_Muting the Cassandras_
A CENTRIFUGE is a large word to describe what is essentially a simple
piece of machinery. A centrifuge is a seat, cockpit, capsule, or
gondola mounted on an arm which whirls around at high speed. I have
often seen a low-grade centrifuge in an amusement park, mounted in a
vertical position. The people whip around in circles right-side up
and upside down, amid screams of delight and fear.
The armed forces have used horizontally mounted centrifuges for many
years to impose G loads on pilots for experimental purposes. When
the gondola whirls in its circle like a bucket of water on the end
of a rope, the pilot in the gondola goes through a series of tests
under severe G. Lights flick on which he is supposed to turn off,
and so on. In this way, the theory goes, the aero-medical officers
can determine man’s reactions and limitations under severe flight
conditions.
The largest and newest centrifuge in the United States, built by
the Navy, is located in Johnsville, Pennsylvania. The gondola is
mounted on a fifty-foot arm. The powerful engine which rotates the
arm from the centrifuge hub can accelerate from zero speed to 250
feet a second in a few seconds. The gondola can be tilted to almost
any angle (for additional tests), and by using cams in the position
control of the gondola, the gondola can be rocked gently or severely,
slowly or rapidly, simulating the motions of an aircraft in distress,
while pulling very high G.
From the beginning, we had been anxious to test the X-15 sidearm
control system under strong G loads. The sidearm control had much
merit (there is no real point in locating the airplane control stick
in the center of the cockpit; it was simply put there in the early
days of aviation and nobody bothered to change it), but I was eager
to see what happened, if anything, when it was operated by wrist
motion under the severe conditions for which it was designed. Thus I
proposed that we put a wrist control in the Johnsville centrifuge and
run some tests. It was a decision I lived to regret.
The Navy’s Aero-Medical Acceleration Laboratory at Johnsville, having
received little attention since inception, was overwhelmed by our
show of interest in their machine. They seized on the X-15 tests
like eager young starlets, and the first thing we knew we had a real
and, at times, disconcerting, show on our hands. After the engineers
rigged a complete X-15 cockpit in the gondola, I spent many hours
whirling around in that crazy machine. Later, the Navy engineers
ingeniously hooked the centrifuge to an electronic computer, which
fed back instrument readings to the panel in the gondola, somewhat
like our North American cockpit simulator. It then became possible to
“fly” the ship on various missions, not only with actual instrument
presentation, but also with theoretical G loads imposed on the pilot,
a fantastically sophisticated tool.
Most of these tests centered on that critical phase of the X-15
flight profile when the ship re-entered the “thick” earth atmosphere
to which we added several emergencies. This was the point, in theory,
when the G loads would be most severe and the temperature the highest
and flying the most difficult. There were many ways to approach
this atmospheric layer in the X-15. The pilot could enter lightly
and slowly, decelerating in the process, or he could dive straight
into it like a swimmer plunging directly into a pool. We favored a
“shallow” penetration, a gradual straightforward descent, such as
a commercial airplane might make on approaching an airport for a
landing.
It was important that the X-15 pilot be “lined up” almost perfectly
for this approach on the atmosphere. If he came in skidding
sideways--yawing--or nose-high--pitching--the re-entry could be
sloppy and subject the X-15 to unnecessary strain and motion; it
would cause high temperatures on areas of the ship not specifically
designed to withstand them. The X-15 nose contains a special “ball”
senser to relay yaw and pitch attitude to the instrument panel. If
the pilot is not lined up properly, he can re-align the ship with the
peroxide-rocket-ballistic controls on the wing and nose.
At Johnsville we conducted hundreds of re-entry tests, in most of
which the X-15 was made to approach the atmosphere under the worst
possible conditions--an extreme emergency. We brought her in cocked
sideways, with severe yaw and pitch angles--almost every way except
upside down and backward, and with failed damping devices. Obviously
under such circumstances, when the G loads approached the maximum the
airplane could stand, we had some interesting results in the gondola
cockpit. Pulling as high as nine or ten G’s, I was squashed into one
corner of the seat. I blacked out and my head fell to one side. My
eyes rolled up and the skin on my face was grotesquely distorted,
but the sidearm control worked beyond our best hopes, even in these
extreme conditions. All of these test runs were recorded by a remote
movie camera mounted in the gondola.
In their eagerness to call attention to their role in the development
of the X-15, the authorities at Johnsville took this movie film,
selected the worst possible frames, and patched them together as a
full-length documentary of their operation. They claimed to have
greatly influenced the X-15; yet we had changed nothing as a result
of the tests. The next thing we knew, the Johnsville people were
showing this film at various aero-medical symposiums and conventions.
Then the word began to spread that the X-15 pilot couldn’t stand the
re-entry loads. The fact that almost all the movie scenes represented
the X-15 in emergency, just short of the point of total destruction,
was not emphasized.
This kind of thing is inevitable, I guess. Specialists in their own
fields, not looking at the overall picture have cropped up all during
history. These people claimed that the steamship, the airplane, the
automobile, the atomic submarine, and who knows what else--perhaps
even the wheel--would fail. They are proved wrong time after time,
yet they reappear to frustrate dedicated people who are trying to
get things done. You may think the engine in your automobile is a
fine piece of machinery capable of operating for months without
repair. Yet I’ll bet I can find a specialist who has run extreme
tests on pistons who can convince you that your engine, under certain
circumstances, would disintegrate. So what?
Inevitably, as the X-15 neared completion, the effects of this
movie and other dire predictions, as well, began to take hold. The
specialists came after us in full fury. To offset this nonsense
I hit the road with charts, movies, and slides which laid out an
honest picture of the X-15 and its flight mission. In the months that
followed I attended no less than a hundred meetings, conventions,
symposiums, and other gatherings of so-called “experts” in various
fields. This “public relations” activity, an attempt at muting the
Cassandras, became a vital factor in the life of the X-15, not to
mention my own. Without it, it is possible that the ship might have
been talked out of existence.
* * * * *
One such problem that developed in the very early days was the
matter of radiation. It is well known that the layer of atmosphere
surrounding the earth provides a kind of umbrella for earthbound folk
against various energy emissions from the sun and space. Long ago a
group of experts began to predict that when man went higher, beyond
the protection of this umbrella, and came into direct contact with
these strong emissions, disastrous things would happen. The tiny,
invisible particles would bombard his body, causing his hair to fall
out, and ultimately bringing premature death from radiation disease.
The predicted altitudes at which these dire consequences would limit
flying moved higher as we flew airplanes and balloons higher and
higher. The meteorite scare followed the same pattern. Ultraviolet
and X rays caused some concern.
* * * * *
“Scotty,” Charlie Feltz said to me one day, “somebody here wants us
to tint the windshield of the X-15. You know anything about this?”
“Well, they tinted the X-2 windshield,” I said. “Tinting might keep
some of the glare out and maybe protect the eyeballs a little against
sunburn, but I don’t think it will make much difference as far as any
other radiation is concerned. I’ll look into it.”
We conducted experiments to tint the X-15 windshield. But they were
complicated by the fact that the X-15 windshield consists of two
layers of glass with a space between for defogging nitrogen gas. The
best we could get out of it was a piece of smeared glass full of
reflection and distortion. To be honest, we really didn’t put much
effort into the scheme.
By then, considerable high-altitude flight experience had been
accumulated by various people. Air Force Major David Simons had
soared to 100,000 feet in a balloon, and several Navy and civilian
types nearly as high, after first sending aloft a dozen-odd mice.
Dave didn’t seem to be suffering unduly, and his reports and data
did much to debunk the radiation myth. By that time, too, the U.
S. had logged considerable experience with the U-2 “high-altitude
research airplane,” designed to overfly the Soviet Union on
photo-reconnaissance intelligence missions. None of the U-2 pilots
were losing their hair--at least not from radiation. Much later, of
course, one of our satellites discovered the Van Allen radiation belt
deep in space. But this layer of cosmic particles is too far out for
the X-15 or earth-orbiting capsules. Deep-space travelers en route
to the moon may have to thread through the belt, like a submarine
through a minefield, but it is a long-range problem, and definitely
not an insoluble one.
“Charlie,” I reported, “this radiation is a lot of bunk. To hell with
trying to tint the windshield.”
“If you say so, Scotty,” Feltz replied.
“Just make damned sure those windshields don’t ice up,” I joked.
“This airplane is not designed to be flown blind.”
* * * * *
Zero G, or weightlessness, which a pilot will experience in flights
beyond the appreciable pull of the earth’s gravity, first came up
with force in early 1950 during a meeting of “space” experts. Some
serious scientific questions were raised. For example, would the
fluid in the inner ears “float” and cause critical disorientation?
How could a man drink water? With no pull of gravity to take it to
his stomach, might he not drown? And so on.
Weightlessness is the one condition we cannot simulate on a machine,
such as the centrifuge, located on the face of the earth. The nearest
we can get at present is to fly an airplane on a parabolic curve,
during which time the airplane, for a variety of complicated reasons,
very briefly becomes apparently disengaged from the pull of gravity.
Chuck Yeager was one of the first pilots in the country to try this
experiment. As early as 1950 he flew weightless trajectories in a
jet airplane for periods of about thirty seconds. He reported slight
disorientation and slight nausea.
I was curious about this because I was then preparing for the
Skyrocket flights which would take me on a parabolic flight-path
at, or close to, weightlessness for a brief period. I took an NACA
F-84 jet and flew about fifty weightless trajectories. I suspended
a pencil on a string in the cockpit to check that I was really
weightless. When the pencil floated and the string slackened, I knew
I had achieved the desired result.
Not once during these fifty flights did I experience any undesirable
effects or dangerous disorientation. As a matter of fact, I rather
enjoyed the sensation. It was fun, like riding a roller-coaster.
Occasionally during the weightless portion of the flight, my
weightless arm would overreach. But soon I adjusted to this and
piloted the airplane without mishap or discomfort. Sometimes I flew
the trajectory upside down. On three occasions during the recovery
from this maneuver, when the airplane was rotating about three axes,
and building from zero to a high G level, I felt weird, as though I
were going into a loop, quite similar to the common experience of an
accelerating or decelerating centrifuge. But this was due, I knew,
solely to the recovery maneuver, not the zero G condition. I wrote a
report down-playing the effect of zero G.
Unfortunately, my notes from these flights actually served for
years as a rallying point for the zero G doom-criers. Some experts
seized on the three inverted-recovery disorientations and trumpeted
them throughout aero-medical circles. I tried my best to curb these
charges, but the truth never caught up. It still hadn’t caught up
when I joined the X-15 project. It was well known that the X-15 pilot
would experience about three to five minutes of weightlessness on the
altitude trajectories. These experts predicted alarming consequences.
To me this was nonsense, if not downright scientific dishonesty.
And it really irritated me to realize my own flight notes were
being used to foster this untruth. I believe people are affected
by weightlessness somewhat as they are by motion sickness. Some
people become air-sick and disoriented; others don’t. Any pilot,
especially a test pilot, will be able to adjust to short durations of
weightlessness in the X-15 or any other sub-orbital space craft.
A prolonged period of weightless flight may be another story
altogether. I don’t know what will happen to spacemen orbiting the
earth for a matter of days. New ways of “forced” eating will have
to be developed. In fact, the Air Force has already come up with a
toothpaste-tube method of injecting water into a weightless body, and
other innovations. Just what effect prolonged weightlessness will
have on the heart, urinal tract, and other vital organs of the body
where moving fluids are located, is a mystery. Thus I quite agreed
with Air Force General Don Flickinger’s MIS aero-medical proposal
to orbit man for progressively greater durations. But I strenuously
fought off any suggestion that the X-15 might be compromised because
of short periods of weightlessness. And I stubbornly resisted the
flight surgeons who proposed “instrumentating” the X-15 pilot’s body,
so that they could listen in on his heart, respiratory system, and
so on. The line must be drawn somewhere.
* * * * *
“Here we go again,” Charlie Feltz moaned one day.
“What is it now?” I asked.
“The low L over D on landing again,” Feltz said. “They’re worried
about it.”
The L over D, or sink rate, of the X-15, I have related, was a
controversial matter from the outset. We all knew the ship would come
in for its landing hot, and falling like a brick. The landing would
be tricky, with little margin for error. But we had concluded long
before that it was well within the capability of a qualified pilot.
It was astonishing to have this matter come up again so late in the
game.
The L over D ratio of the X-15 was about two or three to one. In
other words, for every two or three feet it moved ahead in the glide,
it would drop one foot. During my days at NACA, Edwards, I had made
many low L over D landings. For example, we had made tests in the
X-4 with speed brakes open, calculating the L over D to be less than
three to one. The L over D of the horrible XF-92-A on a dead-stick
landing was about three to one. The L over D of the Skyrocket, which
I flew almost routinely, was about five or six to one.
To lay this matter at rest once and for all, I organized a special
flight-test program to simulate the X-15 sink rate. I found that if
I landed an F-100 with engine idling, dive brakes and gear extended,
and a drogue chute deployed, I could come close to approximating the
X-15 landing glide-path. At Edwards I made hundreds of such landings.
Later I came closer to the real thing by shifting to an F-104. With
the engine idling, the dive brakes extended, and the gear out with
landing flaps down, the F-104 and an L over D of less than three to
one. I demonstrated this simulated X-15 landing scores of times at
Edwards. Even so, some Cassandras remained, bleating in the wings.
These demonstrations to prove that any experienced pilot could land
the X-15 were important for a number of reasons, the biggest of which
we were not then free to discuss. The safe landing was a vital
plank in our case for the _advanced_ X-15. By the fall of 1957 we
had progressed far with this dream--to the point of making drawings
and adding up figures. As a matter of fact, our preliminary design
section had conceived an advanced X-15 which, with powerful boosters,
such as a cluster of Navahos, could be put into _orbit_. We called
this dream craft the X-15B, but we were under orders not to discuss
it beyond the confines of our secret workshop. Stormy was afraid that
if we did the men in white coats would come after us.