LAPCAT II was a logical follow-up of the previous EC-project (LAPCAT I).
The LAPCAT II project had the objective to reduce antipodal flights to less than 2 to 4 hours. Among the several studied vehicles, only two novel aircraft for a Mach 5 and Mach 8 flight were retained in this project. Starting with the available Mach 5 vehicle and its related pre-cooled turbo ramjet, the assumed performance figures of different components were assessed in more detail, i.e.:
- Intake design and performance;
- Environmentally friendly design of combustor;
- Nozzle design and performance;
- Structural analysis.
Once available, the vehicle performance would be re-assessed. The outcome would then allow the definition of a detailed development roadmap.
The cruise flight of the Mach 8 vehicle based on a scramjet seemed feasible, however, the acceleration based on an ejector rocket was not. The integrated design of the airframe and engine throughout the entire trajectory was the prime focus. The only step remaining was to guarantee a successful design. A turbo-based engine would replace the former ejector rocket to assure better performance and fuel consumption during acceleration. Important points to be addressed towards the realisation of these goals were:
- Proper development and validation of engine-airframe integration tools and methodology;
- High-speed air breathing cycle analysis;
- Off- and on-design behaviour of engine and airframe;
- Dedicated experiments to evaluate the design at various operation points;
- Validated tool development should give solid confidence to propose a fully integrated vehicle to comply with the mission goals;
- Once defined, a roadmap will be defined with a step-wise approach to future development.
For vehicles flying at high speeds and high altitudes, limited know-how is available on the environmental impact. The influence of NOx and H2O into the ozone layer and the formation of contrails with its direct and indirect effects were investigated for both the Mach 5 and Mach 8 vehicles.
The dedicated experiments formed the basis for validation of advanced design tools. These numerical tools gave better confidence when proposing a fully integrated vehicle that complied with the mission goals. In particular, nose-to-tail computations should give the simultaneous solution and interaction of an operational propulsion unit and the vehicle aerodynamics. A roadmap towards the final vehicle design would be laid out with a step-wise approach to future developments.
Super-speed aeroplanes on the horizon
Feasible ideas in advanced propulsion technology could lead to developing commercial aircraft that could travel halfway around the globe in just 2–4 hours.
A few years ago, an EU-funded project called LAPCAT worked on identifying and evaluating critical propulsion technologies for radically reducing long-distance flights. It investigated technologies that could, for example, enable a flight from Brussels to Sydney to be completed in 2–4 hours. Following in its footsteps, the latest such project, 'Long-term advanced propulsion concepts and technologies II' (http://www.esa.int/techresources/lapcat_II (LAPCAT-II)), focused on the two most viable concepts emerging from its predecessor, namely cruise flights at the speeds of Mach 5 and Mach 8.
The project bought together 16 partners in the field from 6 European countries to achieve its aims. It evaluated the assumed performance figures of the Mach 5 plane and its pre-cooled turboramjet, including design, performance and eco-friendliness of nozzle, combustion and structure. This led to an improved Mach 5 design, resulting into a detailed roadmap for developing the vehicle.
With respect to the Mach 8 concept which is based on a dual mode ramjet, the project team tackled several problems assuring a good performance both in cruise as in off-design conditions such as take-off, acceleration. In this respect, the team focused on properly integrating airframe and engine throughout the whole trajectory to overcome large take-off mass. It re-evaluated the design of different concepts, including turbo-based and rocket-based engines to achieve optimal performance and fuel consumption.
More specifically, the Mach 8 design involved developing engine–airframe integration tools and methodology, as well as high-speed air-breathing cycle analysis. It also involved off-design and on-design behaviour of engine and airframe, in addition to assessing design related to aerothermodynamics, intakes, nozzles and combustion.
The project and its results have brought us one step closer to developing viable supersonic and hypersonic aircraft that could completely redefine civil aviation in the not so distant future.