Controllable Drogue for Automated Aerial Refueling

Williamson, Walton R.; Reed, Eric; Glenn, Gregory J.; Stecko, Stephen M.; Musgrave, Jeffrey L.; Takacs, John M.

doi:10.2514/1.44758

Cited by 41 publications

(4 citation statements)

References 5 publications

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“…As the measurable effect on the drogue position due to the receiver fore-body aerodynamic effect is estimated by 1.0ft ~1.2ft in the previous section, the actuator is expected to generate about 8.67lbf lateral force and 13.67lbf vertical force, all in a static sense, during a receiver coupling phase for this reference flight condition. A recent study [6] mentions a wind-tunnel test performed by Texas A&M University, which showed 36.0lbf (at 170KIAS, knots indicated airspeed) to 76.0lbf (at 250KIAS) of side force generation by canopy manipulation concept. The drag force generated by a drogue depends on its various configuration characteristics such as strut angle, canopy area, and gore spacing [7], and the required force calculated using eq.…”

Section: Hose-drogue Control Design Modelmentioning

confidence: 96%

Active Control of Aerial Refueling Hose-Drogue Systems

Ro¹,

Kuk²,

Kamman

2010

AIAA Guidance, Navigation, and Control Conference

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Dynamic analysis and control system design for aerial refueling hose-drogue systems during a receiver-probe coupling phase are studied. When a receiver plane approaches to couple with a refueling drogue, the hose-drogue system undergoes transient motion due to the receiver fore-body aerodynamic effect in addition to the tanker motion and downwash, and atmospheric turbulence. At the moment of contact with the drogue, the drag force on the drogue drops resulting in erratic motion of the refueling hose due to loss of tension. Unless carefully regulated, this may lead to critical damages to the refueling assembly and the receiver probe. In this paper, a hose-drogue dynamic model previously developed by the authors is extended to study 1) the receiver fore-body aerodynamic effect on the drogue transient motion prior to coupling, 2) the wave motion of the drogue-hose system due to the tension change in the hose, and 3) some possible active control strategies for the hose-drogue system during the pre-and the post-contact with the receiver probe.

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Section: Hose-drogue Control Design Modelmentioning

confidence: 96%

Active Control of Aerial Refueling Hose-Drogue Systems

Ro¹,

Kuk²,

Kamman

2010

AIAA Guidance, Navigation, and Control Conference

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“…The approach to equip an air-to-air refueling drogue with aerodynamic control surfaces was also examined in recent studies [6], [7], [8]. The main goal of these studies was to compensate disturbances due to wake vortices or turbulences but not to actively position the drogue and perform the capturing maneuver.…”

Section: Figure 2: Iac With Acd Principlementioning

confidence: 99%

UAV Pre-Study for In-Air-Capturing Maneuver

Krause¹,

Cain

2020

2020 IEEE Aerospace Conference

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Implementation of reusable launch vehicle (RLV) missions is a major goal in current aerospace research. One conceptual idea to return a booster stage is the so-called "in-air capturing" (IAC), where a winged stage is captured by an aerial vehicle and towed back to the final destination. This approach has the advantage that a towed winged stage does not need a propulsion system or fuel reserves to arrive to a destination point, compared to alternative approaches as demonstrated by SpaceX. The concept of capturing the RLV in air is based on earlier IAC missions for satellite photo capsules and the probe-and-drogue refueling method. A key difference is that in an air-to-air-refueling procedure a highly dynamic fighter tries to connect to a trailing drogue or rigid boom from a sluggish tanker. Opposite to this procedure, it can be assumed that in IAC case two aerodynamically sluggish aircraft need to be coupled. The challenge is to build up a formation which enables a connection between a gliding RLV and a dynamic coupling device trailing from a large aircraft. To investigate this IAC approach, the German Aerospace Center (DLR) built a scaled demonstration system with smaller unmanned aerial vehicles (UAV) to research different aspects of IAC flight tests. Based on the assumption that at an IAC approach would involve two large aerodynamically sluggish systems, a third highly dynamic vehicle should be introduced to enable a safe and reliable connection. Therefore, the trailing system, which is known from the air-to-air refueling, was modified by DLR with aerodynamic control surfaces and an independent flight control system. This enables a dynamic and independent motion of the coupling device relative to the towing aircraft, as well as the RLV. This paper gives an overview about IAC investigations of DLR, which are validated in experimental flight test demonstrations with scaled unmanned systems. The focus of this work is on building up the formation, from the rough approach with GNSS up to the final approach, where the global, absolute localization is supported by an image based relative position estimation of the coupling device. A major aspect in the formation implementation is the active coupling device (ACD). Therefore, the paper will show the construction of the ACD, its functionality and operation during the formation flight and a validation of its behavior at the flight demonstration. The first flight test results show that our research is heading in the right direction and further tests are expected to provide comprehensive results for the validation of the IAC concept. The presented investigations and results base on work from the DLR funded AKIRA project and the subsequent project FALCon funded by the European commission in the H2020 Program. FALCon has the aim to increase the TRL of AKIRA investigations and results.

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“…For that reason, recently, several research lines about the stability of the system have been developed, emphasizing how to control the drogue and the hose once they have been deployed. For example, the work of [9][10][11] presented methods for controlling an automatic refueling drogue and that of [12] studied an active control strategy based on automatic control surfaces. However, the possibility of aeroelastic problems in aerial refueling systems with hoses and drogues have barely been investigated.…”

Section: Introductionmentioning

confidence: 99%

Aeroelastic Stability of an Aerial Refueling Hose–Drogue System with Aerodynamic Grid Fins

2023

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In this work, the aeroelastic stability of an aerial refueling system is investigated. The system is formed by a classical hose and drogue, and the novelty of our work is the inclusion of a grid fin configuration to improve its stability. The unsteady aerodynamic forces on the grid fins are determined using the concept of a unit grid fin (UGF). For each UGF, the unsteady aerodynamic forces are computed using the Doublet-Lattice Method, and the forces on the complete grid fins are calculated using interfering factors obtained from wind tunnel measurements for the steady case. The static equilibrium position of the system influences the linearized perturbed unsteady motion of the ensemble. This effect, together with the phase lag angle introduced to account for the unsteady aerodynamic forces in the hose, makes the flutter computation of the complete system a non-typical one. The results show that, by adding the grid fins, the stability of the refueling system is improved, delaying or annulling flutter occurrence.

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Controllable Drogue for Automated Aerial Refueling

Cited by 41 publications

References 5 publications

Active Control of Aerial Refueling Hose-Drogue Systems

Active Control of Aerial Refueling Hose-Drogue Systems

UAV Pre-Study for In-Air-Capturing Maneuver

Aeroelastic Stability of an Aerial Refueling Hose–Drogue System with Aerodynamic Grid Fins

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