Retraction: Modeling and development of a fundamentally new way of landing a quadcopter on inclined surfaces (J. Phys.: Conf. Ser 2061 012109)

This article has been retracted by IOP Publishing following an allegation that this article substantially overlaps with [1]. IOP Publishing has investigated in line with the COPE guidelines, and agree that while the reference is listed in the article, the overlap is substantial and is unethical. Consequently, this paper has been retracted by IOP Publishing. Citations to this work should be redirected to [1]. The authors agree to this retraction. [1]. John Bass and Alexis Lussier Desbiens, (2020), 'Improving Multirotor Landing Performance on Inclined Surfaces Using Reverse Thrust', IEEE Robotics and Automation Letters, Volume: 5, Issue: 4, https://ieeexplore.ieee.org/abstract/document/9143402 Retraction published: 23 December 2021

Modeling and development of a fundamentally new way of landing a quadcopter on inclined surfaces

Methods and software and hardware for modeling and developing a fundamentally new way of landing a quadrocopter on inclined surfaces are discussed in the paper. The current state of the project under elaboration is conditioned and described. Various approaches to the solution are feasible due to the complexity of the considered issue. Solutions can differ both in the distribution of control functions between the ground control station and the quadcopter itself, and in the choice of principles that can be used as the basis for the control system and determine its design and dynamic characteristics. Simulation and testing processes demonstrate that reverse thrust alone can increase the landing zone of an average mass quadcopter, almost doubling the maximum tilt angle at which a landing maneuver is made, thus, allowing for a high vertical speed landing. It is clearly shown that low-power adhesion mechanisms such as electrical adhesion, switchable magnets, grippers or dry glue are activated after landing, allowing it to stay on the surface after the back thrust has ceased. This can be useful in situations where sudden interference is likely to occur. Such a result is achieved using a classic quadrocopter as DJI F450 without adding any equipment.

Analysis and experimental research on motion stability of wall-climbing robot with double propellers

This paper presents a wall-climbing robot which can stably hold and move on the ground-wall surface. The robot uses propeller reverse thrust as an adsorption force and can adapt to the surface of several media materials. The influence of the robot’s structural parameters on its power system is analyzed by comparing a single power system test and a robot prototype power test. A structural analysis of the robot is performed under two specific situations; when he is in transition from the ground to a small slope, and when he is on the slope. The force state of the robot is then obtained in different conditions. Experimental results show that the adjustment range of different rotor inclination angles of the robot, the width of the fixed rotor plate and the different near-ground distances, affect the traction of the robot. The robot motion performance and adaptability under different ground/wall environments are analyzed, by conducting the robot climbing experiment under a small slope, a vertical wooden wall surface and a vertical indoor wall surface. Stable adsorption and optimization tests are also performed. Moreover, the stability of the robot’s motion is verified. Finally, a theoretical and experimental accumulation is laid for the realization of the smooth transition of the robot from the ground to the wall.

On the Use of an Inflatable Rubber Lip to Improve the Reverse Thrust Flow Field in a Variable Pitch Fan

The installed Variable Pitch Fan (VPF) reverse thrust flow field is obtained from the flow solution of an integrated airframe-engine-VPF research model for the complete reverser engagement regime during the aircraft landing run. The reverse thrust flow field indicates that the reverse flow out of the nacelle inlet is washed downstream by the freestream. Consequently, reverse flow enters the engine through the bypass nozzle from a 180° turn of the washed-down stream. This results in a region of separated flow at the nozzle lip that acts as a blockage to the reverse flow entry into the engine. To mitigate the blockage issue, a smooth guidance of the reverse flow into the engine can be achieved by using an inflatable rubber lip that would define a bell-mouth like geometric feature with a round radius at the nacelle exit. In nominal engine operation, the rubber lip would be stowed flush within the contours of the nacelle surface. The design space of the rubber lip is studied by considering different rounding radii and locations of the turn radius with respect to the nacelle trailing edge. It is observed that a rounding radius of 0.1x nacelle length is sufficient to reduce the blockage and increase the ingested reverse flow by 47% to 18% in the 140 to 40 knots landing speed range. The inflatable rubber lip represents a design modification that can improve VPF reverse thrust operation, in cases where an augmentation of reverse thrust capability is desired

On the Use of an Inflatable Rubber Lip to Improve the Reverse Thrust Flow Field in a Variable Pitch Fan

The installed Variable Pitch Fan (VPF) reverse thrust flow field is obtained from the flow solution of an integrated airframe-engine research model for the complete reverser engagement regime during the aircraft landing run from 140 knots to 40 knots. The model includes a twin-engine airframe, complete flow path representation of a future 40000 lbf high bypass ratio geared turbofan engine, and a bespoke reverse flow-capable VPF design. The reverse thrust flow field, at all speeds, indicates that the reverse flow out of the nacelle inlet is washed downstream by the freestream towards the engine exit regions. Consequently, reverse flow enters the engine through the bypass nozzle from a 180° turn of the washed-down stream. This results in a region of circumferentially varying separated flow at the nozzle lip that acts as a blockage to the reverse flow entry into the engine. To mitigate the blockage issue, a smooth guidance of the reverse flow into the engine to avoid separation can be achieved by using an inflatable rubber lip that would define a bell-mouth like geometric feature with a round radius at the nacelle exit region. In nominal engine operation, the rubber lip would be stowed flush within the contours of the optimized nacelle surface. The design space of the rubber lip is studied by considering different rounding radii and locations of the turn radius with respect to the nacelle trailing edge. The choices of the design parameters are chosen by considering the nacelle edge thickness, inflation air volume requirement, weight, and thickness of support structures. The effect of these designs on the reverse thrust flow field is studied by incorporating the designs into the integrated model, with realistic installation related restrictions. It is observed that a rounding radius of 0.1x nacelle length is sufficient to reduce the blockage and increase the ingested reverse flow by 47% to 18% in the 140 to 40 knots landing speed range. The inflatable rubber lip represents a design modification that can aid in the improvement of VPF reverse thrust operation, in cases where an augmentation of reverse thrust capability over the baseline is desired.

Flow Distortion into the Core Engine for an Installed Variable Pitch Fan in Reverse Thrust Mode

The flow distortion at core engine entry for a Variable Pitch Fan (VPF) in reverse thrust mode is described from a realistic flowfield obtained using an integrated airframe-engine-VPF research model. 3D RANS solutions are generated for the complete aircraft landing run from 140 to 20 knots at different VPF settings. The internal reverse thrust flowfield is characterized by nozzle lip separation, pylon wake and recirculation of flow turned back from the VPF. A portion of the reverse flow turns 180° with separation at the splitter edge to feed the core engine. The core feed flow exhibits circumferential and radial non-uniformities that depend on the reverse flow development at different landing speeds. The temporal dependence of the distorted flow features is also explored by an URANS analysis. Total pressure and swirl angle distortion descriptors, and total pressure loss are described for the core feed flow at different VPF settings and landing speeds. It is observed that the radial intensity of total pressure distortion is critical to core engine operation, while the circumferential intensity is within acceptable limits. Therefore, the baseline sharp splitter edge is replaced by two larger rounded splitter edges of radii, ∼0.1x and ∼0.2x times the core duct height. This was found to reduce the radial intensity of total pressure distortion to acceptable levels. The description of the installed core feed flow distortion, as in this study, is necessary to ascertain stable core engine operation, which powers the VPF in reverse thrust mode.