Supersonic Fuselage Shape Matching for Sonic Boom Reduction

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Solution Overview

Problem

Existing methods for designing supersonic aircraft airframes to reduce sonic booms face challenges in design time and accuracy when matching equivalent cross-sectional areas to target areas, leading to inefficiencies in sonic boom reduction.

Innovation Solution

The method involves setting an initial shape and target equivalent cross-sectional area, estimating near field pressure waveforms, and using a Mach plane to set design curves that directly align with the target area, simplifying the optimization process by dividing it into smaller, one-to-one optimization problems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional equivalent cross-sectional area matching methods are used to reduce sonic boom, then sonic boom reduction is achieved, but design time becomes excessively long

Engineering Contradiction:
Improvesonic boom intensityVSAvoiddesign time
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent segments the equivalent cross-sectional area matching process into multiple discrete optimization stages. Instead of performing a single comprehensive optimization, the method divides the airframe into multiple cross-sectional areas along the longitudinal axis, and optimizes each section's equivalent cross-sectional area separately through iterative adjustments. This segmentation transforms one complex optimization problem into multiple simpler sub-problems, significantly reducing computational time while achieving the target sonic boom reduction profile.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If conventional equivalent cross-sectional area matching methods are used to reduce sonic boom, then sonic boom reduction is achieved, but design accuracy is insufficient

Engineering Contradiction:
Improvesonic boom intensityVSAvoidequivalent cross-sectional area matching accuracy
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism where the actual equivalent cross-sectional area of each airframe section is continuously measured or calculated, compared against the target value, and used to adjust the next optimization iteration. The method calculates the difference between current and target equivalent cross-sectional areas, then uses this feedback information to guide subsequent shape adjustments. This closed-loop feedback process progressively refines the matching accuracy, ensuring the final design closely achieves the desired sonic boom reduction profile.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If complex optimization processes are used to match equivalent cross-sectional areas, then matching accuracy improves, but design time increases

Engineering Contradiction:
Improveequivalent cross-sectional area matching accuracyVSAvoiddesign efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies segmentation by dividing the complex optimization task into multiple independent cross-sectional area optimizations along the airframe. Each section can be optimized separately with simpler computational requirements, rather than performing one exhaustive optimization of the entire airframe. This segmentation maintains accuracy through systematic iterative refinement of each section while dramatically improving overall design efficiency by parallelizing or sequentializing simpler sub-tasks.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary actions by pre-calculating target equivalent cross-sectional area values for each airframe section based on the desired sonic boom profile before beginning the shape optimization. These pre-determined target values serve as guidelines for the subsequent optimization process, allowing each cross-sectional area to be adjusted toward its predetermined target rather than requiring complex real-time optimization calculations. This preliminary preparation significantly reduces computational burden while maintaining accuracy.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach improves design accuracy and reduces the time required to match the equivalent cross-sectional areas, resulting in more precise and efficient sonic boom reduction.

Implementation Method 1

The shock waves usually generated from the various parts of the supersonic aircraft are integrated into two strong shock waves at the bow and the tail, accompanied by the phenomenon that the large wave of pressure fluctuation propagates faster through the atmosphere

Methodology Applied
Scientific EffectShock wave propagation: Shock Wave

Data Source

PatentEP3778389B1Method for designing shape of fuselage of supersonic aircraft, supersonic aircraft production method, and supersonic aircraft
Publication Date: 2026.02.11 JAPAN AEROSPACE EXPLORATION AGENCY
  • EP3778389B1 patent drawingFigure 1~3
  • EP3778389B1 patent drawingFigure 4~5
  • EP3778389B1 patent drawingFigure 6~7

AI summary

[Object] To realize an improvement in design accuracy and a reduction in design time in a process of matching an equivalent cross-sectional area of a design shape of a supersonic aircraft to a target equivalent cross-sectional area in a sonic boom reduction method based on an equivalent cross-sectional area. [Solving Means] The technique includes: setting an initial shape of the airframe and a target equivalent cross-sectional area of the airframe; estimating a near field pressure waveform for the initial shape of the airframe assuming that the supersonic aircraft flies at a cruising speed; evaluating an equivalent cross-sectional area from the estimated near field pressure waveform for the initial shape of the airframe; and setting a Mach plane corresponding to the cruising speed, and setting a design curve on the Mach plane, the design curve corresponding to an initial curve at which the initial shape of the airframe and the Mach plane intersect so that the equivalent cross-sectional area approaches the target equivalent cross-sectional area. Then, the shape of the airframe is designed based on the design curve.