Studies of the Use of Freon-12 as a Wind-tunnel Testing Medium

Studies of the Use of Freon-12 as a Wind-tunnel Testing Medium PDF Author: Albert E. Von Doenhoff
Publisher:
ISBN:
Category : Dichlorodifluoromethane
Languages : en
Pages : 668

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Book Description
A number of studies relating to the use of Freon-12 as a substitute medium for air in aerodynamic testing have been made. The use of Freon-12 instead of air makes possible large savings in wind-tunnel drive power. Because of the fact that the ratio of specific heats is approximately 1.13 for Freon-12 as compared with 1.4 for air, some differences exist between data obtained in Freon-12 and air. Methods for predicting aerodynamic characteristics of bodies in air from data obtained in Freon-12, however, have been developed from the concept of similarity of the streamline pattern. These methods, derived from consideration of two-dimensional flows, provide substantial agreement in all cases for which comparative data are available. These data consist of measurements throughout a range of Mach number from approximately 0.4 to 1.2 of pressure distributions and hinge moments on swept and unswept wings having aspect ratios ranging from 4.0 to 9.0, including cases where a substantial part of the wing was stalled.

Studies of the Use of Freon-12 as a Wind-tunnel Testing Medium

Studies of the Use of Freon-12 as a Wind-tunnel Testing Medium PDF Author: Albert E. Von Doenhoff
Publisher:
ISBN:
Category : Dichlorodifluoromethane
Languages : en
Pages : 668

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Book Description
A number of studies relating to the use of Freon-12 as a substitute medium for air in aerodynamic testing have been made. The use of Freon-12 instead of air makes possible large savings in wind-tunnel drive power. Because of the fact that the ratio of specific heats is approximately 1.13 for Freon-12 as compared with 1.4 for air, some differences exist between data obtained in Freon-12 and air. Methods for predicting aerodynamic characteristics of bodies in air from data obtained in Freon-12, however, have been developed from the concept of similarity of the streamline pattern. These methods, derived from consideration of two-dimensional flows, provide substantial agreement in all cases for which comparative data are available. These data consist of measurements throughout a range of Mach number from approximately 0.4 to 1.2 of pressure distributions and hinge moments on swept and unswept wings having aspect ratios ranging from 4.0 to 9.0, including cases where a substantial part of the wing was stalled.

Technical Note - National Advisory Committee for Aeronautics

Technical Note - National Advisory Committee for Aeronautics PDF Author: United States. National Advisory Committee for Aeronautics
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1082

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Wind Tunnel Evaluation of a Model Helicopter Main-Rotor Blade With Slotted Airfoils at the Tip

Wind Tunnel Evaluation of a Model Helicopter Main-Rotor Blade With Slotted Airfoils at the Tip PDF 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.

An Experimental Investigation of the Aeromechanical Stability of a Hingeless Rotor in Hover and Forward Flight

An Experimental Investigation of the Aeromechanical Stability of a Hingeless Rotor in Hover and Forward Flight PDF Author:
Publisher:
ISBN:
Category : Rotors (Helicopters)
Languages : en
Pages : 24

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A Selected Listing of NASA Scientific and Technical Reports for ...

A Selected Listing of NASA Scientific and Technical Reports for ... PDF Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 750

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Index of NACA Technical Publications

Index of NACA Technical Publications PDF Author: United States. National Advisory Committee for Aeronautics
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 306

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Flutter Studies to Determine Nacelle Aerodynamic Effects on a Fan-jet Transport Model for Two Mount Systems and Two Wind Tunnels

Flutter Studies to Determine Nacelle Aerodynamic Effects on a Fan-jet Transport Model for Two Mount Systems and Two Wind Tunnels PDF Author: Moses G. Farmer
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 44

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Book Description
Low-speed flutter studies of a dynamically and elastically scaled model of a large multijet transport airplane have been conducted primarily to determine the nacelle aerodynamic effects for high-bypass-ratio fan-jet engines. Data were obtained on a vertical rod mount in two wind tunnels and on a two-cable mount in one of the tunnels. The flutter response of the model was found to be dependent on nacelle aerodynamics, engine-pylon stiffness, mount-system-wind-tunnel configuration, and mass ratio.

Applied Mechanics Reviews

Applied Mechanics Reviews PDF Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 606

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NASA Technical Memorandum

NASA Technical Memorandum PDF Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 462

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Acquisition and utilization of wind tunnels by the National Aeronautics and Space Administration

Acquisition and utilization of wind tunnels by the National Aeronautics and Space Administration PDF Author: United States. General Accounting Office
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 230

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Book Description