Older Article - Sky is the Limit?

Note: This is an older article, written by me, that was posted on Aviationtelegraph.com. Unfortunately, due to inactivity, the website was removed from the Internet.

Sky is the Limit?

“The sky is the limit” is a common quote in the Aviation industry. But is this really true? Last decade, commercial space travel is booming, offering an experience in space for tourists. These spacecraft are designed be used more than once, instead of a ‘classic’ rocket design. Is it possible that on short term airlines will use routes through space and is a trip from Amsterdam to Sidney in two and a half hours possible? (source)

Commercial aircraft are cruising between 30.000 feet and 36.000 feet (about 9-10 kilometers). General Aviation aircraft, like the Cessna Citation X, are reaching a service ceiling of 51.000 feet (source) (about 15 kilometers). Till some years ago, this was the limit for aircraft, because above this altitude there is not enough air for the turbofan engines to operate efficient. Thrust will decrease with an increasing altitude, due to lower air density. For example, at 51.000 feet, the thrust is about 13 percent of the initial thrust on sea level, based on ISA standard atmosphere.

Above these altitudes it is necessary to equip an aircraft with a propulsion type that will not require a mass flow of air, which turbojets and turbofans require. XCOR has designed the LYNX with an engine that uses kerosene and liquid oxygen to propel the spacecraft. (source) The LYNX is able to take-off and land at runways for itself and has a capacity of two pilots and is designed to reach an altitude of 200.000 feet (61 kilometers). It has not been tested yet, the test program is scheduled to start later this year.

Virgin Galactic, subsidiary of the Virgin Group is working on a comparable spaceship as well but uses a different concept: This concept uses a mothership and a spacecraft, mounted under the wings of the mothership. When an altitude of about 50.000 feet is reached, the spacecraft will detach from the mothership and continue by itself. The millionaire Richard Branson recently presented the newest spaceship: the second SpaceShipTwo. (source) This spacecraft has a capacity of eight passengers, including two pilots and could reach an altitude of 71.000 feet (22 kilometers) The spaceship uses a hybrid rocket engine, which combines solid rockets and liquid rocket engines by using a solid fuel source and a liquid oxidizer. (source)

The spaceship was the second built model of SpaceShipTwo. The first one crashed during a test flight in the Mojave Desert, killing one of the two pilots. This states that the spaceships are still in the concept phase and not yet fully capable of transporting passengers with a high safety level, like the commercial aviation does. Space travel is still a futuristic way of traveling, but so was traveling by air in the beginning of the 20^th century. During this century, safety has improved significant and traveling by air is one of the safest ways to travel nowadays. (source)

To answer the question stated in the title: is the sky the limit? No it is not. XCOR and Virgin are developing new spacecraft that could travel the world in a few hours. For the wealthy ones it is already possible to travel to space. In a few years, a rich business traveler maybe could depart after breakfast from Amsterdam for a lunch meeting in Sidney. For the rest of the travelers, space travel is still a futuristic way of traveling. Maybe after enough testing, space travel will slowly emerge. This could mean that airport with geographical advantages will cease to exist, only making the world smaller and easier to travel.