Ascender is a small sub-orbital spaceplane designed to use existing technology and to pave the way for later vehicles on our development sequence. Ascender is specifically designed to generate spaceplane revenues at minimum development cost and risk, and thereby to be attractive to private-sector investment.



Ascender Artist’s Concept
For more Ascender images visit the Media page


Ascender carries one pilot and one passenger or experiment. The passenger remains strapped in his/her seat during the flight. Ascender takes off from an ordinary airfield using its turbo-fan engine and climbs at subsonic speed to a height of 8 km. The pilot then starts the rocket engine and pulls up into a steep climb. Ascender has a maximum speed of around Mach 3 on a steep climb and can reach a height of 100 km.

Stage Altitude
1 8 0.6
2 64 2.8
3 100 0
4 46 3.3
5 24 3.3

At that time, the passenger will see superb views of Earth and will see the sky turn black even in daytime. Then Ascender enters a steep dive, where a passenger can experience two minutes of weightlessness. On reaching the atmosphere, the pilot pulls out of the dive and flies back to the airfield from which they took off 30 minutes previously.


Ascender Leading Data

Span, m 7.6
Length, m 12.9
Jet Engines Two in the 500 kg thrust class
Rocket Engines Two in the 2500 kg class
Rocket Propellants HTP and Kerosene
Maximum Weight, kg 5,500
Empty Weight, kg 2,400
Max Altitude, km 100


Ascender would be the first spaceplane capable of taking off under its own power and of making several flights to space per day. (The X-15 of nearly forty years ago had a somewhat higher performance but had to be launched from a B-52 converted bomber and needed several weeks of servicing between flights.) It has two jet engines sized for taxiing, ferry flights, aborted landings, diversion to other airfields, and to provide back-up thrust in case of rocket engine failure on take-off. Rocket engines provide most of the thrust for take-off and climb.



The rocket engines use hydrogen peroxide (HTP) as the oxidiser. History has shown that rocket engines using HTP are simpler to develop than those using liquid oxygen (LOX). The Ascender rocket engine uses technology developed in the UK in the early 1970s.

Ascender is well within the aeronautical state of the art. The aerodynamics, structure, engines, and systems are all based on those of existing aeroplanes or launchers and uses proven materies. The only innovation is in the concept, which is in essence that of a light aeroplane of hypersonic shape fitted with a rocket motor.

Ascender could be flying in three years as a research aeroplane, and carrying passengers on space experience flights within seven years. Current work is being funded privately, and discussions are taking place with potential strategic partners. Ascender has EUREKA status as a suggested project.

Ascender is based on a design included in a feasibility study for the European Space Agency (ESA). An independent review of this study, commissioned by the UK Minister for Space, “did not identify any fundamental flaws” in the concept.
Bristol Spaceplanes Limited (BSP) Ascender Layout

The design of Ascender has been evolving continuously. As you can see, the artist’s concept above is somewhat different from the layout drawing. The latest version is at present proprietary but will be released soon.


Cost and Programme

The development programme calls for Ascender to fly within three years of full go-ahead. The cost to early operational use is comparable to that of just one fighter aeroplane off the production line. This remarkably low cost is made possible by the design concept and by excluding any component not essential for the basic mission.

After a few years in service, the cost per flight of Ascender would be reduced to a level comparable to that of a jet fighter, i.e., a few thousand pounds. Then routine everyday flights to space (albeit brief) would become possible at a cost affordable by middle-income people prepared to save.

Ascender is specifically designed to generate spaceplane revenues at minimum development cost and risk, to be attractive to private-sector investment.



Ascender has been designed to pave the way for later vehicles on our development sequence.

[Evolution of Ascender]

Ascender’s successor, Spacecab, would be a fully orbital spaceplane and use existing engines and proven materials. With the benefits of full reusability, its cost per flight will be well over 100 times less than that of the Shuttle.

An enlarged development of Spacecab, called Spacebus, is designed to carry 50 people to and from orbit. A second-generation Spacebus would also be capable of carrying passengers from Europe to Australia in some 75 minutes flying time.