Dynamics of Slung Bodies Using a Single-Point Suspension System

Poll, Corrado; Cromack, Duane E.

doi:10.2514/3.60200

Cited by 23 publications

(8 citation statements)

References 3 publications

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“…A stability study in forward flight by Cliff and Bailey [7] partially confirmed the results of Ref. [6] because decreasing the weight improved stability, but longer cables were found to be destabilizing. The differences may be due to the different aerodynamics of the load, which was a much more idealized representation in Ref.…”

Section: Introductionmentioning

confidence: 61%

“…Furthermore, the present model cannot capture the aerodynamic instabilities due to the non-streamlined shape of many suspended loads. These instabilities, described for example by Gabel [13], Poli [6], Sheldon [10], and Simpson and Flower [14], often limit the maximum speed of the helicopter.…”

Section: More Recently Cicolani Et Al Have Reported the Results Of mentioning

confidence: 99%

“…The typical loads are bluff bodies that may be subject to dynamic instabilities triggered by unsteady aerodynamics. Poli and Cromack [6] studied the stability in forward flight of a helicopter carrying an 8 ft × 8 ft × 20 ft container and a 20 ft long, 5.4 ft diameter circular cylinder. Long cables, high speeds, and low weights increased the stability of the loads.…”

Section: Introductionmentioning

confidence: 99%

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Flight Dynamics of an Articulated Rotor Helicopter with an External Slung Load

Fusato¹,

Guglieri²,

Celi³

2001

j am helicopter soc

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The paper presents a study of the flight dynamics of an articulated rotor helicopter carrying a suspended load. The aircraft model includes rigid body dynamics, individual flap and lag blade dynamics, and inflow dynamics. The load is a point mass with a single suspension point. Results were obtained for load masses of up to 2000 kg, with load-tohelicopter mass ratios of up to 28%, cable lengths from 3 to 8 m, turn rates of up to 16 deg/sec, and advance ratios of up to 0.3. The load affects trim primarily through the overall increase in the weight of the aircraft; the influence of cable length is negligible. Substantial coupling can occur between the Dutch roll and the load modes. Because of this coupling, the Dutch roll damping can decrease with a deterioration of handling qualities. The effects on the phugoid are very small. A suspended load modifies the roll frequency response by adding a notch to the gain curves and a 180-degree jump in the phase curves at the pendulum frequencies of the load. The changes in bandwidth and phase delay are small. Notation a L Absolute acceleration of the suspended load, Eq. (4). D Aerodynamic force vector acting on the load, Eq. (6). F H Force applied by the load to the helicopter, Eq. (8). f L Vector of load equations of motion, Eq. (7). i B , j B , k B Unit vectors of the body axis coordinate system (Figure 1). i G , j G , k G Unit vectors of the gravity axis system; the k G vector is directed along the vertical. i H , j H , k H Unit vectors of hook coordinate system (Figure 1). l Cable length. m Mass of the suspended load. n T Load factor. p, q, r Roll, pitch, and yaw rate of the helicopter. R H Position vector of the suspension point with respect to the aircraft CG, Eq. (2). R L Position vector of the load with respect to the suspension point, Eq. (1). S L Equivalent flat plate area of the suspended load. x H , y H , z H Components of the position vector of the suspension point with respect to the aircraft center of mass (Figure 1). Greek Symbols and Subscripts θ L , φ L Coordinates of the suspended load (Figure 1). θ F , φ F Pitch and roll angle of the fuselage. µ Advance ratio.

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Section: Introductionmentioning

confidence: 61%

Section: More Recently Cicolani Et Al Have Reported the Results Of mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flight Dynamics of an Articulated Rotor Helicopter with an External Slung Load

Fusato¹,

Guglieri²,

Celi³

2001

j am helicopter soc

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“…aeroplane speed, rope length, rope properties and the properties of the towed body itself. The main motivation for his and other more recent publications (2,3) was the identification of critical parameters for the slung load transportation at high velocities. Based on this work several attempts were undertaken to improve the stability of the load.…”

Section: Mrmentioning

confidence: 99%

“…Using the deviations from the desired trajectories the controller R trans calculates for each helicopter i the forces F i , which should be generated by its rotors. The helicopter i realises the force F i by adjusting the absolute value of main rotor lifting force F i3 MR and orientation adaption of the main rotor plane or fuselage q* i (1,2) . The values F i3 MR and q * i (1,2) are calculated using algebraical relations in block F -1 .…”

Section: Orientation Controlmentioning

confidence: 99%

Load transportation system based on autonomous small size helicopters

Bernard¹,

Kondak²,

Hommel³

2010

Aeronaut. j.

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one/multiple helicopters transporting a load is introduced. This model is used in a simplified form for the controller design and in full form for simulation. The controller for one and two helicopters, which is based on a state feedback controller, as well as the controller for three and more helicopters, which is based on a non linear controller, are explained in detail. Both controllers utilise an underlying non-linear orientation controller. We propose a feedback loop, based on forces measured in the ropes, to compensate for the influence of the rope. The controllers were tested in simulation and in real flight experiments. The world wide first flight experiment with three coupled helicopters was successfully conducted at the end of 2007.

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