Accession Number:

ADP011142

Title:

Adaptive Rotor Blade Concepts -Direct Twist and Camber Variation-

Descriptive Note:

Corporate Author:

GERMAN AEROSPACE CENTER BRAUNSCHWEIG (GERMANY) INST OF STRUCTURAL MECHANICS

Report Date:

2001-06-01

Pagination or Media Count:

12.0

Abstract:

Applying adaptronics to helicopters has a high potential to significantly suppress noise, reduce vibration and increase the overall aerodynamic efficiency. Since the interaction of nonstationary helicopter aerodynamics elastomechanical structural characteristics of the helicopter blades causes flight envelope limitations, vibration and noise, a good comprehension of the aerodynamics is essential for the development of structural solutions to effectively influence the local airflow conditions and finally develop a structural concept. With respect to these considerations, this paper presents recent investigations on two different structural concepts the direct twist and the camber variation concept. The direct twist allows to directly control the twist of the helicopter blades by smart adaptive elements and through this to positively influence the main rotor area which is the primary source for helicopter noise and vibration. The concept is based upon the actively controlled tension-torsion-coupling of the structure. For this, an actuator is integrated within a helicopter blade that is made of anisotropic fibre composite material. Driving the actuator results in a local twist of the blade tip, in such a way that the blade can be considered as a torsional actuator. Influencing the blade twist distribution finally results in a higher aerodynamic efficiency. The direct twist concept was analytically modelled using an expanded Viassov Theory before a proof-of-principle demonstration structure was manufactured. Subsequently, a Mach-scaled Bo105 model rotor blade with an integrated piezoelectric actuator was designed and successfully tested. Next small scale rotor tests and investigation of thermal loads are planned.

Subject Categories:

  • Helicopters
  • Machinery and Tools

Distribution Statement:

APPROVED FOR PUBLIC RELEASE