28. August 2005 · Comments Off on Flying The Tomcat · Categories: Military, Technology

In response to my recent posts, concerning the F-14, and the movie Top Gun, reader Mike Williams sends this interesting email:

I started flying F-14s in 1973. I was an engineering test pilot at the Naval Air Test Center in Patuxent River, MD. I went on to a department head tour in one F-14 squadron, and to an XO/CO tour in another.

When you compare Navy and Air Force fighters, it’s a little apples and oranges because of the Navy’s carrier suitability requirements. And it’s not just the extra weight in beefed up structures for carrier takeoffs and landings: you also have to take into account the comparatively limited space available on even Nimitz-class carriers for maintenance and storage of spare parts.

As you probably know, the F-14A was originally designed to use the same engine as the F-15A. In fact, if memory serves, the number 7 F-14 was a “B” model with the F-15 engine. I forget the exact designation, but it had considerably more thrust than the “A” model’s PW TF-30, which was a variant of the F-111’s engine.

What some people forget is that both the TF-30 and the F-15A engines were high-energy afterburning turbofans, and that while the TF-30 was operational in the F-111, the F-15A engine was at that time pushing the state of the art. Certainly the F-14A was underpowered for a front-line fighter, and guys like me began referring to it as the twin-tailed turkey. I was a lieutenant (O-3) at the time, but that didn’t stop me from venting my frustrations with the rear admiral who was the F-14 program manager at the Naval Air Systems Command. He listened politely to my rants, and then he said this: You’re right, of course, but when the F-15A engine blew up in afterburner on the test stand for the third time at less than 100 hours, I had to make a hard decision about waiting for the engine to catch up, or getting the F-14 out to the fleet on time.

The difference here is that where the Air Force has the hangar space to yank engines every 100 hours for hot section inspections and to store replacements, aircraft carriers don’t.

Now, as you and some of your readers have pointed out, the Air Force flew the F-111 more as a bomber than a fighter. Not so the Navy with the F-14A. Pilots routinely pushed it to the edges of the envelope – and beyond. And initially we had a lot of compressor stall problems with the TF-30 engines that the F-111 pilots didn’t encounter. It took a while, but over the years we managed to engineer enough upgrades to work these problems out. The downside was that there wasn’t enough money left over to upgrade to the F-15A engine when it finally got beyond 100 hours for a hot section inspection.

I can tell you from experience that the F-14A was a very forgiving fighter. Many is the time I’ve run out of airspeed and ideas in a dog fight, often when the jet was pointed nearly straight up. The problem here was that the F-14 has an unrecoverable flat spin mode, and that an engine stall at high angle of attack increases the susceptibility. The spin axis is somewhere between the NFO’s cockpit and the vertical stabilizers, and the transverse G’s during the spin are enough to incapacitate the pilot. So, if you got into a flat spin, your only alternative was to eject, and you were dependent on the NFO (who was not incapacitated by the transverse G’s) to initiate a command ejection.

The NFO’s concern was the canopy: the command eject sequence was the canopy, the NFO and then the pilot. Because you wanted your pilots and NFOs to survive carrier takeoff and landing mishaps, the time intervals were fairly compressed. Unfortunately, the canopy tended to hover over the aircraft during a flat spin, and there was a chance that the NFO would strike it during ejection – a guaranteed fatality.

To be sure, all the fixes to the TF-30’s compressor stall problem weren’t just for air combat. A compressor stall on a combat-loaded F-14 during a catapult takeoff could also be a big problem. The engines are far enough apart so that with one stalled, and the other blazing away in full after burner, enough roll-to-yaw could be generated in short order to put you on your back. Those Martin-Baker seats might have been zero-zero, but as the airplane rapidly rolled from wings-level to inverted, your odds of surviving an ejection decreased exponentially.

Now about Top Gun. During Vietnam we were focused primarily on MIG-17s and MIG-21s. It turns out that the A-4 is a very good MIG-17 simulator, and the F-5 is a very good MIG-21 simulator.

But let’s digress here a minute and talk about the air war in Korea. At the start of the war, the MIG-15 was the superior air-to-air machine, even compared to early versions of the F-86. But later on, the US put bigger engines in the F-86 and bolted up the leading edge slats. Then the F-86 ruled the skies.

The same thing happened to the Top Gun A-4’s: The Navy bolted up the slats and installed big engines. The durn things were small and hard-to-see, had a thrust-to-weight close to 1:1, and could turn on a dime. In an F-14A, you could get in real trouble in a knife-fight with one of those hopped up A-4s. So – you tried to set the fight up to play to your strengths – which were your radar and missiles – and his weaknesses (but you always conceded GCI, which for him was like radar and an extra set of eyeballs).

We’ll I’m sure you’re bored by now with an old man’s reminisces. In closing, my advice would be to let bygones be bygones, and to look to the future. The F-22 is deploying to Langley AFB as we speak, and Russia and China are partnering up in defense technology. The JSF is coming along, and you could reasonably conclude we’re in another Cold War-style arms race. The GWOT is critical right now, but it’s not the only game in town.

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