1503

Item 1503

OTHER: Rotor Concept - Traversing Ideal Twist - Advanced Method

The following is just the initial work-up toward a fleshed out idea
Overview:

For overview of the subject see; OTHER: Rotor Concept - Reverse Velocity Utilization.

This page is a proposed means of implementing OTHER: Rotor Concept - Traversing Twist - Overview.

An Adjunct: (Whatever that means)

Consider the blade as consisting of a large number of independent elements along the span. During hover and slow forward flight all the elements would receive pitch commands in accordance with those of a conventional blade. As the forward velocity of the craft continually increased, the root element and then adjacent elements would be enveloped in reverse velocity at the 270º azimuth.

An element that is enveloped in reverse velocity at the 270º azimuth then has the activity of its pitch changed so that its pitch is +5º at 90º azimuth, +47º at 135º, +90º at 180º, +132º at 225º, +170º at 270º, +132º at 315º, +90º at 360º and +47º at 45º. Elements that are not enveloped in reverse velocity at the 270º azimuth receive conventional pitch commands.

This is the same as the web page's high twist except that the elements are segmented.

A Proposed Blade Design and Method of Operation:

The span is segmentalized into as many elements as there are carbon tows running in the coardwise direction.

These elements can rotate on an elastomeric bearing about a circular spar. The total range of pitch is from 0º on down and around to -180º.

The pitch angle of each element is determined by the airflow direction that it encounters. It is also based upon the restraint of the elastomeric between it and the two adjoining elements.

A mechanical pitch/collective control sets the 2P root pitch restraint and the 1P tip pitch restraint of the blade, as it rotates about the mast.

The spanwise 'wavy' thread in the skin's composite cloth (see below) are to contain the length of the very high twist to a set percentage of the span. This area will more back and forth and of the ends of the blades as the blade rotates about the mast.

Skin of Airfoil:

The skin consists of bi-directional composite cloth. When applied to the blade, all strands that are parallel to the chordwise dimension consist of carbon.
The majority of the strands that are parallel to the spanwise dimension consist of fiberglass (or some other material with elastic properties). A minority of these strands are 'wavy' carbon. There is greater 'wave' at the 'trailing edge', none at the pitch axis and a little at the 'leading edge'.
The epoxy, which bonds the threads and crates the skin, has a degree of elasticity..

Profile of Blade:

The profile of the airfoil will vary from root to tip.
The root will be thicker than the tip.
a/ The upper and lower surfaces at the root will have greater degree of symmetry than the upper and lower surfaces at the tip.
b/ The front and rear edges at the root will have greater degree of symmetry than the front and rear edges at the tip.
The objectives of a/ & b/ is to shape the blades so they are optimized more for the positive airflow over their surface ( Ie. the advancing side of 180º and more) then for the reverse airflow over their surface.
The objectives of a/ & b/ are, also, to shape the blades so they are optimized for the range of mu between hover and the cruise speed of the particular craft.

Notes:

General Overview of Skin: The skin of the blade is to consist of a sheet that can streatch in on direction and not stretch in the other direction.

Control of Segments Alone Span of Blade: Consider each sector having its own electrical linear actuator and positioning encoder.

Initially Displayed: March 26, 2006 ~ Displayed on PPRuNe and on Rotary Wing Forum: April 7, 2006 ~ Last Revision: June 4, 2007

The above utility invention is openly and publicly disclosed on the Internet to negate an entity from patenting it, to the exclusion of all others whom may wish to use them. ~ Reference patent law 35 U.S.C. 102 A person shall be entitled to a patent unless - (a) the invention was known ... by others in this country, ..., before the invention thereof by the applicant for patent.