Category Space Ship One

Feather Up (5G)

After resolving the avionics malfunction that caused the aborted glide flight, SpaceShipOne and White Knight were back up flying again the very same day. Melvill was dropped at 48,200 feet (14,690 meters) from White Knight flying at a speed of 105 knots. For his first maneuver, he put SpaceShipOne into a full stall to investigate stall characteristics.

The second maneuver was one of the most critical firsts of the entire flight test program. Evaluation of the feather would begin on this flight. The purpose of the feather was to decelerate SpaceShipOne during reentry into the atmosphere.

“That’s something you do in glide tests,” Burt Rutan said. “You don’t have to do that in spaceflight because once you decelerate from your spaceflight, you find yourself in a stable glide, which is identical to the way we flew the airplane on its first glide flight. So, we went out early in the program and put the feather up and put it down.”

Rutan had planned to do a high-speed pull-up in a glide flight and put the feather up as it peaked to simulate zero-g during the beginning of the program. But this turned out unnecessary and would have used up too much altitude. “We started off at 43,000 feet [13,110 meters] and put the feather up to make sure it flew the way we wanted,” Doug Shane said. “We ended up doing feather

Feather Up (5G)

Flight Test Log Excerpt for 5G

Date: 27 August 2003

Flight Number Pilot/Flight Engineer

SpaceShipOne 5G Mike Melvill

White Knight 32L Brian Binnie/Cory Bird

Objective: Same objectives as the aborted flight 31LC/4GC earlier today. Second glide flight of SpaceShipOne. Flying qualities and performance in the spaceship reentry or "feather" mode. Pilot workload and situational awareness while transitioning and handling qualities assessment when reconfigured. As a glider, stall investigation both at high and low altitude and envelope expansion out to 200 knots and 4 g’s. More aggressive, lateral directional characteristics including adverse yaw, roll rate effectiveness and control, including 360 degrees aileron roll, and full rudder side slips.

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

4________________________ J

deployments from tail-slide entries, and it just worked great. Everything was as good as we could have possibly hoped for.”

SpaceShipOne was gliding along at an airspeed of 90 knots when Melvill unlocked and activated the feather. As the tail booms began to elevate to their fully extended position of 65 degrees, the nose of SpaceShipOne pitched up but settled back to a near-level pitch. Melvill encountered a lot of buzzing and buffeting during the 70-second feathered descent.

With the feather deployed, SpaceShipOne dropped at a rate greater than 10,000 feet per minute [3,050 meters per minute]. However, it was extremely stable as it fell to the ground belly first.

“You could change the heading,” Mike Melvill said. “If you were pointing at Cal City, you could turn around and point it to Mojave. And you used the elevons to do that. It was kind of weird because normally it would roll, but your sensation was that it was yawing.”

“If you stepped on the rudders, it wasn’t perceptible to you what was happening. Nothing happened. The only thing that really did anything was lateral spin. It was kind of neat to go over and look at a different view, and look over there and see what was over there. We did that a lot when we were flying as a glider in the atmosphere.”

At 30,000 feet (9,140 meters) Melvill retracted and locked down the feather. SpaceShipOne was back as a glider, as shown in figure 7.6. He expanded the flight envelope for airspeed and g-force. And before landing, he executed SpaceShipOne’s first roll.

Fuselage and Composite Structures

The construction of SpaceShipOne really began with the building of the fuselage. Without its wings and tail attached to the fuselage, SpaceShipOne looks like a stubby little rocket. Figure 4.5 shows the crew compartment in the forward section of the fuselage, the oxidizer tank in the middle section, the rounded pressure bulkhead that separates the crew compartment from the oxidizer tank, and the rocket engine in the aft section. The maximum outer diameter of the cylindrical

Fuselage and Composite Structures

г ^

Fig. 4.5. The cutaway drawing shows the crew positions in the cockpit of SpaceShipOne. A pressure bulkhead separates the crew from the rest of the rocket engine. The oxidizer tank mounted at the center of the fuselage has the rocket engine CTN (case/throat/nozzle) attached directly to it. Mojave Aerospace Ventures LLC, provided courtesy of Scaled Composites

V_____________________________________ )

Fuselage and Composite Structures

f >

Fig. 4.6. A first step in the assembly was to build the carbon fiber/epoxy composite subassemblies that made up the fuselage. The subassemblies were bonded together, except for the nose cone, which was a detachable emergency escape hatch. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

V__________________ )
fuselage is 60 inches (152 centimeters). It is a monocoque design, which means that the fuselage hull provides most of the structural support and load bearing for the spacecraft. However, the rocket engine obviously exerts a tremendous amount of force. So, the oxidizer tank is actually a very important structural member as well.

SpaceShipOne was put together much the same way a small plastic model airplane is put together. Beginning with a bunch of individual parts, they are assembled piece by piece. Woven layers, also called plies, of carbon fiber and epoxy were the primary materials used to make most of the lightweight composite parts of SpaceShipOne. These parts were used to build the fuselage, the wings, and the tail booms.

The whole process began by designing the parts using three – dimensional computer-aided design (CAD). The designs were then fed into an automated computer numerical control (CNC) machine to carefully shape the parts by whittling down foam blocks. Even though these foam parts precisely resembled the actual composite parts, they did not share the same strength, durability, resilience, and imperviousness to temperature. The foam parts were used to create molds that would then be used to create the actual composite parts to build SpaceShipOne.

After the molds were created, lay-up began. Here the composite material was built up layer by layer. Once enough material was added and the layers were to the proper thickness, the parts were vacuum-bagged and oven-cured. The vacuum-bagging process is basically what it sounds like. A part is covered with an airtight bag, which is evacuated by a pump. What this does is remove air from in between the layers and volatile compounds that are in the epoxy, which have become unwanted byproducts. The more thoroughly they are removed, the stronger the composite will be. The oven-curing enables the epoxy to properly set and achieve the desired properties. After the parts for SpaceShipOne were cured, assembly began.

Although the materials may have changed, the building technique was not unlike that used to build European sailplanes over the past forty or fifty years.

The primary structure of the fuselage is made up of only a few very large subassemblies. Figure 4.6 shows the nose cone and cabin section. The subassemblies have edges that fit to one another. They are then fastened with a jig and chemically bonded together. The subassemblies

Fuselage and Composite Structuresr ; л

Fig. 4.7. Piece by piece, the exterior of SpaceShipOne took shape, like the building of a plastic model airplane. As construction proceeded, the wings were attached to the fuselage, and all the wiring, plumbing, linkages, and other components were installed inside. Mojave Aerospace Ventures LLC, photograph by David M. Moore

v________ J

Fuselage and Composite Structures
ґ

Fig. 4.8. Because the cockpit was pressurized and SpaceShipOne faced extreme conditions in space, the walls of the fuselage provided double containment. In between the "shell within a shell" was an insulating layer that also improved the structural strength of the fuselage. Mojave Aerospace Ventures LLC, photograph by David M. Moore

V__________________________________________________________________________________________

Fuselage and Composite Structures

f ^

Fig. 4.9. This photograph shows the early stages of construction for the aft section of SpaceShipOne. A pressure bulkhead will be put in place at about the location of the opening in the fuselage to separate the oxidizer tank from the cockpit. Mojave Aerospace Ventures LLC, photograph by David M. Moore

V____________________________________ J
together form the inner hull or shell of SpaceShipOne. This inner shell is still not strong enough to support the spacecraft.

The nose cone is attached to the rest of the fuselage a little differ­ently. The nose cone is the primary escape hatch. Its edge is keyed so that it can lock and unlock from the fuselage with a quick little turn.

Figure 4.7 shows the cabin section that is forward of the pressure bulkhead in various stages of construction. Figure 4.8 shows the top of the cabin section after even more assembly, and figure 4.9 shows the aft section where the wings mount.

The next step in building the fuselage was to add a core of honey­comb material on top of the inner shell. Nomex, made by DuPont, was used as the honeycomb core. Not only is the honeycomb core lightweight, it offers high strength and it is heat and fire resistant. The honeycomb core, however, cannot serve as the outer layer. It needs further covering. So, panels called skins, manufactured using this composites process, were attached to the honeycomb core. The fuselage is a shell within a shell. The process of adding succes­sive layers creates what is known as a sandwich structure, as the fuselage hull is viewed in cross-section. Figure 4.10 shows an example of a sandwich structure. Another way to look at this is that the fuselage hull is a thick composite made up of several thin composites.

Fuselage and Composite StructuresHoneycomb Sandwich Structure

Fig. 4.10. This diagram shows a honeycomb sandwich structure that is representative of some of Burt Rutan’s designs, including SpaceShipOne. Here, for example, composite plies sandwich a core material shaped like honeycombs in order to provide extremely good strength-to-weight properties. James Linehan

V J

 

Outer Composite Plies

 

Adhesive

 

Honeycomb

Core

 

Inner Composite Plies

 

Fuselage and Composite Structures

After the assembly of the composite parts, SpaceShipOne resembled a spacecraft, but the job was far from over. “The hard part is stuffing all the systems in it and making sure that they are mounted properly,” Rutan said.

Initially the fuselage ended at the throat of the rocket-engine nozzle. During the flight tests, a fairing was added to extend the fuselage to the rim of the nozzle in order to improve aerodynamics.

First Commercial Astronaut (15P)

At 6:47 a. m. PST on June 21, 2004, White Knight lifted off from Mojave’s Runway 30, as shown in figure 8.10, to the cheers of twelve thousand spectators. Several days earlier, Mojave Airport officially became Mojave Air and Space Port after receiving its launch site operator license. It would have been another typical windy desert early morning with the Sun still not fully awake, except for a gangly looking airplane toting a stout little rocket plane on the first part of its journey to the hopeful reaches of space. Figure 8.11 shows the mated pair spiraling up to the launch altitude.

At an altitude of 47,000 feet (14,330 meters), White Knight could no longer guide SpaceShipOne any further and cut the rocket craft free to continue the quest on its own.

“You release the back pressure, and then the airplane starts to climb,” Mike Melvill said. “And at that point you must have the motor running. You unguard the switch that turns the elec – trons on to the ignition system, and you unguard the switch that fires it.

“A rocket motor doesn’t start off like a jet engine. It starts off as hard as it is ever going

Flight Test Log Excerpt for 15P

Date: 21 June 2004

Flight Number Pilot/Flight Engineer

SpaceShipOne 15P Mike Melvill

White Knight 60L Brian Binnie/Matt Stinemetze

Objective: First commercial astronaut flight by exceeding 100 kilometers (328,000 ft).

to be right there. The first time it lights, it is going as strong as it will ever be. In fact, it gets weaker as you go along. The initial kick on your back is very strong—more than 3 g’s. Your eyeballs go in at 3 g’s. And then you make about a 4-g turn. And you do that by just pulling back on the stick. In only 9 or 10 seconds, you are supersonic. You are supersonic about two-thirds of the way through that turn. And then you can’t use the stick anymore. You have to use the trim. So, that transition is something you have to learn in the simulator.”

But before completion of the pull-up, severe wind shear rolled SpaceShipOne to the left. As Melvill tried to regain wings level, SpaceShipOne rolled 95 degrees to the right and then 90 degrees to the left. He soon got control and had SpaceShipOne flying vertical, as in figure 8.12. But he ended up far off course.

A minute into the burn, as the oxidizer ran low in the tank, it began to transition from a liquid to a gas. The roar of the rocket engine made a drastic change. “As it starts sucking gas, it chugs,” Melvill explained. “And it goes boom, boom, boom, boom, boom, boom, boom, boom, boom, like that as it is going up. It really rattles your head. It doesn’t do that for too long. But it is disconcerting the first time it happens. I didn’t know what the heck that was all about.”

But the rocket engine wasn’t finished with its mischief. “The rubber that is on the inside of that thing has got ports in it, pie­shaped ports that run the whole length of the rubber fuel. So, as you are burning all the surfaces of the inside of each of these pie-shaped ports, they are coming together. You end up with a plus – sign—shaped piece of rubber that is very thin that runs the whole length of the machine. It will break off eventually and go out the back. That must have broken off and got sideways in the nozzle or something because it made a tremendous bang. It really rattled the airplane. I thought the whole tail had fallen off the airplane.”

To improve the airflow around the rocket engine for this flight, a fairing was added, which extended from the back of the fuselage over the sides of the nozzle. But heat from the rocket engine caused it to buckle. It was necessary to modify the design slightly for the next flight. It was unlikely the source of the sound Melvill heard.

Melvill seriously wondered if he’d be able to make it back, but Mission Control could see that the tail booms were just fine from the live video feed of the onboard camera. Unfortunately, Melvill didn’t have the capability to view this imagery. A failure of the primary pitch trim control, which Melvill needed while moving at supersonic speed, also occurred while the rocket engine blasted away. This only

First Commercial Astronaut (15P)

Подпись: лr~

Fig. 8.10. As White Knight fired up its engines and began taxiing to the runway, it rounded the corner, around the control tower, to find a crowd of twelve thousand well-wishers lined up along the flightline. At 6:47 a. m. on June 21,2004, SpaceShipOne began its first journey into space. Tyson V. Rininger

First Commercial Astronaut (15P)Подпись:First Commercial Astronaut (15P)r ^

Fig. 8.12. Mike Melvill ignited the rocket engine, "turned the corner," and blasted nearly straight up. The rocket engine burned for 76 seconds and shut down at 180,000 feet (54,860 meters). After reaching a maximum speed of Mach 2.9, SpaceShipOne coasted the rest of the way up to space. Tyson V. Rininger

V_______ )

First Commercial Astronaut (15P)

Fig. 8.13. SpaceShipOne reached an apogee of 328,491 feet (100,124 meters), barely above the Ansari X Prize goal. During Mike Melvill’s 3.5

minutes of weightlessness, he released two handfuls of M&Ms into the cockpit to float around in zero gravity. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

V__________________ )
deepened his worry. However, he was able to get pitch trim control back by switching to the backup.

Melvill obviously had his hands full, and he wasn’t finished battling the rocket engine. He said, “The thrust is supposed to be right down the centerline. The nozzle is an ablative nozzle. It would burn away, and if it burns away a little bit on one side compared to the other side, you can end up with a yaw going on or a pitch. It burned like about a half a degree from being straight.

“Full rudder would only just deal with a half a degree from asym­metry in the thrust. I put the rudder on the floor, but it still went sideways across the ground. It is just amazing how quickly you go from one place to another if that happens.”

By this point, the good-luck horseshoe pin that Sally Melvill pinned to her husband’s flight suit just before the flight must have weighed five pounds.

“Poor trajectory control drew the airplane way far downrange. It spent an awful lot of energy going downrange rather than straight up where you want it to go,” Doug Shane said.

First Commercial Astronaut (15P)

Fig. 8.14. This sequence of images, taken at three-second intervals, shows SpaceShipOne zooming over Earth during a period of less than thirty

 

Г

seconds. The shadow of the feather on SpaceShipOne quickly moved position as SpaceShipOne’s orientation to the Sun rapidly changed. Mojave Aerospace Ventures LLC, screen captures provided courtesy of Discovery Channel and Vulcan Productions, Inc.

Boosting SpaceShipOne to Mach 2.9 (2,150 mile per hour or 3,460 kilometers per hour), the rocket engine cut off at 180,000 feet (54,860 meters) after firing for 76 seconds. SpaceShipOne coasted toward space, but concern rapidly grew whether or not it would reach the Ansari X Prize goal of 328,000 feet (100,000 meters).

Paul Allen could only watch and wait as the Mission Control staff tracked SpaceShipOne’s progress. “You’ve got a human being in a very small projectile that is going straight up at Mach 3,”Allen said, “and me pacing around behind the scenes going, ‘I just want Mike to get back on the ground safely.’ And you got an altimeter that just zips around as SpaceShipOne accelerates upward during the engine burn. And then it starts coasting. The altimeter is just wrapping itself around itself as fast
as it can, and then it starts slowing. You are wondering if SpaceShipOne is going to get high enough, and then it did but barely.”

Before reaching apogee, Melvill raised the feather in preparation for reentry. Gravity was calling SpaceShipOne back, and the spacecraft crept up slower and slower until it finally stopped. Measurements of the altitude were being taken from several different sources, and for a moment, there was nothing but uncertainty. SpaceShipOne did beat the mark by just a fraction, making it to 328,491 feet (100,124 meters), but substantially short of its targeted 360,000 feet (109,700 meters).

Despite the problems Melvill faced in the cockpit, he had a few moments to enjoy the 3.5 minutes of weightlessness. While in zero-g, he wanted to give a good demonstration of the weightless

First Commercial Astronaut (15P)

ґ

Fig. 8.15. After battling wind sheer, an ornery rocket engine, a buckled engine fairing, and a primary pitch-trim malfunction, Mike Melvill had an uneventful reentry. But since SpaceShipOne was off course going up, it reentered about 30 miles (48 kilometers) south of Mojave. This was well within SpaceShipOne’s glide range, though. Tyson V. Rininger

 

First Commercial Astronaut (15P)

Ґ

Fig. 8.16. Burt Rutan welcomed his longtime friend Mike Melvill back from space with a great big hug. Paul Allen didn’t hold back either. With the Scaled Composites team and the backing of Allen, Rutan proved he could design a spaceship and get it safely into space. Tyson V. Rininger

 

First Commercial Astronaut (15P)

experience. From a zipped pocket on the left arm of his flight suit, Melvill grabbed two handfuls of M&Ms, which he had bought on the way to the airport earlier that morning, and cast the multicolored candies out into the cockpit. Figure 8.13 shows Melvill in the cockpit with M&Ms floating about.

“The sky was jet black above, and it gets very light blue along the horizon. And the Earth is so beautiful, the colors of the Earth, the colors of the high desert, and along the coastline. And all that fog or low stratus that’s over L. A. looked exactly like snow. The glinting and the gleaming of the Sun on that low cloud looked to me exactly like snow,” recounted Melvill at a press conference after the spaceflight.

“And it was really an awesome sight. I mean, it was like nothing I’ve ever seen before. And it blew me away. It really did.”

Figure 8.14 shows video frames, at three-second intervals, of SpaceShipOne, with its feather extended, as it races through space over

Earth. In just a matter of seconds, it moves from one side of Earth to the other. Notice how the shadows change position as the orientation of SpaceShipOne rapidly changes with respect to the Sun. By the last frame, the Sun is behind the portside tail boom.

With the pitch trim control anomaly resolved, all Melvill had to do was let SpaceShipOne’s feather handle the “carefree” return into the atmosphere. SpaceShipOne hit 5.0 g’s while reaching Mach 2.9 during reentry.

“We started out over Boron and wound up directly over the top of the Palmdale VOR [VHF omnidirectional radio beacon]. That is a long way south, right out of the restricted area,” Melvill said. In fact, SpaceShipOne reentered over Palmdale Airport at 65,000 feet (19,810 meters), some 30 miles (48 kilometers) south of Mojave Air and Space Port.

“It was perfectly safe to be flying as an airplane or glider out there,” Doug Shane said.

First Commercial Astronaut (15P)г ; ^

Fig. 8.17. In a surprise presentation, Patti Grace Smith, the FAA’s associate administrator for Commercial Space Transportation, awarded Mike Melvill the first-ever commercial astronaut wings. In flying SpaceShipOne above 328,000 feet (100,000 meters), Melvill satisfied the primary Tier One goal of getting to space. Now it was time to set the sights on the prize. Mojave Aerospace Ventures LLC, photograph by David M. Moore

V_____________________________________ )

SpaceShipOne had better than a 60-mile (97-kilometer) glide range. It defeathered at 57,000 feet (17,370 meters) and started to glide back to Mojave.

“I got back to Mojave at 40,000 to 50,000 feet [12,190 to 15,240 meters]. I think we could make it from L. A., LAX probably, if we ended up really off course,” Melvill said.

Doug Shane would eventually get a call from the FAA for a meeting. Palmdale was the location of the air traffic control center responsible for all of Southern California. When Shane met with the FAA, an official enthusiastically said Scaled Composites could have all of LA Center’s airspace, no questions asked. All it would cost is one ride.

Figure 8.15 shows SpaceShipOne coming in for a perfect landing after a tumultuous spaceflight. As the spacecraft came to rest, completing only its fourth powered flight, Melvill, who had worked for Burt Rutan since 1978 and been Rutan’s first employee, became the first commercial pilot of a vehicle to and from space. The Scaled Composites team became the first nongovernment space program to
successfully send a human to space. And figure 8.16 shows Burt Rutan and Paul Allen congratulating Melvill on accomplishing a true milestone of flight. Also waiting to congratulate Melvill was Apollo astronaut Buzz Aldrin, who welcomed him to the club. Melvill became only the 433rd person in space since Cosmonaut Yuri Gagarin was the first to reach space in 1961. This works out to an average of ten new people to reach space per year since the very start of human spaceflight.

During a presentation shortly after the spaceflight, the FAA had a surprise for Melvill. “I am very pleased and honored to present, for the very first time, these FAA commercial astronaut wings to Mike Melvill in recognition of this tremendous achievement,” said Patricia “Patti” Grace Smith, associate administrator for the Office of Commercial Space Transportation.

Figure 8.17 shows Melvill with his astronaut wings standing next to Paul Allen and Patti Grace Smith. “I wasn’t expecting anything like that,” said Melvill. “It was really a thrill.”

The FAA now issues astronaut wings to any member of a crew, including passengers, on a spacecraft that exceeds an altitude of 50 miles (80.5 kilometers) during a spaceflight. The 50 miles (80.5 kilometers) was an arbitrary boundary traditionally used by the U. S. military. Internationally, the bar is higher, and the accepted boundary of space, which was used for the Ansari X Prize, is set by the scientifically based Karman Line of 100 kilometers (62.1 miles).

The primary goal of the Tier One space program set by Burt Rutan and Paul Allen had been achieved once SpaceShipOne returned safely to Mojave after reaching space. To that end, SpaceShipOne was optimized for altitude, not payload. Any unnecessary weight would have adverse­ly impacted performance. So, even though SpaceShipOne made it past the Ansari X Prize altitude goal, the passenger requirement wasn’t met.

Scaled Composites had much to think about now that the focus of Tier One was ready to change. Their first spaceflight had not gone entirely as planned, but the Ansari X Prize was now legitimately within reach. Yes, SpaceShipOne had made it to the altitude required by the Ansari X Prize—with only a few hundred feet to spare. Serious problems were encountered, however, and SpaceShipOne wasn’t even hauling the extra weight of a payload. It was necessary to review the spaceflight data and evaluate and repair the damage to SpaceShipOne. Corrective action was required to ensure these mishaps would not repeat and that the performance was improved to meet the demands of the Ansari X Prize.

The Ansari X Prize was to expire in half a year. Within that time, Scaled Composites had to fly two qualifying flights. Six months sounds like a lot of time, but margins of error for spaceflight are razor thin. For the challenges they faced—risking a test pilot’s life and possibly derailing the drive for private spaceflight for many years if something catastrophic occurred—six months were more like six weeks. The need for an additional powered flight before making an attempt at the Ansari X Prize had to be considered.

First Commercial Astronaut (15P)

Brian Binnie and Mike Melvill each had flown SpaceShipOne on famous firsts. Binnie was first to fly a rocket-powered flight and to break the sound barrier. Melvill was first to fly captive-carry and glide flights. He also took SpaceShipOne to space. But Pete Siebold had flown SpaceShipOne one more time than Binnie and was also more current. Who would fly for the Ansari X Prize? Mojave Aerospace Ventures LLC, photograph by Scaled Composites

 

First Commercial Astronaut (15P)

Construction Begins

Scaled Composites took what it described as an advanced all-composite design approach to building the rocket engine. “We did develop a new configuration of hybrid rocket motor,” Rutan said. “And we patented it. The patent is related to the fact that the whole motor cantilevers off the tank. And doesn’t require additional mounting and doesn’t build up stresses because of the temperature effects and the aerodynamic loads. It’s a key reason that this remains a very simple motor.

“During our development of the new hybrid rocket motor,” Rutan added, “Scaled contracted with four companies to provide components.” Most of the rocket engine was designed and developed in-house, though.

The two main parts of the rocket engine are the oxidizer tank and the integrated case/throat/nozzle (CTN), as shown in figure 5.5 and figure 5.6, respectively.

The oxidizer tank is a very important structural element of the rocket engine and SpaceShipOne as a whole. It is reusable and is bonded to the inside of the fuselage, all the way around, with an elastomeric

Construction Begins

Construction Begins

Construction BeginsГ – ^

Fig. 5.5. This oxidizer tank stored the liquid nitrous oxide (N20). After the tank was filled, it self pressurized, so a pump was not needed to inject the oxidizer into the fuel. The photo shows the inner liner of the oxidizer tank. Mojave Aerospace Ventures LLC, photograph by David M. Moore

compound. The bond is damage tolerant and isolates vibration, and because of the size of the bond area, the loading due to the force from the rocket engine is distributed over a large area.

The oxidizer tank has a fiberglass liner and two titanium interface flanges, fore and aft. After pressure testing the liner, Scaled Composites contracted Thiokol to provide a graphite/epoxy overwrap using a filament-wrap process, which can be seen in figure 5.7.

The CTN is mounted directly on the rear flange of the oxidizer tank with bolts and an О-ring seal (refer to figure 5.8).This cantilever mounting requires no other additional support, and, by design, reduces the number of potential leak paths.

( >

Fig. 5.6. The CTN (case/throat/nozzle) was a large composite casing

filled with synthetic rubber used as fuel. Once the rocket engine was ignited, the exhaust moved through the casing, was compressed by the throat, and then expelled out the nozzle. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

V__________________________________________ J

r ; ^

Fig. 5.7. The oxidizer tank had a special composite overwrap that allowed it to contain the oxidizer at a high pressure of 750 pounds per

square inch (psi). It was permanently bonded to the inside of the fuselage, so it was also an important structural member. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

Construction Begins

Construction BeginsПодпись: лг

Fig. 5.8. The CTN attached directly to the oxidizer tank. This photograph shows the mounting ring used to bolt it on. The hybrid design allowed the fuel and oxidizer to be very close together, which reduced the overall complexity of the rocket engine. Mojave Aerospace Ventures LLC, photograph by David M. Moore

V_________________________________________

The 22-inch – (56-centimeter-) diameter case of the CTN, where the combustion occurs, is essentially a hollow tube lined with the rubber fuel. The throat forced the hot exhaust gases, passing from the case to the nozzles, to converge. The nozzle accelerated the hot exhaust gases to provide even greater thrust. The silica/phenolic high-temperature insulating liner and mounting rings of the case were assembled together with the throat and nozzle using graphite/epoxy composite overwrap. The cantilevered mounting also provided the advantage of being able to vary the length and diameter of the CTN without design modifications.

A safety feature was built into the CTN to warn of an impending burn-through. If the fiber-optic cable sealed between the liner and the overwrap detected a breach in the liner, the flow of oxidizer would be cut off and the rocket engine shut down. As an additional precaution, wires wrapped around the outside of the CTN could also be used to detect a burn-through.

AAE Aerospace supplied an ablative nozzle with an expansion ratio of 25:1 for the CTN. The expansion ratio compares the size of the throat to the size of the nozzle’s opening. The efficiency is altitude dependent, so this ratio gave SpaceShipOne the maximum thrust at launch altitude. The interior of the nozzle eroded away as the rocket engine burned, which helped to minimize the temperature of the nozzle itself.

The entire CTN had to be replaced after each spaceflight.

Scaled Composites looked to outside vendors to supply the remaining components for the rocket engine, which included the injector, the igniter, and the related controls and plumbing. Scaled Composites held a competition of its own to build these components.

Rocket-Engine Competition

Simplicity of design by reducing the number of parts is best illus­trated by an experience Rutan had during his preliminary research into rocket-engine designs. Representatives of a rocket – engine vendor Rutan was visiting wanted to demonstrate how

Construction Begins

Г

Fig. 5.9. At the front of the oxidizer tank are the fill, vent, and dump valves. The vent valve protects from over-pressurization, and the dump valve allows the tank to be drained in an emergency situation. Mojave Aerospace Ventures LLC, photograph by David M. Moore

their valve worked after showing him schematics and describing their engine design. They went out to the back of the building, where the valve was chilled with liquid nitrogen to a cryogenic operating temperature.

“The valve stuck,” Rutan said. “It didn’t work. It failed right there while I was looking at it.”

After they went back inside, he said to them, “Gentlemen, let me ask you, how many of those valves are in this motor?”

Twelve, they replied.

“Did you expect this to work today?” he asked.

There was no answer. Rutan knew enough about rocketry to know if there was such a thing as a simple one that operated at room temperature with one valve, that’s the one he wanted.

Rutan had been looking at more than twenty rocket-engine vendors. With the help of Tim Pickens, a bit of a maverick rocket expert, Rutan sketched up the design and passed it on. “I had sent them a sanitized requirement that didn’t divulge that we were doing manned flight. I said it was a reusable sounding rocket.”

Now, it was necessary to build the remaining engine components. In front of the oxidizer tank was the fill, vent, and dump system as well as the forward tank bulkhead. This was how the liquid nitrous oxide was added to the tank, how pressure was relieved in case of over-pressurization, and how the nitrous oxide could be drained in an emergency situation. These components were kept away from the hot side of the oxidizer tank to improve safety. The locations of these components are shown in figure 5.9.

Arguably the most critical valve of the whole project was the main control valve that supplied the oxidizer to the CTN. Without
the flow of nitrous oxide, there would be no rocket. So, this valve received special attention. Doug Shane cleverly named it the “oxy – no-more-on” valve. Connected to the oxy-no-more-on valve was the injector, which was essentially a showerhead that sprayed the liquid nitrous oxide into the CTN. Both the oxy-no-more-on valve and the injector were located inside the oxidizer tank. What this did was further reduce plumbing and had the added benefit of keeping these components at a constant temperature, which also simplified things. Figure 5.10 shows their positions from a rear view of the oxidizer tank.

The rear tank bulkhead, motor controller, head insulation, and igniter still needed to be built as well. The igniter was the heat source that initiated the reaction between the oxidizer and rubber fuel. The last part that remained was the actual rubber fuel itself, which had to be packed into the CTN.

From the list of more than twenty potential rocket-engine vendors, it came down to two: Environmental Aeroscience Corporation (eAc), of Miami, Florida, and SpaceDev, of Poway, California. This wasn’t a low-bid process. It was performance-based, and the competition would go back and forth. Rutan thought that having just one vendor try to make the last of the components was too much of a risk. “When you sole source, if they stumble, you have to pay them to pick up,” Rutan said. “If you’ve got two of them competing and they stumble, they spend their own money to catch up. That’s what the big ‘C’-word is—competition. And that happened. They both wanted to fly.”

In the middle of 2001, both vendors began to participate in a ground-test program that included cold flow tests, where the oxi­dizer and fuel weren’t ignited, as well as partial – and full-duration

Construction Begins

Construction BeginsГ Л

Fig. 5.10. The CTN mounted on a titanium flange at the rear of the oxidizer tank. Located inside the tank was the main control valve, also known as the "oxy-no-more-on" valve, that released the oxidizer into the CTN. Mojave Aerospace Ventures LLC, photograph by David M. Moore

v__________________ J

г

Construction BeginsConstruction BeginsFig. 5.11. The test stand trailer (TST) was used during the rocket – engine test firings. It contained all of the same components and systems to be used in SpaceShipOne, including an oxidizer tank that the CTNs were mounted onto. Mojave Aerospace Ventures LLC, photograph by David M. Moore

Construction Begins

r ; л

Fig. 5.12. To fill SpaceShipOne or the TST with the oxidizer, nitrous oxide (N20), Scaled Composites used a special tanker truck called the mobile nitrous oxide delivery system (MONODS). Mojave Aerospace Ventures LLC, photograph by David M. Moore

V_______ )

hot-firings. All rocket engine testing employed the same type of compo­nents used in SpaceShipOne. Shaking out the full-scale designs on the ground at a Scaled Composites test site rather than in flight was a much more preferable way to address the “ups”—break up, burn up, and blow up.

In terms of experience, eAc had built a lot of hybrid rocket engines and had run some with diameters of up to 16 inches (41 centimeters). SpaceDev, on the other hand, had only run little hybrids with 15 pounds-force (67 newtons) of thrust.

This meant eAc was off to a quick lead. By June of 2002, the first set of results came in. Scaled Composites selected eAc as the supplier of the front-end propulsion components. However, both vendors continued to develop the remaining rocket-engine components.

To run all the rocket-engine tests, the test stand trailer (TST), a partial, operational mockup of SpaceShipOne shown in figure 5.11, acted as a portable test bed. It comprised the complete rocket engine, including the CTN and oxidizer tank, and the forward section of the fuselage. The TST provided instrumentation to analyze vibration, temperature, and stress conditions that the flight components would face during spaceflight. It also had load cells, which were sensors mounted on the trailer, that allowed engineers to evaluate the rocket – engine performance.

Setup for rocket-engine tests typically took several days. Since the TST was mobile, preparations began inside a hangar at Scaled Composites. Once the CTN was in place and all the other com­ponents were hooked up, the TST was towed out to the firing range. Figure 5.12 shows the specialized tanker truck called the mobile nitrous oxide delivery system (MONODS) that then fills the oxidizer tank.

Mission Control ran the rocket-engine tests remotely, and an under­ground computer near the TST collected and transmitted live data. The countdown procedures for the ground testing are listed in table 5.1.

Since testing occurred on the ground, a nozzle with an expansion ratio of 10:1 was used, as opposed to 25:1 used for actual flights.

SpaceDev had fired first, a 15-second burn on November 21, 2002. The rocket roar was deafening for each hot-fire of the rocket engine. The ground shook. Figure 5.13 shows the tip of a fiery plume stretched out more than thirty feet, scorching the ground and sending smoke billowing across the desert.

“The SpaceDev motor was the only one that had a critical safety issue. In the first round, a valve wouldn’t close and it keep burning and burning,” Rutan said. Although Scaled Composites was slow to extinguish the fire, no significant damage occurred.

After more than nine months of firing rocket engines, the gap between eAc and SpaceDev had disappeared. Each had little differences. For example, SpaceDev used four ports to flow the oxidizer into the CTN, whereas eAc used just one, and they each had a proprietary rubber fuel and system for refueling the CTN. But both had exceeded performance expectations.

With the exception of the fire caused by a stuck valve at the very onset of test firing, the hybrid rocket engine demonstrated safety and reliability. The cantilever mounting concept proved structurally sound, the oxidizer and CTN performed as designed, and the “ups” were avoided altogether.

Scaled Composites had both companies commit prices for compo­nents, not only for the upcoming flight test and Ansari X Prize rocket engines, but for twenty-two other rocket engines slated for what was called Task 21, the spaceflights after the Ansari X Prize attempts.

Construction Begins

Table 5.1 Rocket Engine Test Countdown

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

 

T-48 hours Mounting the CTN

The fully fueled CTN (engine) and valve are mounted to the oxidizer tank using the mounting trolley. Alignment is checked and bolts are tightened to the specified tolerances.

T-36 hours Instrumentation and Integration

The motor controller, pressure bottles, actuation valves, and all the sensors are installed and tested on the test bed. New CTNs require new temperature and strain sensors, while CTNs being fired for the second or third time are "plug and play."

T-24 hours Moving Time

The test trailer with the fully fueled CTN (engine) is moved from Scaled’s hangar to the test site. There it is bolted down, final instrumentation is completed, and the system is connected to Mission Control.

T-4 hours Filling the Tank

Nitrous oxide is transferred from the MONODS to the oxidizer tank on the test trailer after it has been brought up to temperature and pressure. Temperatures and pressures must be carefully controlled to ensure a safe transfer.

T-0 hours The Final Countdown

After final system checks have been made, cameras have been started, and range safety has been checked, a quick countdown is called and the switch is thrown. The motor controller automatically ignites and fires the engine for a preprogrammed period of time.

“SpaceDev’s components were lighter, which helped our perform­ance,” Rutan said. “Keep in mind, we knew that we had to have really the best performance in order to win the X Prize because we had a weight growth. So, we needed all the performance we could get. SpaceDev’s components had a little more efficiency, on the order of three percent for the same weight of propellant.”

SpaceDev actually turned out to be cheaper, too—all characteristics Rutan was very fond of. In September of 2003, the development phase of SpaceShipOne’ s rocket engine was completed. SpaceDev got the nod.

Figure 5.14 shows a rocket engine installed in SpaceShipOne without the fairing in place, so the unsupported ended of the CTN is apparent.

Departure from Controlled Flight (6G)

The focus of the test flight program now began to shift to prepare for the upcoming rocket-powered flights. Up to this point, SpaceShipOne was flown light, but for rocket-powered flight, it would have to maneuver with a fully fueled rocket engine. SpaceShipOne was loaded so the center of gravity (CG), or the single balance point of SpaceShipOne s mass, moved to the aft to simulate these conditions.

When Melvill tested the stall characteristics for the aft-loaded SpaceShipOne, the nose swung upward uncontrollably before the wings reached the angle of attack at which they were expected to stall. SpaceShipOne entered into a spin while Melvill fought to regain control. Figure 7.7 shows SpaceShipOne as Melvill recovered from the tail stall.

“We had a pretty significant departure from controlled flight at high angle of attack, aft CG, due to a tail stall. That really was a big surprise,” Doug Shane said.

Г

Flight Test Log Excerpt for 6G

Date: 23 September 2003

Flight Number Pilot/Flight Engineer

SpaceShipOne 6G Mike Melvill

White Knight 37L Pete Siebold/Matt Stinemetze

and Jeff Johnson

Objective: Third glide flight of SpaceShipOne. Aft CG flying qualities and performance evaluation of the spaceship in both the glide and reentry or "feather" mode. Glide envelope expansion to 95 percent airspeed, 100 percent alpha [angle of attack] and beta [sideslip angle], and 70 percent load factor. More aggressive post-stall maneuvering and spin control as a glider and while feathered. Nitrous temperature control during climb to altitude and performance of upgraded landing gear extension mechanism and space-worthy gear doors.

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

4___________________ J

Г ‘

Fig. 7.6. After quickly correcting the avionics malfunction, SpaceShipOne and White Knight returned to the air several hours after the aborted fourth test flight.

During this flight test, SpaceShipOne extended its feather for the first time. It performed superbly. Mojave Aerospace Ventures LLC, photograph by David M. Moore

v____ J

Departure from Controlled Flight (6G)

Г

Departure from Controlled Flight (6G)Подпись: лFig. 7.7. The sixth glide flight, on September 23, 2003, focused on the handling qualities when SpaceShipOne was loaded in the back, where the heavy rocket engine would eventually be. SpaceShipOne stalled unexpectedly, and the photograph shows the craft right after recovery.

Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

ч___________________________________________________________________________________ У

The feather wasn’t raised during the test flight, but during the climb to release altitude, the pressure test of the oxidizer tank revealed a variation of less than 6 psi. This meant that the temperature of the nitrous oxide inside could be controlled very well by exhaust air ducted in from White Knight.

Scaled Composites needed wind-tunnel data to evaluate the problem with the tail booms. “Except we didn’t have a wind tunnel, but we did have a pickup truck. And we had our aero guy, Jim,” Shane said.

Using a converted pickup truck fitted up with instrumentation, called the Land Shark, engineers aerodynamically tested mockups of the tail boom. With clearance from Mojave Airport, the Land Shark zoomed up and down a runway to collect data.

“We finally ended up doing a fence and a span increase on both the stabilizer and the elevon and resolved the problem,” Shane said.

A triangular strake was also added to each tail boom, right in front of each horizontal stabilizer. SpaceShipOne was ready to go back to flight testing.

r—————————————– Л

Flight Test Log Excerpt for 7G

Date: 17 October 2003

Flight Number Pilot/Flight Engineer

SpaceShipOne 7G Mike Melvill

White Knight 38L Pete Siebold/Cory Bird

and David Moore

Objective: Fourth glide flight of SpaceShipOne. Primary purpose was to examine the effects of horizontal tail modifications at both forward and mid-range CG locations (obtained by dumping water from an aft ballast tank between test points). The tail modifications included a fixed strake bonded to the tail boom in front of the stabilator and a span-wise flow fence mounted on the leading edge of each stab at mid-span. Other test objectives included a functional check of the rocket motor controller, ARM,

FIRE, and safing switches as well as the oxidizer dump valve. Additional planned maneuvers included full rudder pedal sideslips and more aggressive nose pointing while in the feathered configuration.

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

V___________________ J

Crew Compartment

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

г ;

Crew CompartmentFig. 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

V _____________ J

Crew Compartment

r ^

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.”

Capturing the Anasari X Prize

T

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.”

Capturing the Anasari X Prize

Ґ

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

V________________________________________________________________________________ J

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

г >1

Capturing the Anasari X PrizeFig. 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

V__________ J

Capturing the Anasari X Prize

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)

V__________________________________________ у
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.”

Rocket-Engine Operation

On November 18, 2003, Scaled Composites qualified a rocket engine in preparation for the first powered flight of SpaceShipOne.

“The nice thing about this particular type of hybrid motor is the nitrous oxide is room temperature in the oxidizer tank in front. It self-pressurizes to about 750 pounds per square inch,” Doug Shane
said. This eliminated the need for complicated and expensive pumps to flow the oxidizer into the CTN. In figure 5.15a panel on the belly of SpaceShipOne is removed, exposing the engine bay, so the CTN could be easily mounted.

The oxidizer tank was filled with liquid nitrous oxide through its forward bulkhead. The MONODS pumped the nitrous oxide at 300 pounds per square inch and 0 degrees Fahrenheit. To bring the temperature up to room temperature and maintain it there, engine bleed air from White Knight flowed into SpaceShipOne and was directed at both ends of the tank during captive carry.

The rocket engine of SpaceShipOne could only be fired once. After the rocket engine was armed and the fire switch thrown, the igniter produced a significant amount of heat, causing combustion between the oxidizer and fuel.

“SpaceShipOne does not have a throttle. It is on or off,” Rutan said. “There was no need for a throttle.”

For the spaceflights, the force of thrust was 16,800 pounds-force (74,730 newtons). However, because of performance concerns and

Rocket-Engine Operation

Подпись: ~ J ґ

Fig. 5.13. Scaled Composites was able to monitor the performance of each rocket engine tested during the development phase. Data collected by sensors on the TST was relayed to engineers real-time for analysis. Mojave Aerospace Ventures LLC, photograph by David M. Moore

к_________________________________________________________________________________________

Rocket-Engine Operation

Rocket-Engine Operation

г ; ^

Fig. 5.15. Between each spaceflight, it was necessary to replace the spent CTN with a fully fueled CTN. The spent CTN can be refurbished by refueling the rubber inside the casing and replacing the ablative nozzle. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

( >

Fig. 5.14. This photograph shows the rocket engine before the engine

fairing was attached. The cantilever rocket-engine design patented by Scaled Composites had the CTN fixed to the oxidizer tank at one end but completely unsecured at the nozzle end. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

V__________________________________________ J the additional payload required by the Ansari X Prize competition, additional nitrous oxide oxidizer and rubber fuel were added, as well as an increase in burn duration. The thrust and the specific impulse (I$p), a measure of efficiency of the rocket engine, were not officially released by Scaled Composites.

Peak performance occurred once the rocket engine ignited. As the rubber burned away and the oxidizer tank emptied, the amount of thrust gradually reduced.

About sixty seconds into the burn, the nitrous oxide began a transition from liquid to gas because there was more room in the oxidizer tank for it to expand, which caused a significant decrease in thrust. At this point, the combustion was uneven throughout the CTN and caused SpaceShipOne to chug along for about five seconds. The ride then smoothed out for the remainder of the burn now that the nitrous oxide had transformed to gas.

During the flight, the engine performance and parameters could be monitored in the cockpit by the pilot and on the ground in Mission Control.

Rocket-Engine Operation

Brian Binnie stands in front of SpaceShipOne with its feather extended. In addition to the feather, SpaceShipOne required three other systems for control during a spaceflight: the mechanical flight control system for subsonic speeds, the electric flight control system for supersonic speeds, and the reaction control system (RCS) for space. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

 

Rocket-Engine Operation

SpaceShipOne Instruments and Controls

paceShipOne is part airplane, missile, spacecraft, and glider. Like the North American X-1S, it was flown by hand. Figure 6.1 shows SpaceShipOne during a glide test flight with its control surfaces clearly visible on the tail booms.

To complete each spaceflight mission, it had to transition between a variety of flight phases, including takeoff, captive carry, boost, coast, feather, glide, approach, and landing. Flying these phases, SpaceShipOne crossed between three distinct flight regimes: subsonic, supersonic, and zero-g. Different flight control systems were required to operate in each regime. A basic mechanical control system was used in subsonic flight, while an electric – powered control system and a reaction control system (RCS) were required in supersonic and zero-g flight, respectively.

SpaceShipOne had a set of instruments and controls for each flight control system that the pilot had to switch between. Figure 6.2 shows Mike Melvill in the cockpit holding the control stick of SpaceShipOne with the nose cone detached.

Subsonic Flight Control

SpaceShipOne essentially flew like a light airplane—some of the time anyway. It had a mechanical flight control system that operated manually, similar to that of a Cessna 172 or Piper Cub. A simple cable-and-rod linkage tied the stick and rudder pedals

Rocket-Engine Operation

Подпись: Г

Rocket-Engine Operation

г ^

Fig. 6.1. SpaceShipOne was the first manned aircraft to use tail booms attached to the wingtips. Unlike almost every other aircraft, the wings had no control surfaces. The pilot maneuvered SpaceShipOne with control surfaces that were all located on the tail booms, an upper and lower rudder at the back of each tail boom, flying or movable horizontal stabilizers, and elevons at the trailing edge of each horizontal stabilizer. Mojave Aerospace Ventures LLC, photograph by Scaled Composites

Fig. 6.2. With the nose cone detached, Mike Melvill gets some practice at the controls of SpaceShipOne as Steve Losey, the crew chief, looks on. SpaceShipOne had room for a pilot up front and two passengers in the back row. Mojave Aerospace Ventures LLC, photograph by David M. Moore

N

to the control surfaces. The connections between the pilot’s controls in the cockpit and the control surfaces are shown in figure 6.3. No hydraulics were used for flight control.

All of the control surfaces were located on the tail booms. An upper and lower rudder were mounted at the end of each tail boom. The rudder pedals in the cockpit moved the upper rudders for control of yaw. Refer to figure 6.4 for SpaceShipOne s flight axes and rotations. Each rudder pedal worked independently and deflected the corresponding upper rudder outward only. By depressing both, the upper rudders acted a little bit like a speed brake.

On the horizontal stabilizer, elevons combined the functions of conventional ailerons on the wings and elevators on the tail. The control

f ‘ ^

Подпись:Подпись:Подпись:Rocket-Engine OperationFig. 6.3. This diagram shows the different control systems and the linkages from the controls in the cockpit to the control surfaces. The reaction control system (RCS) and the landing gear are also shown in this cutaway. Mojave Aerospace Ventures LLC, provided courtesy of Scaled Composites

V________________ )

Подпись: Not# Skid (Aids runway braking extends only, gravity and spring driven, crush damper) components

f >1

Fig. 6.4. Each of the three flight control systems allowed SpaceShipOne to maneuver along the flight axes. Pitch and roll were controlled by the elevons at subsonic speeds and by the movable horizontal stabilizers at supersonic speeds. The upper rudders and lower rudders controlled yaw at subsonic and supersonic speeds, respectively. RCS thrusters mounted on the wings and fuselage controlled pitch, roll, and yaw in space. James Linehan

V__________________________________________ J

Rocket-Engine Operationf Л

Fig. 6.5. At the trailing edge of each horizontal stabilizer was an elevon. When both elevons moved in the same direction, the pitch of SpaceShipOne changed. When moved differentially, roll changed. The photograph shows the poor airflow over a horizontal stabilizer during a stall test, as indicated by the small strings attached to the surface. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

V______________________________ J

stick moved the elevons, which allowed the pilot to control pitch and roll of SpaceShipOne. Figure 6.5 shows a horizontal stabilizer during testing after modification.

Back on Track (7G)

“A stall is when the air flowing over the wing no longer stays attached to the surface. It’s not developing any lift anymore. And as soon as it stalls, you are not an airplane anymore. You are just a 2,000-pound [910-kilogram] lump falling out of the sky,” Mike Melvill defined in Black Sky, the Discovery Channel documentary about SpaceShipOne.

For this flight, the only modifications to each tail boom were the addi­tions of the strake and flow fence. The enlargement of the horizontal stabilizers would wait until the next test flight. However, the new mod­ifications did improve the aerodynamics, and the uncommanded pitch-up of the nose at aft CG was eliminated. Melvill was able to then turn his attention to the feather and rocket-engine controls. Figure 7.8 shows the feather deployed as he continued to push maneuverability limitations.

After the functionality of the rocket-engine instruments and controls checked out, Melvill was ready to land. Figure 7.9 shows a view from the camera mounted in his helmet as SpaceShipOne neared the runway. The glide flight lasted 17 minutes and 49 seconds.

Back on Track (7G)

Ґ ^

Fig. 7.8. Several modifications were put in place to address the stall problem encountered in the previous flight, including the addition of a triangular strake mounted in front of each horizontal stabilizer and a flow fence attached midspan on each horizontal stabilizer. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

V___________________ J

г ^ ^

Back on Track (7G)Fig. 7.9. Flying the first six piloted flights, two captive carries, and four glide flights, Mike Melvill continued to expand the flight envelope. Step by step, he pushed SpaceShipOne to perform a little harder so the engineers could get a more complete picture of its flying qualities. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

V____________________________________________________________ )

Подпись: f Fig. 7.10. On November 14, 2003, Pete Siebold became the second test pilot to fly SpaceShipOne. The Scaled Composites team had to wear many hats. Siebold was also responsible for developing the software for the Tier One navigation unit (TONU) and flight simulator. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc. V .

Подпись:Подпись: Pilot/Flight Engineer Pete Siebold Brian Binnie/Matt Stinemetze

Wings

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.

WingsWingsг л

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

v__________________ J

“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.