pilots incapable of properly conducting an air-start program.