Supersonic - Transport Takeoff Silencing

Abstract

All the projects of supersonic transport have been cancelled because none of the projects comply with noise regulations. The purpose of this paper is to systematically review the acoustical properties and power performances of engines and ejectors. Based on this review we should be able to put together a realistic design solution. The model will be a collection of elementary models, which are based on first principles and empirical coefficients. The requirements are based on jet noises and margins are included for certain other noise sources, for example fan noises. Additionally, fixed and stowable engines have to be considered. Method: A parametric analysis of March 2 aircraft illustrates the following: The fixed engines should have a bypass ratio (BPR) of BPR >1, which is the highest ratio permitted for the supersonic cruise. Ejectors are not an economical solution because they are too heavy. On the other hand boost (stowable) engines with large BPR – if their auxiliary systems and structures add less than 50% of their own weight – can provide a satisfactory solution. The sensitivity of those statements to the model estimates is discussed. Conclusion: A supersonic transport is feasible at no technological risk since the required engines (no variable cycle) already exist or are close to available technology.