Chuck Yeager, in his our words, regarding his experience with the NF-104
Excerpted from an interview from the Academy of Achievement (www.achievement.org),
February 1st, 1991, in Cedar Ridge, California
Interviewer: There is a fairly exciting chapter in your life that we didn't cover, back in 1963, your Lockheed Starfighter experience. Can you describe, first, the plane's capabilities?
Yeager: When I was commandant of the astronaut school, we had to train the guys in a simulated space environment. We took three F-104As, which was a mach two airplane, and we put a hydrogen peroxide rocket engine in the tail, above the normal jet engine [which] gave us an additional 6000 pounds of thrust. And with this aircraft, we also added 24 inches to the wingtip and two hydrogen peroxide thrusters, one out the top of each wing tip and one out the bottom. That's for roll control above the atmosphere. We extended the nose of the airplane out and put thrusters in the top and bottom and each side for pitch control and yaw control of the airplane.
A typical mission that we flew with that airplane, and I flew it 40 some times working out a profile for the students to fly as a test pilot on the airplane, we would take off with the afterburner on the engine, getting airborne. Clean the gear up on the airplane and the flaps, then accelerate out to climb speed, four to five hundred miles an hour, climb up to about 36,000 feet, then go into afterburner which accelerates the airplane out to about twice the speed of sound. Ease it up to about 45,000 feet, fire off the hydrogen peroxide rocket and accelerate it out to about 2.4 mach number. Then pull 4 Gs, or pull the airplane up into about a 70 degree climb angle. The characteristics of the J-79 engine, which is in the 104, as you go through about 55,000 feet, the afterburner blows out because of lack of oxygen. When this happens you gotta come out of afterburner position with the throttle in mil power and make the eyelids close to get more thrust out of the turbine engine. You gotta keep one eyeball on the tail pipe temperature, because that engine is going to over-temp at about 70,000 feet; it is not designed to run any higher. And when it does, you have to shut it down.
We shut it down and the hydrogen peroxide rocket takes you on over the top. We got the airplane up to roughly 118,000 max altitude. But then you are above 90 percent of the atmosphere, so you have to use these hydrogen peroxide rockets to change the altitude of the airplane to follow its flight path. When the airplane leaves say, 100,000 feet going up like this, if you don't do anything, it's going to come back in that way. So you have to rotate it to make it come back in nose first.
We knew the 104 had a pitch-up problem, meaning when the airplane stalled, it pitched up. I was the first military pilot to fly the 104, on August 3, 1954. I was the test pilot on that airplane, so I knew it intimately. I spun the airplane a lot, and stalled it. I knew we had this problem.
What we were trying to establish was: when this airplane comes back into the atmosphere at a little higher angle of attack than we want, at what altitude will this aerodynamic force which causes the nose to pitch up on the airplane, be more than the thrust of the hydrogen peroxide thruster in the nose which is pushing the nose down. We ran a series of flights; I was the pilot on it. Start at 118,000 feet, 116, 114, 112, coming into the atmosphere at about a 50-degree angle of attack, open up the thrusters at the top, push the nose down and then measure the rate. You can plot, at each altitude, at what rate the airplane recovers. We noticed it was starting to run into resistance at about 108,000 feet; 106,000 feet was a little slower. If you take the curve and extrapolate, it looks like we are going to run out of thrust in this hydrogen peroxide rocket where the aerodynamic pitch up will be more than the thruster, at about 92,000 feet. So we thought we were in pretty good shape.
We thought we would run one more. I flew a flight in the morning, with a pressure suit on, I think at 108,000 feet, and we measured the rotation. Then I landed and wanted to make another flight after lunch. I didn't get out of my pressure suit because if you get out of it, it's wet and you can't get back in. I made another flight at about 1:30 in the afternoon, at 104,000 feet. For some reason, we had dual thrusters on the bottom of the nose and dual thrusters on the top. We don't know, we may have had one thruster fail, but at 104,000 feet, when I came into the atmosphere at 50 degrees angle of attack, I couldn't get the nose down on the airplane. You've already shut your engine down, and it gradually is slowing down. But the engine is still turning over, giving you hydraulic pressure, which runs the horizontal stabilizer for pitch control, the ailerons and the rudder.
What happened on previous flights, when you re-enter and force the nose down with the hydrogen peroxide thrusters, the altitude controllers, then you come back into the atmosphere nose first. Then you start getting air through the intake ducts of your airplane, that keeps your engine windmilling, you bring the airplane on down to about 40,000 feet, level out, hit the igniter and then come out of idle, out of stop cock with your throttle into idle. That gives you fuel and you start you engine up again. But if it doesn't work, you go on down, dead stick into Rogers Dry Lake, which I did three or four times.
What happened on this flight was that when the airplane came into the atmosphere, at about a 50-degree angle of attack, I couldn't get the nose down. The airplane pitched up and went into a flat spin. Now airplane is in a flat spin and, because there is no air going through the intake ducts, the engine stops. When that stops, then you no longer have hydraulic pressure to run the horizontal stabilizer, the aileron or the rudder. So you are in a no-win situation. That's exactly what it is. You sit there. But you have one other alternative, that's eject. I also had a drag chute on the airplane that we use for landing. The airplane was in a very flat, slow spin. I had my pressure suit on and it was inflated. I sat there and watched. I was talking to Bud Anderson who was chasing me in a T-33. He was down, way down though, looking at me coming.
I was talking to the space position branch, where the guys were recording data. I said, "I got a real problem. There is just no way of getting this thing out of a spin."
So, as I went through 30,000 feet, I deployed the drag chute, which you normally deploy. When I did, the drag chutes comes out and it popped the nose down on the airplane, but there is a link that the drag chute is hooked to the airplane with, that is designed to shear at 180 miles an hour. That's in case the drag chute comes out accidentally while you are flying, it won't stop the airplane. It just so happened the nose went down as I went through 180 miles an hour, the drag chute sheared, the parachute released and the airplane pitched back flat because 180 miles an hour going through the intake duct is not going to give you engine rpm, it takes about three hundred miles an hour. So when this happened, it flipped back flat. I don't think it turned, it just fell at one hundred miles an hour.
Now, you've got the egress systems, you know them intimately and it pays off, because a lot of times you have to use them in a semi-conscious state. I knew my rocket seat that I was riding in, I knew it's capabilities. So, I rode it down to about 6,000 feet, which is not low, and ejected. The rocket seat blows you out of the airplane and gives you about one hundred mile an hour velocity away from the airplane. It just so happened that the airplane was falling at about 100 miles an hour, so when I used the seat, the airplane just fell away from the seat. The seat sat there, and then two seconds after you leave the airplane, the lap belt blows open on the seat, which is what holds you on the seat. You've got leg restrainers, cables that hold your heels into the seat for flailing when you come out at high speed.
I sat and watched the seat go through a sequencing, knowing when it was going to happen. Finally the lap belt popped open, and there is a butt kicker that kicks you out of the seat. I felt that go and also my cable cutters cut my leg restrainer cable from me [and] I fell through. When this happened, the F-5 release on your parachute is armed and as you fall through 1400 feet, the chute opens. Well, I was below 1400 feet, so the chute opened the minute that the F-5 release said to open, and it did. The problem was, I didn't have enough velocity through the air, I was just starting to fall again, to pull that quarter bag which is on the canopy of your parachute. The reason that bag is on the canopy is that when you eject at high speeds, four or five hundred miles an hour, it keeps your canopy on the parachute from popping immediately. The little pilot chute on that quarter bag needs about sixty miles an hour to pull it off the quarter bag. I didn't know anything like this was going on, all I know is that I am free falling, my chute has released, but I haven't got a canopy slowing me down because I can feel it flopping in the breeze.
At about this time, the seat, which kicked me out up here, is also falling and it became entangled in the shroud lines of the parachute. I didn't know this either, but this is the way it happened. Finally I picked up enough speed, sixty or seventy miles an hour, with the canopy up there following, that quarter bag came off, the canopy popped and when it popped, the damn seat that is entangled in the shroud lines flopped me up like this (hand gestures).
The seat hit me in the face piece of my pressure suit. And what hit me was the butt end of the rocket on the seat, which still had glowing propellant burning. When this happened, and you are feeding 100 percent oxygen. It's like a blow torch.
Fortunately, when this happened, the visor on my pressure suit was busted and frayed, it cut my eye down and my eye socket filled with blood, so it didn't hurt my eyeball. I got burned pretty bad on my neck and shoulder and it was very difficult to breathe. The only thing I knew, I was stunned from the blow, I knew I had to get the visor up on my pressure suit helmet. There is a button on the right, you push it and then you raise your visor. It's the way you get your visor up on most pressure suits. I knew I had to get it off, get that visor up to shut the oxygen flow from my kit that was in the back of my pressure suit to get all this fire out. So I did that. Then I swung a couple times and hit the ground. I couldn't see too much and I was having trouble breathing because there was a lot of smoke and fire.
But it worked out, you either do or your don't, and I didn't get killed in the flat. I stood up and Andy buzzed me. Since I had been talking to them on the way down, four minutes from the first spin to impact, they had a helicopter off with a flight surgeon aboard, a doctor at Edwards. He got out there, probably within five minutes of the time I landed, picked me up, gave me a shot of morphine and took me back to the hospital. They worked on me, cut my pressure suit off and that was about it.
Interviewer: Normally, somebody else gets you out of the pressure suit, right? But you had to think fast.
Yeager: No, I just knew it. See, I wore pressure suits half my life.
Interviewer: It sounds like you had a tough time after that, dealing with your burns.
Yeager: Well, they can do a lot of scraping and ultrasonic work on your skin, a little skin grafting and stuff like that. That was part of the deal.
Interviewer: You look amazingly well, considering your...
Yeager: Your body is a very forgiving thing.
Interviewer: Did you get the feeling that day that some big aviator in the sky was smiling down on you?
Yeager: Nope. You waste your time thinking about anything except surviving.
Interviewer: But, I bet at some point during that fall, you weren't sure that you were going to survive.
Yeager: Well, you are too busy. You don't think about anything like that. You are too busy trying to survive. Obviously, had I not known intimately my egress systems, meaning my pressure suit and ejection seat and parachute, I probably wouldn't have survived. But I just make it a point to know it and it pays off a lot.
Interviewer: The other thing that is extraordinary, hearing about this, is your ability to think under pressure instead of panicking.
Yeager: Well, you don't talk anything about it. Obviously you can't. You are too busy working the systems through.
Interviewer: The idea of problem solving -- you were good at math -- obviously it carried through.
Yeager: Well, knowing your egress systems is the answer. And also a little bit of luck was involved.