08 May 2007

Aircraft I Have Loved, Part One Continued

More about my favorite airplane, the F-4 Phantom II. The first F-4 I was ever up close and personal with was at NASA Dryden, back in the late '60s when I was a summer hire. We had an F-4 then. I don't know why or what it was used for and my copy of Hallion's book about the history of Dryden, like my copy the revised and updated version by Gorn and Hallion, is, for some inexplicable reason, at my house in Lancaster, not here in Palm Desert.

Anyway, one day this F-4 was out flying and the fuel pressure relief valve in one wing stopped working. Shortly thereafter the pressure of the fuel blew a hole right through the (wet) wing. Naturally, the pilot, Hugh Jackson, RTBd (Returned To Base) and landed right away. Some time later they brought the plane into the hangar and we all went down to see it. 'd never seen anything like it and probably wouldn't have believed that the fuel could generate enough pressure just from a little aerodynamic heating to blow a hole clear through the wing had I ever thought about it before it happened. It was quite amazing. Of course, we just repaired the wing and finished the program and somewhere along the line the airplane went away.

The next F-4 I was associated with was the analog fly-by-wire F-4 that McAir and the USAF were examining with an eye to reducing battle damage. I've written a bit about that one elsewhere and won't repeat it here.

At the same time, there was the F-4 that McAir was using for safety chase for the new F-15. This was an old F-4, bailed to McAir by the USAF years before and used for all sorts of experiments and programs, from testing new hardware to being safety chase. In its youth, it had been used to set some sort of speed record, in fact. With all those years as a testbed, it had picked up a lot of extra weight. When they'd install some bit of hardware it would have wiring and power supplies and other components, so when that particular test program was over they wouldn't go back and rip out everything they'd installed. Instead, they'd take out the pieces that were easy to reach, but they'd mostly just dyke the wiring off and leave it in place.

Carrying all this extra wire and other bits and pieces made the F-4 heavy and slow, so McAir decided to clear all that junk out. They sort of tore the airplane apart and pulled wire out like crazy. The crew accumulated all the wire and stuff they removed and, when they were done, built an awesome heap of it in the middle of the hangar. It was almost as high as the cockpit sill (11 ft) and proportionately large at the base. Of course, they crumpled the wire into balls, so the pile was pretty fluffy, but still that's a lot of wire and stuff. I was really impressed. The airplane was a lot faster, too.

Before I go on, I should mention that using an older airplane this way isn't at all uncommon. NASA Dryden, for example, only ever bought three new airplanes, the Lockheed F-104N Starfighters (which were actually F-104Gs without the weapons suites) to be support aircraft. All the rest were second-hand military aircraft. Even many of the research aircraft were hand-me-downs from the military, although the X-planes, for example, weren't.

Having said that, it won't be so surprising to read that the next F-4 I had something to do with belonged to AFFTC (the USAF Air Force Flight Test Center), having come there when the USAF exhibition team, the Thunderbirds, switched from F-4s to F-16s. That was back in the first energy crisis, in about 1973. This airplane, an F-4E, still had the oil smoker system from its days as a Thunderbird airplane installed, as well as an inverted oil system. It also had a controller box from its days as a cruise missile safety chase, when the engineer in the back seat was there in part to use that box to take control of the cruise missile and put it into a loiter mode until it ran out of fuel and fell out of the sky. The intent, of course, was that the falling out of the sky part should happen somewhere over the vast, extremely lightly populated desert, not over Lancaster or Santa Barbara.

How do I know so much about an AFFTC F-4? I got a ride in it is how. A good friend, whom I had helped when he was a student at the USAF Test Pilot School, had gotten tired of giving F-4 rides to TV actors (this was just after filming had ended for a made-for-TV movie about Pancho Barnes). He pitched giving me a ride to his CO by pointing out that I could actually recognize and identify an F-4 without help, just as I could identify all the other planes of the flightline, and that I had loved F-4s for decades, being well-known in some circles for my fondness for them. That flight was one of the highlights of my life. I wrote up a description at the time and I'll figure out how to get that posted, for anyone who is interested.

The last F-4 came to Dryden as the testbed for an experiment using spanwise blowing to control the flow over the wing. I believe it was part of the extensive laminar flow experimentation that our aerodynamics people were doing. The idea was to use engine bleed air blown down the wing (from root to tip) to attach the flow and reduce the boundary layer. At least, that's what I think it was, but I'm not an aerodynamicist and I could be wrong. Dryden got this F-4 from the USAF and started modifying it. However, further calculations ended up showing that there wasn't enough bleed air to work, even if they used all of it, which they couldn't. As a result, the experiment was abandoned, the airplane was put back the way it had been, and returned to the USAF. Not long after that, the USAF retired its F-4s completely. The AFFTC F-4Es were the last ones to go.

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