Overview
Many projects have been carried out in Europe and in other countries addressing the large supersonic transport aircraft market. None have yet emerged due to the difficulty to overcome economic and environmental issues. However, beyond the current market for small subsonic aircraft, there is a substantial segment of customers interested in flight time being reduced by 20% to 50% as compared with current subsonic business aircraft on distances over 6 500 km (which is the minimum required for transatlantic flights).
The objectives of the 'Environmentally friendly high speed aircraft' (HISAC) project were:
- To identify the characteristics of aircraft that could meet the prospective requirements;
- To provide policy makers with a set of recommendations for future environmental regulations (several sets of commercial characteristics of the aircraft will be considered);
- To provide progress on: Elementary technologies; Associated design and optimisation multidisciplinary methods;
- To identify the roadmaps for further technology maturation;
- To provide general trade-offs.
The project was structured into five work packages, which in turn included several sub-tasks:
Work package 1
The work package included the following sub-tasks:
- WP 1.1: Noise criteria
- WP 1.2: Atmospheric emissions criteria
- WP 1.3: Sonic boom criteria
Work package 2
The work package included the following sub-tasks:
- Task 2.1: Noise modelling
- Task 2.2: Emission modelling
- Task 2.3: Sonic boom modelling
- Task 2.4: Engine modelling
- Task 2.5: Aerodynamic modelling
- Task 2.6: MDO process
The objectives of WP 2 were:
- to select and validate analysis and design models, tools and methods,
- to perform focused improvements, in the fields of noise, emissions, sonic boom, engine models, aerodynamics, and multidisciplinary design optimisation (MDO). Input to this task are pre-existing modelling tools available at each partner.
Work package 3a
The work package included the following sub-tasks:
- WP 3.1: Variable cycle engine technologies
- WP 3.2: Nozzle noise reduction technologies
The work started on definition of requirements to CCV modelling tool update. It was done upon CCV cycle and performance analysis. First loop cycle analysis of CCV engine was performed on a base of pre-existing engine cycle model in WP2.4 for engine specifications coming from WP5.1.
Work package 3b
The work package included the following sub-tasks:
- WP 3.3: Forced laminar flow
- WP 3.4: High lift devices
- WP 3.5: Variable geometry wing
WP3b focused on wing airframe technologies that are critical and specific to supersonic aircrafts.
Work package 4
The work package included the following sub-tasks:
- Aerodynamic design and assessment
- Sonic boom design and assessment
- Acoustic design and assessment
Work package 5
The work package included the following tasks:
- Technical aspects
- Description of the exchanges between wp5 and the other work packages
- Design activities
- Trade-off activities
- Synthesis task
Funding
Results
Summary of the results achieved in the WPs:
Work package 1
Eurocontrol, ONERA, NLR, and CIAM participated in the analysis of future noise constraints and concluded that progress in technology would seem realistic, and a new class for noise certification is likely to be created. Maximum noise level limits for depend on the aircraft weight: higher levels are allowed for heavier aircraft, with constant levels below and above some critical weights. The correspondence between the two levels (ground level for environmental airport protection purposes, and aircraft certification level), using different metrics, needs to be verified; furthermore, a short safety margin must be added to the certification level as a technical precaution. Regarding future local noise constraints, a review of the current local noise constraints has been performed. This overview of the practices of about one hundred airports, and their development over recent years, has been used to establish a draft typology of airports based on the effective combination of elementary actions to cope with noise. The initial objectives were to identify future international emission standards and policies, including airport requirements, to summarise different impacts from aviation: airport, climb, cruise, descent, airport, and derive from this synthesis emissions data sets, giving an assessment of permissible emission index regulations for S4TA. This database provided by the studies enable a comparison for an assessment of influence of fleet of small high speed jets dependent on altitude and latitude.
Work package 2
Results from this WP have been used:
- for the detailed configuration assessment in WP 4,
- for the MDO process in WP 5.
Work package 3a
The conclusion was made that modelling of CCV engine requires higher degree of model resolution and fidelity to be confident that engine cycle and performance are adequate. The work continued for model adjustment in respect of multi fidelity. The analysis showed that advantages of CCV cycle with respect to performance, jet noise, dimensions and etc. over CONV cycle, that were given in WP2.4, still exist. Geometry models of variable confluence component were delivered to SENER in order to have the first preliminary mechanical considerations. During the first phase, all partners worked on different designs based on thermodynamic data of gas generators provided by Snecma. Particularly, the aerodynamics,
Technical Implications
The HISAC Project has been an important intermediate step towards the feasibility of an environmentally compliant S4TA. Today, no major issue to overcome has been identified. Nevertheless, international research efforts currently carried out show that there is a strong interest in this subject and that the maturation of the required technologies and of the new international standards is a long term process.