anything below 100k feet is the same. unless they were testing different functionality of the plane/glider itself.
there's been lots of talk about this virgin galactic plane, but they have not tested it at re-entry altitutdes, let alone re-entry speeds.
you put this thing up at 100 miles altitude, half that of the ISS, and when it comes back down, gravity is going to bring it to speeds above mach 4, which is only 2800 miles an hour. shockwaves and reverberations resulting from that speed cannot be tested by dropping it at 70k feet. not even close.
virgin galactic is years away from accomplishing anything of substance.

"Virgin galactic is years away from accomplishing anything of substance."
What? They've already gone to space twice in the SS1. What are you talking about? The SS2 is not going to 100 miles up, it's going to 100 km up.
Personally I don't like their feathering idea. I think it puts too much stress at the joint. If it moves, it breaks. I think a nonmoving solid design would be better. Just use control jets when in space like the X-15 did.
Go Scaled Composites!

@zevulon - You have several misconceptions in your post. You state that it will be flying to 100mi. It will not fly that high. Spaceship Two is a sub orbital vehicle it flies to "space" at 62mi or 100km then glides back. The tail changes position and it presents its flat side to the air.
Spaceship one was the predecessor to this vehicle and used all the basic tech that spaceship two uses. It performed the exact same flight multiple times to win the Ansari X Prize and become the first fully commercial vehicle to achieve access to "space". It does not require the reentry shielding and hardening you mention as it never achieves a velocity high enough to cause the problems you describe.
Virgin Galactic is making incremental steps to certifying spaceship two for commercial use. That means baby steps and not EVER blowing up your crew. They are also being even more cautious than certification would require due to the ground test accident that killed several engineers.
They have achieved remarkable and substantial things. They have a road-map to suborbital commercial flight performed in small incremental steps that minimize risk to the crew and the companies investors. I imagine that SpaceX achieving orbital launches and working toward man-rated rockets kind of dwarfs the idea of suborbital work, but suborbital will occur first even at the rates the two companies are progressing. Suborbital will also offer an easier entry point for tourist than orbital flights. Even with everything SpaceX has planned for cost reduction an orbital flight would still cost millions which is huge when compared to $250K for a suborbital flight.

zevulon "2014 will be the year when we will finally put our beautiful spaceship in her natural environment of space" Richard Branson
Space is beyond atmosphere, which means re-entry required. I believe Mr. Branson begs to differ with you.

virgin galactic is years away from accomplishing anything of substance
Thanks, I'll add that to my collection...
"Heavier-than-air flying machines are impossible." -- Lord Kelvin, President, Royal Society, 1895
"There is no hope for the fanciful idea of reaching the moon because of insurmountable barriers to escaping the earth's gravity" -- Dr. F. R. Moulton, University of Chicago astronomer, 1932
In 1969 the New York Times published an apology for once printing derisive comments about an inventor's theory. Robert Goddard was on the receiving end of the Time's criticism of his contention that rockets could operate in outer space. The apology was printed the day after Apollo 11 left earth orbit for the moon.
"My imagination refuses to see any sort of submarine doing anything but suffocating its crew and floundering at sea." -- Jules Verne, author of "20,000 Leagues Under the Sea", 1800's
"Computers in the future may weigh no more than 1.5 tons." -- Popular Mechanics, forecasting the relentless march of science, 1949
"I am looking for a lot of men who have an infinite capacity to not know what can't be done." -- Henry Ford
"Any significantly advanced technology is indistinguishable from magic." "The only way of discovering the limits of the possible is to venture a little way past them into the impossible." -- Arthur C. Clarke
In 1876 when G.G. Hubbard learned of his future son-in-law's invention, he called it "only a toy." This daughter was engaged to a young man named Alexander Graham Bell.
[...]

@zevulon This thing will never experience re-entry because it will never get into orbit, it's a sub-orbital-only craft, which allows it to keep the costs down to well below $1M per person. Rather like a Vomit Comet on steroids.

might be years away... yes, but still... decades in-front of any one else willing to dare.

Zevulon, I don't think these guys are inventing the wheel from scratch here. The data regarding stresses, temperatures etc for reentry is available and obviously the engineers would have started with this information as the minimum design standard... I mean..do u really believe they just drew in on a white board with no design specifications?

Great 18klm, only another 82Klm to go before it becomes usefull

We need to be lowering the environmental footprint of humanity and this will not help. But it warms my heart to know that Brad and Angelina will be the first celebs to copulate in zero gravity.