Scaled Composites Tier One
Tier One is Scaled Composites' program of sub-orbital human spaceflight using the spacecraft SpaceShipOne and its launcher White Knight. In 2004 it made the first privately-funded human spaceflight.
Overview
The stated objective of the program is to demonstrate sub-orbital human spaceflight operations at low cost. Scaled Composites hope that by about 2013 it will be possible for members of the public to experience a sub-orbital flight for about the price of a luxury cruise. Tier One itself will not carry paying passengers; it is a testbed for the necessary technology.
The design concept is to air launch a three-person piloted spacecraft which climbs to slightly above 100 km altitude using a hybrid rocket motor and then glides to the ground and lands horizontally. Scaled Composites list the following components of the program:
- launch aircraft (White Knight)
- human-rated spacecraft (SpaceShipOne)
- hybrid rocket propulsion system
- mobile propulsion test facility
- flight simulator
- intertial-nav flight director
- mobile mission control center
- pilot training program
- flight test program
Spacecraft
Main article: SpaceShipOne
Tier One's spacecraft is designed to:
- carry three humans (one of them a pilot) in a sea-level pressurised cabin
- be propelled by rocket from an altitude of 15 km to in excess of 100 km
- reenter atmosphere and shed kinetic energy in an aerodynamically stable configuration
- glide transonically and subsonically
- land horizontally on a standard runway
Most of the volume of the fuselage is divided between the cabin and the hybrid rocket motor. Most of the rest of the craft's volume is the wings, which can be pneumatically switched between two configurations: conventional wings for gliding, and tilted up into a high-drag ("feathered") shape to slow reentry.
The stable high-drag shape removes most of the need to actively control attitude during reentry: Scaled Composites refer to this as "care-free reentry". This is a novel aerodynamic design, and is inherently far safer than the only comparable craft previously built, the Space Shuttle, which glides hypersonically, undergoes enormous aerodynamic stresses, and must be precisely steered. (To be fair, the Shuttle starts reentry at much higher speed than SpaceShipOne, but the comparison holds when one considers only similar stages of reentry.)
The craft has three distinct flight control systems: a manual system for subsonic use, an electric system for supersonic use, and a gas reaction control system for extra-atmospheric use.
The cabin, designed to hold three humans, has a diameter of 1.5 m. It is pressurised, maintaining a sea level breathable atmosphere. Oxygen is introduced to the cabin from a bottle, and carbon dioxide is removed by a scrubber system. The cabin has sixteen round double-pane windows, affording a moderately good naked-eye view.
Launch aircraft
Main article: White Knight
Tier One's launch aircraft is designed to take off and land horizontally and attain an altitude of about 15 km, all while carrying the Tier One spacecraft in a parasite aircraft configuration. It has turbojet propulsion.
It has the same cabin and avionics as SpaceShipOne, allowing it to be used as a high-fidelity moving platform flight simulator for SpaceShipOne. The same pilots fly White Knight as fly SpaceShipOne.
Hybrid rocket motor
Tier One uses a hybrid rocket motor, with solid rubber fuel and liquid nitrous oxide oxidiser. The motor itself is being developed separately by two companies in competition, Environmental Aeroscience Corporation and SpaceDev.
The nozzle of the rocket motor must be replaced between firings. This is the only part of the craft, other than the propellant, that must be replaced.
History
According to Scaled Composites, the concept for the program originated in April 1996, preliminary development begain in 1999, and full development begain in April 2001. It was initially kept secret, even after White Knight first flew on August 1 2002. The program was announced to the public on April 18 2003, when SpaceShipOne was ready for flight tests. Its first flight test, a captive carry test, took place on May 20 2003.
After months of glide tests and powered atmospheric tests, on June 21 2004 the program succeeded in making the first privately-funded human spaceflight, SpaceShipOne flight 15P. The program is expected to win the Ansari X Prize by making repeated spaceflights later in 2004.
Pilots
The pilots for the Tier One program are:
Future
The name raises the question, "What will Tier Two be?". Scaled Composites operates a policy of not discussing planned future programs, so anything that can be said here is pure speculation. It can be reasonably expected that future manned spaceflight programs will aim to go faster, with a goal of reaching orbit, and to carry greater loads.
External links
- Tier One home page at Scaled Composites' website