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Patent Issued for Aerodynamic Profile with a Reversibly Deformable Contour for Aircraft, in Particular for Rotary Wing Aircraft

July 23, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventor Pfaller, Rupert (Riemerling, DE), filed on May 27, 2009, was published online on July 8, 2014.

The patent's assignee for patent number 8770523 is Aircus Helicopters Deutschland GmbH (Donauwoerth, DE).

News editors obtained the following quote from the background information supplied by the inventors: "In the state of the art, to this effect, discrete rotor blade flaps on the trailing edge of the rotor blade are known, which by means of a pivoting bearing are movably held to the rotor blade, compare DE 101 16 479 A1. The rotor blade flap is controllable by a piezo actuator, wherein the piezo actuator is arranged in a profile depth direction spaced apart from the flap in a front profile region of the rotor blade profile body. The actuating forces generated by the piezo actuator are transmitted to the rotor blade flap by way of strip-shaped or rod-shaped tension elements.

"Due to the joints, this type of rotor blade is subjected to increased wear as well as being exposed to dust, dirt and water. Since the interior space of the rotor blade is difficult to seal in front of the flap, a short operating time to the exchange of the joints, or reduced effectiveness result due to frost and dirt particles that enter.

"According to DE 103 34 267 A1, a rotor blade with an integral elastically movable rotor blade flap has become known, which can be actuated by means of piezoelectric actuators that are arranged in the rigid cover skins of the wing profile or immediately underneath the cover skins that are rigid per se or on the rigid cover skins. Actuating one of the two piezoelectric actuators on the top cover skin or on the bottom cover skin of the wing profile results in displacement of the respective cover skin relative to the other cover skin, as a result of which the top cover skin is shortened or lengthened relative to the bottom cover skin. Due to the relative shortening of a cover skin relative to the other cover skin, the rigid rotor blade flap that is affixed to the cover skins is displaced and moved upwards or downwards. A similar arrangement is also shown in DE 103 04 530 A1.

"Since the piezoelectric actuators are either integrated in the profile without flap, or alternatively are provided exclusively in the flap, for system-related reasons the actuators need to be arranged near the trailing edge of the profile cross section. Since in this region of the rotor blade, due to slewing moments and centrifugal forces, considerable tensile strain occurs and since piezoelectric actuators as a rule are sensitive to strain, the centrifugal force that occurs can already during startup of a rotor lead to failure of the actuators. Furthermore, elastic bearings have a requirement spectrum of material, which spectrum is difficult to meet, namely high tensile-compressive strain, no energy absorption as a result of plastic behaviour, transmission of the aerodynamic forces without excessive deformation. Furthermore, the skin must be designed so as to be deflection resistant between the supporting locations (e.g. ribs, spars, webs etc.) in order to prevent undesirable profile deformation as a result of the aerodynamic loads that occur. Furthermore, the skin should be deflection resistant in order to prevent any interior supports from showing through on the exterior skin, thus negatively affecting the aerodynamic quality of the profile. On the other hand, the skin should be designed so as to be flexible in order to achieve corresponding deformation and in order to be able to deform the profile with little energy. These requirements are contradictory and so far it has not been possible to meet them."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "It is thus the object of the invention to avoid the disadvantages of the known aerodynamic profiles, in particular of the known rotor flaps of the type in question in the present document, and to significantly improve said aerodynamic profiles.

"This object is met by the characteristics of claim 1. Advantageous improvements of the invention are stated in the subordinate claims.

"As a result of the design and arrangement, according to the invention, of the aerodynamic profile with elastically reversibly deformable profile regions due to cover skins that enclose the profile, which profile regions in each case for a sandwich-like design comprise a relapsing soft elastic core, the profile can be given a reversible sinuous effect that is controllable in a targeted manner by way of actuators, by means of which sinuous effect the hitherto used adjustable discrete flaps that were arranged in the rear profile region are replaced. In this way both the discrete flap bearings which in practical application were exposed to increased wear due to high vibration frequencies and elements such as dust, dirt and water, and the disadvantages of hitherto used integral rotor blade flaps are avoided."

For additional information on this patent, see: Pfaller, Rupert. Aerodynamic Profile with a Reversibly Deformable Contour for Aircraft, in Particular for Rotary Wing Aircraft. U.S. Patent Number 8770523, filed May 27, 2009, and published online on July 8, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8770523.PN.&OS=PN/8770523RS=PN/8770523

Keywords for this news article include: Aircus Helicopters Deutschland GmbH.

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Source: Journal of Engineering


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