The spaceship designs are as varied as the origins of the teams, making use of established as well as innovative technology.
Several teams took the "oldie but goodie" tack, basing their sub-orbital rockets on technology developed as early as the 1940s. A popular design to copy was the German V-2, a World War II rocket that launched vertically from the ground into the Earth's stratosphere so as not to be detected and destroyed by enemy aircraft -- the world's first guided ballistic missile. Teams that chose this model for their spacecraft, such as Canadian Arrow, were forced to make some serious adjustments to fulfill the contest's requirements: Primarily, the rocket had to be large enough to carry three people, and the passengers couldn't explode when the rocket touched back down. To tackle this, some teams divided the rocket from the launch vehicle, turning the launch into a two-stage affair. The first stage involved lift-off from the ground, the craft propelled by the main rocket engine. During the second stage, the cabin of the spacecraft disengaged from the bottom portion, propelled by its own engines into sub-orbit. In the case of the Canadian Arrow, the two portions were equipped with parachutes to ease the landing.
The most successful teams in the contest took a slightly different tack. Using the rationale that launching from the Earth's surface is twice as difficult as launching from high altitudes, Scaled Composites and the da Vinci Project developed spacecraft that actually launched from the sky care of a carrier plane and a gigantic helium balloon, respectively. These high-altitude launches reduce the amount of rocket fuel required (a major factor in keeping down weight and cost) because the rocket has a shorter distance to travel to get to sub-orbit, and the thin air provides less resistance than that on the Earth's surface. Scaled Composites' SpaceShipOne released from its carrier plane White Knight at about 45,000 feet (~13,700 meters), boosted itself into sub-orbit, cut its engines for a three-minute view of the Earth in weightless conditions and then fell back down to Earth, slowing its decent by creating aerodynamic drag (see How SpaceShipOne Works for detailed information of the flight).
The da Vinci Project used a slightly different approach, dangling its spaceship from a reusable helium balloon until reaching 80,000 feet (~24,400 meters), at which time the engines were fired. Since propelling the rocket straight up would destroy the balloon (disqualifying the entry), the GPS-guided vessel first shot out at a 75-degree angle to clear the balloon and then changed to a 90-degree trajectory to go straight up to sub-orbit. The cabin then separated from the bottom portion and, after three minutes of weightlessness and an awe-inspiring view, plummeted back to the Earth while using parachutes on both sections to break the fall.
Some of the more unique designs did not make it to the flight-testing stage, but certainly deserve an "E" for effort. American Discraft of Portland, Oregon, had the inspired idea to create a 100-foot-diameter (~30.5-meter) "hypersonic wave rider aerospace craft" -- a flying saucer. In theory, the ship (called the Space Tourist) would take off horizontally from a runway at 60 miles per hour (~97 kph) by creating suction along the top surface and would then thrust the air through the ship's exhaust to create propulsion and steering.
In the next section, we'll discuss future developments and what is expected to arise from the efforts of the Ansari X Prize contestants.