The plane would climb with its jet engine, assisted by the two rocket tubes in take-off only, until 40,000 feet. May would then fire all four tubes to make his high-speed run.
He was ready for take-off; he gestured, the crew stood back, and the engineers and technicians ran for the cars standing by. They started the motors so they could follow alongside the plane during take-off, watching the tail for a successful rocket “light.”
A roar and she rolled rapidly, picking up speed, the green cars barreled alongside her at close to 100 miles an hour for over a mile of the lakebed. Into Carder’s car the pilot called, “Okay, I’m lighting one.” A 20-foot streak of orange fled into the air.
Carder called back, “One is good.”
And immediately: “Here goes two.”
A second orange streak shot out, Carder saw it and said close into the mike, “Two is good.” The blast from the rockets jolted the moving cars and the plane was still eating up the lakebed, far ahead of us now. Another quarter of a mile and the Skyrocket began to shed the ground; hanging heavily over the desert she reluctantly rolled a bit, the gear went up. I tensed with the pilot in the ship; if anything went wrong at this moment – that would be all! The seconds went by and she gathered speed, rocked obediently over and began the steady climb up. The sky held, only for a few more seconds, the two bright spots with the chase pilot diving to catch up . . . and then the planes were absorbed into the distance.
Scott Crossfield’s engine explodes
The US government’s research program into rocket-propelled aircraft made its tests at Edwards Air Force Base (formerly Muroc Army Air Force Base). Between 1950 and 1955 Scott Crossfield flew nearly all of the experimental aircraft under test at Edwards. These included the X-1, XF-92, X-4, X-5, D-558-I and the Douglas D-558-II Skyrocket. On 20 November 1953, he became the first man to fly at twice the speed of sound.
NACA was primarily concerned with research and did not usually try to break records, although in the case of Mach 2 it was allowed to make an exception to gather the research data.
In 1988 Crossfield described many of his experiences, including the value of the experimental aircraft program:
The research airplane program was probably the most successful government research program on record. It involved about 30 airplanes for 30 years, running from 1945 to 1975, and probably produced almost all of the information that has been essential to our transonic and supersonic flights, our transonic transports, and our space program.
Crossfield described the purpose of the X-1 program:
The X-1 was the first of the research airplane series – post-war research series. Its primary purpose – or its sole purpose – was to see if we could, in fact, exceed the speed of sound with a manned aircraft. There were a lot of people who said that we could not. And a lot of reputable opinions that said that we could.
It was very simply designed. It was an airplane that incidentally was patented by Bob Wood in 1945. It used an RMILL4 engine which was the beginning of our successful rocket era [and was] developed by the Navy and Bob Truax. The all-point simplicity and design – and the objectivity and design – made it very successful. It did accomplish its end of flying supersonically in 1947, of course, [we all know] with Captain Charlie Yeager at the controls.
The design of the D-558-II Skyrocket became the standard model for swept-wing aircraft. Crossfield commented:
The D-558-II was one of the research airplanes funded by the Navy. That is the reason that it did not have the “X” designation.
It was primarily the review to look at what the transonic effects of the swept-wing would be. With it we flew some several hundred flights and wrote the book on how we could design and build modern swept-wing airplanes. It proved many of the things that we have learned since then.
The D-558-II was a very productive airplane. Almost every airplane in the air today has a little bit of the D558-II basic information – or what we learned from it – in it.
Crossfield gave a specific example of this:
It has been well known for many years that a characteristic of swept-wing aircraft is instability at high angles of attack. With the D-558-II, we learned many many ways to relieve that instability so that we could get the handling qualities that pilots need to fly airplanes in a commercial environment. Handling qualities . . . engineering ease for controllability . . . [are all] desirable characteristics.
Test pilots, like Crossfield, often had to fly several different experimental aircraft during a single day. Crossfield described such a day:
In the days of the research airplane program, things were somewhat different than the bureaucracy that we find ourselves in today. For instance, there could be a day where I would do an X-1 launch early in the morning, fly the X-4 over lunch hour, and do a D-558-II launch in the afternoon. That was not a typical day, but there were days of that type. We were very versatile in our operation in those days.
Crossfield gave his impression of the different handling characteristics of the X-1 and the D-558-II:
Well, I flew both the X-1 and the D-558-II. They were quite different in their flying characteristics even though they were both pretty good flying airplanes. [They were not] . . . necessarily as good as we would like to see because they were experimental.
I am often asked what goes through your mind when you are flying these airplanes? The answer has to be that you do not have time to [ponder] philosophical considerations of what is in your mind. You are concentrating all of your capabilities on the job at hand.
The basic shape of the X-1 came from the .50 calibre bullet. Crossfield:
When they were designing the X-1, we did not have the capability to do wind tunnel testing transonically. So they made a very good . . . decision. They made the forebody of the X-1 shaped like a 50 caliber bullet which was a well-known supersonic projector at the time.
It was [that kind of] judgmental design characteristic that was essential at that time; but we had no way to test [it]. And that is the sole reason for the research airplane program. We had the capabilities with engines to speeds and altitudes; [but] we had no capability to test. We did not know how to analyze, so flight test was the only way.
Crossfield described the development of the X-15, including discussions with Walt Williams:
Well, as I remember the genesis of the X-15, one time coming home from a fishing trip with Walt Williams (who was my boss at NACA) . . . We heard on the radio that a 75,000 pound thrust Viking rocket engine was successfully fired at Santa Suzanna. Of course nothing would do but I got a piece of paper out of his glove compartment and we decided what we could do to man a plane with a 75,000 thrust rocket. That became the X-15. We gave that idea to Hilbert Drake who developed it in 1955. In that year the X-15 went under contract.
Crossfield described what they were trying to achieve at that stage of X-plane development and how it contributed to the drive toward space and eventually hypersonic travel:
The research airplane program’s primary goal was to develop technology that we could put to useful purpose – supersonic high-speed aerodynamics . . . We had plans to take us [all the way] into space. That was part of the long-range goal for the research airplane program. Unfortunately, that got diverted by many other circumstances.
The productivity of an airplane is gauged by its speed times its payload, divided by its fuel consumption. The way to get that productivity is to go fast. And the way to go fast is to go high. With the engines that we were developing in those days, we were trying to find out what it took to go high so that we could go fast and get the productivity that we needed for the air transport as we saw it at that time – and the way we see it today.
Unfortunately, we took a moratorium on that development for some years; but we are back on track today with the National Aerospace Plane, which is nothing more than an extension of the very successful research airplane program.
On his third flight on the X-15 Crossfield ran into longitudinal instability with
pitch oscillation. Crossfield described his actions in the cockpit and how he responded to the problems with the aircraft:
Well, the checkout in the X-15 was rather abrupt in that, on our first flight, we flew it as a glider alone. That gave me three minutes and fifty-eight seconds to learn how to fly the airplane and bring it in for a landing.
On the approach and landing, I had a control problem that really turned out to have a very simple solution. But the airplane, for all intents and purposes, appeared to be unstable and pitched to me, which meant that it was very difficult to control it. The pitching oscillations got very high and I had to figure out a way to get the airplane on the ground at the bottom of the pitching oscillation so that it would not wrap up in a ball of metal.
As it turned out, I succeeded. However, I landed at 140 knots instead of my anticipated 174 knots.
Crossfield described how they adapted the controls to enable the pilot to handle the aircraft when it was in violent motion:
With the X-15 we anticipated that there could be some rather violent motions on re-entry or in some of its maneuvers. One of the difficulties with flying the high speed jet aircraft with the powerful flight control systems is that the man’s arm gets into the thing. The weight of his arm feeds the action of the airplane. That is the so-called “JC Maneuver.”
For the X-15 to preclude that possibility, we made a control system such that [the pilot] could put his arm into a rest that would resist all of these external forces and control the airplane only with the movement of his wrist. With the axis of control being in this manner – with the roll control – we made it so that it could roll on the armrest . . . So we took all of this spring and mass system – [the pilot’s] arm out of the control system – to make it a very precise control system. It was part of the design of that system that [caused] the problem I had on the first landing. And it was easily correctable.
Crossfield commented on the distinction between pilots and “test pilots”:
Well, we keep talking about test pilots but there is no such thing as a “test pilot.” There are all kinds of people. There are tall people, small people. Some of them are functionally illiterate and some are intellectual. Some are moral. Some are immoral. They are all just people who incidentally do flight tests. It is a profession just like anything else. There is not, to my mind, any common thing called a test pilot.
The opportunity to be a test pilot . . . is there for all – and probably within the grasp of most. In my mind, we should divest ourselves of this idea of special people [being] heroes, if you please, because really they do not exist.
Crossfield described how his experience has been applied to contemporary aircraft:
At one end of the jet airplane era – with very powerful control systems – we found that the [pilot’s] arm began to become an important part of the inertia. As we got into the jet era and high-speed flight – the very powerful control system that we had – we began to see the effects of a man’s arm on the control stick having an effect on the airplane as the forces on his arm varied.
With the X-15, we anticipated . . . some of the violent maneuvers [on re-entry] that could probably cause us some problems. So what we did was design a sidearm controller to preclude any input from his arms. It consisted of an armrest that you could hold your arm down on so that the only thing that was involved in the control of the airplane was the rotation of the wrist, with the pitch axis being . . . through that point and rolling your arm on the armrest. As a consequence then we could take all of that spring and mass system out of the control system. This proved to be a very useful development that we now find very often in our current-day fighters which would have had the same problems if they didn’t go to something of this nature.
Also, that sidearm control was a contributor to the problem that I had on the first landing and we corrected that quite easily.
Crossfield described what happened with the ground test on the first XLR99 engine. He explained why he was in the cockpit when the engine exploded and what happened to him:
When we installed the large engine on the X-15, [because of] our flight test plan we were going to demonstrate that the engine could be started. It could be throttled from 50 to 100 percent as designed on the first flight. The way that we were flying, I was limited to the speeds that I could allow the airplane to get so it took a very precise engine-on-off and thrust program to stay within that flight plan. To make sure that all of the systems would respond to this plan we made the last test of the engine on the airplane on the ground.
This is kind of humorous because the pilot gets into the airplane to run the engine. Everybody else gets into the block house. That is called “developing the confidence of the aviator.” In doing that run, we had a propulsion system failure that was born of something unique to the ground run that caused the airplane to blow up. About 1,000 gallons of liquid oxygen and 1,200 gallons of . . . and 800 pounds of 98% hydrogen peroxide got together and did their chemical thing. It was a pretty violent activity for a moment or two. It was like being inside the sun. It was such a fire outside that it was a very brilliant orange. The fore part of the airplane, which was all that was left, was blown about 30 feet forward – and I was in it. Of course I was pretty safe because I was in a structure that was designed to resist very high temperatures of re-entry flight.
Crossfield explained how he became a test pilot:
Well, I am an aeronautical engineer, an aerodynamicist, and a designer. My flying was only primarily because I felt that it was essential to designing and building better airplanes for pilots to fly. My professional endeavor really was more in that line than being a pilot per se. It was part of the whole circumstance of designing and building airplanes.
Chapter 2
Rockets Away – Escape from Earth
From the Second World War to the space race
On 8 September 1944 a German V-2 rocket hit Chiswick, West London. The V-2 was a ballistic missile known to its engineers as Aggregate-4. Nazi propaganda minister Joseph Goebbels announced it as Vergeltungswaffe-2 or V-2, the second in a series of “vengeance weapons”, the first being a robot jet plane known as the V-1. The V-2 was fuelled by liquid alcohol and liquid oxygen (LOX), weighed 14 tons and carried 1 ton of high explosive.
The V-2 was designed by a group of German scientists led by Wernher von Braun. As a youth von Braun had been inspired both by science fiction and by the theories of Professor Herman Oberth. Like other German scientists he had been impressed by the 1926 Fritz Lang film The Woman in the Moon and by Oberth’s The Rocket into Planetary Space (1923). He joined a group of like-minded enthusiasts who formed an amateur rocketry club, the Verein fuer Raumschiffahrt: VfR (Space Travel Association).
Inspired by Oberth’s theoretical arguments, the Germans in the VfR conducted numerous static firings of rocket engines and launched a number of small rockets. Meanwhile, in 1931, the German Army inaugurated a modest rocket development program, hoping that rocketry could become an extension of long-range artillery. The program employed several of the VfR members.
The German Army’s ordnance ballistic section was interested in long-range bombardment weapons which were not forbidden to them by the Treaty of Versailles (1919). Under the terms of this Treaty, which had been concluded at the end of the First World War, Germany’s military power was strictly limited, but in 1919 rockets had not been considered to be serious weapons so they weren’t forbidden.
Von Braun was encouraged to continue his studies, completing a degree in aeronautical engineering in 1932 and a Ph.D two years later. His thesis was on rocket engines and was classified as a military secret.
After the Nazi party gained political power in 1933, von Braun’s rocket team continued their research. While Germany rearmed itself von Braun’s rocket team developed larger, longer ranged liquid-fuelled missiles. In 1939 the air force, the Luftwaffe, funded a joint service rocket research centre at Peenemunde and gradually overcame the basic problems of rocket engineering: flig
ht stability, fuel management, steady combustion pressure, engine cooling and guidance. The commander of the army, the Wehrmacht, granted the Peenemunde centre additional funds and personnel so that they could produce a prototype operational missile, which should be able to carry 1 ton of explosives to a target 180 miles away. This was achieved on 3 October 1942. After an air raid (17 August 1943) on Peenemunde, production of the V-2 was removed to a secret location in the Harz Mountains.
By January 1945 it was clear to the German rocket scientists that Germany would lose the war and von Braun called a meeting to discuss to which Allied power they should offer their expertise. He said, “Let’s not forget that it was our team that first succeeded in reaching outer space. We have never stopped believing in satellites, voyages to the moon and interplanetary travel.”
He organized the escape of his team and their technical archives to the advancing US forces and on 2 May 1945 they made contact. The Americans responded with an effort called Operation Paperclip. This secured the Germans’ technical archives and parts for 100 V-2 rockets, which were taken to the USA.
The Soviets also recognised the value of German rocket designers and recruited some themselves, among whom was Hans Endert. He told Reg Turnhill, the BBC correspondent, after he heard that von Braun had gone over to the United States: “Knowing that the Americans knew everything, I had no scruples about helping the Russians because they offered me a decent salary and food rations which I could get nowhere else.”
The Soviets were aware that their former Allies had significant advantages in long-range bomber aircraft, so to counter this they were interested in developing long-range ballistic missiles. The Soviet leader, Joseph Stalin, imagined a more powerful version of the V-2, armed with a nuclear warhead. They set up a German engineering team under Helmut Grottrup at a base north-west of Moscow where they were to develop their own intercontinental ballistic missiles (ICBMs).
The Mammoth Book of Space Exploration and Disaster Page 4