o 100 km (62.5 miles). The rocket makes a nose-first reentry, with foam insulation protecting the aluminum nose section from reentry heating. A drogue chute frees the main parachute, and landing is cushioned by an expendable aluminum nose cap that compresses on touchdown.
Another approach to the problem of achieving HTOL from Kelly Space & Technology - towing the vehicle like a glider at take off in order to save using fuel in the early part of the flight, thereby starting at high altitude with full propellant tanks. It should be possible to get this to work - like in-air re-fuelling and two-stage HTOL. Which will end up with the lowest operating costs? Time will tell!
The SpaceClipper SC-1 is a suborbital reusable VTOL spaceplane proposed by SpaceClipper International, designed to carry up to ten passengers and two flight crew to an altitude of 140 km and back. Although it descends horizontally, it takes off and lands vertically.
The SC-1 features shield doors which protect the craft during ascent and descent, but open to allow views of space and Earth for the four minutes that the vehicle is weightless at the top of its trajectory.
A follow-on fully orbital spaceplane dubbed SC-2 is also proposed, building on the experience gained in developing and operating the SC-1.
Xerus is a two-person reusable spaceplane proposed by XCOR Aerospace, which takes off and lands like a conventional aircraft. It is capable of climbing suborbitally to 100km using a cluster of reusable rocket engines developed by XCOR to use non-toxic propellants. After a short period of weightless free fall the vehicle then re-enters the atmosphere. While the primary market for Xerus is space tourism, the vehicle is also being targeted at microsatellite delivery and suborbital science payloads.
XCOR's Lynx, announced in March of 2008, is a follow-on design based on Xerus. Like Xerus, Lynx is a two-person suborbital spaceplane designed for the space tourism market but also aimed at science and research applications.
XCOR's primary business is the development of reusable rocket engines, in pursuit of which they previously developed and flew the EZ-Rocket airplane as a demonstrator and test bed for their reusable rocket technology. Much of the engineering team previously worked on the propulsion systems of Roton at the former Rotary Rocket company.
The Alpha Project is a fully reusable two stage vehicle proposed by World Aerospace, Inc. The upper stage, dubbed the Alpha CX-1A SRV (Space Reusable Vehicle) is a three-person spaceplane designed to take one pilot and two mission specialists into space. Intended to use off-the-shelf technology where possible, the CX-1A may also be launched from the ground as a suborbital spacecraft.
Interestingly, three potential configurations for the lower stage (or launch vehicle) are being proposed as development proceeds:
The first is an Air Launched Horizontal Landing (ALHL) solid rocket booster RLV derived from the Pegasus by Orbital Sciences Corporation. This vehicle will carry the CX-1A upper stage for the flight test phase.
The second is a HTOL liquid rocket flyback booster RLV. This vehicle will carry the CX-1A in the piggyback configuration and is ultimately expected to evolve into the final RLV lower stage as the design matures.
The third is a VTOL rocket booster option. In this configuration the CX-1A will be launched atop currently available commercial launch vehicles such as the Boeing Delta IV-M EELV, the LMCO Atlas V 500, and an RLV based on the Thor (a former USAF ICBM)
An innovative HTOL design by Mitchell Clapp using in-flight refuelling of a single-stage vehicle to enable it to reach orbit. Taking off with almost no liquid oxygen in its tanks, it can then effectively "take off" with full tanks at high altitude. The upper stage of a 2-stage vehicle is limited to a mass of about 100 tons, whereas Black Horse could have a fully-fuelled mass several times this. Air forces use in-flight refuelling routinely and have accumulated enormous experience, so safety should not be a problem. Currently being pushed by the