Slashdot Mirror
SpaceShipTwo Tests Its Rocket Engine and Goes Supersonic
ehartwell writes "It's official. This morning, after WhiteKnightTwo released SpaceShipTwo at an altitude of around 50,000 feet, pilots Mark Stucky and Mike Alsbury ignited the engine for a roughly 16-second blast. After the engine cutoff, the plane coasted back to its landing back at the Mojave airport. Virgin Galactic tweeted that the pilots confirmed 'SpaceShipTwo exceeded the speed of sound on today's flight!' Its predecessor, SpaceShipOne, first went supersonic December 17, 2003."
So after exceeding the speed of sound the next step is the speed of light? ;-)
Why is it taking Virgin Galactic so long for development? Is it a financing or technical issue?
SpaceX was founded in 2002 and is already making re-supply missions to the ISS. Granted that's not quite the same as human spaceflight but it seems like there's a lot faster advancement occurring at SpaceX than at Virgin Galactic.
SpaceX charge rather more than $200,000 per seat to fly into space. And there's a big difference between NASA 'man rating' and being safe enough to routinely fly tourists; if SS2 flew daily and was as 'man rated' as the shuttle, they'd kill everyone on board every two months.
I got a chance to meet Rutan a few years ago here in Colorado Springs at the USAFA - he spoke passionately to the cadets about the fact that when he started in aerospace the speed/power/altitude curve was bent upwards, and then after the shuttle it bent back over itself into decline (think about the fact that the SR-71 is the fastest aircraft in the world right now, and we haven't built a new one in a LONG time). Then he talked about his work, building year after year on the EZ and other aircraft to become an expert at composite fabrication and aircraft.
The gist of his talk was loosely - `get out there and do it - and this time STAY`. I'm pretty sure if you asked him why Scaled is running so "slowly" you'll get an earful about how much they've learned. What is missing from Scaled is the money and industry savvy that Elon pumped into SpaceX. Scaled was really only made to win the X prize, and even with Brason on-board hyping the hell out of it, Rutan is not a "run flat-out" kind of guy. A big difference between the software engineer mindset (Elon) and the test-pilot "I damn sure hope this plane flys" aerospace engineers.
I think the "Space" part of it is a side show to what Virgin is really pushing for.
The bigger goal, IMO is being able to enable flight from the US/Europe to Australia in a matter of hours by a "plane" jumping into low Earth orbit and circling the globe in 2 hours. Imagine being able to "jump" to the other side of the Earth in an 1 hour? A 2 hour flight to China? Australia? Europe?
It takes 88 minutes in LOE to circle the globe.
It would simply be revolutionary. IMO that is the near term end goal of Branson's interest in space flight. I think the "manned space flights" are tangential to what the immediate goals are. Hammering out the science to allow cheap cross earth flights, is simply incredible.
Nope, no X-plane ever made it into orbit. They were very-high-altitude rocket planes, and were much too small to contain enough fuel to reach orbit. More fuel would necessitate a bigger plane to contain it, and hence a bigger motor to propel it, and hence more fuel to run the bigger motor, etc... That's why rockets get around this problem with multiple stages. They jettison excess mass on the way to orbit. A true "space plane" that lands and takes off on a runway and doesn't dump stages along the way would need to be Single-Stage-To-Orbit (SSTO). So far, there are no true SSTO vehicles, even rockets. A space plane would need to haul along landing gear, wings, conventional engines, etc, and would be much more difficult to do than a simple SSTO rocket.
There is a vast difference between SSO, or even SST, and what you propose. SSO and SST just go straight up and straight back down. There is very little ground track in their flight envelope. In order to get to orbit, you need to go straight up, and then go about double that to really get out of the atmosphere, and then tack on around 8km/s velocity. You're looking at a few dozen times more energy, and around a hundred times more fuel. A sub-orbital transcontinental flight won't need quite that much, but you're still way up there in comparison. Add in the fact that you're actually going to need a real thermal protection system for re-entry. They're not even in the ballpark.
It's not a jet turbine burning kerosene with oxygen, it is a hybrid rocket motor. It is burning a solid composite material with a nitrous oxide oxidizer. It will never be a "clean looking" burn; expect something closer to what the solid boosters on the shuttle produced.
They're not even in the ballpark.
Energy is not hard to come by. SpaceShipOne generated about a sixth of the delta-v it'd need to reach orbit. I consider that fairly close given the type of engine and relatively low mass fraction. SST is supposed to have slightly better performance in that regard. But neither is intended for this particular role.
But I think naysayers are overstating the difficulty of more delta v and a different thermal protection system. Sure, it might need a radical vehicle redesign. But guess who demonstrated that they can design such suborbital vehicles?
I think you're understating the difficulty of more d-V. Six times the d-V doesn't simply mean six times the fuel. Energy is proportional to velocity squared, so you immediately need thirty-six times the energy. When you factor in the exponential behavior of the rocket equation, and the fact that you need yet more fuel just to take up the additional fuel needed to accelerate the spacecraft itself, your fuel consumption balloons fast.