You know, if they’d get a working engine and actually start flying, I don’t think they’d need as big a promotional budget.
[Update a couple minutes later]
WhiteKnightTwo just took off with SpaceShipTwo, presumably for a glide test. Meanwhile, Jeff Foust has a story on plans for powered flight test.
[Update a while later]
Meanwhile, just down the flight line, here’s what it looks like to build a Lynx.
Here are eight coming soon (maybe), via technology.
I’ve updated yesterday’s piece at Ricochet to clarify, for those in comments. I’ve probably discussed this here before, but…
Per discussion in comments, there seems to be some confusion about the difference between high-altitude flight, suborbital flight, and orbital flight. As John Walker points out, orbital flight requires a minimum speed to sustain the orbit, but while that is necessary, it is not a sufficient condition. In fact, a flight can be suborbital with the same speed (energy) as an orbital flight. The best, or at least, most rigorous way to define a “suborbit” is an orbit that intersects the atmosphere and/or surface of the planet. So if you launched straight up at orbital velocity, it would still be a suborbit, because it would (after an hour or two, I haven’t done the math) fall back to the ground. So John’s numbers in terms of comparative energy are roughly correct for the particular vehicles being discussed here (XCOR Lynx and VG SpaceShipTwo), they can’t be generalized for any suborbital vehicle (e.g., a sounding rocket isn’t orbital, but it goes much higher than those passenger vehicles, often hundreds of kilometers in altitude).
The speed necessary to achieve orbit is partly a function of the mass of the body being orbited, but it is also a function of its diameter, and whether or not it has an atmosphere. If the earth were a point mass, an object tossed out at an altitude equivalent to the earth radius (that is ground level) would have very little velocity, but it would have a lot of potential energy. It would fall, gain speed, whip around the center and come back up to the person who had tossed it. That is, it would orbit. So even for the relatively low-energy suborbital vehicles discussed in this post, the reason that they’re not orbital is simply that the planet gets in the way.
One other interesting point is that, under the definition above, subsonic “parabolic” aircraft flights in the atmosphere, to offer half a minute or so of weightlessness (offered by the Zero G company), are suborbital flights, in terms of their trajectory. I put “parabolic” in quotes because in actuality, if properly flown, they are really elliptical sections, as all orbits and suborbits are. The parabola is just a close approximation if you assume a flat earth, which is a valid assumption for the short distances involved. Galileo did his original artillery tables based on flat earth, which is why beginning physics students model cannonball problems as parabolas, but modern long-range artillery has to account for the earth curvature, and it does calculate as elliptical trajectories.
Finally, one more extension. Ignoring the atmosphere, every artillery shell fired, every ball thrown or hit, every long jumper, every person who simply hops up into the air, is in a suborbit. The primary distinction for the vehicles discussed is that they are in a suborbit that reaches a specific altitude (at least a hundred kilometers to officially be in “space”), and leaves the atmosphere.
Clear as mud?
…into Seattle. It does make a lot of sense to get gamers involved.
Thoughts from Sarah Hoyt on the privilege of the naive left.
Here’s your feel-good story of the day.
That sounds like a big explosion. I wonder if it was a tactical nuke?
I wonder if it occasionally occurs to David Axelrod that the incompetent ideological community organizer he helped foist on the country is also a political idiot?
Space Adventures has announced that it’s found the needed second passenger, but Ed Wright points out that there may be some political problems.
May be about to explode?
The wheels of justice, as they say, grind slowly. As with other Obama administration scandals, Barack’s effort is to run out the clock. It may be that by the time we learn the full extent of the Obama administration’s lawlessness, the administration will be over. But the remaining options are not good: either Austan Goolsbee, a senior adviser to Obama, made up a smear of Koch Industries out of whole cloth, or else Obama’s IRS allowed the White House illegal access to confidential taxpayer data for political purposes. That’s a crime for which at least two people should go to jail.
Not if the media has anything to say about it. They’ll just ignore it.
I have some thoughts and links on the 10th anniversary celebration, over at Ricochet:
Basically, the late Jim Benson of SpaceDev (now part of the Sierra Nevada corporation, which finally seems to have given up on its own plans to use a hybrid motor for its Dream Chaser vehicle) sold Burt Rutan a bill of goods with the hybrid, with claims of simplicity and safety. In fact, as many of us told him at the time, he’d have been a lot better off purchasing a liquid engine from XCOR, but they didn’t have a sufficient track record at the time for him to think they could meet the deadline to win the prize. Then, once they’d (sort of) succeeded in flying something into space, they continued on with what they thought they knew. They’ve been in a sunk-cost trap ever since, unable to get themselves out of the hybrid-propulsion rut.
As I’ve long noted, the delays in the arrival of commercial spaceflight have been a combination of people who knew what to do not having money, and the people how had money not understanding the problem, and being too arrogant to listen to the veterans. Only now is the crucial combination of money and know how finally coming together.
As I note there, I stopped by XCOR in the morning before the event. Looks like they’re making good progress in bringing the spacecraft together.