Slashdot Mirror
Paul Allen's Stratolaunch Finally Flies The World's Biggest Plane (geekwire.com)
"Stratolaunch, the aerospace venture founded by the late Microsoft co-founder Paul Allen, sent the world's biggest airplane into the air today for its first flight test," report GeekWire.
The twin-fuselage plane, which incorporates parts from two Boeing 747 jumbo jets and has a world-record wingspan of 385 feet, took off from Mojave Air and Space Port in California for a flight that lasted two and a half hours. For more than seven years, Stratolaunch has been working with Mojave-based Scaled Composites on the project, which aims to use the plane as a flying launch pad for orbital-class rockets. The first flight test had been anticipated for months. "We finally did it," Stratolaunch CEO Jean Floyd said today during a briefing.
Stratolaunch's plane, which has been nicknamed Roc after a giant mythical bird, took off at 6:58 a.m. PT and went through a series of in-flight maneuvers, including roll doublets, yawing maneuvers, pushovers and pull-ups, steady heading side slips and simulated landing approach exercises. Stratolaunch said it reached a maximum speed of 189 mph and maximum altitude of 17,000 feet.... The plan ahead calls for further tests over the next 12 to 18 months, with the aim of getting the plane fully certified by the Federal Aviation Administration. Stratolaunch has already struck a deal to use Northrop Grumman's Pegasus XL rocket to send payloads weighing as much as 816 pounds (370 kilograms) to low Earth orbit...
Stratolaunch's air-launch system is designed to carry multiple rockets up to an altitude of about 40,000 feet, and then drop them into the air to fire up their rocket engines. The advantage of such a system is that it can take off from any runway that's long enough to accommodate the plane, fly around bad weather if need be, and launch a satellite into any orbital inclination.
Stratolaunch CEO Jean Floyd said their team had dedicated the flight to Paul Allen.
"[A]s the plane lifted gracefully from the runway, I did whisper a 'thank you' to Paul for allowing me to be part of this remarkable achievement."
Stratolaunch's plane, which has been nicknamed Roc after a giant mythical bird, took off at 6:58 a.m. PT and went through a series of in-flight maneuvers, including roll doublets, yawing maneuvers, pushovers and pull-ups, steady heading side slips and simulated landing approach exercises. Stratolaunch said it reached a maximum speed of 189 mph and maximum altitude of 17,000 feet.... The plan ahead calls for further tests over the next 12 to 18 months, with the aim of getting the plane fully certified by the Federal Aviation Administration. Stratolaunch has already struck a deal to use Northrop Grumman's Pegasus XL rocket to send payloads weighing as much as 816 pounds (370 kilograms) to low Earth orbit...
Stratolaunch's air-launch system is designed to carry multiple rockets up to an altitude of about 40,000 feet, and then drop them into the air to fire up their rocket engines. The advantage of such a system is that it can take off from any runway that's long enough to accommodate the plane, fly around bad weather if need be, and launch a satellite into any orbital inclination.
Stratolaunch CEO Jean Floyd said their team had dedicated the flight to Paul Allen.
"[A]s the plane lifted gracefully from the runway, I did whisper a 'thank you' to Paul for allowing me to be part of this remarkable achievement."
Launching rockets from airplanes has been done before but the plan with Stratolaunch is to do so on a larger scale with functionally a bigger rocket. There are some advantages and some disadvantages. One major disadvantage is that there's functionally a size limit: one cannot really put that large a rocket on a plane (and the fact that to get this to work they need to use what is by multiple metrics the largest airplane ever reflects that).
The plane is functioning to some extent like a reusable first stage, but a plane isn't likely to go as high or as fast as as a true first stage, like the Falcon 9's first stage, so it isn't the same as having a true reusable first stage in terms of power.
At the same time, a plane is a well understood, reliable technology. Another connected advantage of air launch is that one is much less beholden to weather events. since the plane can fly above or around bad weather. The Falcon 9 in contrast frequently needs to be delayed due to weather issues (which are made worse in its case because it is a very long and thin rocket); one does have things like the Soyuz which is able to launch in functionally blizzard conditions, but that's pretty rare for a rocket and is in a large part due to the fact that it was originally designed to be an ICBM.
To me, the most interesting aspect of Stratolaunch is the flexibility enabled by positioning your "launch pad" at just the right place. But I don't know if that will be enough to sustain them in the current market. A lot has changed since they started working on this project, with SpaceX and Rocket Lab both providing "budget" launch services, not to mention Blue Origin waiting in the wings. It will be interesting to see how/if they manage to find their niche.
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
The biggest advantage is lower air pressure. Rocket engines must keep the pressure of the exhaust gas higher than the atmosphere the launch in. This means the engines at sea level launch will have a lower exhaust speed and therefore be less efficient.
Next you don't have to push through 40,000 feet of atmosphere. Rockets launched from sea level do not accelerate at their maximum rate because they want to reduce loss due to air resistance.
Third is flexibility of launch location. You can now launch from anywhere your plane can get to. Launching from the equator to geostationary orbit is easier than going form south Florida.
Last you start a little higher and with an initial velocity. This is probably the least advantage but it still counts. Rockets are all about change in velocity and its an exponential equation. Want to go an extra 1500m/s double the size of your rocket. So a little initial altitude and velocity can mean a huge difference in the amount of fuel needed to reach your intended orbit.