Wind-Tunnel Testing of Aeroelastically Scaled Helicopter Rotor Models PDF Download
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Author: Charles Eugene Hammond
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
The use of aeroelastically scaled helicopter rotor wind-tunnel models in establishing or verifying the dynamic characteristics of new or existing rotor designs is discussed. A model, termed the generalized rotor aeroelastic model (GRAM), which has been developed for testing aeroelastically scaled rotor models is described, and the utility of the model in being able to test a variety of rotor systems to meet a broad range of test objectives is demonstrated though presentation of data from recent tests. Data are presented from tests of an AH-1G Cobra model to determine whether or not the two-blade teetering rotor can experience stall flutter, tests of two wide chord teetering rotors to evaluate the effect of the wide chord on blade loads and rotor performance, and tests of a new four-blade flex-hinge rotor configuration to provide information for the designer relative to its dynamic characteristics. Since the GRAM was developed for testing in a wind tunnel which has the capability of using Freon-12 as a test medium, some of the advantages of Freon-12 for testing of aeroelastically scaled models are also discussed. (Author).
Author: Charles Eugene Hammond
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
The use of aeroelastically scaled helicopter rotor wind-tunnel models in establishing or verifying the dynamic characteristics of new or existing rotor designs is discussed. A model, termed the generalized rotor aeroelastic model (GRAM), which has been developed for testing aeroelastically scaled rotor models is described, and the utility of the model in being able to test a variety of rotor systems to meet a broad range of test objectives is demonstrated though presentation of data from recent tests. Data are presented from tests of an AH-1G Cobra model to determine whether or not the two-blade teetering rotor can experience stall flutter, tests of two wide chord teetering rotors to evaluate the effect of the wide chord on blade loads and rotor performance, and tests of a new four-blade flex-hinge rotor configuration to provide information for the designer relative to its dynamic characteristics. Since the GRAM was developed for testing in a wind tunnel which has the capability of using Freon-12 as a test medium, some of the advantages of Freon-12 for testing of aeroelastically scaled models are also discussed. (Author).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
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Book Description
Author: John D. Berry
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Book Description
A wind-tunnel investigation has been conducted using an articulated helicopter model rotor system to determine the effects of several blade tip designs on both the performance and acoustic characteristics of the rotor. Only the performance characteristics are presented in this paper. Six tip shapes were tested: a square (baseline) tip, an ogee tip, a subwing tip, a swept tip, a winglet tip, and a short ogee tip. Tests were conducted at two rotor rotational speeds and five advance ratios including hover. In hover at the lower rotational speed and a given lift coefficient, the swept, ogee, and short ogee tips had about the same torque coefficient, and the subwing and winglet tips had a larger torque coefficient than the baseline square tip blades. In simulated forward flight, the ogee tip had values of torque coefficient very close to or less than the baseline square tip blades. In simulated forward flight at 1200 rpm, the ogee tips showed a decrease in torque coefficient relative to the baseline blades as drag coefficient decreased. The swept tip blades required less torque coefficient at lower rotational speeds than the baseline square tip blades and roughly equivalent torque coefficient at higher rotational speeds in forward flight. The short ogee tip was tested in limited forward flight conditions and it required higher torque coefficient at higher lift coefficient than the baseline square tip blade. (Author).
Author: Michael Anthony Capasso
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This thesis reports on the construction of a 1/12th scale model of the award winning Arapaho attack helicopter design and wind tunnel test to determine both the model and full scale equivalent flat plate area. Tests were conducted for lg level flight and included yawed flight conditions up to 10 degrees. The significance of equivalent flat plate area for helicopters is that it is the principal parameter that establishes rotor propulsive force requirements. The Model was constructed from the original design submitted by the 1993 NPS Helicopter Design Team and is 47.5 inches long with a 48-inch main rotor diameter. The model was tested in the NPS Low Speed Wind Tunnel to measure the drag force on the main body of the model at wind tunnel velocities up to 72 knots. Drag force on the model was also measured with the rotor head and longbow radome installed, and at various yaw angles up to 10 degrees. The equivalent flat plate area was then calculated from these measurements and compared to other helicopters. Recommendations for further wind tunnel testing were made.
Author: Jeffrey D. Singleton
Publisher: DIANE Publishing
ISBN: 1428915508
Category : Rotors (Helicopters)
Languages : en
Pages : 86
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Book Description
Author: John L. McCloud
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 38
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Book Description
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781724710666
Category :
Languages : en
Pages : 250
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Book Description
This report provides data obtained during a wind-tunnel test conducted to investigate parametrically the effect of blade nonstructural mass on helicopter fixed-system vibratory loads. The data were obtained with aeroelastically scaled model rotor blades that allowed for the addition of concentrated nonstructural masses at multiple locations along the blade radius. Testing was conducted for advance ratios ranging from 0.10 to 0.35 for 10 blade-mass configurations. Three thrust levels were obtained at representative full-scale shaft angles for each blade-mass configuration. This report provides the fixed-system forces and moments measured during testing. The comprehensive database obtained is well-suited for use in correlation and development of advanced rotorcraft analyses. Wilbur, Matthew L. and Yeager, William T., Jr. and Singleton, Jeffrey D. and Mirick, Paul H. and Wilkie, W. Keats Langley Research Center NASA/TM-1998-206281, NAS 1.15:206281, ARL-TR-1401, L-17353 RTOP 505-63-36-02...
Author: Julian L. Jenkins
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 46
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Book Description
Author: Walter Castles
Publisher:
ISBN:
Category : Rotors (Helicopters)
Languages : en
Pages : 86
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 134
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Book Description
Data for rotors using unconventional airfoils are of interest to permit an evaluation of this technology's capability to meet the U.S. Army's need for increased helicopter mission effectiveness and improved safety and survivability. Thus, an experimental investigation was conducted in the Langley Transonic Dynamics Tunnel (TDT) to evaluate the effect of using slotted airfoils in the rotor blade tip region (85 to 100 percent radius) on rotor aerodynamic performance and loads. Four rotor configurations were tested in forward flight at advance ratios from 0.15 to 0.45 and in hover in-ground effect. The hover tip Mach number was 0.627, which is representative of a design point of 4000-ft geometric altitude and a temperature of 95 degrees F. The baseline rotor configuration had a conventional single element airfoil in the tip region. A second rotor configuration had a forward-slotted airfoil with a -6 degrees slat, a third configuration had a forward-slotted airfoil with a -10 degrees slat, and a fourth configuration had an aft-slotted airfoil with a 3 degrees flap (trailing edge down). The results of this investigation indicate that the -6 degrees slat configuration offers some performance and loads benefits over the other three configurations.
