Category Space Ship One

Unplugged (12G)

After a little less than three months, SpaceShipOne was ready to return to the air again, with Pete Siebold at the controls. However, its rocket engine would be quiet during this test flight.

“It was after the famous 11P flight, which resulted in significant damage to the aircraft on the hard landing,” Siebold recalled. “It was

Unplugged (12G)Unplugged (12G)in one respect what we would call a functional check flight after any major modifications to the airplane. We wanted to go fly it in a semi – benign environment and try and shake down any of the problems that we may have overlooked or additional problems that had been created due to the modifications.

“The other reason was we made some modifications to the aero­dynamic shape. We added the thermal protection to the aircraft. If you look at the artwork of that flight, it shows the red leading edges and shows the TPS addition. That actually changed the wing shape slightly and the aerodynamic shape. So, we wanted to go and fly that and see if there were any ill effects to that modification for the flight.”

Siebold started off his second time flying SpaceShipOne at an altitude of 48,500 feet (14,780 meters), which was the highest point that White Knight ever released SpaceShipOne. Scaled Composites had originally planned on releasing SpaceShipOne from an altitude of 50,000 feet (15,240 meters). However, White Knight had a very difficult time flying this high and too frequently had come out of afterburners or flamed out altogether at an altitude even below this one. The lower launch altitude did actually work in SpaceShipOne’s favor.

During powered flight, the first thing that SpaceShipOne had to do was “turn the corner” as soon as it possibly could, but the higher the altitude, the less air there was for the wings to bite into in order to make a quick turn upward. So, in terms of utilizing the energy from the rocket engine as efficiently as possible, launching below 48,000 (14,630 meters) feet gave better overall performance, since SpaceShipOne would spend more time pointing up than over.

However, since Siebold wasn’t concerned with lighting off the rocket, he wanted all the altitude he could get for the glide flight. “There were some minor glitches,” he said. “The thermal protection system started cracking at low temperatures, and I think there was actually a formulation change made between that flight and the actual powered flight.”

But the thermal protection system (TPS) wasn’t the only system being checked out. Siebold also evaluated the reaction control system (RCS) that would be used to maneuver SpaceShipOne while in the absence of the atmosphere. This and other testing worked out smoothly, and SpaceShipOne touched down safely, even in the presence of a strong crosswind.

Air and Electrical Power

Clean, dry air was used in the pneumatics to pressurize the actuators. The cabin was also pressurized with air. Each system had its own high-pressure bottle and a backup bottle. The feather, environmental control system (ECS), and reaction control system (RCS) each had a bottle A and bottle B. The initial pressure of these six bottles was 6,000 pounds per square inch (psi). Other systems also required pressurized air, but they fed off of these bottles. Electricity was provided by an array of lithium batteries.

SpaceShipOne was the first manned spacecraft to use a hybrid rocket engine, which is a cross between a liquid-fueled rocket engine and a solid – fueled rocket engine. Designed by Scaled Composites, it ran by using a combination of synthetic rubber and nitrous oxide. Mojave Aerospace Ventures LLC, photograph by David M. Moore

Two Last Flights for SpaceShipOne

Scaled Composites received about $25 million from Paul Allen for twenty tasks that Burt Rutan had specifically outlined, which covered
building SpaceShipOne all the way through competing with it. “Task 21 was that we would fly SpaceShipOne every Tuesday for five months, reasoning that if we did that you could then make with confidence a commercial business plan,” Rutan said.

But Task 21 wasn’t funded. Rutan figured that once he got the data on the real costs of flying SpaceShipOne, he would then approach Allen. “That would be the opportunity for Paul and me and both of our friends to be astronauts,” Rutan explained. “If you just count only the passengers, you’ve got forty-four people. So, maybe twenty of my friends could be astronauts and twenty of his friends could be astro­nauts. That would be kind of cool. That was the plan. But something got in the way of the plan. I underestimated the impact of SpaceShipOne on the media and the public, and I underestimated its effect on historians.”

Shortly after Melvill flew SpaceShipOne into space the first time, Rutan received a letter from Valerie Neal, the curator of post-Apollo human spaceflight for the Smithsonian Institution’s National Air and Space Museum. “It was clear to all of us right away once Mike Melvill had made the first flight in June that this was a remarkable achievement, whether or not it won the Ansar і X Prize,” Neal said.

Two Last Flights for SpaceShipOne
“We think that SpaceShipOne either itself may prove to be the pivotal craft that leads to a commercial spaceflight space-tourism industry, or it’s the leading edge of that. You know there are enough developments going on right now. It looks as if this is the cusp of a new revolution in spaceflight.”

So, the National Air and Space Museum expressed its interest in acquiring SpaceShipOne to join it with other remarkable vehicles in the Milestones of Flight gallery, which includes the original 1903 Wright Flyer, Spirit of St. Louis, and the Bell X-l that broke the sound barrier, Glamorous Glennis. But the National Air and

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Two Last Flights for SpaceShipOne

Two Last Flights for SpaceShipOne

Fig. 10.11. When SpaceShipOne made it first spaceflight on June 21,2004, the National Air and Space Museum of the Smithsonian Institution immediately recognized the significance of the event. By becoming the first non­governmental, privately funded vehicle to reach space, SpaceShipOne earned a place in the Milestones of Flight gallery with the Spirit of St. Louis, Bell X-1, 1903 Wright Flyer, and Apollo 11 command module Columbia.

Courtesy of Virgin Galactic

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Fig. 10.10. On June 27, 2005, Burt and Tonya Rutan, in SpaceShipOne, and Mike and Sally Melvill, in White Knight, landed at Oshkosh, Wisconsin, for the Experimental Aircraft Association’s (EAA) 2005 AirVenture. An active EAA member, Burt Rutan introduced the VariViggen, the first aircraft he designed and built, at the 1972 AirVenture. Now he and Melvill, also a longtime EAA member, gave a special showing of SpaceShipOne and White Knight to many of their closest supporters. Tyson V. Rininger

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Space Museum didn’t realize the extent to which Allen was involved. Rutan said that he would have to bring Allen into the dialog as well.

“So,” Neal recalled, “it was right at the end of November or early December when Allen and Rutan both said, ‘Yeah, we’re really interested

in donating this to the museum. Come on out and let’s talk and let’s have a look at it together.’”

Rutan had to face a tough decision. He explained, “When we got that request, Paul Allen called and said, ‘Listen, I don’t want you to fly it anymore. Just get the X Prize. Two more flights and

Two Last Flights for SpaceShipOne

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Fig. 10.12. Carrying a small piece of SpaceShipOne, the space probe New Horizons, launched in 2006, races to the edge of the Solar System. The first mission ever to the dwarf planet Pluto, it will arrive in 2015. NASA/Johns Hopkins University Applied Physics Laboratory-Southwest Research Institute

V______________________________________________________________________________

that’s it.’ We had three or four motors, so we could have easily flown one more flight. My first thought was to fight with him. I said, ‘No, you’ve got to prove a business plan. If this is going to go on to the next step, you got to do this.’ And then I realized that he really was right.”

Preserving the legacy was more important.

Valerie Neal recalled, “What I had asked Rutan to do before he delivered it to us was to return it to its June configuration. After that June flight, before the X Prize flights, quite a number of decals were added to it, and the Virgin Galactic logo was added to it. And the appearance was considerably different.”

Even the dent in the engine fairing from that flight was put back. That’s how seriously Scaled Composites took her request. So, right after SpaceShipOne was hung in the museum, the damage drew some quick notice. “The director of the museum came in and said, ‘I hope we didn’t do that last night.’ And I said, ‘No, no, it came that way,’” Neal said.

However, even before being transferred to the museum, Rutan wanted to fly White Knight and SpaceShipOne to Oshkosh. He wanted to do something special for the Experimental Aircraft Association (EAA), which had stood by him from the time of his very first aircraft. With Mike Melvill behind the stick of White Knight and SpaceShipOne attached below, he flew from Mojave but stopped right before reaching the air show in Madison, Wisconsin, to pick up some very important passengers. Burt Rutan and his wife, Tonya, climbed into SpaceShipOne, while Sally Melvill joined her husband in White Knight.

They touched down at Oshkosh on June 27, 2005. “It was very emotional because it was like a homecoming for the triumphant sol­dier,” said Tom Poberezny, president of EAA. “And here was Burt coming home to an audience that truly appreciated what he did because they’ve grown up with him. They’ve appreciated every design innovation he has ever done, his successes, his failures, his trials, his tribulations.”

Figure 10.10 shows the EAA crowd gathered around SpaceShipOne andWhite Knight.

When the air show ended, Melvill took off with a small crew to head for Dulles Airport in Washington, D. C., after first stopping over in Dayton, Ohio, the hometown of the Wright brothers. But the adventure was far from over. White Knight doesn’t have very long legs. Its range is only about 500 miles (800 kilometers). When it reached

Dulles Airport, someone must have noticed White Knight carrying a missile-like object. “So, they turned us around and drove us away right in the middle of the approach,” Mike Melvill said.

“I said, ‘If you turn us around, we will run out of gas.’ And the air – traffic controller said, ‘I don’t care. Make a one-eighty and get out of here. I don’t want to see you again.’ And I said, ‘You need to get your supervisor because this has all been pre-briefed.’ Pretty soon the airline guys on the same frequency were saying, ‘Hey, come on. This is the guy delivering SpaceShipOne to the National Air and Space Museum.’”

Even after arrangements had been made with the airport and with the officials from the National Air and Space Museum on the ground, Melvill was denied. But he could always be counted on when the situation did not go exactly as planned. With almost no gas, he was able to land on a runway that wasn’t being used by the airlines. After detaching SpaceShipOne from White Knight and spending about an hour on the ground, Melvill lifted off in White Knight. The mothership had left its baby for good. Figure 10.11 shows SpaceShipOne in the Milestones of Flight gallery after the donation ceremony on October 5, 2005, hanging next to Spirit of St. Louis and Glamorous Glennis.

Although SpaceShipOne’s mission was suborbital spaceflight, it was actually able to completely break away from Earth’s gravitational pull. In 2007, a small piece of SpaceShipOne, aboard the space probe New Horizons, zipped by Jupiter on its way to a rendezvous with Pluto and its moon Charon. It will then continue on further to the edge of the Solar System into the mysterious Kuiper Belt, a region of space responsible for the demotion of Pluto from a planet to a dwarf plan­et after the discovery of a tenth planet. Launched in 2006, this is the first mission aimed at exploring these celestial objects. Figure 10.10 shows a conceptual drawing of the space probe on its journey.

In June of 2015, New Horizons and the SpaceShipOne fragment will have completed the interplanetary cruise phase on the way to Pluto. Earth will be 3.06 billion miles (4.92 billion kilometers) away when the closest approach occurs. Eleven years earlier, to the month, SpaceShipOne had first entered space, giving real hope to those with dreams of floating free in space.

A character in Clarke’s 2010: Odyssey Two, in summarizing what he expected from an upcoming space trip, simply stated, “Something wonderful.” By the time New Horizons actually reaches Pluto, that phrase will be invoked many times thanks to the accomplishments of commercial space travel that are to come.

A: SpaceShipOne Flight Data

 

Date

Intended

Mission

SpaceShipOne

Flight Pilot/ Flight

Flight

No.<2)

Pilot

Flight

Time

{minutes}

Release

Altitude

(feet (meters)}

Release

Speed

{knots}

Top

Speed

{Mach}<b>

Rocket

Burn

{seconds}

Shutdown

Altitude

{feet (meters)}

Apogee

{feet (meters)}

Maximum

g-Force

{G}<b>

No.(2>

Flight

Engineer

1 ime

{hours}

5/20/03

Captive

Carry

01C

24C

Pete

Siebold/

Brian

Binnie

1.8

7/29/03

Captive

Carry

02C

Mike

Melvill

29C

Brian Binnie/ Cory Bird

2.1

8/7/03

Captive

Carry

03G

Mike

Melvill

19.00

47,000

(14,330)

105

30L

Brian Binnie/ Cory Bird

1.1

8/27/03

Glided)

04GC

Mike

Melvill

31LC

Brian Binnie/ Cory Bird

1.1

8/27/03

Glide

05G

Mike

Melvill

10.50

48,200

(14,690)

105

32L

Brian Binnie/ Cory Bird

1.1

9/23/03

Glide

06G

Mike

Melvill

12.25

46,800

(14,270)

115

37L

Pete

Siebold/

Matt

Stinemetze and Jeff Johnson

1.5

10/17/03

Glide

07G

Mike

Melvill

17.82

46,200

(14,080)

115

38L

Pete Siebold/ Cory Bird and David Moore

1.1

11/14/03

Glide

08G

Pete

Siebold

19.92

47,300

(14,420)

115

40L

Brian

Binnie/

Matt

Stinemetze

1.4

11/19/03

Glide

09G

Mike

Melvill

12.42

48,300

(14,720)

115

41L

Brian Binnie/ Cory Bird

2.1

12/4/03

Glide

10G

Brian

Binnie

13.23

48,400

(14,750)

115

42L

Pete

Siebold/

Matt

Stinemetze

1.3

12/17/03

Powered

11P

Brian

Binnie

18.17

47,900

(14,600)

112

1.2

15

(d)

67,800

(20,670)

3+

43L

Pete Siebold/ Cory Bird

1.2

3/11/04

Glide

12G

Pete

Siebold

18.50

48,500

(14,780)

125

49L

Brian

Binnie/

Matt

Stinemetze

1.3

4/8/04

Powered

13P

Pete

Siebold

16.45

45,600

(13,900)

125

1.6

40

(d)

105,000

(32,000)

(d)

53L

Brian

Binnie/

Matt

Stinemetze

1.3

5/13/04

Powered

14P

Mike

Melvill

20.73

46,000

(14,020)

120

2.5

55

150,000 (45,720)

211,400

(64,430)

3.5

56L

Brian

Binnie/

Matt

Stinemetze

1.5

6/21/04

Powered

15P

Mike

Melvill

24.08

47,000

(14,330)

(d)

2.9

76

180,000

(54,860)

328,491

(100,124)

5.0

60L

Brian

Binnie/

Matt

Stinemetze

1.6

9/29/04

Powered

16P

(XI)

Mike

Melvill

24.00

46,500

(14,170)

(d)

3.0

77

180,000

(54,860)

337,00

(102,900)

5.1

65L

Brian

Binnie/

Matt

Stinemetze

1.6

10/4/04

Powered

17P

(X2)

Brian

Binnie

24.00

47,000

(14,360)

(d)

3.25

84(e)

213,000

(64,920)

367,500

(112,00)

5.4

66L

Mike

Melvill/

Matt

Stinemetze

1.6

(a) C, G, L, and P denote captive carry, glide, launch, and powered, respectively, for the intended missions of SpaceShipOne and White Knight. A second letter in the flight number indicates the actual mission if different than the intended mission.

(b) The highest value is given whether occurring during boost or reentry.

(c) Flight aborted prior to SpaceShipOne separation from White Knight, so SpaceShipOne was not released.

(d) Data not reported in Combined White Knight/SpaceShipOne Flight Tests provided by Scaled Composites.

(e) The value of 84 seconds is used based upon the transcript of 17P.

 

Подпись: Appendices A & В

Two Last Flights for SpaceShipOne

В: Chase Plane Crews

Flight No.

Duchess: Low Altitude

Extra 300: High Altitude

Alpha Jet: High Altitude

Starship: High Altitude

01C

(a)

(a)

(a)

(a)

02 C

(a)

(a)

(a)

(b)

03G

(a)

(a)

(a)

(b)

04GC

Jon Karkow

Pete Siebold

05G

Jon Karkow

Pete Siebold

06G

Brian Binnie

Jon Karkow

07 G

Chuck Coleman

Brian Binnie

08G

Mike Melvill Chuck Coleman

Jon Karkow

09G

Chuck Coleman Matt Stinemetze

Pete Siebold

10G

Mike Melvill Chuck Coleman

Marc de van der Shueren Jeff Johnson

Jon Karkow

11P

Mike Melvill Chuck Coleman

Marc de van der Shueren Jeff Johnson

Jon Karkow

12G

Mike Melvill Chuck Coleman

Jon Karkow

13P

Mike Melvill Chuck Coleman

Marc de van der Shueren Jeff Johnson

Jon Karkow Robert Scherer

14P

Pete Siebold Dave Moore

Marc de van der Shueren Jeff Johnson

15P

Chuck Coleman Cory Bird

Marc de van der Shueren Jeff Johnson

Jon Karkow Robert Scherer

16P

Chuck Coleman Cory Bird

Marc de van der Shueren Jeff Johnson

Jon Karkow Robert Scherer

17P

Chuck Coleman Cory Bird

Marc de van der Shueren Jeff Johnson

Jon Karkow Robert Scherer

(a) Data not reported in SpaceShipOne/ White Knight Flight Log.

(b) The Starship, owned by Robert Scherer, was flown during this flight, but the crew was not reported.

Going it Alone (3G)

“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.

A Third of the Way There (13P)

Why did the desert tortoise cross the runway? Now that Scaled Composites planned a longer burn, it could no longer fly under the radar of the FA A. Scaled Composites needed a commercial launch license, and the Office of Commercial Space Transportation (AST) of the FAA required Scaled Composites to do an environmental impact report as part of the application process.

Doug Shane explained, “One of the caveats that came back with that [application] is before taking off in White Knight and before landing in SpaceShipOne, we had to do a sweep of the Mojave runway for desert tortoises. And if we found a desert tortoise, we couldn’t move it. We couldn’t touch it. We couldn’t talk to it. We couldn’t negotiate with it. We couldn’t threaten it. We couldn’t bribe it in any way.

“What we had to do was call the desert tortoise control specialist from Ventura County, about a three-hour drive away, and let them come and negotiate some kind of a successful conclusion.”

Ґ————————————————————————– A

Flight Test Log Excerpt for 12G

Date: 11 March 2004

Flight Number Pilot/Flight Engineer

SpaceShipOne 12G Pete Siebold

White Knight 49L Brian Binnie/Matt Stinemetze

Objective: The twelfth flight of SpaceShipOne. Objectives included: pilot proficiency, reaction control system functionality check, and stability and control and performance of the vehicle with the airframe thermal protection system installed. This was an unpowered glide test.

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

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Fortunately, Scaled Composites got their license, no tortoises made runway excursions, and flight 13P was a go. Pete Siebold, who would have the controls of SpaceShipOne for the second power flight, recalls, “That was the first time that we flew basically at our heavy weight. First time we put all the nitrous on board. The airplane was fully ballasted to be a representative weight for the spaceflights. It was part of that incremental weight expansion.”

Right upon release from White Knight at 45,600 feet (13,900 meters) and 125 knots, though, SpaceShipOne ran into problems. “We pulled the nose up to maintain our speed, and we realized that the wings at that weight and speed could not lift the vehicle,” Siebold said. “So, the wings were stalling earlier than anticipated. So, there was this problem that we were faster than we wanted to be to light the rocket, which would result in an overspeed.

But we also didn’t want to abort the flight, because we had some really questionable handling qualities if we dumped all the nitrous to our landing weight. It would send our CG dangerously far aft.”

Flight Test Log Excerpt for 13P

Date: 8 April 2004

Flight Number Pilot/Flight Engineer

SpaceShipOne 13P Pete Siebold

White Knight 53L Brian Binnie/Matt Stinemetze

Objective: The second powered flight of SpaceShipOne. Forty seconds motor burn time. Handling qualities during boost, through transonic and supersonic. Reaction control system functionality inflight and feather configuration stability during transonic reentry. Evaluation of radar tracking capability.

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

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A Third of the Way There (13P)A Third of the Way There (13P)Fig. 8.5. Nearly four months after the first rocket-powered flight test, Pete Siebold ignited the rocket engine of SpaceShipOne for 40 seconds and reached an apogee of 105,000 feet (32,000 meters). He hit a top speed of Mach 1.6 on the boost and Mach 0.9 on the way down. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

V_________________________________________________ )

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Fig. 8.6. SpaceShipOne reached a third of the way up to the Ansari X Prize goal of 328,000 feet (100,000 meters). This was all part of the incremental testing plan. Although not able to test the feather while moving supersonically, Pete Siebold was high enough to test the reaction control system (RCS). Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

V

A Third of the Way There (13P)

Ignition was delayed by two minutes as Mission Control tried to decide whether to abort the flight or just to go ahead with the burn.

“One of the benefits we had in delaying was we went to a lower altitude, which would allow us to turn the corner much faster, which minimized the risk of overspeed in starting the flight at a higher than expected airspeed,” Siebold said.

After dropping for more than a mile, Siebold lit the rocket engine at 38,300 feet (11,670 meters). Figure 8.5 shows Siebold during the pull-up after rocket engine ignition.

SpaceShipOne was moving at Mach 1.6 when Siebold shut down the rocket engine after a 40-second rocket burn. The rocket plane reached an apogee of 105,000 feet (32,000 meters), which was about a third of the distance SpaceShipOne needed to climb for the Ansari X Prize. On descent, SpaceShipOne experienced Mach 0.9 while feathered.

The flight overall was a success. Burn duration increased signifi­cantly from the 15 seconds of the first rocket-powered flight.

“We also were able to demonstrate that we could maintain control during the pull-up, which was something on 11P that was sort of in question. Brian was fighting the vehicle trying to keep the wings level. So, overall, I think the only objective that we weren’t able to meet was the supersonic feather reentry” Siebold said.

Figure 8.6 shows Siebold flying SpaceShipOne back to Mojave.

SpaceShipOne Rocket-Engine Design

S

pacecraft have used both solid and liquid rockets, and in some cases both, to blast out of the atmosphere, into orbit, to the Moon, and out of the Solar System. The Space Shuttle, for example, uses two solid rocket boosters (SRB) mounted to the external tank (ET) and its three liquid-fueled main engines to reach orbit.

SpaceShipOne had a much different set of challenges to face, so its rocket engine had to be equally unique. There was no off-the-shelf rocket engine that Scaled Composites could simply install. Rutan had to design the rocket engine from scratch. It would be the first that Scaled Composites would have to build. Once the design was complete, Sealed Composites enlisted four subcontractors to provide the rocket-engine components that were not built in-house.

SpaceShipOne would be the first manned spacecraft to use a hybrid rocket engine. Figure 5.1 shows an external view of SpaceShipOne’s hybrid rocket engine.

The Rocket Engine

In 1999, Scaled Composites began researching rocket-engine technology. By January of 2000, it had not only identified the type of rocket engine and selected the propellants, but it had developed a new concept for its configuration.

SpaceShipOne Rocket-Engine Design

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Fig. 5.1. A hybrid rocket engine offers advantages of both liquid-fueled and solid-fueled rocket engines. The rocket engine can be shut off at any time during the burn and can be constructed without complicated plumbing and pumps. The disadvantage, though, is that it has lower performance than the other two types. Mojave Aerospace Ventures LLC, photograph by David M. Moore ______________________________________________________________________________________________________

Rutan believed that the highest risk of the program from the technical stance was the operation of the rocket engine. Reentry was dangerous, of course, but the “carefree” approach using the feather dramatically minimized this danger.

“I ruled out solids because I couldn’t do flight tests with them,” Rutan said. “I couldn’t do flight-test envelope expansion. I couldn’t do partial burns. Also, I knew that likely during a burn, I might be accelerating into a Mach number that I’d never been to. And I may not like it. I wanted to be able at any time to shut the motor off just like that.

“I ruled out liquids because they had a large number of failure points that were difficult to improve safely by making them all redundant. If you did, you ended up with a complex system, which historically has been shown to be less safe than not having the redundancy.”

A hybrid rocket engine fit Rutan’s requirements. It was very safe and very simple and very robust. Just as the name suggests, a hybrid
rocket engine is part liquid rocket engine (like the Space Shuttle’s main engines) and part solid rocket engine (like the Space Shuttle’s solid rocket boosters). Figure 5.2 shows the basic designs of liquid, solid, and hybrid rocket engines.

Essentially, a hybrid rocket engine is a tank that contains the liquid part and a motor that contains the solid part. Upon ignition, the liquid flows into the motor and out come the flames. It can be stopped instantly, unlike a solid, and its propellants are room temper­ature as opposed to cryogenic. However, there is a tradeoff. Hybrid rocket engines are typically less efficient than liquid or solid rocket engines. This means that for equal amounts of propellant by mass, hybrids deliver less thrust. But in the case of SpaceShipOne, the lower performance was acceptable.

“Would I use a hybrid motor to go to orbit? Probably not unless we could develop one that was close to the efficiency of the liquids,” Rutan said.

Liquid Rocket Engine

Fuel Pumps Throat

SpaceShipOne Rocket-Engine Design

Подпись:Oxidizer

Solid Rocket Engine

Flame Front Throat

 

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Fig. 5.2. The main difference between liquid, solid, and hybrid rocket engines is the state of the fuel and oxidizer used. A liquid rocket engine uses a liquid oxidizer and liquid fuel that are stored separately. The oxidizer and fuel for a solid rocket engine are combined ahead of time to form a solid propellant. A hybrid rocket engine, on the other hand, uses a liquid oxidizer and a solid fuel that mix once it fires off. James Linehan

V _________________ J

 

Hybrid Rocket Engine

Injector Flame Front Throat

 

Exhaust

 

Combustion.

Chamber Nozzle

 

Oxidizer

 

Fuel

 

SpaceShipOne Rocket-Engine DesignSpaceShipOne Rocket-Engine Design

SpaceShipOne Rocket-Engine Design

Flight Aborted (4GC)

The fourth flight of SpaceShipOne was scheduled to be a glide flight. Figure 7.4 shows preparations being made the day before the flight. Melvill had successfully opened more than 60 percent of the subsonic flight envelope on the previous flight. This included speeds from stall to 150 knots. Now it was planned to open up the envelope even further.

The flight envelope indicated all the ways SpaceShipOne could safely fly, which included variations and combinations of speed, altitude, attitude, and other factors. The crews flew the easiest stuff, as the pilots and engineers gained confidence and began to nail down the flying characteristics. Step by step, they pushed the boundaries as they flew the vehicle more aggressively to reveal its limitations.

However, twenty minutes prior to separation, the launch had to be aborted due to a GPS malfunction with the avionics system. Figure 7.5 shows the mated pair during the aborted test flight prior to landing. Initially designated as 4G and 31L for SpaceShipOne and White Knight, respectively, the flight numbers were modified to 4GC and 31LC as a result of the abort. But it was possible to complete some systems testing prior to landing.

Flight Aborted (4GC)

Flight Test Log Excerpt for 4GC

Date: 27 August 2003

Flight Number Pilot/Flight Engineer

SpaceShipOne 4GC Mike Melvill

White Knight 31LC Brian Binnie/Cory Bird

Objective: Second glide flight of SpaceShipOne. Flying qualities and performance in the spaceship feather mode. Pilot workload and situational awareness while transitioning and handling qualities assessment when reconfigured. As a glider, deep stall investigation both at high and low altitude and envelope expansion out to 200 knots and 4 g’s. Lateral directional characteristics including adverse yaw, roll rate effectiveness and control, including aileron roll and full rudder sideslips.

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

Flight Aborted (4GC)

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Fig. 7.4. SpaceShipOne and White Knight are poised before the fourth test flight. Planned as SpaceShipOne’s second glide flight, the flight had to be aborted midair. Mojave Aerospace Ventures LLC, photograph by David M. Moore

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Flight Aborted (4GC)

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Fig. 7.5. It was necessary to abort the fourth test flight because of an avionics malfunction involving the global positioning system (GPS) prior to separation. However, before returning to Mojave, test pilot Mike Melvill completed some systems testing. Mojave Aerospace Ventures LLC, photograph by David M. Moore

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Overall Dimensions

At 28 feet (8.5 meters) in length, 8.8 feet (2.7 meters) in height, and 27 feet (8.2 meters) in width, which is the distance between the tips of SpaceShipOne’s horizontal stabilizers, the spacecraft is only slightly smaller than the Bell X-l. Table 4.1 shows a size comparison between SpaceShipOne, the X-l, the X-l5, and the Space Shuttle. Although the width of SpaceShipOne is slightly wider than the wingspan of the North American X-l5, it is about half the length of the X-l5. Every time SpaceShipOne flew, it had a different weight. The final spaceflight was
the heaviest, with an empty weight of 2,646 pounds (1,200 kilograms) and maximum weight of 7,937 pounds (3,600 kilograms).The weight advantage of SpaceShipOne was clear when compared to the gross weights of 12,250 pounds (5,557 kilograms) and 38,000 pounds (17,237 kilograms) for the X-l and X-l5, respectively.

Feather at Supersonic (14P)

Nearly one full year since flight testing began, SpaceShipOne was on the verge of making a spaceflight. One critical piece of infor­mation was missing, though. “The object of that flight was to do a supersonic feathered reentry,” Mike Melvill said. “We needed that data before we could go beyond that.” Figure 8.7 shows SpaceShipOne mated up to White Knight in preparation for the third powered flight.

Ten seconds after releasing from White Knight at 46,000 feet (14,020 meters), Melvill lit off the rocket engine. Figure 8.8 shows a dramatic rearward view of the rocket engine’s fiery plume and exhaust.

“During the boost after he reached the vertical part of the trajec­tory, the avionics display started flickering and then went blank,” Doug Shane said. “We all had good displays in the ground station. And Mike said, T looked out the window, and we were going pretty much straight up. So, I stayed with her.’ Gotta love a guy like Mike. Of course it came back on as soon as the motor shut down.”

The rocket engine burn duration was set by a timer. As Melvill looked out the windows to navigate, SpaceShipOne boosted to 150,000 feet (45,720 meters) and Mach 2.5, and then its rocket engine shut down. SpaceShipOne

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Flight Test Log Excerpt for 14P

Date: 13 May 2004

Flight Number Pilot/Flight Engineer

SpaceShipOne 14P Mike Melvill

White Knight 56L Brian Binnie/Matt Stinemetze

Objective: The third powered flight of SpaceShipOne. 55 seconds motor burn time. Handling qualities during boost and performance verification. Reaction control system use for reorientation to entry attitude. Supersonic feather stability and control.

Feather at Supersonic (14P)

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Feather at Supersonic (14P)

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Подпись: Ґ s ^ Fig. 8.8. SpaceShipOne had several video cameras mounted inside the cockpit and on its exterior. This video-capture image shows a rearward view from the top of the fuselage of the rocket engine's plume and exhaust. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc. к ) continued its ascent to an apogee of 211,400 feet (64,430 meters). But since Melvill had lost his avionics during boost, the trajectory was not exactly spot on. “I was doing forward loops, or something, at the top. It slowed down but came back in, and then it was swinging around a lot.” Melvill used the RCS to dampen the oscillations. In the feather configuration, SpaceShipOne reentered the atmosphere at Mach 1.9 and 3.5 g. SpaceShipOne quickly stabilized and made its feathered “carefree”

Fig. 8.7. The photograph shows SpaceShipOne being prepared for its third rocket-powered test flight. SpaceShipOne had made its very first test flight just about a year earlier. The main goal of this test flight was to evaluate the performance of the feather at supersonic speed. Mojave Aerospace Ventures LLC, photograph by David M. Moore

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Feather at Supersonic (14P)Fig. 8.9. SpaceShipOne reached an apogee of 211,400 feet (64,430 meters), and the video camera in the tail boom recorded the feather in the extended position. While high above Los Angeles, SpaceShipOne was technically not in space, even though the curvature of Earth can be clearly seen. However, the curvature is somewhat exaggerated due to the auto focus lens used. Mojave Aerospace Ventures LLC, video capture provided courtesy of Discovery Channel and Vulcan Productions, Inc.

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Feather at Supersonic (14P)

reentry just as expected. It actually descended more smoothly at supersonic speeds than it did at subsonic speeds. Figure 8.9 shows SpaceShipOne above Earth, with Los Angeles and the California coast­line in the background.

Back on the ground, engineers traced the avionics malfunction to a dimmer, a small electrical component. And since the thermal protection data looked good, Scaled Composites felt that SpaceShipOne performed well enough to continue forward.

Propellants

The force that causes a rocket engine’s thrust results from combus­tion. This type of chemical reaction is similar to burning wood. The wood, which is a fuel, and the air, which is an oxidizer, react to form gases and other substances. Both the fuel and oxidizer must be present for combustion to occur.

The difference with a rocket engine is that the fuel and the oxi­dizer release much higher energy, and the gases from the reaction travel out of the nozzle at very high speeds. These high-speed gases provide the thrust.

Each Space Shuttle SRB contains 1,100,000 pounds (500,000 kilograms) of solid propellant, 70 percent ammonium perchlorate for its oxidizer and 16 percent aluminum powder for its fuel. The balance consists of binders, curing agents, and catalysts. These burn until there is nothing left to burn. The liquid propellants are contained in separate pressurized tanks within the ET. These tanks hold 1,350,000 pounds (612,000 kilograms) of liquid oxygen oxidizer, often called LOX, and 227,800 pounds (103,000 kilograms) of liquid hydrogen fuel. The main engines produce thrust when the liquid oxygen and liquid hydrogen are pumped together.

Propellants

Propellants

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Fig. 5.3. To reach orbit, the Space Shuttle uses three liquid-fueled rocket engines, the shuttle main engines (SME) at the rear of the orbiter and two solid rocket boosters (SRB), which are attached to the external tank (ET). Dan Linehan

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SpaceShipOne is a tiny fraction of the Space Shuttle’s mass, and it reaches less than a third of the height the Space Shuttles does. So, the propellant requirements are quite different. SpaceShipOne used nitrous oxide (N20), a colorless liquid or gas naturally occurring in the atmosphere. Nitrous oxide is commonly used as laughing gas, as a hot rod fuel additive for a quick boost of speed, and as a propellant for whipped cream. The N20 is liquefied and used as the oxidizer. The oxidizer enables the fuel to burn at a near-explosive rate. The oxidizer tank contains 3,000 pounds (1,360 kilograms) of N20.

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Fig. 5.4. When the oxidizer and the fuel combine, a vigorous chemical

reaction takes place. The very hot gases from this combustion produce the thrust and resulting fiery plume. Mojave Aerospace Ventures LLC, photo provided courtesy of Discovery Channel and Vulcan Productions, Inc.

Hydroxyl-terminated polybutadiene (HTPB) is the solid used for the fuel and is a synthetic rubber, like that used to make tires. About 600 pounds (270 kilograms) fuel the rocket engine. Both the oxidizer and the fuel can easily and safely be stored and transported. In fact, unlike liquid oxygen and liquid hydrogen, which react together spon­taneously, N20 and HTPB will not react together unless an igniter is first used. For the reaction to occur, the temperature must be greater than 570 degrees Fahrenheit.

The combustion products from the combination of N20 and HTPB are mostly carbon dioxide, carbon monoxide, hydrogen, nitrogen, and water vapor. This is not as clean burning as the Space Shuttle’s main engines but is much less polluting than the Space Shuttle’s solid rocket boosters, which produce a giant, toxic acid cloud. Figure 5.3 and figure 5.4 show the rocket engines of the Space Shuttle and SpaceShipOne firing, respectively.