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Author:  30mike-mike [ 02 Dec 2004, 08:43 ]
Post subject: 
The usual "Friend of a friend...etc"

Subject: Fw: Mike Melvill - Space Ship 1
> >
> >
> > From a friend:
> >
> > I just had the extreme pleasure of speaking with Mike
> > Melvill yesterday, the pilot of SpaceShipOne's first two flights above
the
> > Karman 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.


So, you have trouble. We all have trouble. Build a bridge and get over it.
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