An Aerodynamic Study for the 3rd Configuration of JAXA High Speed Compound Helicopter

2021 ◽  
Vol 69 (6) ◽  
pp. 257-261
Author(s):  
Noboru Kobiki ◽  
Yasutada Tanabe ◽  
Hideaki Sugawara ◽  
Keita Kimura ◽  
Masahiko Sugiura
Keyword(s):  
High Speed ◽  
Compound Helicopter

scholarly journals Propeller control strategy for coaxial compound helicopters

2018 ◽  
Vol 233 (10) ◽  
pp. 3775-3789 ◽  
Author(s):  
Ye Yuan ◽  
Douglas Thomson ◽  
Renliang Chen
Keyword(s):  
Control Strategy ◽  
High Speed ◽  
High Performance ◽  
Control Strategies ◽  
Flight Dynamics ◽  
Axial Thrust ◽  
Handling Qualities ◽  
Speed Range ◽  
Compound Helicopter ◽  
Flight Dynamics Model

The coaxial compound configuration has been proposed as a concept for future high-performance rotorcraft. The co-axial rotor system does not require an anti-torque device, and a propeller provides axial thrust. A well-designed control strategy for the propeller is necessary to improve the performance and the flight dynamics characteristics. A flight dynamics model of coaxial compound helicopter is developed to analyze these influences. The performance and the flight dynamics characteristics in different propeller strategies were first investigated. The results show that there is an improvement in the performance in high-speed flight when the propeller provides more propulsive forces. It also illustrates that a reasonable allocation of the rotor and the propeller in providing thrust can further reduce the power consumption in the mid speed range. In other words, the propeller control strategy can be an effective method to improve the cruise-efficiency. The flight dynamics analysis in this paper includes trim and handling qualities. The trim results prove that the propeller strategy can affect the collective pitch, longitudinal cyclic pitch, and the pitch attitude. If the control strategy is designed only to decrease the required power, it will result in a discontinuity in the trim characteristics. Handling qualities are investigated based on the ADS-33E-PRF requirement. The result demonstrates that the bandwidth and phase delay results and eigenvalue results in various speed at different propeller strategies are all satisfied. However, some propeller control strategies lead to severe inter-axis coupling in high-speed flight. Based on these results, this paper proposes the propeller control strategy for the coaxial compound helicopter. This strategy ensures good trim characteristics and handling qualities, which satisfy the related requirements, and improves the flight range or the performance in high-speed flight.

Compound Helicopter X3 in High-Speed Flight: Correlation of Simulation and Flight Test

2021 ◽  
Vol 66 (1) ◽  
pp. 1-14
Author(s):  
Constantin Öhrle ◽  
Felix Frey ◽  
Jakob Thiemeier ◽  
Manuel Keßler ◽  
Ewald Krämer ◽  
...  
Keyword(s):  
High Speed ◽  
Reverse Flow ◽  
Flight Test ◽  
Maximum Deviation ◽  
Analysis Tool ◽  
Bending Moments ◽  
Wake Interactions ◽  
Advance Ratio ◽  
Compound Helicopter ◽  
Drive Train Model

This work presents the correlation of simulation results and flight-test data for a high-speed (V = 220 kt), high advance ratio (μ > 0.5) flight of the compound helicopter X3. The simulation tool chain consists of state-of-the-art coupling between the computational fluid dynamics (CFD) code FLOWer and the comprehensive analysis tool HOST. By applying a freeflight trim procedure, the experimental flight state is accurately represented in the simulation. The deviations of most trim controls is below 1°, and the maximum deviation is less than 1.4°. The analysis of the high-fidelity CFD results illustrates key features of the flow physics at this high advance ratio, such as wake interactions, reverse flow, and advancing side loading. The correlation of rotor dynamics data between simulation and flight test is favorable. Good accordance is demonstrated for flap bending moments, torsion moments, and pitch link loads. In contrast, the correlation is weaker for the chord bending moments for which it is shown that the interblade damper and drive train model mostly determine the structural loads.

Interactional Aerodynamic Analysis of an Asymmetric Lift-Offset Compound Helicopter in Forward Flight

2021 ◽  
Author(s):  
Jan-Arun Faust ◽  
Yong Su Jung ◽  
James Baeder ◽  
André Bauknecht ◽  
Jürgen Rauleder
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Particle Image Velocimetry Data ◽  
Operating Conditions ◽  
Test Case ◽  
Forward Flight ◽  
Compound Helicopter ◽  
Thrust And Torque

Recently, an asymmetric lift-offset compound helicopter has been conceptualized at the University of Maryland with the objective of improving the overall performance of a medium-lift utility helicopter. The investigated form of lift-compounding incorporates an additional stubbed wing attached to the fuselage on the retreating side. This design alleviates rotor lift requirements and generates a roll moment that enables increased thrust potential on the advancing side in high-speed forward flight. In this study, a numerical model was developed based on the corresponding experimental test case. Three-dimensional unsteady Reynolds-averaged Navier–Stokes equations were solved on overset grids with computational fluid dynamics–computational structural dynamics (CFD–CSD) coupling using the in-house CPU–GPU heterogeneous Mercury CFD framework. Simulations were performed at high-speed, high-thrust operating conditions and showed satisfactory agreement with the experimental measurements in terms of the cyclic control angles, rotor thrust, and torque values. CFD results indicated that for an advance ratio of 0.5 with a collective pitch of 10.6°, a vehicle lift-to-equivalent-drag ratio improvement of 47% was attainable using 11% wing-lift offset. The CFD-computed flow fields provide insights into the origin of a reverse flow entry vortex that was observed in particle image velocimetry data, and they characterize the wing–rotor interactional aerodynamics.

Coupled and Trimmed Aerodynamic and Aeroacoustic Simulations for Airbus Helicopters' Compound Helicopter RACER

2019 ◽  
Vol 64 (3) ◽  
pp. 1-14 ◽  
Author(s):  
Constantin Öhrle ◽  
Felix Frey ◽  
Jakob Thiemeier ◽  
Manuel Keßler ◽  
Ewald Kräamer
Keyword(s):  
High Speed ◽  
Flight Mechanics ◽  
Main Rotor ◽  
Noise Emission ◽  
Tool Chain ◽  
Aeroacoustic Noise ◽  
Rotor Wing ◽  
Compound Helicopter ◽  
Cost Efficient ◽  
Cruise Flight

In recent years, various helicopter manufacturers increasingly have been focusing on the development of new high-speed rotorcraft configurations, one of them being the compound helicopter RACER (rapid and cost-efficient rotorcraft) of Airbus Helicopters (AH). However, these new configurations encounter new aeromechanic challenges, in terms of aerodynamic interactions, flight mechanics stability, rotor dynamics, or aeroacoustic noise emission, to name only a few. To support AH at the minimization of risk of RACER's first flight, the Institute of Aerodynamics and Gas Dynamics provides high-fidelity coupled and trimmed aerodynamic and aeroacoustic simulations of the complete helicopter by the application of a multidisciplinary tool chain. In its first part, the work focuses on the description of this advanced tool chain and on important features for the analysis of this new configuration. In the second part, exemplary simulation results for a hover and a high-speed cruise flight condition are shown, and the main aerodynamic interactions between the different components are identified. As expected for this configuration, numerous interactions are found for both flight cases, e.g., main rotor–propeller interaction in hover or main rotor–wing interaction in high-speed flight. Finally, aeroacoustic results are shown for hover with a close look at the propellers' contribution.

Piloted Simulation Evaluation of Tracking Mission Task Elements for the Assessment of High-Speed Handling Qualities

2020 ◽  
Vol 65 (3) ◽  
pp. 1-23
Author(s):  
David H. Klyde ◽  
Sean P. Pitoniak ◽  
P. Chase Schulze ◽  
Paul Ruckel ◽  
James Rigsby ◽  
...  
Keyword(s):  
High Speed ◽  
Effective Means ◽  
Evaluation Process ◽  
Performance Criteria ◽  
Handling Qualities ◽  
Forcing Function ◽  
Compound Helicopter ◽  
Command Signals ◽  
And Performance ◽  
The Military

Updates to the military rotorcraft handling qualities specification are currently being considered that address the high-speed flight regime envisioned for the Future Vertical Lift platform of the U. S. Army. A team that features industry and academia has developed and evaluated a set of mission task elements (MTEs) that are defined to address vertical takeoff and landing (VTOL) high-speed handling qualities. Following the mission-oriented approach upon which ADS-33E-PRF is based, the MTEs were designed to meet different levels of precision and aggressiveness. Tracking MTEs based on a sum-of-sines (SOS) command signal were defined for precision, aggressive, and precision, nonaggressive applications. The command signals were derived from fixed-wing analogs that have long been used to evaluate aircraft handling qualities. While the precision, aggressive SOS tracking tasks, the primary subject of this paper, are surrogates for air-to-air tracking and nap-of-the-earth tracking, the known forcing function allows for complete open- and closed-loop pilot—vehicle system identification. The MTE objectives, descriptions, and performance criteria were assessed and refined via several checkout piloted simulation sessions. Formal evaluations were then conducted by Army test pilots at four simulator facilities, each featuring a unique high-speed platform including a generic winged-compound helicopter, two tiltrotor configurations, and a compound helicopter with coaxial rotors. To aid in the MTE evaluation process, baseline VTOL configurations were varied to achieve different handling qualities levels. Quantitative measures based on task performance and qualitative measures based on pilot ratings, comments, and debrief questionnaires were used to assess MTE effectiveness. The piloted simulation results demonstrated that the SOS tracking MTEs provided an effective means to discern precision, aggressive handling qualities in high-speed flight.

scholarly journals Vibration and Performance Analyses Using Individual Blade Pitch Controls for Lift-Offset Rotors

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Jae-Sang Park ◽  
Do-Hyung Kim ◽  
Sanghyun Chae ◽  
Ye-Lin Lee ◽  
Jeong-In Go
Keyword(s):  
Phase Angle ◽  
High Speed ◽  
Actuation Frequency ◽  
Control Phase ◽  
Coaxial Rotor ◽  
Compound Helicopter ◽  
And Performance ◽  
And Control ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This work attempts to reduce the hub vibratory loads of a lift-offset rotor using IBC (individual blade pitch control) in high-speed forward flight. As a lift-offset rotor for the present study, the rigid coaxial rotor of a XH-59A compound helicopter is considered and CAMRAD II is used to predict the hub vibration and rotor performance. Using the IBC with a single harmonic input at 200 knots, the vibration index of the XH-59A rotor is minimized by about 62% when the 3/rev actuation frequency is applied with the IBC amplitude of 1° and control phase angle of 270° (3P/1°/270°); however, the rotor effective lift-to-drag ratio decreases by 3.43%. When the 2/rev actuation frequency with the amplitude of 2° and control phase angle of 270° (2P/2°/270°) and the 3/rev actuation frequency using the magnitude of 1° and control phase angle of 210° (3P/1°/210°) are used in combination for the IBC with multiple harmonic inputs, the vibration index is reduced by about 62%, while the rotor effective lift-to-drag ratio increases by 0.37% at a flight speed of 200 knots. This study shows that the hub vibration of the lift-offset rotor in high-speed flight can be reduced significantly but the rotor performance increases slightly, using the IBC with multiple harmonic inputs.

Compound Helicopter: Insight and Optimization

2015 ◽  
Vol 60 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Omri Rand ◽  
Vladimir Khromov
Keyword(s):  
High Speed ◽  
Pareto Frontier ◽  
Optimization Process ◽  
Design Parameters ◽  
Forward Flight ◽  
Rotor Systems ◽  
Coaxial Rotor ◽  
Trade Offs ◽  
Compound Helicopter ◽  
Free Wake

The paper presents an insight into the complex task of design and optimizing a compound helicopter configuration. It introduces the “drag versus power chart” (DP chart) as a tool for separating the rotors, thrusters, wings, and fuselage contributions and understanding their optimal combination in a generic compound configuration. The analysis shows the dependency of the optimal configuration on the efficiencies of the rotors, the thrusters, and the wings, and a way to carefully examine the effect of many design parameters. As such, the analysis may be applied to various configurations including single and coaxial rotor systems. Among other conclusions, it is shown when and why a thruster is absolutely essential for high speed and clarifies the role of the wing in such cases. The paper also supplies a unique optimization process, which is based on a comprehensive and detailed nonlinear free-wake analysis of a compound configuration that includes a thruster and fixed wings. The optimization process is twofold: First, for a global search, a variety of randomly selected configurations are analyzed to determine an initial hover-forward flight Pareto frontier. Then, various types of local analyses are carried out to improve the above frontier. Such successive frontier refinements lead to an improved, detailed, and continuous frontier that may be exploited for a variety of missions. The configurations on the resulting Pareto frontier show design trade-offs between configurations that are more efficient in hover and those that are more efficient in high-speed forward flight.

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