Spaceplanes are, and perhaps have always been, one of the most romantic future transport fantasies humans could conceive. Marrying aircraft and spacecraft together, they implied an accessible future where access to orbit could eventually be as mundane as flying, not a unique experience you achieve through a single, monstrously powerful rocket launch. Thanks to their potential for reusability, they promised a cheaper, faster and more frequent method of transport one that could launch, land, and launch again, on a regular runway.
Unlike current rockets which tend to be expendable after a single trip, spaceplanes were developed with the goal of reuse. Designers envision vehicles that can transport people, scientific gear and commercial cargo into orbit in a simpler, cheaper manner an ambitious project intended to smooth the transition from Earth’s familiar air to the unfamiliar vastness of space.
But history is also littered with high-profile aerospace programs that didn’t make it all the way to the target. These spaceplanes often had many of the technical innovations that would come to define future spacecraft but were ultimately grounded by technical constraints, soaring development costs, political winds or changing priorities. Each these abandoned dreams illustrates how difficult it is to take an amazing idea and turn it into a flying machine.
1. Boeing X-20 Dyna-Soar
The Boeing X-20 Dyna-Soar: A Visionary Spaceplane in The making One of the most advanced early spaceplane projects in history was undertaken by the US Air Force in the 1950s to develop the Boeing X-20 Dyna-Soar, also known as the Space Plane. It was supposed to carry out military and research missions and feature both the stability of a jet aircraft and the remarkable speed and height of a space shuttle.
Key Programme Features:
- Early reusable spaceplane concept
- Military and research mission plans
- Aircraft-inspired glider design
- Rocket-launched orbital operations
- Influenced future spacecraft development
The X-20 had a futuristic, streamlined, glider-type body; this was very avant-garde for the period. It would be fired into space vertically by an adapted Titan rocket, then would detach in orbit. After finishing its mission, it would come in and glide back into the atmosphere to land on a runway a reusable spacecraft was on the horizon, and would play a part in programmes after.
However the Dyna-Soar idea was eventually cancelled. Changing priorities saw a redirection towards the US Apollo Moon landing programme and other Cold War initiatives. While the X-20 did not fly, it did allow researchers to gain experience in reusable aerospace vehicle technology, atmospheric re-entry and techniques which could be employed in the development of future spacecraft like the Space Shuttle.
2. Buran
In essence, the Soviet Union had its own counterpart to the Space Shuttle program. Launched by the Soviet space agency during the 1970 and 1980, NPO Molniya designed one of the finest Soviet aerospace achievements, creating an independent launch capability for the Union. The vehicle itself was a reusable shuttle spacecraft which could carry a crew and pay load into space.
Key Buran Programme Features:
- Soviet reusable shuttle development
- Energia rocket launch system
- Automated orbital flight capability
- Advanced spacecraft engineering design
- Short-lived but historic programme
In contrast to the American Space Shuttle, Buran did not have its own on-board engines on the day of launch. Buran instead used the massive Energia booster for launch. The design enabled Buran to be more fuel-efficient and offered more design and development flexibility for its airframe and systems.
Its only operational flight in 1988 had proven its abilities as a manless, fully automated landing and Buran was also considered a major accomplishment of aerospace engineering demonstrating reusable spaceflight technology. However, the disintegration of the Soviet Union meant budgetary crisis and funding could not be maintained for the shuttle programme. Despite having little use for its brief life span, Buran is a symbol of the pinnacle of design achievement for reusable spacecraft during that period.
3. Hermes
Hermes spaceplane This European project had ambitions to be the start of European manned spaceflight. The European Space Agency (ESA) designed and built it in the 1980s and early 1990s in the hope of designing a European space shuttle to transport humans and smaller cargo to low Earth orbit.
Key Hermes Programme Features:
- European reusable spaceplane concept
- Independent crewed spaceflight goal
- Ariane 5 launch integration plan
- Focus on orbital missions
- Influenced later ESA research
In a contrast to the Space Shuttle from the US, Hermes had a less complicated system of launching into space, because Hermes’ was not going to have its own propulsion at launch, rather the rocket which was to develop in future ( Ariane 5 rocket) would carry Hermes to space. Thus the vehicle could concentrate more on orbital work and re-enter and landing on the runway.
While Hermes had impressive ambitions, the project was plagued by ever-increasing development costs, technical problems and shifting political agendas following the Cold War, leading to the eventual cancellation of the project by ESA in 1993, abandoning European ambitions of developing their own reusable crewed spaceplane. However, the engineering and research involved in Hermes did bring many lessons which would be fed into later European space programmes and the ongoing study of reusable spacecraft.
4. MiG-105
The MiG-105 was part of the Spiral program which produced one of the coolest and most unique spaceplane ideas ever developed during the Cold War. The space plane was intended to be a small, reusable vehicle in orbit, and had a wedge-shaped hull which earned it the name “Lapot” literally “Little Shoe.” It’s pretty cool how much they seemed to be concerned about a vehicle which landed on the Earth like a glider.
Key MiG-105 Programme Features:
- Soviet Spiral spaceplane project
- Reusable orbital vehicle concept
- Wedge-shaped aerodynamic design
- Atmospheric flight testing programme
- Influenced Soviet space research
The Spiral project tested more exotic solutions to getting and managing a military spaceplane in orbit. One idea was for the aircraft to be strapped to the top of a fast Tupolev high speed transport plane and then released when at a sufficient altitude. While the launch system was never built the MiG-105 served as a very important research and test aircraft testing such ideas as: flight control, landing procedures, and challenges associated with developing a re-usable spacecraft.
More in the same category: Test programme of Soviet BOR / MiGsat The MiG-105 aircraft performed a few atmospheric test flights between 1976 and 1978 where engineers could learn about atmospheric re-entry and controlled re-entries. The wider Spiral programme had already been discarded in favour of the Buran shuttle program, and even though the MiG-105 itself did not achieve space flight the associated BOR test vehicles served to test many technologies which would make it a relevant component of the Soviet space program.
5. HL-20 Personnel Launch System
HL-20 Personnel Launch System One of the most functional concepts to ever fly in the spaceplane form NASA pursued was this HL-20, which aimed to deliver a more reliable, versatile, and affordable system for taking humans into space. This Langley Research Center design of the late 1980s was supposed to be a sort of “space taxi” a re-usable vehicle to regularly ferry astronauts and small loads to low Earth orbit and back.
Key HL-20 Programme Features:
- NASA reusable spaceplane concept
- Designed as orbital space taxi
- Lifting-body aerodynamic design
- Vertical launch capability planned
- Influenced modern spacecraft development
Inspired by Soviet BOR-4 research vehicles, the HL-20, unlike its winged aircraft brethren, employed a lifting body design, in which a rounded “wings” surface the vehicle as it travels through the atmosphere, generating lift and also minimizing heat and stresses as it returns from orbit. Vehicle engineers intended for the vehicle to accommodate a small crew, be launched vertically with existing rocket capabilities, and land on a horizontal runway after returning to Earth.
The HL-20 was not fielded for operational missions. Nevertheless, the development of the HL-20 advanced the body of knowledge in the fields of reusable vehicle design, crew transportation, and aerodynamic performance. The research done on the HL-20 had an impact on subsequent design work in the commercial space flight sector, and affected modern approaches to affordable reusable vehicles for access to space.
6. HOTOL
A shot in the dark, for the country’s more ambitious space ambitions: one of Britain’s failed attempts to produce a reusable space plane was HOTOL. The horizontal Take Off and Landing project was an effort in the 1980s by British Aerospace (working with Rolls-Royce) to make Britain’s solo bid to enter space a reality after some early launch programmes folded. It was designed as an entirely reusable, single stage to orbit space plane essentially a rocket with aeroplane wings and an engine.
Key HOTOL Programme Features:
- British reusable spaceplane concept
- Horizontal take-off and landing design
- Single-stage-to-orbit vehicle goal
- Advanced air-breathing engine technology
- Ambitious but cancelled development
The most novel concept underpinning the HOTOL vehicle was its suggested RB545 “Swallow” engine. It was an incredibly advanced, multi-functional propulsion system, intended to operate as both an air-breathing engine and a rocket. It would utilise atmospheric oxygen to combust the hydrogen fuel during the initial part of the flight, and thus minimize the oxidizer load carried. The engine would then shift to on-board liquid oxygen to continue the journey to orbit at higher altitudes.
Although its engineering proposals were very innovative, HOTOL suffered from a range of difficult technical and financial problems. A single-stage to orbit shuttle was more complex to implement successfully than anticipated and government funding support eroded, resulting in the cancellation of the program without a working demonstrator, making it the most complex reusable shuttle vehicle to fail to reach flight operations.
7. Lockheed Martin X-33 / VentureStar
The Lockheed Martin X-33, one of the 1990s’ most audacious dreams for a single-stage reusable spacecraft to orbit, was intended to serve as a technology demonstrator for a projected VentureStar commercial spaceplane that would, ideally, lower the cost of reaching orbit by being more of an airplane than a rocket.
Key X-33 Programme Features:
- Reusable single-stage spacecraft concept
- VentureStar technology demonstrator
- Lifting-body aerodynamic design
- Linear aerospike engine development
- Focus on lower launch costs
Key innovations in the X-33 design involved its lifting-body configuration and aerospike linear engines. Unlike standard rocket engines, aerospike technology was conceived to be highly efficient across a range of altitudes by passively adjusting to variations in atmospheric pressure as the vehicle ascended. When married with light-weight composite construction, developers thought these technologies would be capable of producing an extremely fuel-efficient, reusable launch vehicle.
Nevertheless, the program’s technological sophistication posed significant challenges for the developers. Chief among them was the development of the lightweight composite fuel tanks, which had significant structural integrity issues when tested. Mounting cost overruns and design flaws ultimately caused NASA and Lockheed Martin to abandon the program; they determined that the technology had not matured sufficiently for its intended application, shelving the VentureStar concept while contributing important data to the development of later reusable vehicles.
8. Sänger II
One of the most futuristic and aesthetically beautiful European spaceplane projects of the 1980s came from West German company Messerschmitt-Bkow-Blohm and took inspiration from Eugene Sanger’s concept (known as the “Silbervogel”) but was reorientated towards a non-military, civilian-oriented space launch system. It envisaged a reusable, two-stage-to-orbit spaceplane intended to drastically reduce the cost and increase the efficiency of space access.
Key Sänger II Programme Features:
- European reusable spaceplane concept
- Two-stage-to-orbit architecture
- Aircraft-based launch approach
- Focus on affordable space access
- Advanced aerospace research project
The concept relied on a unique air-launch scheme which used a large mother ship aircraft to carry a small space aircraft into high altitudes. Once released by the carrier craft, the stage of the space aircraft would ignite its rocket engine and would take the aircraft to orbit. The mother ship would then come back to earth where it could land like a regular plane and complete the cycle again.
Despite the innovative spirit and design ingenuity put into the development of Snger II, the concept never got beyond the research and development stage. Due to the cost and technical complexities, along with political agendas, Snger II failed to gain further financial backing and was cancelled in the long-term as a political project. However, it has become a prime example of European technological progress in the re-useable spacecraft.
9. Rockwell X-30
The Rockwell X-30 was produced during the United States’ National Aero-Space Plane (NASP) program in the 1980s, which sought to accomplish one of the most ambitious engineering challenges in aerospace: an aircraft that could take off from a runway and then rocket directly into orbit and land. This would have effectively become a single airplane-spaceship combo.
Key X-30 Programme Features:
- Hypersonic spaceplane concept
- National Aero-Space Plane project
- Scramjet propulsion technology
- Aircraft-like orbital operations
- Advanced material research
Central to the X-30 was its scramjet propulsion system. This type of engine intended to employ the vehicle’s high velocity to compress air passing into it for ignition, thus enabling the craft to carry its own oxidiser for atmospheric use while it is traveling at these high speeds and in turn allow the mission a lesser onboard oxidiser, and perhaps gain some of the required efficiency gains that allow a vehicle to get into orbit.
Unfortunately, transforming the X-30 concept from a design into a viable spacecraft would have been a very difficult endeavor. Engineers would have had to design revolutionary materials to endure the high heat associated with hypersonics and engineer a robust scramjet engine. Combined with escalating costs and numerous other design challenges, this project was ultimately scrapped and the X-30 became one of aerospace’s greatest “would-have-beens.”
10. Skylon
Skylon represented the continuation of Britain’s long-running ambition to develop a fully reusable spaceplane. Created by Reaction Engines Limited, the project built upon ideas explored during the HOTOL programme and aimed to develop an unmanned, single-stage-to-orbit vehicle capable of launching from a conventional runway. Its futuristic design attracted worldwide attention from engineers, researchers, and space enthusiasts.
Key Skylon Programme Features:
- British reusable spaceplane concept
- Single-stage-to-orbit vehicle design
- SABRE hybrid propulsion system
- Runway-based launch operations
- Focus on affordable space access
The heart of Skylon was the SABRE engine, an advanced propulsion system designed to combine air-breathing and rocket technologies. Similar to the concepts explored in HOTOL, SABRE was intended to use atmospheric oxygen during the early stages of flight before switching to onboard liquid oxygen once the spacecraft reached space. Its most important innovation was the precooler system, which was designed to rapidly reduce incoming air temperatures and protect the engine during extreme-speed flight.
Reaction Engines made progress by successfully testing key parts of the SABRE technology, keeping the possibility of Skylon alive for many years. However, creating a complete engine and full-scale spacecraft required massive financial investment and further development. In 2024, Reaction Engines entered administration, effectively ending active Skylon development. Although it never reached the skies, Skylon remains one of the most ambitious examples of humanity’s effort to create practical and reusable access to space.
