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I Flew the U-2

One of Lockheed’s former chief test pilots for high altitude reconnaissance describes the joys and terrors of the U-2.

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(Continued from page 1)

But we were saddled with trying to maintain that climb schedule for long, long periods of time, so we would never go to altitude without an autopilot. You engaged the autopilot as you were climbing out, and then you got into the climb-Mach schedule, and you engaged “Mach hold,”; you had a small Mach trim wheel so you could tweak it just a little—more Mach or less Mach. And it maintained that climb schedule. It was almost impossible to “hand-fly” it—disengage the autopilot and try and fly it up through there with the yoke.

When Francis Gary Powers (we called him “Frank”) got shot down, he was having trouble with the autopilot, and he had to descend to a lower altitude to hand fly it, and that’s when the surface-to-air missiles were able to get him.

How did it help to descend?

At lower altitudes, the airplane was more stable and there was more margin between the stall buffet and critical Mach number buffet. During the cruise phase of the mission, as you burned off fuel and the aircraft got lighter, you had a little more margin even as it gained more altitude. The envelope expanded as you got higher and higher and lighter and lighter. Then you got more margin between the Mach buffet and stall buffet. If you encountered buffet, the first thing you did was go faster. You’d assume it was stall buffet, and you wanted to go faster because if you guessed wrong and slowed down, then it would stall and quit flying altogether. It would flip over on its back, and that’s how we lost a lot of the airplanes. It stalled at altitude, it would head straight down, and the tail would snap off.

Is that why the change was made to the longer wing?

No, I think the reason they went to a larger airplane was that they wanted more range and a larger payload—more capability. They wanted the same altitude, but we never got to the same altitude in the bigger airplane that we could in the little one. The smaller airplane was lighter and had a higher thrust-to-weight ratio, and it would get up there. We could get up to 74, 75,000.

How would it tell you that you couldn’t get any higher?

We’d have it at maximum EGT [exhaust gas temperature], so you were getting everything you could out of the engine and it didn’t have any more thrust to overcome the drag to give you what you needed to go higher. If you increased you angle of attack to generate more lift, it would generate more drag, and airspeed or Mach wouldn’t hold up.

You flew two aircraft that were structurally damaged, and you were advised to eject both times.  Why did you keep flying?

We went back and pulled a lot of U-2Cs out of storage, and we had to verify that they had them all back together right.  What happened on one of the airplanes was that on the hot section of the engine, they used a Teflon fairlead [a fitting mounted on a bracket to guide a cable]; that’s what control cables went through—these Teflon fairleads on the inside of the fuselage near the hot section of the engine. They had small holes, just so that the control cables could slide back and forth.

It’s interesting that these sophisticated airplanes had manual control with cables.

Oh yeah, the U-2, both the little one and the big one, did not have boosted flight controls. It was all pushrods, bell cranks, and pulleys and cables. We did not have boosted ailerons in either airplane. That’s why it had a yoke in it rather than a stick—to provide you with the leverage that you needed to move the control surfaces.

Why were there no hydraulics for boost?

To keep it light.  The lighter it was the higher it would go.  Every pound that the airplane weighed was a foot of altitude that you lost, so you wanted to keep it as light as you possibly could to get it as high as you could. When they added a new system, a new camera, a new radar that weighed ‘x’ pounds, that was altitude that you were going to give up.

And you’d have to fly that new camera or system to find out what impact it had on the altitude.

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