Monday, December 6, 2010

The Next Generation

Just after dawn, Mark Stucky and Mike Alsbury get airborne from Mojave in White Knight 2, carrying Spaceship Two under the centersection of the mothership. The crew of White Knight Two sits in the right hand fuselage, so always land offset from the centerline of the runway.
Photo - David Brown

The end of 2010 is a time of change in space. The last NASA Shuttle flights are being completed before the retirement of the Shuttle Orbiter, and both Scaled Composites and Spacex, with totally different vehicles, are making their first steps towards getting humans into space, hopefully at a much lower cost than the Shuttle. Will private enterprise succeed here? It’s a real David vs. Goliath situation.

The philosophies are different. Scaled Composites will use the rocket-powered Spaceship Two to reach space for a few moments above the 100km altitude. Spacex is on the point of flying a conventional vertically-launched rocket (Falcon 9) to achieve orbital flight which will eventually carry humans in a capsule (Dragon) in the same style as the Apollo program. The Spacex rocket is due to be launched within a few weeks.

Spaceship Two is air-launched from a Mothership, White Knight Two. Captive tests and two drops have been completed. Today is the third glide flight during this phase of flight testing.

The sun rises at Mojave on 17th November to reveal White Knight 2 (WK 2) on the ramp. SS2 is nestled beneath the center section of the twin-fuselage WK2. Both crews are already on board. Pete Siebold and Clint Nichols are flying SS2 today, with Mark Stucky and Mike Alsbury piloting the Mothership WK2. The engines are running and the control surfaces on WK 2 move as the pilots check them. Finally the large airbrakes on the trailing edge of the wing are deployed, then retracted. Mechanics on ladders are fussing with the engines on WK 2, and eventually the cowlings are buttoned up and WK 2 slowly taxis out to the east end of the field, to complete the pre-takeoff checks.

By this time I have made my way down to the base of the Control Tower, the nearest accessible vantage point to the main runway.

0710 WK 2 turns onto the runway, the engines come up to power and it starts its takeoff roll. After a surprisingly short run WK 2 is off the ground and by the time it passes the Tower the big aircraft is already a hundred feet in the air.

With the thrust of the four big turbofans, WK 2 is soon off the ground and climbing away.
The high aspect ratio of the WK 2 wing is optimized for the climb, while the low aspect ratio wing of SS 2 gives the required supersonic performance.
Photo: David Brown

The back end of Spaceship Two, a flat plate where the rocket nozzle will be on future flights, today sports plumbing for the water ballast carried inside. Today's flight will include flying at an aft cg, and the water will be jettisoned before landing to regain the normal c.g. position.
Photo: David Brown

Climbing steeply WK 2 banks right and continues to climb northwards towards California City. It will take a long time, well over an hour, to climb to altitude. WK 2 can climb at 1500 feet/min during most of the climb, although above 40,000 feet the rate of climb will drop to a few hundred feet per minute. I can still see the white shape of WK 2 far off in the distance as they turn southwest and head towards Tehachapi, then some minutes later reverse course and make for California City again.
WK 2 reports on the radio that they are at 25,000 feet. Later in the climb, contrails start streaming from the four turbofans of WK 2 as it passes over California City then heads north.

0825 and the photo chase Extra flown by Mike Melvill snarls off the ground and heads north. Chase will pick up SS2 on its return but his lot today is also to make a climb to over 15,000 feet to eventually rendezvous with SS2.

0830 The contrailing WK2 reappears heading south, heading for Mojave. They fly overhead, then make a lazy circle and head back north. Not quite high enough to drop yet.

Like a time-lapse photograph, I have been conscious during this period that each time I look around more people have joined me at the base of the tower. Eventually I count fifty or more. These are mainly the young and very enthusiastic engineers from Scaled Composites who have been wrapped up in producing SS2 for the last couple of years. They have made the trek down the ramp to see their pride and joy actually fly.

Another fifteen minutes and WK 2 appears again, once more flying south with the contrails heading straight for Mojave airport.

At an altitude of well over 40,000 feet, and approaching the launch point. All pre-launch checks have been completed and SS2 is trimmed out. The SS2 crew of Pete Siebold and Clint Nichols are ready for the drop.
Photo: David Brown

As WK 2 comes overhead, SS2 silently drops away. The crowd audibly shows its delight. SS2 starts accelerating out in front of WK 2, heading south towards Mount Soledad, while WK 2 banks away to the right in a tight spiral, deploys those big speedbrakes and comes downhill rapidly, joining up on SS2s right wing.

SS2 is going through its test card, in a wide left hand turn to keep it close to the field.

This includes expanding the flight envelope to 246 knots, 3.5 gs and to look at the stall boundary at aft cg.

While south of the field SS2 vents a white cloud as they jettison the water ballast, marking the conclusion of the aft-cg tests.
In the gin-clear desert air, I can see the Extra dash in from the north and join in on the SS2s left wing.

After the drop over Mojave, the crew of Spaceship Two are completing their test cards as they glide down over the field in a left hand turn. WK 2 with speedbrakes deployed is keeping station on the right wing, while the Extra chase plane is maneuvering to get on the inside of SS2 to take photos.
Photo: David Brown

Back overhead now and the formation continues through a second left hand orbit to land back on runway 30. It has been about 12 minutes since the drop. SS2 flares for a perfect landing and the two flanking chase planes do low approaches, then power back into the sky for their individual landings.

Another day of testing complete.

Another step on the way to commercial flights into space.

1 comment:

Mark said...

Nice article but for the record, WK2 has never not dropped SS2 because they weren't ready to (at the proper altitude and speed). The time to climb is typically driven by the flight test cards as the team usually has test points at various altitudes, some of which may take extended periods. Once the mated test points of the day are completed then the WK2 crew simply flies the required orbit to be at the drop point at the required launch conditions.