The ”Flight Demonstration of Quiet Technology to Reduce Noise from High-lift Configurations (FQUROH)*” project was commenced in 2015. This project applies low-noise technologies to the high-lift devices and landing gear—the primary noise sources of passenger aircraft—and demonstrates their effectiveness in reducing noise during flight tests. Through this, JAXA and its partners aim to acquire the design technologies necessary for the practical implementation of the low-noise technologies.
* FQUROH is pronounced “foo-koo-roh,” meaning “owl” in Japanese
Background
Aircraft noise around airports has been significantly reduced over the years due to the increased bypass-ratios of aeroengines. However, with a projected 2.4-fold increase in air transport demand over the next 20 years, further noise reduction remains an important challenge in aircraft development.
Although flyover noise has decreased substantially due to the improvement of engines, approach noise has stagnated for about 20 years. The primary cause of this is airframe noise — aerodynamic noise generated by high-lift devices (e.g., flaps, slats) and landing gear (main and nose gear). To realize quieter future aircraft, establishing technologies to reduce this airframe noise is essential.
Noise reduction of 15 dB was achieved in the past 50 years.
Noise reduction has stagnated at 10 dB for the past 50 years, indicating that reducing noise during landing approaches remains a challenge.
We can see that airframe noise accounts for 76% of aircraft noise sources.
Purpose of the Project
JAXA has established cooperative relationships with domestic and international manufacturers, research institutions, and universities (Figure 4). We have developed foundational CFD (Computational Fluid Dynamics) and CAA (Computational Aeroacoustics), as well as wind tunnel testing techniques, to elucidate the noise generation mechanisms from high-lift devices and landing gear. Concurrently, we have researched noise reduction technologies applicable to actual aircraft. However, a technical gap still exists globally in applying these research results to actual aircraft development.
For example, predicting noise levels involves uncertainties arising from modeling physical phenomena using numerical analysis methods and scale differences between full-scale aircraft and wind tunnel models. To use these technologies as design tools for actual aircraft, knowledge and experience regarding their reliability are essential. Furthermore, in actual aircraft design, both high-lift devices and landing gear must achieve the targeted noise reduction while meeting constraints such as aerodynamic performance, structural strength and weight, and stowage mechanisms. To mature noise reduction technologies to this practical level, it is necessary to demonstrate the practicality of design techniques and noise reduction methods on actual aircraft and iterate through technical improvements.
Therefore, the FQUROH project will design low-noise high-lift devices and landing gear for actual aircraft, building upon previous research results. Based on these designs, the aircraft will be modified, and flight tests will be conducted to investigate the effectiveness of the low-noise measures. The goal is to establish low-noise technologies applicable to passenger aircraft.
We are conducting joint research with domestic and international manufacturers toward practical application.
Project History
The project is divided into two phases: FQUROH-1 (the original "FQUROH" project) and FQUROH-2.
Using JAXA’s jet research aircraft “Hisho”, the project established the process up to demonstration and obtained validation results. It included geometric studies of low-noise devices on flaps and main landing gear, with flight demonstration tests conducted in 2016 and 2017.
Building on the technologies from FQUROH-1, this phase focuses on implementation for medium-size passenger aircraft. In addition to flaps and landing gear, it also develops low-noise devices for slats, which were not present on “Hisho”.
- 2005
- Initiation of basic airframe noise research
- 2015
- Launch of the FQUROH project for the practical implementation of low-noise technology, initially targeting JAXA’s jet research aircraft “Hisho” as the demonstration aircraft, then a larger 90-seat regional jet.
- 2016
- Preliminary flight demonstration tests at Noto Satoyama Airport
- 2017
- Successful flight demonstration tests with “Hisho”
- 2021
- Collaboration framework established targeting medium-size passenger aircraft
- 2024
- Launch of FQUROH-2