Flight Dynamics and Control of an eVTOL Concept Aircraft with a Propeller-Driven Rotor

Saetti, Umberto; Enciu, Jacob; Horn, Joseph F.

doi:10.4050/jahs.67.032012

Cited by 7 publications

(6 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A multi-loop dynamic inversion (DI) control law largely based on [12,20] is designed to enable fully autonomous flight of the helicopter in autorotation. The schematic of the closed-loop helicopter dynamics is shown in Figure 3.…”

Section: Autonomous Flare Control Lawmentioning

confidence: 99%

“…These phases are shown qualitatively in Figure 1. The steady-state descent phase of the maneuver is fairly straightforward to automate in the sense that the aircraft state can be driven to the known autorotative trim state using standard feedback control techniques [12]. The challenge of automating the steady-state descent phase largely lies in planning a path to the selected landing point; this problem has been addressed in [6,7,13].…”

Section: Introductionmentioning

confidence: 99%

“…However, the plant model used for feedback linearization still needs to be scheduled with the flight condition. NDI has also been applied to rotorcraft autorotation problems in a limited number of studies [6,12], but its use as a control law in autorotative flare has not been studied extensively to date.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation

Saetti,

Rogers,

Alam

et al. 2023

Aerospace

Self Cite

View full text Add to dashboard Cite

A novel trajectory generation and control architecture for fully autonomous autorotative flare that combines rapid path generation with model-based control is proposed. The trajectory generation component uses optical Tau theory to compute flare trajectories for both longitudinal and vertical speed. These flare trajectories are tracked using a nonlinear dynamic inversion (NDI) control law. One convenient feature of NDI is that it inverts the plant model in its feedback linearization loop, which eliminates the need for gain scheduling. However, the plant model used for feedback linearization still needs to be scheduled with the flight condition. This key aspect is leveraged to derive a control law that is scheduled with linearized models of the rotorcraft flight dynamics obtained in steady-state autorotation, while relying on a single set of gains. Computer simulations are used to demonstrate that the NDI control law is able to successfully execute autorotative flare in the UH-60 aircraft. Autonomous flare trajectories are compared to piloted simulation data to assess similarities and discrepancies between piloted and automatic control approaches. Trade studies examine which combinations of downrange distances and altitudes at flare initiation result in successful autorotative landings.

show abstract

Section: Autonomous Flare Control Lawmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation

Saetti,

Rogers,

Alam

et al. 2023

Aerospace

Self Cite

View full text Add to dashboard Cite

show abstract

“…More specifically, the hovering aerodynamic efficiency of the lower rotor is lower than that of the upper rotor. Based on the Momentum Theory developed by Leishman [1] that has been utilized in optimizing the aerodynamic design of a coaxial rotor [15][16][17][18] or propeller [19] in hover and axial flight conditions, the inflow of the lower rotor not only contains its own induced velocity but also the wake of the upper rotor, thus resulting in reduced efficiency. The same trend was obtained by Syal for a coaxial rotor using a free vortex method [20].…”

Section: Rotor Hover Performancementioning

confidence: 99%

Wind Tunnel Studies on Hover and Forward Flight Performances of a Coaxial Rigid Rotor

et al. 2021

View full text Add to dashboard Cite

The aerodynamic performance of a reduced-scale coaxial rigid rotor system in hover and steady forward flights was experimentally investigated to gain insights into the effect of interference between upper and lower rotors and the influences of the advance ratio, shaft tilt angle and lift offset. The rotor system featured by 2 m-diameter, four-bladed upper and lower hingeless rotors and was installed in a coaxial rotor test rig. Experiments were conducted in the Φ3.2 m wind tunnel at China Aerodynamics Research and Development Center (CARDC). The rotor system was tested in hover states at collective pitches ranging from 0° to 13° and it was also tested in forward flights at advance ratios up to 0.6, with specific focus on the shaft tilt angle and lift offset sweeps. To ensure that the coaxial rotor was operating in a similar manner to that of the real flight, the torque difference was trimmed to zero in hover flight, whilst the constant lift coefficient was maintained in forward flight. An isolated single-rotor configuration test was also conducted with the same pitch angle setting in the coaxial rotor. The hover test results demonstrate that the figure of merit (FM) value of the lower rotor is lower than that of the upper rotor, and both are lower than that of the isolated single rotor. Moreover, the coaxial rotor configuration can contribute to better hover efficiency under the same blade loading coefficient (CT/σ). In forward flight, the effective lift-to-drag (L/De) ratio of the coaxial rigid rotor does not monotonously change as the advance ratio increases. Increases in the required power and drag in the case with a high advance ratio of 0.6 leads to the decreasing L/De ratio of the rotor. Meanwhile, the L/De ratio of the rotor is relatively high when the rotor shaft is tilted backward. The increasing lift offset tends to result in reduced required rotor power and an increase in the rotor drag. When the effect of the reduced rotor power is greater than that of the increased rotor drag, the L/De ratio increases as the lift offset increases. The L/De ratio can benefit significantly from lift offset at a high advance ratio, but it is much less influenced by lift offset at a low advance ratio. The forward performance efficiency of the upper rotor is poorer than that of the lower rotor, which is significantly different from the case in the hover flight.

show abstract

“…Thus, improving aerodynamic efficiency is a significant factor in the adoption of eVTOLs. Recently, optimization has been performed using different methods (such as gradient-free and gradient-based methods) in order to increase the efficiency of eVTOL aircraft [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic optimization of eVTOL rotor profiles

Yeganehdoust,

Karbasian,

Vermeire

2023

Progress in Canadian Mechanical Engineering. Volume 6

View full text Add to dashboard Cite

Electric Vertical Take-Off and Landing (eVTOL) aircraft are currently being developed to fill a gap in the air transportation sector and, simultaneously, provide zero-emissions alternatives to current generation carbon-intensive short-haul aircraft. However, unlike conventional fixed-wing or rotary aircraft, eVTOL rotors operate in both hover and forward flight configurations. This significantly increases the range of operating conditions experienced by the rotor, introducing multiple aerodynamic design challenges. Additionally, the efficiency of these rotors is particularly important, since it has a direct impact on power draw and aircraft range. In this presentation, a classical airfoil, the ClarkY, is used as a baseline configuration for an eVTOL rotor section. A gradient-based optimization framework using an adjoint solver in Discrete Adjoint with OpenFOAM (DAFoam) with the Reynolds Averaged Navier-Stokes (RANS) approach is then used. In this study, a control point-based free form deformation (FFD) method is used in the framework in order to change the aerodynamic shape. The objective function for this optimization is the lift-to-drag ratio, with additional target lift and geometric constraints. The baseline design is first validated against experimental data, and then the optimization is completed for several target lift coefficient values. Results demonstrate that the lift-to-drag ratio can be increased significantly while maintaining the desired target lift coefficient. Preliminary results for complete rotor optimization using RANS will then be presented, followed by preliminary airfoil optimization using Large Eddy Simulation (LES).

show abstract

Flight Dynamics and Control of an eVTOL Concept Aircraft with a Propeller-Driven Rotor

Cited by 7 publications

References 4 publications

Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation

Tau Theory-Based Flare Control in Autonomous Helicopter Autorotation

Wind Tunnel Studies on Hover and Forward Flight Performances of a Coaxial Rigid Rotor

Aerodynamic optimization of eVTOL rotor profiles

Contact Info

Product

Resources

About