You're the Pilot

On a clear but breezy summer day, SpaceShipOne pilot Mike Melvill and I have just passed through "high key" above Mojave Airport in California. It's SpaceShipOne's entry point for a modified 360-degree approach pattern for Runway 30 (high key is how test pilots refer to an engine flameout pattern where the aircraft is positioned over the end of the runway at a high altitude). We're at 8,500 feet msl, Mojave is at 2,280 feet, and because of the limited forward visibility, I see the runway one-half mile off the right side of the aircraft through one of the porthole windows.

"One hundred thirty-five knots indicated, descending at 2,500 feet per minute," I hear through the headset. Moments later we start a right turn. "Passing through 7,200 over the runway, 135 knots, everything looks good." The rush of air outside the cockpit adds to the falling sensation from the steep approach. And despite the fact that the airport is still almost 5,000 feet below us, Melvill is careful not to let the winds blow us too far east. Because SpaceShipOne is a glider, he can't use power to get us closer to the runway if we wander from the planned teardrop approach.

On the downwind we're still dropping fast. "There's low key, 5,500 feet, 135 knots." We're now abeam the numbers and starting the 180-degree arcing turn to final. Despite still having more than 2,500 feet below us and the runway just off the right side, Melvill says making the runway in SpaceShipOne can be difficult from this far out.

Turning to final we've managed to keep some altitude. "The runway is made, 130 knots; this is where the gear goes down." With the gear down, SpaceShipOne's glide ratio drops from roughly 7-to-1 to about 5-to-1 (if the gear were to inadvertently deploy before entering the pattern, high key would be raised to 13,200 feet).

The runway fills the view out front as our approach steepens.

On short final, the nose is still pointed down. This sight picture takes some getting used to, especially because we're still maintaining so much speed.

With our touchdown point at one-third the distance down Runway 30, we begin to flare at about 20 feet with the indicated airspeed dropping to 115 knots. This is where the lack of visibility is noticeable; in SpaceShipOne, you can't see the runway as you flare, so a chase pilot calls out the wheel height until contact is made.

We float a bit at first. There isn't the large sink rate you'd expect from such a stubby-winged glider. The wings on the aircraft we're flying — the Long EZ that Melvill and Brian Binnie used to become the first civilian astronauts in space — aren't that stubby, of course. Melvill says the float is the only part of our approach in the Long EZ that doesn't replicate the real thing in SpaceShipOne.

"In the spaceship we would have just settled right down on the runway," he explains. "With the Long EZ you'll just float all the way down the runway." Eventually the wheels do make contact, with some encouragement from the stick, and Melvill applies full power as we begin our climb for another " SpaceShipOne approach."

Simulator training

We're practicing approaches in one of several simulators — flying and ground-based — that the SpaceShipOne team used to hone their flying skills before the historic flight last June that put Melvill into space. The airplane we are flying approaches in is Melvill's own Long EZ, which he built more than 20 years ago and has flown around the world. He and Binnie used it numerous times to practice the base-to-final part of the SpaceShipOne approach. Cardboard covered the inside of the cockpit window — minus four small holes cut into it — to replicate the limited visibility of SpaceShipOne.

"It's a damn good simulator," Melvill says of his Long EZ's ability to replicate the spacecraft on final. "With the gear and speed brake down and the power pulled, the approach speed and rate of descent are identical to the spaceship. Even the position of the main gear is pretty close," he adds.

Simulation was the secret for the SpaceShipOne team. No wind-tunnel testing was done, but hundreds of hours were flown in a ground-based computer simulator. Dozens of hours also were flown in White Knight, the aircraft that carried SpaceShipOne to altitude before dropping the spacecraft and which can be configured to fly like the spacecraft. And there were several hours spent lapping the Mojave pattern in Melvill's Long EZ. But the most valuable training and development tool was the ground-based simulator. "Pete just did an incredible job with that thing," says Melvill.

Pete is Peter Siebold, the 34-year-old test pilot, engineer, and software developer who designed, wrote, and tested all the software that ran the avionics for both White Knight and SpaceShipOne as well as the simulator. This work was in addition to flying both aircraft, including the first flight above 100,000 feet on only the second powered flight.

The ground-based simulator Siebold designed is a full-size mock-up of the SpaceShipOne cabin, right down to a paper cutout of the Garmin GPSMap 296 like the real thing found in the cabin. Much of the flying in both aircraft and the simulator is instrument based with a single-screen flight-director display linked to a GPS inertial navigation system. The package is called the TONU (pronounced tuh-noo, Tier One Navigational Unit). The simulator includes a view of the surroundings via 11 computers with monitors bolted to the outside of the side porthole windows and a rear projection screen placed in front of the four front windows.

With ground-based sim flights in the thousands, Siebold became very familiar with the return flight to Mojave. "So I flew it inverted several times just to mix things up. If I could do it inverted, I was really confident I could do it upright. I remember thinking after my first real flight that, wow, that was just like a simulator flight — it was that close to the real thing."

In the cockpit

All the practice in the ground-based simulator makes the cockpit of SpaceShipOne feel as familiar to the pilots as a Cessna 152 does to a flight instructor. The pilot sits in the center of the cockpit with two seats behind him. Directly in front of the carbon-fiber seat is the stick topped with a grip the team found advertised for crop dusters. Pitch trim is controlled by a switch on top of the grip. In the completely manual SpaceShipOne, the stick is attached to pushrods and cables to control the elevons; there are no hydraulic or fly-by-wire systems.

"The only stability this thing gets is mechanically from your hands and feet or electrically from the trim switches," Melvill says, admiring the true stick-and-rudder nature of the flight. "It's the pilot's brain that's keeping this thing on track. There's no autopilot or even augmented stability, not even a yaw damper." The trim control and stabilizer adjustment are operated by electric motors.

In front of the stick is the single-screen TONU, which at first glance looks like many of the new glass-cockpit displays found in general aviation aircraft. The TONU provides the pilot with all the necessary flight data for each stage of a flight on several screens that can be chosen by the pilot or set on automatic, in which case the computer automatically displays relevant information depending on where the airplane is on the flight (boost, space, re-entry, or glide).

If you were the pilot

Sitting in a somewhat reclined position, the pilot's feet rest on the rudder pedals, which are approximately at the same height as the seat.

Lacking enough room on the ring-shape panel that follows the arc of the fuselage, the communication equipment is all located in the right armrest. Nothing too fancy here. A pair of Garmin Apollo SL40 nav/coms are used because of their light weight and low profile, and just aft of them are the transponder and a PS Engineering audio panel.

The left armrest is the site of much activity. Where a throttle lever might normally be located sits the turtle, a contoured knob that fits in the palm of the pilot's hand and is used for yaw trim by controlling the lower half of the split rudders on the tail (the pedals control the upper half). Just in front of the turtle is a roll trim switch, and in front of that are two guarded switches — one to arm the rocket, the other to light it. Ahead of the rocket switches sits the lever to drop the landing gear.

Aft of the turtle are three buttons for controlling the information displayed on the TONU. And underneath the left forearm of the pilot sits a pair of nested levers; one unlocks or locks the feather system (Burt Rutan's breakthrough design that folds the tail section to near vertical, allowing for a safe and simple shuttlecocklike reentry to the atmosphere), the other raises or lowers the feather. This also is the location of the two switches that activate the RCS (Reaction Control System), which uses small thrusters to maneuver the craft in space.

While the TONU dominates the cockpit and gives it a very modern feel, the rest of the view from the pilot seat is remarkably simple and low tech. There's even a ping-pong ball hanging from a string as a G-force indicator — in case having your head slammed against the seat didn't tell you anything.

After preflight inspections are completed on the ground, with the aid of the crew chief who can confirm that flight surfaces are moving properly as the pilot exercises the stick and pedals, the last couple of pins are pulled from the gear and drop mechanism.

There are several checklists on the ride up. At 48,000 feet, the pilot checks the trim settings for launch. To make the climb to vertical after being dropped from White Knight ("turning the corner," as the pilots call it), a nearly full nose-up stabilizer trim setting is used for the release.

There's a twist to the normal flight-plan filing. The team received clearance to operate in the military operations area (MOA) on the ground where they also received separate transponder codes for White Knight and SpaceShipOne. To avoid confusion during mated flight, the SpaceShipOne pilot waits until just before release to turn on his transponder. He then gets landing clearance before being dropped, climbing to more than 328,000 feet, and gliding back to Mojave. Once the transponder is on and the landing clearance is given, the countdown to release begins.

With stick full forward to ensure there isn't a collision because of the nose-up trim, the drop is made at between 125 and 135 KIAS. "Anything below 120 at this weight and altitude and you start getting a buffet on the spaceship," says Siebold. As soon as the release is made there's a bit of wobbling as the aircraft begins to fly. The stick comes back to a neutral position, the arm switch is flipped, and moments later the fire switch is flipped. Now the fun begins.

"The minute you drop off, you get the feeling like, oh, this thing is going to stall. It's very mushy," says Melvill. "But as soon as the motor lights, the acceleration is so enormous, it's 3 Gs, eyeballs in, immediately, and the airplane becomes much more stable and it's much more controllable."

The first several seconds are the most important. This is when the trajectory to apogee is determined. "The stabilizer trim setting set prior to launch will ensure the pilot will turn the corner at maximum lift capability," Siebold says. "Performance is made in the first five to 10 seconds of the flight; it's how quickly you can turn that corner after being dropped and lighting the rocket. Once you're pointed up, you start pitching forward, reducing the amount of nose-up trim you have and fine-tuning the flight path so you can reenter at the intended point."

One of the biggest challenges facing the pilot is keeping the airplane wings level. SpaceShipOne ended up with excessive dihedral effect, according to Rutan. This makes it extremely sensitive to roll input. And because of the dihedral effect, roll inputs are made via the rudders. "It's very much like learning to fly a 152," says Siebold, an instrument and multiengine instructor. "[It's like] when you're doing approach-to-stall [maneuvers] and your instructor tells you to get off the ailerons to keep the wings level, and you're just using rudders."

For the first 10 seconds or so this roll control can be done with the pedals, but after pushing through the sound barrier both the stick and rudder are ineffective at moving the control surfaces. "I had a lot of trouble with that," Melvill says, referring to the natural tendency to want to push with your hands and feet. "Past the transonic stage you are simply not strong enough to push the stick and change something."

Passing Mach 1

As you continue to climb past Mach 1, all control inputs are made with either the stabilizer trim on top of the stick or the turtle on the left armrest, which controls yaw trim, which in this case results in a roll. There is the other switch for roll trim, which can move one stabilizer up and the other down, but it is only used to synchronize the stabilizers.

The TONU, which started at drop with a screen dominated by an artificial horizon with blue on top and brown on the bottom and a moving map, has switched to boost mode. The artificial horizon now is a ball that shows all blue, indicating you're climbing, and the moving map has been replaced by a diagram showing rocket fuel remaining as well as trim settings. In the upper right is an altimeter that is winding really fast (peak climb rate is about 180,000 fpm), and below it is an apogee predictor that tells you how high you would go if you were to shut down at any particular moment.

Passing through 100,000 feet, the sky darkens and, if everything is going as planned, you're approaching Mach 2 as you continue to make adjustments to pitch and roll with the trim settings. Those are needed because of small thrust asymmetries that occur during the rocket burn. Just a handful of seconds later you're passing through 150,000 feet, indicated airspeed is dropping toward zero, but true airspeed is climbing to Mach 3.

When the motor shuts down (the burn varied from 76 to 83 seconds during the actual space flights) several things happen. The 3-G load ends immediately, and weightlessness begins. The TONU changes once again to RCS mode, showing tank pressures for the thrusters, rate indicators, and an indicator showing the angle of the tail section in feather. Now you're coasting, but coasting very fast, according to Siebold. "We're at 250,000 [feet] with the motor shut down, coasting up, going 1,500 KTAS, Mach 2.7, and my indicated airspeed is 3 knots, so we've effectively left the atmosphere." It's possible to be upside down, backwards, or even pointed in the right direction, but it won't affect your trajectory because there is very little aerodynamic load on SpaceShipOne at this point.

The RCS is activated with the stick and rudder pedals, which have switches at the extreme stops requiring full throws of the controls. Because there is no opposing force, every roll, yaw, or pitch input with the RCS must be stopped with an opposite input. The clicking of actuators in front of the seat and the sound of the thrusters just outside the cockpit give some tangible sense of flying in space. As apogee is approached (it was 328,491 feet, 337,500 feet, and 367,442 feet, respectively, on the three space flights) the feather unlock is pulled, followed by the feather activation lever, raising the tail.

This is where the pilots had a few moments to enjoy the view of the black sky, the sliver of blue atmosphere, and the expansive Earth below.

As SpaceShipOne begins to descend, the indicated airspeed slowly starts to build, which causes the feathered tail to orient the vehicle in the proper entry attitude. During reentry, the pilot has the least control over the vehicle. There are oscillations in both roll and yaw, and the pilot is really just along for the ride. The TONU reads 30 KIAS, 2,000 KTAS straight down, as reentry begins. "The goal is to slow down in the very thin parts of the atmosphere," Siebold says. The entire belly of the aircraft is now the leading edge and after reentry will reach terminal velocity in feather at 85 KIAS. Peak-G forces occur as the atmosphere thickens during descent, hitting about 5.5 Gs (G forces last for about a minute; 10 seconds at 5.5). During the initial, supersonic part of the descent, the ride is fairly smooth. But once SpaceShipOne slows down, the ride gets bumpier. "Once you go subsonic, that's where the rumbling really starts. It's pretty significant, so right about 55,000 feet we take the feather out and fly it like a normal glider," says Siebold.

"Landing this thing is very similar to what you'd do in a Cessna or a Cherokee when you're doing an emergency landing when your engine fails," he adds. "You circle over your intended point of touchdown until you get to an altitude where you've got some knowns." In this case, the known is that high-key mark at 8,500 feet just west of Runway 30 at Mojave.

Stick forces are light during glide with "nice harmony in the pitch and the roll and good rates," Siebold says demonstrating a "turbulence upset," the nose is lowered to gain a little speed, pull back on the stick, and once the nose comes up, put in some right stick and right rudder to help it come around. SpaceShipOne can do a nice roll, something Melvill knows firsthand. "On my last flight I did 29 on the way up [not on purpose], and one on the way down [on purpose]."

Maintaining 135 KIAS, Siebold aims for a point on the moving map indicating high key. Making a slow, easy, arcing right turn, he hits high key at 8,500 feet and uses the TONU to check altitudes at key points in the pattern. Cross the runway at 7,000 feet, downwind abeam the numbers at 5,500 (low key), turn base at 4,500, turn final at 3,500 (1,220 feet agl). Once the runway is made and the aircraft is below its 130 KIAS VLE, the gear is lowered and immediately the nose is dropped to avoid a stall. At this point the pilots like to gain some energy for the flare by increasing the speed to 140 KIAS on short final. "It'll flare...once," says Melvill. "But there's no power, and there's no way to fix it if you over-flare; it's just going to hit really hard. But if you just fly it on at 110 knots, it's a piece of cake." With a chase pilot calling out wheel heights during the flare, the main gear is down; after a few seconds the nose skid makes contact, and SpaceShipOne comes to a stop on the runway.

Jason Paur is a pilot and journalist living in Seattle.

How Would You Do in SpaceShipOne?

When SpaceShipOne is gliding, Mike Melvill thinks, most pilots would not have too much trouble. Using the rudder pedals and trim to control roll takes some getting used to, but he believes that with some practice in the simulator to learn the approach — especially the technique of maintaining the high pattern speed (135 KIAS) — it would be possible for the average pilot to fly it to the runway.

Powered flight is a different story. Melvill says the chances of success here are much less for a pilot without experience. He says SpaceShipOne is a very difficult vehicle to fly under power. When the spaceship is pitched almost 90 degrees for about 80 seconds during the vertical climb, it's an unusual attitude for any pilot. Small changes in the rocket motor's thrust during burn, quickly changing winds aloft, and the sensitivity to roll inputs require extreme concentration. While Melvill managed to fly VFR during one of his powered rides, it's not a flight that you can do by looking out the window, he says. Because of the high volume of information coming from the TONU, he believes an instrument-rated pilot would stand a better chance. But Melvill adds that flying it isn't easy for anybody, including himself.

And few of the famous pilots who flew the sim were able to land on Runway 30 on their first try. — JP

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