Going to space is expensive -- about $10,000 per pound, in fact. So until recently, only governments could afford to go into space. But in 2004, the commercial spacecraft SpaceShipOne made two sub-orbital flights into outer space, winning the $10 million Ansari X Prize. SpaceShipOne dropped from an airplane between about 46,000 to 48,000 feet, ignited its rocket engine, traveled to 150,000 feet, re-entered the Earth's atmosphere and glided to a landing. But can a commercial spacecraft take off on its own from the ground, travel into outer space and land again on a runway? That's the goal of XCOR Aerospace, and it starts with the EZ-Rocket.
In this article, we'll learn about the technology behind the EZ-Rocket and see how XCOR plans to expand on this technology in the future.
The EZ-Rocket is the first privately built and flown rocket plane, and serves as the test bed for new technologies. XCOR Aerospace designed the EZ-Rocket, which they modified from Bert Rutan's Long-EZ airplane. The Long-EZ is a homebuilt aircraft kit manufactured by Rutan's Aircraft Factory. It is a fixed-wing canard aircraft, which means that its tailplane is ahead of its wings instead of behind them. This gives the plane good gliding characteristics, making it ideal for a rocket plane.
Public domain photo by Adrian Pingstone
The EZ-Rocket's modifications included the following:
- Two liquid-fueled rocket engines to replace the aircraft propeller engine in the rear
- A pressurized fuel tank underneath, filled with isopropyl alcohol (rubbing alcohol)
- Two aluminum tanks (Styrofoam-insulated) in the rear that hold the oxidizer, liquid oxygen
Rutan added the external fuel tank because the original Long-EZ tanks were not designed to hold alcohol or withstand high pressure. He added the oxygen tanks because rocket engines must carry their own supply of oxygen (airplane engines get their oxygen from the atmosphere).
Each rocket engine on the EZ-Rocket produces 400 pounds of thrust, or force (each Space Shuttle Main Engine, or SSME, produces about 375,000 pounds of thrust). Rocket engines do not need to produce the huge amounts of force that the space shuttle does because they do not have to lift as much mass as the space shuttle does. Like the space shuttle's engines, EZ-Rocket's engines are regeneratively cooled. This means that the cold liquid fuel is pumped around the combustion chambers to remove excess heat and keep them from melting. The EZ-Rocket carries enough fuel for only 3.5 minutes of rocket burn time.
We'll look at exactly how the EZ-Rocket works next.