Category Space Ship One

SpaceShipOne has a space-qualified environmental control system (ECS). Its pressurized cabin has room to fit three people. The pilot sits up front in the nose, and behind him and up against the pressure bulkhead is a row of two seats for the passengers.

The pilot and the passengers sit upright but slightly reclined, as shown previously in figure 4.5. This helps them tolerate the g-forces they face during the boost and reentry phases of the mission. They do not have to wear spacesuits or g-suits, but SpaceShipOne has an oxygen system with oxygen masks for them to wear.

The backseat row is less than 2 feet from the oxidizer tank, but the pressure bulkhead separates the cabin from the oxidizer tank and the rest of the rocket engine. The dome shape of the pressure bulkhead is necessary. “These shapes are real important as pressure vessels,” Rutan said. “And it is pressurized all the way to the nose. There is not another bulkhead up in front.”

For test flights, the pilot pressurized the cabin to 4,000—6,000 feet (1,220—1,830 meters). An airliner sets the pressure inside its cabin to about 8,000 feet (2,440 meters). This means that no matter how high or low it flies, the passengers inside will always feel a pressure equal to what they would feel if they were standing on a mountain with a height above sea level of 6,000 feet (1,830 meters).

The cabin was sealed but did have a small amount of leakage. The pilot watched the cabin altimeter, which was used to measure the cabin pressure, and manually adjusted it as necessary.

SpaceShipOne does not have its own heating or cooling system. During captive carry, however, the vehicle was heated by bleed air from White Knight’s engines, which pumped the hot air to the pressure bulkhead. The cabin temperature did not change by more than 15 to 20 degrees Fahrenheit from the time the door was closed on the ground. Again, the short duration of the mission really played to Rutan’s design principles of simplicity and low construction cost.

At low altitudes, the pilot could get fresh air by opening two 4-inch (10-centimeter) plugs located on either side of the fuse­lage. Similar to the design of airliner doors, the plugs open inward and are beveled, like corks, so that the high pressure inside the cabin helps keep them closed tight and prevents opening at high altitudes. “You didn’t need cooling,” Doug Shane said. “You could keep the airplane cool on the ground with the [external] air con­ditioner. Once you took off, you could wait to put the plugs in until you were at 10,000 to 12,000 feet [3,050 to 3,660 meters], where it is pretty cool.”

The plug on the pilot’s right-hand side has a safety pressure relief valve that could be capped in case it failed. The other plug has a manual ball valve that opens to dump the pressure in the cabin if necessary. This plug also has a big tab riveted to it. In an emergency situation where the crew would have to bail out, they would have to wait for the cabin to depressurize through a small valve. The tab provided the leverage so the pilot could peel off the plug fast, allowing the cabin to rapidly depressurize. Once SpaceShipOne was all sealed up, it was essentially a trapped volume of air. “There’s no exchange of air. So you’ve got to be concerned about humidity and carbon dioxide,” Shane said.

A second hose coming off each oxygen mask collected the exhaled air in order to control the carbon dioxide (C02) levels and humidity. The exhaled air was dried, and a scrubber using an absorbent material was used to remove excess C02. But because of the mission’s short duration and the fact that the cabin was sealed off from the atmosphere

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Fig. 4.11. Looking from underneath into the engine bay, these are the two main spars running perpendicular through the fuselage, one in front of the oxidizer tank and one behind it. These provided the structure to support the fixed and movable sections of the wings. Mojave Aerospace Ventures LLC, photograph by David M. Moore

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Fig. 4.12. SpaceShipOne’s wings had to be very rigid and strong because they not only supported the tail booms and feather mechanism, they also had to withstand the very high forces encountered during boost and reentry. This photograph shows how thick the ribs inside had to be. Mojave Aerospace Ventures LLC, photograph by David M. Moore

V__________________________________________ J for a relatively short time, little C02 buildup occurred, and makeup oxygen (02) was not necessary.

“We actually demonstrated on White Knight that we had adequate control with three people on board for a three – or four-hour flight,” Shane said. “We knew it would be fine for one hour.”

s soon as SpaceShipOne was able to fly, flight testing began. This didn’t mean it was fully operational—not by a long shot. But the only way to learn more about the spacecraft was to get it up in the air and see how things worked.

The purpose of flight testing was to understand how the parts of SpaceShipOne operated individually and collectively while in flight. Only so much can be eval­uated by ground tests and computer models. SpaceShipOne was, after all, designed to fly, not to take up idle space inside a hangar.

SpaceShipOne’s flight test program proceeded incrementally, as with most flight test programs. After each step, Scaled Composites knew a little bit more how SpaceShipOne flew. Resolving problems, expected and unexpected, by making modifications or procedural changes is a normal part of any flight test program. And this one was no different.

SpaceShipOne completed fifteen test flights before attempting to capture the Ansari X Prize: three captive carries, eight glides, and four powered flights. These test flights, beginning on May 20, 2003, enabled the team to qualify the instruments, controls, systems, and test pilots as well as expand the flight envelope of SpaceShipOne.

Flight testing of SpaceShipOne actually began in White Knight. Since the cockpits were virtually identical, as were many of the controls and compo­nents, SpaceShipOne had a tremendous head start by the time it finally reached the sky.

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Fig. 7.1. White Knight flew more than four times the number of flights as did SpaceShipOne because it was also used to shake-out the components that were common to SpaceShipOne. Because they shared very similar cockpits and some similar flight characteristics, White Knight was also an effective flight trainer for SpaceShipOne. When White Knight and SpaceShipOne did fly together, a "cave painting" was added to the fuselage of White Knight to acknowledge each mission. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

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In this chapter and the following chapters, excerpts taken from the flight log of Scaled Composites are given for all the flights made by SpaceShipOne during the flight test program, including the Ansari X Prize attempts. The key information given for each includes the date, the flight numbers for both SpaceShipOne and White Knight, the crew members, and the test flight objective. From the photographs, the sequence of modifications to the tail booms, engine fairing, thermal protection system, and paint scheme becomes apparent.

For both SpaceShipOne and White Knight, the flight numbers were sequential, representing each time the vehicle flew. White Knight flew many more times because it was flown first and also used as a trainer for SpaceShipOne. For captive-carry test flights, a C was added to the end. For a glide or powered test flight, a G or P was added, respec­tively, while L denoted a launch for White Knight. Appendix A lists important data about each of the flights.

Piloting rotated between Pete Siebold, Mike Melvill, and Brian Binnie. But while one of these test pilots flew SpaceShipOne during a test flight, one of the others always flew White Knight. The remain­ing of the three test pilots typically flew a chase plane to closely observe the test flight. Appendix В gives details about the chase planes for the flights.

To commemorate the completion of each SpaceShipOne flight, a “cave painting” was added to the side of White Knight, as shown in figure 7.1.

Being a test pilot is a risky occupation, as history has continually proven. Anytime a new aircraft is flown, there are many unknowns. The test pilot has to be prepared for the worst case, though. The nose cone of SpaceShipOne was specially designed to detach from the fuse­lage, so, in an emergency, the test pilot could make a quick escape and parachute to safety. The job of the test pilots was to fly SpaceShipOne and, with the help of the entire test flight team, turn those unknowns into knowns.

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Flight Test Log Excerpt for 1C

Date: 20 May 2003

Flight Number Pilot/Flight Engineer

SpaceShipOne 1C none

White Knight 24C Pete Siebold/Brian Binnie

Objective: First captive-carry flight with mated White Knight and SpaceShipOne. Vibration and aerodynamic interface assessment. Mated handling qualities evaluation. Envelope expansion to 130 knots/Mach 0.5 above 45,000 feet [13,720 meters]. Stalls and 2/3-rudder sideslips. SpaceShipOne systems inactive, controls locked, and cabin unmanned. Launch system was qualified and functional for this flight.

(source: Mojave Aerospace Ventures LLC, provided courtesy of Scaled Composites)

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ime was running out. Scaled Composites announced that they would be making their attempt at the Ansari X Prize on September 29, 2004. To win, SpaceShipOne would have to fly not just on that day, but would have to fly once more by October 13th, leaving less than three months before the Ansari X Prize would expire. A major setback would take SpaceShipOne out of contention.

Brian Feeney’s team scheduled to launch their spacecraft Wild Fire on October 2, 2004. But there was a concern as to whether or not they would be ready to launch. What would happen if the January 1,2005, expiration rolled by without a winner?

“We had a contingency plan that whoever won it would get a trophy but not ten million bucks,” Erik Lindbergh said. “But whether or not it would have been as effective was a question. Whether or not it would have gained as much media attention was a question. And also whether or not we would have been able to keep the doors open was a question.”

The X Prize Foundation wanted desperately to award the Ansari X Prize. To them, this wasn’t a one-shot deal. Winning the Ansari X Prize meant jumping the first, but highest by far, hurdle on the path to public space access. But having the prize unclaimed was not their only fear. They knew that progress would only come from the successes and the failures of flying over and over again.

“It was very tense the night before and in the morning as we were gathering in the cold in Mojave to watch the launch,”Anousheh Ansari said. “We were very anxious. We had to prepare ourselves for all sorts of possibilities.”

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Fig. 9.1. When Mike Melvill made it to space in SpaceShipOne, it was like a great awakening. Scaled Composites gave proof to the world that commercial spaceflight was for real. Millions of people seemed to catch the space craziness as the Ansari X Prize attempts were made and broadcasted

live on television and over the Web. Dan Linehan

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There was no doubt of the risks involved with spaceflight. And although SpaceShipOne s first spaceflight earlier that June had some unexpected difficulties, the spacecraft and the pilot made it back safely. This was no guarantee for subsequent missions, which would continually stretch the flight envelope. After all, SpaceShipOne was still a research vehicle.

Everyone felt the enormity of the events. “To watch how the wives said goodbye to their husbands before they went up and wished them well was certainly a moment when you felt the respon­sibility of being involved in a project like this,” Paul Allen said, “and them being worried for their husbands and you being worried, too.” The attempts at the Ansari X Prize would have unprecedented media coverage as well. Tens of thousands of people gathered to
watch the launches in person (refer to figure 9.1 and figure 9.2). And the launches were broadcast live over television and the World Wide Web in a way like none other.

“The whole world was watching,” said Gregg Maryniak, the executive director of the X Prize Foundation. “Most people don’t appreciate that this was the first spaceflight ever that had video coming down that people—regular people—were watching in real time from a manned spaceship. It has never happened before. It has happened where in flight you could see snippets but never during ascent. When was the last time you saw NASA showing footage from inside the shuttle?”

The Ansari X Prize received upwards of six billion media impressions over its course, with a large percentage of them focused

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Fig. 9.2. A giant screen gave crowds a live, up-close view of SpaceShipOne from inside and outside the cockpit as it made its way to and from space.

These same images were being seen on televisions and computers all over the world.

Dan Linehan

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on the small company from the Mojave Desert that was ready to prove that its first spaceflight wasn’t a novelty.

“The entire Tier One team that was taking this vehicle through flight testing had been working really, really hard for the last six weeks or so to where there was almost always someone at Scaled doing something with the vehicle or preparing for the flights or in the simulator,” Brain Binnie said.

“We had a lot of anxiety between our first flight to space with Mike with the lightweight vehicle and trying to decide how we were going to make the adjustment to carrying 600 pounds [270 kilograms] of pay – load for the X Prize flights and still get to those same altitudes. There was concern that the

Flight Test Log Excerpt for 16P

Date: 29 September 2004

Flight Number Pilot/Flight Engineer

SpaceShipOne 16P Mike Melvill

White Knight 65L Brian Binnie/Matt Stinemetze

Objective: First X Prize flight: ballasted to simulate 3 place and to exceed 100 kilometers (328,000 ft).

(source: Mojave Aerospace Ventures LLC, provided courtesy of Scaled Composites)

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rocket motor didn’t have enough energy or impulse for us to get there. We had spent a lot of time worrying about that, wondering whether we needed to augment the motor with some other boosters. We eventually settled on a scheme that was really quite clever, but it took a while to work out the details.”

The design of the wings had to take into consideration more factors than most other winged aircraft must consider. The wings of SpaceShipOne had to perform from subsonic to supersonic, withstand reentry into Earth’s atmosphere, and incorporate the mechanism of movable wings. No other winged vehicle has had to tackle all these at the same time.

Swept wings, which look like delta wings with the wingtips cut off, are attached high on the fuselage. This shape was required for supersonic flight. A tail boom with an outboard horizontal stabilizer is mounted to each wingtip.

The wings have an airfoil shape, but a hinge runs along the full length of the wingspan. The hinge allows the aft section of the wings to pivot up for the feather maneuver and back down after reentry. The forward wing sections, which are roughly the front two-thirds of each wing, do not move.

The wing area is approximately 160 square feet (15 square meters) and the wingspan is 16.4 feet (5.0 meters). However, since the horizontal stabilizers of the tail booms extend out farther than the wings, the width is 27 feet (8.2 meters).

The aspect ratio of the wing is 1.7, which is very low compared to the high aspect ratios of the long, thin wings of sailplanes. For traditional gliders, the lift characteristics are a key design factor. But for SpaceShipOne, it requires only enough lift to be able to point its nose upward during rocket-powered ascent in the atmosphere and to be able to glide back after reentry to the landing site for a safe touchdown.

There are two main spars that each run through the wing from tip to tip. One spar goes in front of the oxidizer tank, and one goes behind it, which can be seen in figure 4.11.

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Fig. 4.13. NASA had designed the Ames-Dryden-1 (AD-1) to explore the use of an oblique wing that could pivot during flight. During takeoff, the AD-1’s wing was perpendicular to the fuselage, like a traditional aircraft. In order to evaluate fuel efficiency, it was possible to pivot the wing to a maximum of 60 degrees, as shown in this photograph. NASA contracted Burt Rutan’s RAF to analyze design and loading characteristics. NASA-Dryden Flight Research Center

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“The wing is not tapered in total thickness,” Rutan said. “It is as thick at the tip as it is at the root. It has to do with meeting the stiffness to support the boom. And of course for the hinge line of the boom, it has to be a perfectly straight line or it would bind.”

There are no control surfaces on the leading or trailing edges of the wings like other aircraft. Wings on most aircraft also store fuel. But since fuel is stored in the rocket engine itself, which runs through the fuselage, and the oxidizer is in a large tank behind the cockpit, the wings have plenty of room to fit other components and systems, as shown in figure 4.12.

Thirty-two days after Scaled Composites revealed its space program to the world, SpaceShipOne was about to take to the air for the first time. “Here we are about to embark on a flight test program with a spaceship,” said Doug Shane, the director of the flight test program. “And we started off with an unmanned captive-carry flight just to make sure the interactions between the two airplanes were fine.” The first test flights off the ground were captive carries, where White Knight and SpaceShipOne took off attached together in the mated configuration and did not separate during the flight. This was just like a giant wind tunnel, but instead of an enormous fan blowing air on SpaceShipOne, White Knight moved SpaceShipOne through the

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Fig. 7.2. SpaceShipOne took to the air for the first time on May 20, 2003, for an unmanned captive carry. A primary goal of the flight was to ensure that the two vehicles could safely fly while mated. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

air. Figure 7.2 shows SpaceShipOne and White Knight during the first captive carry.

With Pete Siebold at the controls and Brian Binnie in its backseat as flight engineer, White Knight carried the unmanned SpaceShipOne to an altitude of 48,000 feet (14,630 meters), which would eventually be the approximate launch altitude. They reached a speed of Mach 0.53 after the 700 feet per minute (210 meters per minute) climb to this altitude. Siebold and Binnie flew for 1.8 hours and found that White Knight had excellent handling qualities and could perform the captive carry without any stability, interference, or vibration problems. SpaceShipOne was now ready for a pilot.

SpaceShipOne Now Manned (2C)

Within specifically designated airspace, Mike Melvill rode inside SpaceShipOne during a 2.1-hour-long captive-carry test flight. Aside

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Flight Test Log Excerpt for 2C

Date: 29 July 2003

Flight Number Pilot/Flight Engineer

SpaceShipOne 2C Mike Melvill

White Knight 29C Brian Binnie/Cory Bird

Objective: First manned captive-carry flight of SpaceShipOne. A man-in-loop launch rehearsal and inflight checkout of all ship systems, including flight controls and propulsion system plumbing.

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Fig. 7.3. Two months after SpaceShipOne’s first test flight, Mike Melvill became the first test pilot to get behind the stick of SpaceShipOne. This mission was a captive carry, though. The Starship, designed by Burt Rutan, flew as a chase plane. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

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Flight Test Log Excerpt for 3G

Date: 7 August 2003

Flight Number Pilot/Flight Engineer

SpaceShipOne 3G Mike Melvill

White Knight 30L Brian Binnie/Cory Bird

Objective: First glide flight of SpaceShipOne.

(source: Mojave Aerospace Ventures LLC, provided courtesy of Scaled Composites)

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from checking systems, Melvill preformed a full rehearsal for the first glide-test flight with Brian Binnie and Cory Bird, who crewed White Knight.

Figure 7.3 shows this test flight and the Starship chase plane trailing behind. Several chase planes flew alongside SpaceShipOne and White Knight at various stages during the flight test program. They monitored how SpaceShipOne performed from an external standpoint, and, should SpaceShipOne or White Knight run into difficulties, they provided a valuable extra set of eyes.

During this rehearsal, SpaceShipOne also practiced the communi­cation that would take place, which included sending data and video down to Mission Control on the ground.

Although pilots trained to fly SpaceShipOne with the simulator and White Knight, this was the first time that a pilot could actually feel the forces on the controls during flight. After Melvill exercised all the different systems aboard SpaceShipOne, which included parts of the feather and propulsion systems, SpaceShipOne was ready for the big next step.

As White Knight came in for a landing, though, Melvill couldn’t help trying to land, even though SpaceShipOne still remained fixed to White Knight. From the chase plane video, SpaceShipOne7s elevons moved as White Knight flared for landing. Afterward, Melvill joked with Binnie by congratulating him on such a fine landing.

“Ladies and gentlemen, we are at the start of the personal spaceflight revolution, right here, right now. It begins in Mojave, today. What is happening here in Mojave today is not about technology. It is about a willingness to take risk, to dream, and possibly to fail,” said Peter Diamandis during the morning of September 29, 2004, as XI, the name of the first required flight of SpaceShipOne in the quest for the Ansari X Prize, prepared to launch.

Mojave was abuzz. A little more than three months earlier, Mike Melvill had earned his astronaut wings as he piloted SpaceShipOne on a history-making flight just past the 100- kilometer (62.1 miles or 328,000 feet) line demarking the start of space. Now Rutan’s team set their sights on the most exciting and influential prize of the new millennium.

Pete Siebold, who had already flown two glide flights and one powered fight in SpaceShipOne, was selected to pilot the flight. Siebold had been training for three years for this moment, but a health scare forced a very disappointing change.

“There were two other guys that were more than qualified to fly that flight,” Siebold said. “At the time, I didn’t feel as though I was doing the team any justice by putting myself in that situation and flying
the mission when I probably wasn’t in the right frame of mind and not to mention healthy enough.” Siebold made the tough decision, but very fortunately his health issues were eventually determined to be nowhere near as serious as first suspected.

Rutan then turned to the test pilot with the most experience flying SpaceShipOne. Mike Melvill would get his chance to become an astronaut a second time, but to do so, he’d have to get back into training again. Figure 9.3 shows Melvill at the controls in the cockpit of SpaceShipOne preparing for XI.

Like Spirit of St. Louis, SpaceShipOne was stripped of anything absolutely nonessential. The lighter the craft, the greater the margin SpaceShipOne had for clearing the 100 kilometers (62.1 miles or 328,000 feet) because the removal of each and every pound enabled the spacecraft to go an additional 150 feet (46 meters) higher. SpaceShipOne needed all the help it could get. Melvill’s earlier spaceflight had cleared the 100 kilometers by only the slimmest of
margins, less than 500 feet (150 meters). And during this spaceflight, SpaceShipOne was not even carrying the full payload required by the rules of the Ansari X Prize.

Ironically, as the Scaled Composites team scrimped for a pound here and a pound there, removing a total of about 45 pounds (20 kilograms), they would have to add weight to simulate two passen­gers. “We had to carry 400 pounds [180 kilograms] in the back seat, which was a heck of a lot more load in that thing than we ever had before. And I had to be ballasted,” Melvill said.

Since Melvill weighed only 160 pounds (73 kilograms), he had to be ballasted up to 200 pounds (90 kilograms).These were the rules. But keeping the gross weight as low as possible was still critical. Every pound that didn’t have to be carried was a pound that the force from the rocket engine didn’t have to lift.

Figure 9.4 shows Melvill gesturing “okay” from a removable port as final preparations were made. SpaceShipOne was carried

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Fig. 9.4. Mike Melvill gives the thumbs up from the cockpit of SpaceShipOne as last-minute preparations are made. For the Ansari X Prize,

SpaceShipOne had to carry enough weight to simulate three 198-pound (90-kilogram) people. SpaceShipOne just barely made it past 328,000 feet (100,000 meters) without the extra weight, so it was necessary to bump up the performance of the rocket engine. Mojave Aerospace Ventures LLC, photograph by David M. Moore

into the air at 7:12 a. m. PST by White Knight with Brian Binnie behind the controls.

Separation occurred at 8:10 a. m. PST when flight engineer Matt Stinemetze, who sat in the back seat of White Knight, released SpaceShipOne from an altitude of 46,500 feet (14,170 meters). Clear of White Knight and no longer pushing forward on the control stick, Melvill fired the rocket engine, which had been enhanced to provide greater performance by increasing the amount of propellant and burn time.

“You could sure hear it,” Melvill said. “It was very loud—it was extremely loud.

“But it is a fabulous ride going up. I think that people who go on the next one—the passengers—will get the most exciting thing they ever did. A lot of noise. They are going really fast. The acceleration is dramatic. You are accelerating at a huge rate. You just watch the speed going up.”

The cockpit shook as Melvill pulled the nose up, making a very sharp turn toward the sky above. “The straighter you flew it, the

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Fig. 9.5. A video-capture image shot from a chase plane shows SpaceShipOne spiraling up during its boost. Melvill struggled to control the rolls but still allowed SpaceShipOne’s rocket engine to fire so he would be sure to pass the 328,000-foot (100,000-meter) mark. SpaceShipOne rolled twenty-nine times. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

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higher it would go in the same amount of time,” he said. “We didn’t need to burn the motor for its full length that it was capable of burning because it went up there quite easily.”

During his previous flight, though, he had battled wind shear, rocket asymmetries, and pitch control failure. These had prevented him from flying a very straight trajectory. Melvill was more than determined to nail the trajectory on this flight.

As SpaceShipOne blasted through the upper atmosphere, Melvill had closed up the two donuts on theTONU display, which meant he was doing a great job flying the planned trajectory, and he monitored the energy altitude predictor, an instrument that predicted how high SpaceShipOne would go once the rocket engine was shut down.

“You may be at 160,000 feet [48,770 meters],” Melvill said, “and it will say, if you turn it off right now, you’ll go all the way to 328,000 feet [100,000 kilometers]. So, you watch that instrument. That’s the primary instrument to know when to turn it off. Initially, we did it with a timer, and we just said you’re going to run 55 seconds. And at the end of 55 seconds, we’d shut it off.”

But only 60 seconds after lighting the rocket engine, traveling at Mach 2.7, SpaceShipOne was in trouble. The crowd hushed as the contrail from SpaceShipOne switched from a nice, smooth line to a wild corkscrew in the sky. Things happened fast. But from the angle of the shot displayed on the jumbo screen, it was hard to tell what was actually happening. Figure 9.5 shows SpaceShipOne rolling out of control, viewed from the cockpit of a chase plane.

“When he started doing the rolls, I thought he was dead,” recalled Erik Lindbergh. “I thought that was it—the craft was going to break up and he was done.”

Thousands of people were gripped in silence.

“I didn’t think he was doing rolls. I thought he was tumbling at that point,” Lindbergh recalled.

SpaceShipOne rolled right uncontrollably at an initial rate of 190 degrees per second, spiraling up toward space.

“I had one of the walkie-talkies, and I could hear Melvill talking to ground control,” Ansari said. “He said that everything is fine. It didn’t look fine. But because he was convinced that everything was fine, I felt comfortable.”

The rocket engine kept burning while SpaceShipOne still spun its way up, reaching a maximum speed of Mach 2.92 (2,110 miles per hour or 3,400 kilometers per hour). Melvill still kept his eye on the energy altitude predictor. As he explained, “Unless you see 328,000 feet [100,000 meters] in that window, you are not going to win the X Prize. So, you don’t want to turn it off until you read at least that much or more. And so that was why I didn’t turn it off when we were doing all those rolls, because it didn’t say 328,000 feet [100,000 meters] yet. I went to turn it off thinking, wow, something was wrong here. And when I looked at the energy height predictor, it was not predicting that we would go high enough. So, I just left the motor running and just ignored the rolling.”

At a total burn time of 77 seconds, Melvill finally shut off the rocket engine. His altitude was 180,000 feet (54,860 meters) at that point and only about halfway through its ascent. But as Melvill got higher and higher, the air became too thin for him to counteract the rolls with either the subsonic or supersonic flight controls. SpaceShipOne left the atmosphere still rolling at 140 degrees per second.

Melvill was able to keep from being disoriented by focusing on the Tier One navigation unit and not glancing out the windows. He acti­vated the feather and then focused on nulling-out the rolls with the reaction control system. “I just pushed it on, turned on both systems, and just left it on until it stopped it,” Melvill said.

By the time SpaceShipOne stopped rolling, it had completed twenty – nine rolls. The vehicle now continued to coast to an apogee of 337,700 feet (102,900 meters), but now Melvill could enjoy the 3.5 minutes of weightlessness and the view while still having time to take a few photos out the window.

On reentry, SpaceShipOne hit a top speed of Mach 3.0. Still in the feathered configuration, it decelerated from supersonic to subsonic,

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Fig. 9.6. By using the reaction control system (RCS), Mike Melvill stopped the rolls. He reached an apogee of 337,700 feet (102,900 meters), which gave him about 10,000 feet (3,000 meters) to spare.

Now, coming down was the easy part. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

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Fig. 9.7. SpaceShipOne’s second spaceflight was nearly over as it approached Mojave’s runway. But before Melvill had gotten close to the airport, he did some early celebrating by rolling SpaceShipOne once more to make it an even thirty. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

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Fig. 9.9. On October 4, 1957, Sputnik became the first man-made object to orbit Earth. The Soviet Union had launched the beach ball­sized satellite, which circled the planet for three months. Sputnik put the space race between the United States and Soviet Union into overdrive. Decades later, on this day, SpaceShipOne was ready to finish a race of its own. NASA

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while it reached a peak g-force of 5.1 g’s at 105,000 feet (32,000 meters).

At 61,000 feet (18,590 meters), Melvill retracted the feather to begin his glide back to Mojave. As SpaceShipOne descended, the chase planes caught up and tucked in behind. Figure 9.6 shows the view of SpaceShipOne from the Alpha Jet.

During the 18-minute glide to Mojave, SpaceShipOne suddenly rolled completely around, surprising the chase planes. But this roll wasn’t uncommanded. Melvill performed a victory roll, rounding out his total rolls for the flight at thirty.

Figure 9.7 shows SpaceShipOne coming in for a landing as the crowds lining the runway cheered.

“It was fabulous—it really was—knowing that we at least were halfway there. We went plenty high. And coming back and all the excitement, everybody was just thrilled to death,” Melvill said.

Melvill’s flight exceeded the altitude requirement by nearly 10,000 feet (3,050 meters) and satisfied the other rules set by the Ansari X Prize. To fulfill the remaining conditions, SpaceShipOne had to repeat the spaceflight within two weeks. Standing on SpaceShipOne, Melvill celebrated successfully completing the XI, as shown in figure 9.8.

“We knew what we had to do. My task was to not damage the air­plane. I wasn’t going to go for any altitude records but just plenty of margin and burn the engine as little as possible and land the airplane as smooth as possible so we didn’t have to fix anything. We didn’t even change the tires. We refueled it, and it was ready to go. We could have gone the next day,” Melvill said.

All the flight control surfaces are on the tail booms, which are mounted to the wingtips and pivot with the aft wing sections when the feather is deployed. Each tail boom has a vertical stabilizer and horizontal stabilizer.

Upper and lower rudders are mounted at the back of each vertical stabilizer for yaw control. Pitch and roll is controlled by elevons that are attached to the trailing edges of the outward extending horizontal stabilizers. The fiberglass construction of the elevon skin gives radio transparency for antennas. For control during supersonic flight, the entire horizontal stabilizer on each tail boom pivots.

Minor modifications were made to the tail booms during flight testing. To resolve an aerodynamic problem, the distance from tip to root of the horizontal stabilizers was increased by 16 inches (41 centimeters). Also, a triangular strake was added in front of each horizontal stabilizer, and a flow fence was added midspan on each horizontal stabilizer.

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Fig. 4.15. Critical to the safe return from space, the feather had only two positions, all up or all down. Redundant pneumatic actuators raised and lowered the feather. While retracted, the feather was held in place by a redundant locking system. However, only the force from the pressurized

actuators was needed to keep the feather fully extended. Mojave Aerospace Ventures LLC, photograph by David M. Moore

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Fig. 4.16. During reentry and with the feather extended at an angle of about 65 degrees, SpaceShipOne descended nearly level on its belly. It did not drop straight down, though, but instead moved forward as it fell. The diagram shows the angle of attack at 60 degrees, which is a measure of the direction of motion with reference to the position of the wing.

James Linehan

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“What a great thing to be able to fly glide selections without worrying about the rocket propulsion system or any of the other elements. And by separating all these variables out, you can learn how to fly the air­plane and make sure all the subsonic stuff is going to work,” Doug Shane said. In theory and in practice, yes, but it was still unnerving from a test pilot’s point of view when it came down to a vehicle that had never been flown before.

“The first glide flight was probably the one that was my least favorite because we didn’t even know if it would fly,” Mike Melvill said. “If you think about a normal airplane with an engine, we don’t just go out and fly it. We go out and taxi it slowly. We figure out if the brakes work, whether the steering works, and then we go a little bit faster until we can finally lift it off a few inches and say, ‘Yeah, looks like its going to fly.’ And then we fly.

“For this one, we just hooked it on the bottom of White Knight, went to about 50,000 feet [15,240 meters], and dropped it off. So, we didn’t have a clue how it would fly or whether it would be good, bad, or indifferent. It wasn’t great. We had to modify it a little bit. But it was flyable, and I was able to bring it back. But that was the scariest flight, I think. We just didn’t have any knowledge other than Burt’s ‘That looks about right. ’ It had never been in a wind tunnel. There was no formal wind-tunnel testing of the airplane at all. And so we tested it in the real wind tunnel.”

White Knight flying at 105 knots, 12 miles (19 kilometers) east of Mojave, released SpaceShipOne at an altitude of 47,000 feet (14,330 meters).The spaceship and mothership separated cleanly. SpaceShipOne flew freely for the first time and was stable once disconnected.

Over the 19-minute flight time, Melvill evaluated the handling and performance. During that short time, the controls and avionics oper­ated as expected while he began to expand the flight envelope. At Mojave Airport on Runway 30, SpaceShipOne came in nice and easy to make its first landing.

The twenty-nine rolls not only caused great concern for safety, but now doubt and skepticism started to creep into the back of people’s minds. One or two rolls wouldn’t have been so dramatic, and would not have left such a vivid impression. But with twenty-nine, even the most inexperienced spectator could tell things weren’t going as planned. The public had not yet bought into the whole idea of personal space travel. There was a big difference between being enthusiastic and thinking something was cool and being willing to put your own butt in the seat strapped to a rocket engine. Some people would of course be willing to take any risk to get into space. But that certainly wouldn’t be the best way to jumpstart an industry in this day and age. Sometimes perception, unfortunately, weighs heavier than fact.

“We saw this rolling departure, and that was cause for concern,” Binnie said. “Not from a safety or structural standpoint but a concern of perception. Others thought, ‘Well, they are just loose cannons out there. They don’t understand what they are doing. They are certainly not ready for prime time or carrying the trusting public.’ And so the clock is ticking.

“We had planned this to where we could potentially pull off three flights in two weeks if need be. But we were all getting kind of tired. We really didn’t want to have a problem on our second attempt. Everybody on the team was well aware of what was at stake and what would all be necessary should it have to come to a third flight. And any number of things could put us there. It could be bad weather, an avionics hiccup, range issues, telemetry things, and issues totally unrelated to flying the vehicle could have scuttled that event and forced us into a third evolution.”

The fact was that after evaluating the data from X1, the team determined Melvill had done too good of a job at pointing SpaceShipOne straight up. In this orientation, SpaceShipOne had no aerodynamic lift to correct unwanted motion. “You’ve got to be careful that you don’t go over on your back,” Melvill said. “It is real easy to pull so hard that you end up overturning.”

With the nose of SpaceShipOne pointed straight up, a degree or two off one way or the other was not much of a change in angle. But it turned out to be a tremendous change in terms of SpaceShipOne’s stability. So, when Melvill went beyond 90 degrees, he naturally tried to bring the nose back on track. This caused the angle of attack, the direction SpaceShipOne was pointing in relation to the direction of actual motion, to go to zero.

“The wing wasn’t lifting anymore, there was zero lift on the wing, then it departed,” Melvill explained. “It did a snap roll. And that was caused by the design of the airplane. The airplane was designed with a high wing and swept leading edge. Had that been a low wing, it would not have done what it did. We learned that lesson. On the next flight, we didn’t change the airplane at all. We just changed the pull – up schedule.”

The new plan for the trajectory was a more gradual pull-up during boost while making sure never to go to vertical. “And as

long as that wing is lifting, it won’t stall like that. But when it gets to zero lift, then you get separation on it, and the slightest little perturbation of airplane will cause it to roll or do something odd,” Melvill said.

None of the flights previous to XI had flown at high Mach numbers while at a zero angle of attack. Essentially, SpaceShipOne lost directional stability, so there was no way Melvill could counteract the weak thrust asymmetry, a wandering thrust line, coming from the rocket engine at the time. SpaceShipOne was still rocketing up, so by the time the first few rolls occurred, the atmosphere had disappeared. Aerodynamic forces were not longer causing the rolls, but since there was no air pressure to resist the rolling motion, once SpaceShipOne started to roll, it just kept going and going.

The structural loading on SpaceShipOne from the rolling was very low. Melvill’s safety was never in jeopardy, only his breakfast, which thanks to all of the unusual-attitude training in the Extra 300 aerobat­ic plane, remained in place. The very next day, Scaled Composites not only figured out what caused the rolling departure but also deter­mined a way to keep it from happening again.

As with the first rocket-powered launch of SpaceShipOne, Rutan wanted to fly on a significant day in aviation history. The anniversary of the first man-made object to orbit Earth was approaching. Russia’s Sputnik, as shown in figure 9.9, was launched on October 4, 1957, and circled Earth about 1,400 times at a peak apogee of 588 miles (947 kilometers). This milestone of spaceflight sent the space programs of the United States and the USSR into warp speed.

“We had three days to finesse this in the simulator,” Binnie said. “Between Mike’s flight and the final flight, it was Friday, Saturday, Sunday. It looked promising, but it was still only our sixth powered flight in the vehicle. There was no guarantee that we really under­stood it or that there weren’t some other gremlins that were going to leap out and get us.”

Mechanically, the most complicated system on SpaceShipOne was its feathering system. It was also the most important system on board for ensuring the safety of the pilot and the success of the mission. Rutan already had experience with movable-winged aircraft. His RAF analyzed the designs and loads for NASA’s scissor-wing AD-1 (refer to figure 4.13).

Before SpaceShipOne reentered the atmosphere, the aft section of both wings, including the tail booms, rose up as if the spacecraft were almost folding in half. With the feather extended, SpaceShipOne could reenter the atmosphere with very little pilot input required. This “carefree” reentry was one of the most important elements of Scaled Composites’ entire space program.

The feather is a separate structure from the forward wing sections and has its own spars and ribs. However, the aft wing sections and the tail booms do not move independently. Figure 4.14 shows the spar that runs through the fuselage from one end of the movable wing to the other, tying the feather all together.

Left and right pneumatic actuators, which are just cylinders with movable pistons, used air power to pivot the feather up or down along the hinge. The lower ends of each actuator are attached to the fuselage, and the upper ends are attached to the inner face of the aft wing section, as shown in figure 4.15.

There are just two positions of the feather, up or down. The angle the feather makes with the fuselage is preset to 65 degrees, so the pilot did not have to make any adjustments. It took about 13—14 seconds to raise or lower. The feather could be elevated on ascent once the airspeed was less then 10 knots equivalent airspeed. Figure 4.16 shows the 60-degree angle of attack for SpaceShipOne descending in the feather condition.

When the feather got to the fully extended position, there was no lock. It was just the force from the actuators that held the feather up. “As it turns out, it takes no load to put it up because you are weightless,” Rutan said. “When you are weightless, there are no aerodynamics. It takes no force. In fact, if you would unlock it in space, you could take a little cable and pull it right up. There is no load on it. Okay. But, you need to hold it up for reentry.” The reentry force on the flight test actually tried to push the feather down.

If the feather were to move or become disengaged at the wrong time, the results could be disastrous. To keep the feather in the retracted position and to keep it from moving during the other phases of flight, two I-shaped clasps from the locking system secure the trailing edges of the aft wing sections. To unlock the feather so it could be deployed, separate pneumatic actuators were pressurized to retract the clasps.

The design had built-in redundancy for the components that make up the feather system. The two clasps were coupled so they moved together. But they had separate pneumatic sources, lines, regulators, valves, and again, separate actuators. “So, I could have a fire. I could have a line come off. I could have a loss of pressure. I could have all of these things go wrong, and it doesn’t affect the other,” Rutan said.

The two different pressure sources could run either actuator. The redundancy of the locking system was identical to the redundancy of the elevating systems. They were two independent systems that, under normal conditions, acted in unison. However, either system could engage or disengage the clasps of the other system. Once SpaceShipOne was flying subsonically after reentry and the loading drops below 1.2 g, the pilot could retract the feather.