“_The Real Significance_”
The big single-barrel XLR-99 rocket engine designed to blast the X-15
on its ultimate mission to the fringes of space arrived in California
in April, 1960, about a year and a half behind schedule. It was
shipped to Edwards and bolted to the ground-test stand. During May
the North American and Reaction Motors engineers ran the engine in a
series of exhaustive tests. It was a sight to see: that small barrel
spewing smoke and flame, thrust almost four times as great as the
combined thrusts of the two smaller X-1-type engines then powering
the X-15. The rocket-engine noise boomed across the desert for thirty
miles.
In late May the first big engine was installed in X-15 number three,
the ship we had specifically reserved for this first engine. And in
early June X-15 number two, after my ninth and final powered flight
in that craft, was torn down and the two smaller engines removed in
preparation for the arrival of the second big engine. Meanwhile, we
got set to ground-test the big engine which was installed in number
three.
The ground tests of this engine, which has as much power as an
Army Redstone missile and almost three times the power of the
Navy’s Vanguard missile, were elaborate for Edwards (though stark
compared to the blank-check missile operations). We had made some
improvements on the ground-test stand. The engineers had built
special steel clamps to hold the X-15 to the concrete apron. They
had installed underground concrete observation bunkers, which looked
like Maginot-Line pillboxes. The telemetry engineers rigged elaborate
equipment to transmit a record of everything happening in the X-15
during the engine run to a master console in the NASA administration
building. For this big moment in the history of our craft, nothing
would be left to chance.
Late in the afternoon of June 8 I arrived at the ground-test area
wearing street clothes. X-15 number three, with her powerful new
engine, was clamped in place on the stand. She was brimming with Lox
and new fuel for the big engine--ammonia, more powerful or “exotic”
than the Walc used in the two smaller engines. A thick coating of
ice had formed on the fuselage around the Lox tank. Wispy Lox vapor
trailed off into the afternoon sky. A snarl of electrical power
connections--the umbilical cords--ran from a hole in the concrete to
the ship’s side tunnels.
Harry Gallanes, North American’s power-plant test boss, greeted
me: “Looks like we’re all set, Scotty.” He and his crews had been
working without let-up since dawn. They had pretty much kept to this
dawn-to-dusk (sometimes later) schedule since the day the big engine
arrived, another manifestation of that curious enthusiasm for things
mechanical which seemed to infect all members of the flight-test team.
I climbed into the cockpit and donned a Scott Airpack breathing
device similar to the unit skin divers wear underwater. It would
supply my oxygen, pumped into the airplane from an external
connection. The simple airpack was more comfortable and far less
bother than the X-15 full-pressure suit, which I did not need on the
ground. I closed the canopy and turned on the nitrogen gas flow,
to cool the electronic equipment in the cockpit and to build up
a pressure which would block out possible ammonia fumes or other
toxicants, should something go wrong during the engine run.
On this ground test--my second in this airplane--we intended to
simulate all the events of a real drop from the mother plane with
rocket-engine light-off. If all went well, we hoped to make an actual
flight a month later, perhaps sooner. Harry Gallanes and his men
retired to the bunkers. Gallanes manned the radio circuit as test
director. Q. C. Harvey took up his post in the forward bunker. Soon
we were well through the countdown. At six minutes to “drop” I turned
on the APUs. X-15 number three was completely on her own. It was time
for the big test.
A siren whined a warning. The mechanics, protectively dressed in
hooded clothing, evacuated to the bunkers. They had been hanging
around checking for leaks or other possible malfunctions until the
last moment. A group of fire trucks, parked about two hundred yards
away, were ready to rush to the rescue, if needed. Otherwise there
was no sign of life. Alone in the cockpit I checked the gauges. As
we approached the time for engine light-off, three movie cameras,
mounted outside and aimed at the rear of the X-15, began to roll.
Inside the cockpit I turned on the data recorders.
I called each step of the engine-start procedure on the radio,
pausing briefly after each item on the check-list.
“Master switch coming on NOW.”
“Prime.”
“Pre-cool.”
“Pump idle.”
“Igniter idle.”
I then moved the main engine throttle from its stowed position to
the engine-start position. The engine is designed to light-off at
half-thrust. When I moved the throttle, in effect opening the main
fuel and Lox lines, the engine cracked to life with a tremendous
roar. The ship vibrated powerfully in her steel mounts. The engine
ran smoothly as designed. Slowly I opened the throttle to full power.
The noise was terrific.
The North American X-15 Mach 2.0 speed and 100,000-foot altitude
restrictions are still technically in force. If I allowed the big
barrel to run full-bore in flight, I would quickly exceed those
limits by a great margin and perhaps go hurtling off to the fringes
of space. Thus for my big-engine “demonstration” flights we had
worked out a system whereby in the air I would shut down the engine
periodically and restart it after the speed and altitude fell off.
Now simulating my actual flight plan, I pulled the throttle back and
shut down the engine. As prescribed, I waited fifteen seconds and
then restarted the engine at fifty per cent thrust.
Rocket engines are equipped with special engine safety devices.
If these devices “sense” anything abnormal in burning or engine
operation, they automatically shut the engine off and “safety” all
the electrical circuits. Evidently after my restart one such device
“sensed” a vibration. Almost immediately after I moved the throttle
to half-thrust, the engine shut down automatically. There was no sign
of trouble in the cockpit, so I prepared to restart the engine once
again.
To restart the engine after an automatic shut-down, the pilot must
push a special switch which “unsafeties” the engine, or in effect
resets all the circuits the automatic device has closed down. If
these can be reset, the engine is again ready for start. Beginning
the restart procedure, I put the throttle in the stowed position and
pressed the reset switch.
It was like pushing the plunger on a dynamite detonator. X-15
number three blew up with incredible force. The rear section of the
airplane, from the trailing edge of the wing aft, was instantaneously
demolished. The front section of the airplane, including the
cockpit and the pilot, hurtled twenty feet across the concrete ramp
at indescribable speed, the shortest and fastest rocket ride in
history, subjecting me to an acceleration force of maybe fifty G’s.
Fortunately, my head was reclining in the headrest on the seat;
otherwise my neck might have been broken.
Nine hundred gallons of ammonia and sixty gallons of hydrogen
peroxide, a total of 16,000 pounds of powerful liquid, had ignited
simultaneously. I knew, of course, that there had been a tremendous
explosion, but I had no way of knowing precisely what happened. All I
could think of was the possibility of a second explosion that might
hurl my part of the airplane halfway across Edwards and through the
main hangar and workshop. In the cockpit I moved swiftly to do what
I could to prevent this. I turned off the APUs and all external power
supply and shifted from external oxygen to X-15 oxygen supply. Then
I braced my feet on the instrument panel and put my arms across my
face, waiting. There was no panic, no fear. I was concerned primarily
for the safety of the other people--those outside--and I thanked
God that He had given us the time to install the concrete pillbox
bunkers, which were being used tonight for only the second time.
Half a minute later I watched a mass of red approaching the X-15. It
was the fire truck. Its hoses pumped a great spray of water over the
ship, smothering the fire still raging in the shattered rear section.
A few seconds later I saw Art Semone and another mechanic hunched
outside the cockpit. They were trying to pull the canopy handle to
let me out. At that point I would have preferred to remain inside
the cockpit, one of the safest places in the world in the event of
fire. But I could see that no amount of hand-signaling would dissuade
Semone, and rather than expose him to possible danger I helped open
the canopy and leaped out.
Semone must have thought I was injured. When I jumped from the
cockpit, he caught me in mid-air and tried to carry me out of the
smoke and flames. I whopped him on the shoulder to let him know I was
all right and then we all ran quickly to a spot about a hundred feet
distant and I checked the bunkers. Everyone, it seemed, had survived,
and for this I was very grateful. As it turned out, no one, including
me, was even slightly injured. I had someone relay that fact to Alice
as soon as possible, knowing the news would be on the radio before
the fire was out.
* * * * *
The documentation of that explosion, like everything else about
the X-15, was first-rate. In fact it was probably one of the best
documented airplane accidents in history. Immediately afterwards,
Q.C. gathered all of us in a room, and there we recalled in detail
all that we could remember while it was still fresh in our minds.
These eye-witness accounts, added to the miles of telemetry data and
the film strips from the three movie cameras, would enable us to
establish the cause of the explosion very quickly. It was not the
fault of the engine. A sequence of coincidences, again hidden in
the mysteries of Murphy’s Law, had trapped us. We moved rapidly to
avert any possibility of a recurrence in X-15 number two, meanwhile
accelerating our efforts to install the big engine in that ship.
NASA prudently grounded X-15 number one until we could do everything
possible to make sure a similar disaster could not happen.
The fate of number three was quickly decided. She would be rebuilt.
Some parts--nose, cockpit, wings--might be salvaged. This was
obviously a major task requiring more time and money. The destruction
of this airplane is simply part of the price man must pay for
progress. Measured against the loss of fifty or so Atlas, Titan, and
Polaris missiles at Cape Canaveral, each costing more than a single
X-15, it was a drop in the bucket, although a painful one because
it temporarily reduced our complete air fleet by thirty-three and
one-third per cent.
Inevitably the newsmen got on my trail. When they called, I was ready
with the wisecrack I knew they wanted. “The only casualty,” I said,
“was the crease in my trousers. The firemen got them wet when they
sprayed the airplane with water.” Too late I realized how this might
be interpreted.
“Are you sure it was the firemen?” the reporter asked.
“Yeah, I’m sure,” I said. I pictured the headline:
SPACE SHIP EXPLODES; PILOT WETS PANTS
“Mr. Crossfield,” the reporter went on. “What is the real
significance of all this?”
“The _real_ significance?” I asked. “Have you got about ten or
fifteen hours, maybe?”
“No,” he said. “I’ve got about two minutes to meet a deadline.
Just tell me what’s going to happen now? Where does this leave the
program?”
“We’re not sure yet. There will naturally be some investigations.
In all probability we’ll accelerate putting the big engine in X-15
number two. A little later we’ll put the big engine in NASA’s X-15
number one.”
“Does this affect your role in the program? Will you still go ahead
and make a demonstration flight with the big engine?”
“I don’t know,” I said. “I was only supposed to make one or two
low-speed demonstration flights with the big engine and then that was
the end of my participation in the project. Bob White and Joe Walker
would take it from there. They might change that now. I have no
reason to believe there will be any change. There could be. I might
not make the big-engine demonstration flights. I honestly don’t know.
It’s all very indefinite.”
“Well, thanks. Some day I’d like to talk to you about the real
significance. But not now.”
It was always the same: hurry, impatience, no time for thoughtful
reflection. Move on quickly to the next story, the next pilot, or
missile, or space vehicle, for a bigger and better headline.
“Okay,” I said. “I’ll be seeing you.”
* * * * *
The real significance of the X-15, I hope, has come through in the
foregoing pages. It is not just another airplane, another headline.
It is another of man’s restless attempts at perfection, and in the
aviation world the greatest ever mounted. The X-15 sprang from a
deep pool of aeronautical knowledge, the end product of fifty years,
and more, of probing this frontier. It was created and built at
tremendous cost in terms of money and sweat by some of the most
skilled engineers in the free world. As always, we did not achieve
our dream of perfection. Only God, I believe, can create the perfect.
But in reaching out, we provided some water for man’s never-ending
thirst. We learned a great deal. We had set man on his path toward
the stars.
Some day, I believe, he will get there. Not so quickly as one
might think from reading the newspapers. The speed of this massive
scientific effort is like that of the convoy, geared to the pace
of the slowest vessel. Thus this daring adventure is regulated not
so much by grandiose plans emanating from the increasing layers of
scientific administrators in Washington as by the simple function of
a valve, an APU unit, or a radio plug. Our tale of adversity with
the X-15 is not unique; rather, it is typical of our age. Similar
stories, many with fewer points of success, were taking place at
the same time in our nation with Atlas, Polaris, Titan, Mercury,
Minuteman, a dozen others I cannot recall. Some day, too, perhaps
these stories will be written.
In time, our splendid engineers will de-bug the big X-15 engine. I
may or may not be allowed to make one or two low-speed flights. Then
in the months ahead, depending on the speed of the scientific convoy,
Bob White or Joe Walker or perhaps someone else will begin the first,
tentative “space” flights in the X-15. They will launch over the
designated point in Utah, light off the powerful rocket barrel, and
roar heavenward. With God’s help they may reach a speed of 4,000
miles an hour and an altitude of perhaps 100 miles. I hope that
many, many pilots will have the opportunity to make these pioneering
voyages into space.
Ultimately our work, and the work of the tens of thousands of
other engineers in this nation, will be merged to form a more
advanced space machine. The bottom of this machine might not look
like an Atlas or Saturn. The top might not look like an X-15.
But the complete vehicle will be the sum product of all the work
of all the engineers in this country. This machine will not rise
effortlessly and gracefully from the earth on the first day.
Dedicated people such as Charlie Feltz and Harrison Storms must
first expend limitless sweat and tears. The machine may crash and
explode. So might the second and third, perhaps the fourth and
fifth. Congressional committees will investigate, and new layers of
scientific administrators will grow atop the old in Washington. But
the engineers will prevail in spite of them.
Some day this machine will rise from the face of the earth. It
will take man into an orbital path about the earth. It will enable
him to build a space station. From there he will shove off to the
moon. Then he will go to the nearest planets in our solar system. A
hundred years from now, if we have not destroyed our own planet in an
ideological war, man may enter the solar system of the nearby stars.
He will go there because he must. He is curious and intelligent. He
is seeking answers--about himself, his universe, and his God. Because
man is a creature of God and the instrument of God, he will not be
denied. There will always be another dawn.