Video: SpaceShipTwo Lights the Candle
Keith’s note: 1.7 million views so far. I have ridden a full acceleration simulation of SpaceShipOne’s flight in the NASTAR Centrifuge. Rest assured – this has got to be quite a kick – even more so in reality.
It seems that Richard Brason will make money. With the blessings of God that nothing fails, he will be able to make easy money.
I dunno… That flight was hairy both during the powered and unpowered phases; she was dancing all over the place at some points!
Lot of dutch roll in that one. They called a couple times “ADC miscompare”, which may have kicked out the yaw damper, among other things that are normally handled automatically. I don’t know how they have their control system configured, but hopefully it’s a computer issue, not design.
The apparent loss of auto stabilization showed that the design is stable on entry. A liquid propellant engine (which would reduce the landing weight and give a smoother ride) must be high on the list for improvements.
There have been statements by VG that when LauncherOne’s liquid engine is ready work begins on porting it to SS2.
Constantly changing speed, altitude, and attitude throughout the entire flight, with extremes on all three. Quite a complex environment to fly in, with only X-15 and Shuttle experience to draw on. As time goes on I’ll bet they will learn quite a lot about how to manage it all. I remember one of the SpaceShipOne flights went into a slow uncontrolled vertical barrel roll, but they didn’t seem too worried about it. I’m guessing that at those extreme altitudes they expect a bit of wiggling around since inertia will have a more dominant effect than it would in thicker atmosphere.
With X-15 all of this was a much bigger worry because the attitude during entry interface was critical, but I think the shuttlecock feature is supposed to solve most or all of that problem by getting the vehicle oriented correctly before it starts hitting the thicker atmosphere.
To me, the constant fluctuations, which appeared to be in six degrees, was reminiscent of a Gemini-Titan II launch, which peaked at over 8 g’s, and Jim Lovell described it years later as the roughest ride of them all. Apollo-Saturn was easier on the astronauts, and the Shuttle, at 3 g’s max, was a joy ride by comparison. The strain in the pilot’s voice in this video reminded me of Alan Shepard counting (grunting) off the g’s during MR-4.
I’m glad this flight went well, but it looks like they’ve still got some refinement to do before taking on passengers.
Sounds like you mean Gemini 8
“By now the spin rate had reached one revolution per second, giving the astronauts blurred vision, and putting them in danger of loss of consciousness.”
http://en.wikipedia.org/wik…
Actually, that isn’t what I was thinking of. During Gemini 8, after they had docked with the Agena target vehicle, they experienced one or more thrusters that were either stuck on or firing intermittently without being commanded by either the pilot or the engaged autopilot mode. They went into a six-degree spin and tumble that came close to costing Armstrong and Scott their lives before Armstrong figured it out and they got it under control by first disabling selected thrusters. At this point they terminated the mission, but it was considered to be an amazing recovery, and popular theory is that this was what won Armstrong the command seat on Apollo 11.
I was comparing the constant corrections that Steve Pemberton described above to the Titan II launch vehicle in general, used for all Gemini missions. It didn’t have aerodynamic stabilization (fins at the tail), but instead corrected deviations from the lateral flight line with quick puffs from thrusters around the base of the tail. It was a standard negative feedback control system, and it worked well, but it was a rough ride because of the combination of thrust variation, high max thrust (> 8g), and constant attitude corrections. The Titan II, like most LVs of that era, started life as an ICBM and in the conversion to a launch vehicle model there were always some trade-offs. The Titan II had the necessary thrust to loft a Gemini capsule, and then some, but it was no Rolls-Royce to ride in. it was a rough ride during the first couple of minutes. I have a video interview of Jim Lovell (from an Apogee Books DVD) where he describes the Gemini-Titan II launch.
From the Saturn V onward, a LV usually used a combination of attitude correction methods, with gimbaled main thrust nozzles being the primary control. Although more complex, this is the best (fastest) performing system for attitude control during flight in both atmosphere and space. Smaller, faster responding and more accurate accelerometers and other inertial sensors are key components of this type of system.
So, in this respect, SpaceShipTwo seems like a bit of a throw-back, but I’d prefer to be optimistic and suggest that, rather, it’s a work in progress.
I bet he turns more of a profit and does it quicker than SpaceX.