Pilot Report on SpaceShipOne

The Federal Aviation Administration classifies it as a glider. One of its pilots says in the early and later stages of its flight it flies like a Piper Cub. It has an 'N' number. But it is a long, long way from a Piper Cub or even a high performance jet fighter. It is SpaceShipOne, the aircraft/spacecraft designed and built by Burt Rutan's Scaled Composite Company.

On October 4, 2004'a date selected to coincide with the 47th anniversary of the Russian launch of Sputnik, the first space vehicle'SpaceShipOne made its second voyage into space to win the Ansari X ten million dollar prize as the first non-government successful space flights to exceed 328,000 feet twice within a period of 14 days.

SpaceShipOne was flown by different pilots on each of its two official flights. On the first venture into space Mike Melvill was at the controls and on the second flight Brian Binnie piloted the flight to a height of 69.6 miles.

Fresh from that flight, Melvill gave a 45-minute presentation at the Aircraft Owners and Pilots Association (AOPA) EXPO where he received a standing ovation. Thomas Wall was in attendance and later spoke with Melvill. This is Mr. Wall's account of Melvill relating his experiences with SpaceShipOne.

Speaking to pilots, Melvill didn't have to translate for the "general public" or pull many punches. He spent almost half of his time going over the flight controls and the entire cockpit layout inside of SpaceShipOne, explaining how it is flown.

There are actually four separate flight regimes, and each is flown differently. Just after launch, SpaceShipOne flies like a Piper Cub, using a joystick and rudder pedals with mechanical linkages to the controls (no hydraulic assists). When it goes supersonic, the aerodynamic forces are too high to be able to move the stick, and the controls are subject to flutter. An electrically powered trim system is used with a "top hat" switch on the joystick and a couple of grips on the arm rest of the pilot's seat. (There are backup switches to the left of the instrument panel, which had to be used on one flight.) This moves the entire horizontal stabilizers, not just the elevons on the trailing edges. Eventually, the flight reaches an altitude where the air is thin enough that manual controls can again be used, although the response is totally different from that at lower altitudes. This goes away as the ship exits the atmosphere; the Reaction Control System nozzles are then used for maneuvering in space. Coming back down, the pilot reverses the sequence. There is no automated switchover of control systems; the pilot must move from one system to the next at the right times.

Rudder pedals are not linked. Each controls one of the two vertical stabilizer rudders separately. Both rudder pedals may be pushed at the same time, and a fairly effective speed brake is produced with both rudders canted outward. Push both fully forward and they engage the wheel brakes. However, these are not very effective and are useful only for steering input during rollout. The real brake is on the nose skid: a piece of maple wood, with the grain aligned down the centerline of the airplane. Melvill reported this was the most effective braking material the designers and engineers could find.

Melvill told the pilots that he gets hit with about 3Gs kicking him backwards as soon as he lights the rocket motor. He's supersonic within about eleven seconds. But he immediately starts to pull up into an almost vertical climb, so he also gets about 4.5Gs pushing him down into his seat just from that maneuver. The combined force is 'somewhat disorienting' and Mike says its "important not to black out" at that point. He's going 1,880 knots true airspeed, straight up within 70 seconds.  On re-entry, the aircraft goes from being absolutely silent while in space to generating a deafening roar as it hits the atmosphere again. Speed is about Mach 3.2 by that time, and the pilot has to survive a peak, momentary 5.5Gs, and he is above 4 Gs for about 30 seconds and lesser G forces for one minute, as it slows down.

The 'feather' system is what makes re-entry possible. Once outside the atmosphere, the entire tail boom and half of the wing is swung upward. On re-entry, this orients the spacecraft so that the fuselage and forward half of the wing is at 70 degrees angle of attack, creating very high drag. Once back in the atmosphere, the tail feather is lowered and SpaceShipOne becomes a glider. The boom is pneumatically powered, and it either works or it doesn't. If it doesn't work, they are toast, quite literally.

SpaceShipOne has a standard "N" registration number; but it is licensed as an experimental glider. There was a huge bureaucratic hassle trying to license it as a rocket powered spacecraft, which they just sidestepped by calling it a glider. When asked if it had a yaw string; Melvill laughed and said that lacking a center window, we could not use a Yaw string. The registration number is N328KF, where 328K is the number of feet in 100km, the official edge of space. (White Knight'the aircraft that took SpaceShipOne aloft'is N318SL - Burt Rutan's 318th design.)

Melvill reported that the flight director system (called a TONU) was developed completely in-house by a couple of 29-year-old programmers, and is absolutely fantastic to fly. On the second flight, Mr. Wall noted that Brian Binnie had re-booted the TONU just before the landing approach and it took quite a while for it to come back up. Melvill explained that during re-entry, the TONU loses its GPS lock. It keeps trying to go back to catch up, re-interpolate and compensate for the missing data, and this keeps it a little behind in its actual position calculations.

The pilots have no straight-ahead vision and so they have a real issue landing: they can't see the runway! To land, they fly directly down the runway at 9,000 feet; then do a military style break and fly a full 360-degree pattern right to the landing. The TONU gives the pilot a "blue line" to follow and a target airspeed (which produces a given rate of descent). When the pilot follows the blue line to the break point and through the two 180 degree turns, the ship will fly right onto the runway at what ever touchdown point the pilot selects.

SpaceShipOne pilots don't wear pressure suits. The cabin has two needle valves and two compressed dry-air bottles - primary and backup - to control cabin pressurization. The cabin leaks slowly however and, to control internal pressure, Melvill had to manually adjust the valves as outside pressure changed. The higher he went, the greater the pressure difference, the faster air leaked out, and the wider the valves needed to be opened to compensate. Then, as he re-entered, air leaked more slowly and the needle valves had to be closed. If not careful, he could have come down with cabin pressure at over 6000 ft. below sea level: popping of ears and decompression problems could result. But Melvill says that, if he's careful, the cabin pressure will match the airport altitude when he lands. There is just an internal altimeter that he uses for reference.

Melvill does wear an oxygen mask that is a standard issue Air Force diluter/demand system. But since the cabin is pressurized at close to sea-level pressure, they almost never use any oxygen: he's just breathing cabin air through the mask. They do use a return hose though, to remove CO2 by running it through a CO2 scrubber. Otherwise, they would have CO2 buildup in the cabin and asphyxiate. So they wear a mask to handle the CO2 and for safety just in case of emergency depressurization.

An interesting side effect of having a pressurized cockpit involves escape in case of emergencies. To bail out, the pilot must go through the nose: the nose cone comes off. It twists onto a round bracket, forming a seal with the crew compartment, and a latch handle locks it on. To get it off, they must first depressurize the cabin to release the seal enough to be able to twist it off. They then can unlock it and twist it open. But they then re-pressurize to actually force the nose off. Only then could they get out.

Melvill talked in detail about the rocket motor, and showed photos of its insides after firing. The nozzle throat actually ablates as the motor burns, enlarging the interior throat diameter as the burn progresses. He described the problem they had on the June 21 flight: The rocket motor nozzle was skewed by about - degree to one side. This generated a surprisingly high lateral torque trying to turn the aircraft. If it had been up or down pitch rather than lateral, the controls could have handled it; but the lateral yawing forces were too great for Melvill to compensate as the atmosphere thinned. The result was that he was pretty far off course.

For one of the pre-flight static burn tests, fire and safety crews were standing a - mile away, ready to duck if anything went wrong. In the middle of the test, Melvill and Burt Rutan walked to the front of the motor assembly and felt the pressure vessel that contains the N2O. Melvill said he knew he was going to have this motor strapped onto his back soon and he wanted to know how much it vibrated, how hot it got, and how loud it was. It was deafening, literally. It turns out that, with the nozzles they use at high altitudes, it's actually not that noisy inside the spacecraft, but Melvill still wears hearing protection.

Scaled Composites fabricated the rocket motor case themselves. The Liquid Nitrous Oxide tank (which is also the structural core of the spacecraft) and the nozzle injector head assembly, were manufactured by outside vendors.

Mike Melvill was the first civilian private pilot to receive FAA-issued Astronaut wings. He holds Civilian Astronaut license #1 for his first flight into space, on June 21. He has twice been awarded the Ivan C. Kincheloe trophy by his fellow test pilots, first in 1999 for his work on developmental high altitude flight testing of the Proteus Aircraft, and again in 2004 for his SpaceShipOne flight testing. He was Program Manager of the Voyager non-stop around-the-world flight. The 63 year-old is Vice President and General Manager of Scaled Composites.