:09 Adams: “Experiment, camera. Give me a 45-second call.”
:22 B-52: “Forty-five seconds now, zero-eight.”
:26 Adams: “Rog.”
:30 Adams: “Prime, igniter ready.”
:36 Adams: “And precool, igniter, and tape. And give me 15 seconds Joe, will you? I missed that.”
:51 B-52: “Fifteen seconds, zero-eight.”
:54 Adams: “Pump—good igniter.”
10:30:02 B-52: “Five seconds, zero-zero-eight.”
:03 NASA-1: “Looks good here, Mike.”
:07 Adams: “Rog, two, one, launch.”
:11 NASA-1: “Rog, we got a good light here, Mike. Check your alpha and your heading.”
:21 NASA-1: “Right on track, Mike, you’re coming up on profile.”
:29 NASA-1: “Standby for theta.”
:33 NASA-1: “How do you read, Mike?”
:39 NASA-1:
-- “Check your boost guidance null, Mike, and how do you read?” [squelch break]
:44 NASA-1: “OK, Mike, we have you right on the track, on the profile.”
:45 B-52: “You’re on track and profile, Mike.”
:52 Adams: “Roger.”
:54 B-52: “I’ll relay, Pete.”
NASA-1: “OK.”
10:31:01 NASA-1: “Standby for 83,000, Mike.”
:04 B-52: “Standby for 83,000.”
:09 NASA-1: “Do you read us at all, Mike?”
:12 NASA-1: “OK, you’re right on the track.”
B-52: “Right on the track, Mike.”
:19 NASA-1: “Coming up on 110,000.”
B-52: “Coming up on 110,000.”
:22 NASA-1: “On the profile, on the heading.”
:24 B-52: “On profile, on heading.”
:26 NASA-1: “Standby for shutdown.”
:27 B-52: “Standby for shutdown.”
:33 NASA-1: “Precision attitudes, Mike.”
:35 B-52: “Precision attitudes, Mike.”
:39 NASA-1: “Alpha to 0.”
:40 B-52: “Alpha to 0.”
:42 NASA-1: “And rock your wings and extend your experiment, Mike.”
:45 B-52: “Extend your experiment, Mike.”
:50 NASA-1: “On the heading, on the profile.”
:52 NASA-1: “Have you going a little bit high, that’s all right.”
:54 B-52: “On the heading, on the profile, maybe a little bit high.”
:58 Adams: “I am reading him now. I got a computer and instrument light now.”
10:32:03 NASA-1: “OK, Mike.”
:08 NASA-1: “We’ll go ahead and try computed alpha at 230, Mike.”
:14 NASA-1: “Check your computed alpha now.”
:18 NASA-1: “And you’re right on track, Mike.”
:27 Adams: “I lost my pitch and roll dampers.”
:31 NASA-1: “OK, Mike, let’s try and get them on.”
:32 Adams: “They reset.”
:34 NASA-1: “Did they reset?”
:35 Adams: “Yep.”
:36 NASA-1: “OK.”
:37 NASA-1: “And I’ll give you a peak altitude, Mike.”
:42 NASA-1: “Have you coming over the top. You’re looking real good. Right on the heading, Mike.”
:51 NASA-1: “Over the top at about 261, Mike.”
:54 NASA-1: “Check your attitudes.”
10:33:02 NASA-1: “You’re a little bit hot, but your heading is going in the right direction, Mike.”
:09 NASA-1: “Real good.”
:11 NASA-1: “Check your attitudes. How do you read, Mike?”
:14 NASA-1: “OK, let’s check your dampers, Mike.”
:17 Adams: “They’re still on.”
:18 NASA1: “OK.”
:24 NASA-1: “A little bit high, Mike, but real good shape.”
:33 NASA-1: “And we got you coming downhill now. Are your dampers still on?”
:37 Chase-1: “Dampers still on, Mike?”
:39 Adams:
-- “Yeah, and it seems squirrely.”
– [squelch break]
:44 NASA-1: “OK, have you coming back through 230, ball nose, Mike.”
:50 NASA-1: “Let’s watch your alpha, Mike.”
:58 NASA-1: “Let’s not keep it as high as normal with this damper problem. Have you at 210. Alpha, beta, and check your alpha, Mike.”
10:34:02 Adams: “I’m in a spin, Pete.”
:05 NASA-1: “Let’s get your experiment in and the camera on.”
:13 NASA-1: “Let’s watch your theta, Mike.”
:16 Adams: “I’m in a spin.”
:18 NASA-1: “Say again.”
:19 Adams: “I’m in a spin.”
:21 NASA-1: “Say again.”
:27 NASA-1: “OK, Mike, you’re coming through about 135 now.”
:34 NASA-1: “Let’s get it straightened out.”
:37 - - [two squelch breaks]
:42 NASA-1: “OK, you got theta 0 now.”
:44 NASA-1: “Get some angle of attack up.”
:50 NASA-1: “Coming up to 80,000, Mike.”
:53 NASA-1: “Let’s get some alpha on it.”
:57 NASA-1: “Get some g on it, Mike.”
:59 NASA-1: “Let’s get some g on it.”
10:35:02 NASA-1: “We got it now. Let’s keep it there. Coming around.”
:09 NASA-1: “OK, let’s keep it up, Mike.”
:14 NASA-1: “Keep pulling up. Do you read, Mike?”
:20 NASA-1: “Let’s keep pulling it up, Mike.”
:27 NASA-1: “OK, 130 let’s head down that way.”
:37 NASA-1: “He was abeam Cuddeback, 130, three-five-eight.”
:42 NASA-1: “Chase-4, do you have anything on him?”
:44 Chase-4: “Chase-4, negative.”
:47 NASA-1: “OK, Mike, do you read?”
:52 Chase-4: “Pete, I got dust on the lake down there.”
:55 NASA-1: “What lake?”
PART 1
THE INGREDIENTS
Chapter 1
The Machine
The X-15 was the third aircraft type in a series of higher-speed experimental aircraft. The first was the X-1, the second the X-2, the third the X-15. A fourth was to be the Dyna-Soar X-20. The X-1 was developed to break the sound barrier and to explore the low supersonic flight region. The X-2 was intended to investigate aerodynamic heating phenomena up to speeds of Mach 3. The X-15 was designed to explore the hypersonic speed regime and the fringes of the upper atmosphere. The original design speed and altitude of the X-15 were Mach 6.6 and 250,000 feet respectively. The design Mach number was later reduced to Mach 6.0. The X-20 Dyna-Soar was intended to be the follow-on to the X-15 to explore the high-hypersonic flight region up to Mach numbers near 18. Dyna-Soar was subsequently upgraded and designed to go into orbit on the new Titan III booster, but the program was cancelled shortly after production of the spaceplane began.
To provide some perspective, the hypersonic-speed regime starts at Mach 5 or roughly 5,000 feet per second (3,300 MPH) and it extends on up to orbital speeds of roughly 24,000 feet per second (18,000 MPH). The modified X-15 (X-15A-2) achieved a maximum speed of Mach 6.7 or approximately 6,700 feet per second (4,520 MPH). To more fully appreciate what this means, the speed of a bullet fired from a high-performance hunting rifle is approximately 3,000 feet per second. The X-15 could fly over twice as fast as that rifle bullet. Tank cannons have a higher muzzle velocity than most any other gun. Those muzzle velocities average about 5,500 feet per second. The X-15 could fly 1,200 feet per second faster than those shells. A Mach number of 6 is roughly equivalent to 4,000 miles per hour. This equates to more than one mile per second. The X-15 was pretty damn fast!
There were a number of other early research aircraft in the X-series which were not high-speed airplanes. The X-3, the X-4, the X-5, and the XF-92 were unique configurations, rather than high-speed aircraft. The D-558-I and the D-558-II type aircraft were high-speed aircraft, but they were funded by the U.S. Navy a
nd thus, were not recognized by the air force as real X-type aircraft. The air force controlled the X-number designation. Both the D-558-I and the D-558-II established speed records, but their records were short-lived.
The original X-1 type had a follow-on version which included the X-1A, the X-1B, the X-1C, and the X-1D. These vehicles were somewhat larger, carried more propellant, and expanded the maximum speed of the X-1s to Mach 2.5. The X-15 also had a follow-on version in the rebuilt number two aircraft which ultimately achieved a maximum speed of Mach 6.7. For a more detailed description and discussion of these earlier research aircraft, I would refer you to several books written by Richard P. Hallion, an excellent aviation historian. He is also a pilot historian. He writes about old pilots like me.
The early X-airplanes were rather simple airplanes with purely mechanical systems, reminiscent of World War II fighter aircraft. The control systems were cable and pulley type systems with some power boost. There were no stability augmentation systems nor were there any other avionics systems. Thrust-to-weight ratios were less than one even on the rocket aircraft.
The X-15, by comparison, was a much more state of the art airplane. It had a high gain, high authority, stability augmentation system and an advanced command augmentation type control system in the number three aircraft. It utilized an inertial platform for attitude and velocity information and a special ball nose for air data. The X-15 was part spacecraft with a reaction control system and a thermal protection system to withstand the heat of reentry. Thrust to weight ratio of the X-15 was more typical of missiles and space boosters with a maximum T/W of four just prior to burnout. The empty weight of the airplane was approximately 15,000 pounds. Engine thrust was roughly 60,000 pounds.
The X-15 was the first aircraft designed for flight above the atmosphere. Some may quibble about whether the X-15 flew above the atmosphere since there are some air molecules above 100 miles altitude. In actuality, the major portion of the atmosphere is below 100,000 feet. The edge of the sensible atmosphere is very visually obvious as you climb through 100,000 feet. The sky changes from blue to black and there is no apparent atmospheric haze above that altitude. The space shuttle people consider 400,000 feet to be the edge of the atmosphere, since that is where they first sense some atmospheric effects at orbital speeds, but no airplane will ever cruise at that altitude. A hypersonic transport or the “Orient Express” as the Reagan administration referred to it, will not cruise much above 100,000 feet.
Why was the X-15 built? The glib answer was “to explore the hypersonic-flight regime.” The real answer was to find out if we were smart enough to design an airplane that could fly and survive at hypersonic speeds. We knew much about hypersonic flight from theory and subscale wind tunnel testing, but there were still some real basic questions that needed answers. Could we design an airplane that was stable and controllable at hypersonic speeds? Could we design a structure that would survive the high heating rates associated with hypersonic speeds? Could we design an airplane that would be controllable outside the atmosphere and one that could successfully reenter the atmosphere at high speed and steep entry angles? More important, could a pilot survive and function adequately in this high-energy environment?
The only way to answer these questions was to design and build an airplane and then attempt to fly it at hypersonic speeds. If it survived, we were right. If it didn’t, we had more to learn.
To me, the X-15 was a big propellant tank with a cockpit on the front end and an engine on the back end. It was 50 feet long, but the propellant tanks constituted approximately 25 of those 50 feet. The X-15 weighed roughly 15,000 pounds without propellants and 33,000 pounds with them. The propellants consisted of approximately 1,000 gallons of liquid oxygen and 1,400 gallons of anhydrous ammonia. The tanks for these propellants made up the major portion of the fuselage. The outer skin of the aircraft fuselage was the exterior wall of the tank.
All of the hydraulic and electrical lines from the front to the back of the aircraft were housed in the fairings along the sides of the tanks. The tanks were made in a toroidal shape, like a doughnut in cross section with a void in the middle. In essence, they were a long cylindrical tank with a hole going through the core of the cylinder. In that core of the liquid oxygen tank, there was a long, skinny cylindrical tank that contained the high pressure helium gas used to pressurize the propellant tanks to get the propellant moving to the engine pump.
Figure 1. Three-view drawing of X-15 aircraft.
Figure 2. Cutaway drawing of X-15, showing location of components.
On the nose of the airplane was the airflow sensor which determined the airflow direction and the airflow impact pressure. This sensor was referred to as the ball nose. It was servo-driven to align with the airflow impacting the nose of the aircraft. From this, we obtained angle of attack, angle of sideslip, and impact pressure of the air flowing over the aircraft. The ball nose was cooled with liquid nitrogen to prevent it from melting during high-speed flight.
Behind the ball nose were the pitch and yaw reaction control jet nozzles. There were two nozzles on top of the nose pointing up and two on the bottom of the nose pointing down. There were two yaw rockets on each side of the nose. The twin jets in each direction were part of separate, redundant systems, one jet on each system. Thus, if one system failed for any reason, you still had the jet in the other system for control. The roll rockets were in the outboard wing panels, two on each wing. Redundant or duplicate systems are common on aircraft for safety reasons and are beginning to show up in automobiles for the same reasons. Dual brake systems on cars, for example, are the norm in this day and age and have been for some time. They were used in aircraft over 40 years ago. The nose landing gear compartment was located just behind the reaction control jet compartment.
The cockpit forward bulkhead was located just aft of the nose gear compartment. The cockpit compartment was an aluminum structure suspended inside the Inconel-X outer aircraft structure. The aluminum cabin, isolated from the outer structure to keep it cool, was sealed and pressurized to keep the cabin at a maximum 35,000 feet pressure altitude regardless of how high the aircraft flew. This level of pressurization prevented the pilot’s pressure suit from inflating during a normal flight. It was difficult to fly the aircraft with an inflated pressure suit, but it obviously could be done under emergency conditions. The cabin was pressurized with pure nitrogen. Nitrogen was used instead of air or oxygen to minimize the risk of a fire. The nitrogen environment was a pain in the butt, however, because we did not dare open our pressure suit faceplate. Although it is not toxic, nitrogen gas can be very deadly. One or two breaths of pure nitrogen will start an irreversible process of asphyxiation over which you have no control. I would occasionally tempt fate by opening my pressure suit faceplate to scratch my nose or wipe sweat off my brow, but I would hold my breath until I had closed my faceplate again.
The X-15 cockpit was quite roomy. In fact it was larger than the cockpit of most fighter planes that I have flown. The only feature that made it seem small was the raised portion of the canopy which contained the windows. The pilot’s head was enclosed rather snugly by the raised portion of the canopy. The pilot had good visibility straight ahead or laterally, since the windows were right next to his head but the wider fuselage below the windows restricted the downward vision. In order to see the runway during the unpowered approach it was necessary to roll over to a 60- or 70-degree bank. One very unusual thing about the visibility out of the X-15 windows was that the pilot could not see any part of the airplane. He could not see the nose, he could not see the wings—nothing. Normally, in an aircraft, pilots use the nose and the wings for attitude reference. In the X-15, all we had for a reference was the window frame—very disconcerting.
In addition to all the normal gauges, switches, levers, and controls, the X-15 cockpit contained an enormous ejection seat. The seat weighed 270 pounds. It had two large stabilizing fins that deployed after ejection, and two large telescopic booms that also
extended for seat stabilization. The ejection handles were large, beefy handles that pivoted out from the arm rests and locked the pilot’s arms and body firmly in place prior to ejection. Some metal leg restraints also clamped down on his legs during the ejection sequence to prevent the legs from flailing. In some ways that seat reminded me of a throne and in other ways of an electric chair or a chair designed for torture. The pilot was strapped in tight initially, but enveloped even further in case of ejection. I never did trust that seat to work properly. It was too complicated. It was designed to operate at speeds up to Mach 4 and up to 120,000 feet altitude, but few of the pilots really believed that. In case of an emergency, most of the pilots would have stayed with the airplane until it slowed down to lower speeds before ejecting. No pilot had to make that decision except perhaps Mike Adams. He may have tried to eject but we will never know. The evidence was inconclusive.
Behind the cockpit, there was a fairly large bay for instrumentation. We carried approximately 1,200 pounds of instrumentation for measuring things like airspeed, altitude, pitch rate, roll rate, yaw rate, control surface positions, tank pressures, wing bending loads, landing gear loads, wing leading edge temperatures. If it moved, we measured it. And if it did not move, we measured it to find out why not. The instrument compartment was big enough to hold a man. A couple of our flight planning engineers were almost serious about volunteering to ride in that compartment just to get a ride. It was pressurized, but other than that it was very inhospitable. However, I really think they might have tried it if they had ever had the opportunity.
The auxiliary power units (APU) supplied hydraulic and electrical power for the airplane. The APU compartment was behind the instrument compartment. In a conventional jet aircraft, hydraulic and electrical power would normally be provided by pumps and generators on the jet engine. The X-15 did not have an engine to generate this power, so auxiliary power units were required. These units were small steam turbine units. Highly concentrated (90 percent) hydrogen peroxide was forced through a silver catalyst bed to cause the peroxide to decompose into steam and oxygen. This steam was then directed through the turbines to drive the hydraulic pumps and generators.
At the Edge of Space Page 5
