Stolen from another forum without permission:
[ QUOTE ]
I just had the extreme pleasure of speaking with Mike Melville yesterday, the
pilot of SpaceShipOne's first two flights above the Kerman line of 100 km.MSL,
and with his wife. He gave a 45 minute presentation to the Aircraft Owners and
Pilots Association conference in Long Beach on Thursday, and got a
several-minute standing ovation. I was able to speak with him for a short while
after his talk.
Since he was speaking to pilots, he 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. I think this is the first time this has been
explained publicly in such detail, and it was amazing. There are actually four
separate flight regimes, and each is flown differently. Just after launch, it
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. So they use an electrically powered trim system, flown
using the "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,
they get high enough and the air gets thin enough that they can again use
manual controls, although the response is totally different than lower down.
But that goes away as they exit the atmosphere; the Reaction Control System
nozzles are then used for maneuvering in space. Coming back down, the pilot has
to reverse the sequence. There is no automated switchover of control systems;
the pilot has to remember to move from one system to the next at the right
times.
The rudder pedals are not linked. Each controls one of the two vertical
stabilizer rudders separately. You can push both rudder pedals at the same
time, and get a fairly effective speed brake, with both rudders canted outward.
Push both fully forward and they engage the wheel brakes. But these are not
very effective and are only really useful 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. He said it was the most effective
braking material they could find.
Stephen, we talked about G forces on Tuesday, and I got some of it wrong. He
says that he gets hit with about 3Gs kicking him backwards as soon as he lights
the rocket motor. He's supersonic within about 9 seconds later. But he
immediately starts to pull up into an almost vertical climb. So he also gets
over 4.3Gs pushing him down into his seat just from that maneuver. The combined
force is "very stressful" and Mike says it's "important not to black out" at
that point. He's going 1880 knots 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. He's going about Mach 3.2 by
that time, and has to survive about 5.5Gs for over 30 seconds, and lesser G
forces for longer than that, as it slows back down. It sounds really intense,
both as he explains it and on the radio.
A couple of interesting side notes: SpaceShipOne has a standard "N"
registration number; but it is licensed as an experimental "glider". Apparently
there was a huge bureaucratic hassle trying to license it as a rocket powered
spacecraft, which they just sidestepped by calling it a glider. I asked him if
it had a yaw string; he laughed and said that would have burned off. By the
way, the registration number is N328KF, where 328K is the number of Feet in
100km. (White Knight is N318SL - Burt Rutan's 318th design.)
Mike says that the flight director system (called a TINU) was developed
completely in-house by a couple of 28-year-old programmers, and is absolutely
fantastic to fly. That's why they don't need a yaw string. But I had heard over
the radio that Brian Binnie had re-booted the TINU just before the landing
approach during the X2 flight, and it took quite a while for it to come back
up. So I asked Mike what that was about. He says that during re-entry, the TINU
loses its GPS lock. So 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 pilot has no straight-ahead vision at all, so
they have a real issue landing: they can't see the runway! The way they do it
is to fly directly down the runway at 9000 feet; then they do a (military
style) break and fly a full 360 degree pattern right to the landing. The TINU
gives the pilot a "blue line" to follow and a target airspeed (which produces a
given rate of descent). If the pilot follows the blue line, right to the break
point and through the two 180 degree turns, it will put him right onto the
runway at what ever touchdown point he selects. But the TINU has to be
absolutely current when this is going on. So at something above 15,000 feet
they reboot the TINU and get it re-synched with the GPS satellites again before
setting up for the landing!
He also talked in detail about the rocket motor, and had 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 ½
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 Mike to compensate as the atmosphere thinned. The result was that he was
pretty far off course. Mike says he reached apogee, rolled the spacecraft over,
and was surprised to see the Palmdale VOR directly beneath him. That was 30
miles away from Mojave and a long glide home. He says its amazing how fast a
relatively small deviation can produce large distances when you're going Mach
3!
For one of the static burn tests, they had fire and safety crews all standing a
mile away, ready to duck if anything went wrong. In the middle of the test,
Mike and Burt Rutan walked up to the front of the motor assembly and felt the
pressure vessel that contains the N2O. Mike knew he was going to have this same
thing strapped onto his back soon, anyway, 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 he still wears hearing protection.
Scaled Composites seem to have fabricated quite a bit of the rocket motor
themselves, including the N2O tank (which is also the structural core of the
spacecraft) and the nozzle casings. It would be interesting to hear from
Michael's friend exactly what parts SpaceDev designed and what they
manufactured.
[/ QUOTE ]
[ QUOTE ]
I just had the extreme pleasure of speaking with Mike Melville yesterday, the
pilot of SpaceShipOne's first two flights above the Kerman line of 100 km.MSL,
and with his wife. He gave a 45 minute presentation to the Aircraft Owners and
Pilots Association conference in Long Beach on Thursday, and got a
several-minute standing ovation. I was able to speak with him for a short while
after his talk.
Since he was speaking to pilots, he 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. I think this is the first time this has been
explained publicly in such detail, and it was amazing. There are actually four
separate flight regimes, and each is flown differently. Just after launch, it
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. So they use an electrically powered trim system, flown
using the "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,
they get high enough and the air gets thin enough that they can again use
manual controls, although the response is totally different than lower down.
But that goes away as they exit the atmosphere; the Reaction Control System
nozzles are then used for maneuvering in space. Coming back down, the pilot has
to reverse the sequence. There is no automated switchover of control systems;
the pilot has to remember to move from one system to the next at the right
times.
The rudder pedals are not linked. Each controls one of the two vertical
stabilizer rudders separately. You can push both rudder pedals at the same
time, and get a fairly effective speed brake, with both rudders canted outward.
Push both fully forward and they engage the wheel brakes. But these are not
very effective and are only really useful 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. He said it was the most effective
braking material they could find.
Stephen, we talked about G forces on Tuesday, and I got some of it wrong. He
says that he gets hit with about 3Gs kicking him backwards as soon as he lights
the rocket motor. He's supersonic within about 9 seconds later. But he
immediately starts to pull up into an almost vertical climb. So he also gets
over 4.3Gs pushing him down into his seat just from that maneuver. The combined
force is "very stressful" and Mike says it's "important not to black out" at
that point. He's going 1880 knots 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. He's going about Mach 3.2 by
that time, and has to survive about 5.5Gs for over 30 seconds, and lesser G
forces for longer than that, as it slows back down. It sounds really intense,
both as he explains it and on the radio.
A couple of interesting side notes: SpaceShipOne has a standard "N"
registration number; but it is licensed as an experimental "glider". Apparently
there was a huge bureaucratic hassle trying to license it as a rocket powered
spacecraft, which they just sidestepped by calling it a glider. I asked him if
it had a yaw string; he laughed and said that would have burned off. By the
way, the registration number is N328KF, where 328K is the number of Feet in
100km. (White Knight is N318SL - Burt Rutan's 318th design.)
Mike says that the flight director system (called a TINU) was developed
completely in-house by a couple of 28-year-old programmers, and is absolutely
fantastic to fly. That's why they don't need a yaw string. But I had heard over
the radio that Brian Binnie had re-booted the TINU just before the landing
approach during the X2 flight, and it took quite a while for it to come back
up. So I asked Mike what that was about. He says that during re-entry, the TINU
loses its GPS lock. So 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 pilot has no straight-ahead vision at all, so
they have a real issue landing: they can't see the runway! The way they do it
is to fly directly down the runway at 9000 feet; then they do a (military
style) break and fly a full 360 degree pattern right to the landing. The TINU
gives the pilot a "blue line" to follow and a target airspeed (which produces a
given rate of descent). If the pilot follows the blue line, right to the break
point and through the two 180 degree turns, it will put him right onto the
runway at what ever touchdown point he selects. But the TINU has to be
absolutely current when this is going on. So at something above 15,000 feet
they reboot the TINU and get it re-synched with the GPS satellites again before
setting up for the landing!
He also talked in detail about the rocket motor, and had 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 ½
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 Mike to compensate as the atmosphere thinned. The result was that he was
pretty far off course. Mike says he reached apogee, rolled the spacecraft over,
and was surprised to see the Palmdale VOR directly beneath him. That was 30
miles away from Mojave and a long glide home. He says its amazing how fast a
relatively small deviation can produce large distances when you're going Mach
3!
For one of the static burn tests, they had fire and safety crews all standing a
mile away, ready to duck if anything went wrong. In the middle of the test,
Mike and Burt Rutan walked up to the front of the motor assembly and felt the
pressure vessel that contains the N2O. Mike knew he was going to have this same
thing strapped onto his back soon, anyway, 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 he still wears hearing protection.
Scaled Composites seem to have fabricated quite a bit of the rocket motor
themselves, including the N2O tank (which is also the structural core of the
spacecraft) and the nozzle casings. It would be interesting to hear from
Michael's friend exactly what parts SpaceDev designed and what they
manufactured.
[/ QUOTE ]
