LAPCAT (Long-Term Advanced Propulsion Concepts and Technologies) was a 36-month European FP6 study to examine ways to produce engines for a

Mach number The Mach number (M or Ma), often only Mach, (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It is named after the Austrian physicist and philosopher Erns ...

4-8

hypersonic flight Hypersonic flight is flight through the atmosphere below altitudes of about at Hypersonic speed, speeds greater than Mach 5, a speed where Dissociation (chemistry), dissociation of air begins to become significant and high heat loads exist. Spe ...

aircraft. The project ended in April 2008. It was funded by the

European Commission The European Commission (EC) is the primary Executive (government), executive arm of the European Union (EU). It operates as a cabinet government, with a number of European Commissioner, members of the Commission (directorial system, informall ...

research and development fund (rather than ESA), and cost 7 million euros. LAPCAT II, a 10 million euro, four-year, follow on project, started in October 2008. The study aims to refine some of the results of the first study "allowing the definition of a detailed development roadmap" of a Mach five vehicle.

Objectives

Two major technologies were to be considered: * ram-compression, which needs an additional propulsion system to achieve its minimum working speed. * active compression, which has an upper Mach number limitation but can accelerate a vehicle up to its cruise speed. Key objectives were the definition and evaluation of: * different propulsion cycles and concepts for high-speed flight at Mach 4 to 8 such as turbine-based and rocket-based combined cycles * critical technologies for: ** integrated engine/aircraft performance ** mass-efficient turbines and heat-exchangers ** high-pressure and supersonic combustion experiments ** modelling Intended results were: * definition of requirements and operational conditions for high-speed flight at system level * dedicated experimental data-base specific to high-speed aerodynamics for supersonic and high-pressure combustion and flow phenomena. * setting-up and validating physical models supported by numerical simulation tools to address supersonic and high-pressure combustion, turbulence and transition phenomena. * feasibility study of weight performance turbine and heat exchanger components

Results

Among the several vehicles studied, only two novel concepts were retained for LAPCAT II: a Mach five vehicle and a Mach eight vehicle.

Mach five vehicle

One possible supersonic transport aircraft being researched as part of this project was the A2 by

Reaction Engines Limited Reaction Engines Limited (REL) was a British aerospace manufacturer founded in 1989 and based in Oxfordshire, England. The company also operated in the USA, where it used the name Reaction Engines Inc. (REI). REL entered administration on 31 ...

. The researchers studied at an aircraft capable of flying from

Brussels Brussels, officially the Brussels-Capital Region, (All text and all but one graphic show the English name as Brussels-Capital Region.) is a Communities, regions and language areas of Belgium#Regions, region of Belgium comprising #Municipalit ...

(Belgium) to

Sydney Sydney is the capital city of the States and territories of Australia, state of New South Wales and the List of cities in Australia by population, most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Syd ...

(Australia) in 2–4 hours, significantly reducing journey times across the globe. To attain and maintain such high speeds, Reaction Engines Limited would need to develop its newly designed concept engine called the Scimitar, which would exploit the

thermodynamic Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of th ...

properties of

liquid hydrogen Liquid hydrogen () is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecule, molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point (thermodynamics), critical point of 33 Kelvins, ...

. The engine would be theoretically capable of powering the A2 to a sustained Mach 5 throughout flight with an effective exhaust velocity of 40,900 m/s or

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine, such as a rocket engine, rocket using propellant or a jet engine using fuel, generates thrust. In general, this is a ratio of the ''Impulse (physics), ...

of 4170 s, SFC . "Results so far show the Mach 5 vehicle from Reaction Engines can avoid later technology pitfalls and could travel from Brussels to Sydney," says ESA's LAPCAT project coordinator Johan Steelant. The developers said in 2009 that it would be able to fly from

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

in under five hours, compared to around a complete day of travel with normal aircraft. The cost of a ticket was aspirationally roughly

business class Business class is a travel class available on many commercial airlines and rail lines, known by brand names that vary by airline or rail company. In the airline industry, it was originally intended as an intermediate level of service between e ...

level. The A2 design did not have

window A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent ma ...

s. The heat generated by the hypersonic airflow over the body puts constraints on window design which would make them too heavy. One solution Reaction Engines proposed was to install

flat panel display A flat-panel display (FPD) is an electronic display used to display visual content such as text or images. It is present in consumer, medical, transportation, and industrial equipment. Flat-panel displays are thin, lightweight, provide better ...

s, showing images of the scene outside.

Mach eight vehicle

Although the cruise flight of the

scramjet A scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully b ...

based Mach eight vehicle seems feasible, the fuel consumption during acceleration requires a large fuel fraction, severely affecting gross take-off weight. Initial studies of a first-stage rocket ejector concept gave poor range with large take-off mass..

Notes

References