1060

Item 1060

OTHER: Aerodynamics - Vibration - Rotor Induced - Individual Blade Control (IBC)

The rotor disk is a 2D coordinate system with the coordinates being radius and azimuth. Higher frequency IBC is the means of setting the angle of attack around the disk, for a specific radius. . Active Blade Twist is the means of setting the angle of attack along the span of the blade, for a specific azimuth.

Preamble:

I suspect that it will be impossible to significantly decrease rotor-induced vibration by physically changing the pitch of the blades by rotation. Their moment of inertia about the feathering axis will prohibit oscillatory rotation at all but the lowest of frequencies. Perhaps a short duration localized change in thrust can be achieved by leading and/or trailing 'flap(s). Perhaps this may even cause a 'spike' or overshoot. These flaps may not even be fast enough.

Reducing the twist during forward flight will reduce the vibration. See: OTHER: Aerodynamics - General - Active Blade Twist

Computerized Control ~ Related Specifically to the Absolutely Rigid Blade and IBC:

Since this blade is a single rigid entity, it may not be necessary to know whereabouts on the span of the blade the perturbation is taking place. The vibration is past to the hub via the blade's root, therefor what is required is a real-time measurement of the stress on the top and the bottom of the blade's root. This, plus the azimuth of the blade can be input to the CPU. The CPU then can output to the following blade's activator a pitch correction in advance of its reaching this location.

The CPU will be continually adjusting the blade pitch at various azimuths based upon the discrepancy between the previous output and the current input. This input/output may be blended with that of the other two or other five blades. This input/output may require dampening by the storing and reading of previous recent activity This way, changes in the flight profile will be quickly adapted to.

What is to be used as the actuator? It may be necessary for this correction to take place somewhere within the inner 75% of the blade's span. (ie. between the lift's mid point and the root).

Related web Site: UniCopter ~ Vibration - Rotor Induced - Control - Closed-Loop Controller 1095

Location of IBC Device(s):

Assumptions based on UniCopter:

Disk radius is 9'-6"

Stagger is 2'-6"

Cutout is 3'-0"

The IBC device only causes a pitch increase and therefore it only operates when the blades is the lower one.

The azimuth where the bade is subjected to the strongest downwash may be 270º during hover.

In the above location, the span of the blade that is subject to downwash is from r = 3'-0" to r = (9'-6" - 2'-6") = 7'-0". This means that the span length of the blade subjected to downwash is 4'-0" long.

Specific Methods:

	UniCopter ~ Vibration - Rotor Induced - Control - Output - Boundary Layer Control	1085
	UniCopter ~ Vibration - Rotor Induced - Control - Output - High Frequency Leading & Trailing Edge Flaps	1087
	UniCopter ~ Vibration - Rotor Induced - Control - Output - High Frequency Modifiable Tip Control	1544
	UniCopter ~ Vibration - Rotor Induced - Control - Output - Lower Surface Flap(s)	1112
	UniCopter ~ Vibration - Rotor Induced - Control - Closed-Loop Controller	1095
	Maybe fluidics might work??

Alternatives:

Higher Harmonic Control: (HHC)

Related Information:

This Web Site:

OTHER: Aerodynamics - General ~ Circulation Control

Outside Web Sites:

Individual Blade Control

Design of a High Efficiency, Large Stroke, Electromechanical Actuator

Preliminary Testing of a Mach-Scaled Active Rotor Blade with a Trailing Edge Servo-Flap

Fast Rotor Blade Adjustment

AEROELASTIC ANALYSIS OF HELICOPTER ROTOR BLADES INCORPORATING ANISOTROPIC PIE

Projects

http://www.pkn.co.za/pap-XZDTM.html ~ Have hard copy.

http://www.pkn.co.za/pap-YCGHJ.html ~ DESIGN OF A HIGH EFFCIENCY, LARGE STROKE, ELECTROMECHANICAL ACTUATOR

http://www.pkn.co.za/pap-SYDMJ.html

http://www.pkn.co.za/pap-FMLNG.html

http://www.sm.go.dlr.de/~wolfgang/

http://www.spa.com/smtdnoise.htm

NASA TM-110252, May 1996

An Aeroelastic Analysis of Helicopter Rotor Blades Incorporating Piezoelectric Fiber Composite Twist Actuation

Dynamic Flow Control on Rotor Blades (PDF-File) ~ Have hard copy.

http://www.sm.go.dlr.de/~wolfgang/erf.2000.pdf ~ New Rotor Airfoil Design Procedure for Unsteady Flow Control, ~ Have hard copy.

http://www.sm.go.dlr.de/~wolfgang/corsica.99.fr.pdf ~ Transition and Turbulence Modelling for Dynamic Stall and Buffet, ~ Have hard copy.

~ Experimental and Numerical Investigations on Steady and Unsteady

Comprehensive Multibody AeroServoElastic Analysis of Integrated Rotorcraft Active Controls

http://www.me.sc.edu/research/lamss/pdf/CONFERENCES/ARO99-2.pdf

http://www.glue.umd.edu/~bernhard/DOCS/ahs01_v7.pdf

http://www.starboardinnovations.com/Downloads/Papers/AHSDerham01.pdf

FULL-SCALE WIND TUNNEL TEST OF AN INDIVIDUAL BLADE CONTROL SYSTEM FOR A UH-60 HELICOPTER http://rotorcraft.arc.nasa.gov/publications/files/Jacklin_AHSF02.pdf

Patents:

Search on: "blade vortex interaction"

6,200,096 ~ Actuation system for an active rotor control system Of no value

6,196,796 ~ High torque actuation system for an active rotor control system ~ Not looked at.

Have not looked into the following patents yet.

Search on: "blade pitch" AND tabs

5,165,854 ~ Mechanism for controlling pitch change in helicopter blades ~ Of no value

5,067,668 ~ Compound helicopter with no tail rotor ~ Of no value

4,928,907 ~ Compound helicopter with no tail rotor ~ Of no value

4,789,305 ~ Self-feathering rotary wing ~ Of no value

4,630,998 ~ Apparatus for control of collective and cyclic pitch of the blades of a rotor ~ Not looked at.

4,461,611 ~ Helicopter rotor with blade trailing edge tabs responsive to control system loading ~ Of no value

4,314,795 ~ Advanced airfoils for helicopter rotor application ~ Not looked at.

4,248,572 ~ Helicopter blade ~ Not looked at.

3,972,491 ~ Two-position helicopter main rotor ~ Of no value

Piezoelectric Actuators:

The movement appears to be about 1000th of the length of the actuator. It has a reasonably high force.

Web Pages:

http://www.morgan-electroceramics.com/pzact4.html

http://www.sensortech.ca/main.html

http://materials.searchabstracts-asap.com/info/com.csa_materials_A00-44234.html

http://techreports.larc.nasa.gov/ltrs/cit.html and search on the word 'piezoelectric'.

Other Web Pages:

Langley Tech Report:

W. Keats Wilkie, W. Keith Belvin and K. C. Park, Aeroelastic Analysis of Helicopter Rotor Blades Incorporating Anisotropic Piezoelectric Twist Actuation , 1996 Fall American Society of Mechanical Engineers Congress and Exhibition , Atlanta, GA, November 17-22, 1996, pp. 11, In Proceedings of the ASME Aerospace Division, ASME 1996, AD-Vol.52, pp.423-433. (343KB).

Format(s): Postscript, or PDF

W. K. Wilkie and K. C. Park, An Aeroelastic Analysis of Helicopter Rotor Blades Incorporating Piezoelectric Fiber Composite Twist Actuation , NASA TM-110252, May 1996, pp. 62, (612KB) ERRATA .

Format(s): Postscript, or PDF

M. C. Brennan and A. R. McGowan, Piezoelectric Power Requirements for Active Vibration Control , SPIE's 4th Annual Symposium on Smart Structures and Materials, San Diego, California, March 3-6, 1997, (930KB).

Format(s): Postscript, or PDF

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Last Revised: February 3, 2007