1680

Item 1680

OTHER: Aircraft - VTOL - AeroVantage - Central 2-rotor - Overview

~ Forget (for now). Too many problems ~

Overview:

Centrally located coaxial tilting Prop/Rotors,

A number of different arraignments under consideration

Drawing:

A/ Variable Diameter Rotor for the Large Rotor:

C/ Single Blade for the Large Rotor: Problems

General Notes:

US Patent 6,382,556 ~ VTOL airplane with only one tiltable prop-rotor Have hard copy.

11 other patents have referenced this patent.

It appears that the inventor Roger Pham (of Texas) is also interested in electrical vehicles.

He has a number of US patents.

Freewing Flight Technologies

If, during hover, the torque of the large PropRotor was designed to be greater than that of the small one the vertical wings might be employed to counter this uneven torque.

The use of a single rotor-disk should overcome any concerns about asymmetrical vortex ring-state.

OTHER ~ Flight Dynamics - Rotor Hub - Elastomeric CVJ - Patents Why is this here?

Alternatives:

A/ Variable Diameter Rotor for the Large Rotor:

The Attributes of a Variable Diameter Rotor System Applied to a Civil Tiltrotor Aircraft. Have copy in E-drive

DESIGN: AeroVantage ~ PropRotor - Outside Information - Sikorsky's Variable Diameter Tilt Rotor Sikorsky has many patents related to changing the disk area loading by varying the diameter of the rotor. It is intended for tilt-rotor craft.

B/ Using the Large Rotor as a Canard:

Perhaps the larger rotor does not reduce its diameter for cruise. Instead it might stop its rotation and act as a canard. The one propeller would thereby provide the forward thrust.

C/ Single Blade for the Large Rotor:

See: Single-Bladed All Electric Rotor

This will eliminate the need for a Variable Diameter Rotor.

Notes:

The single-bladed rotor appears to only be good for axial flight, with perhaps some limited radial movement. However this should not represent a problem for the concept on this page since the rotors tip forward, and this results in a near-axial flow during all modes of flight. A limitation might be that of relatively slow lateral and backward flight when in the hovering mode.

The single blade could be stopped, once the transition to forward flight has been completed. Then this single blade is feathered (90º pitch) and then rotated down and back over (into?) the fuselage. The counterweigh will go ??? PROBLEM ~ As the blade looses lift and stalls, on the way to 90º pitch, the chordwise center of thrust will move from 25% of chord to 50% of chord and this flat plate area will create a very large moment about the pitch axis.

The counter weight will be given a useful function, such as ???

Consider locating the electric motor between the propeller and the rotor. The motor's rotor drives the propeller and the stator drives the single blade rotor. The propeller and the rotor therefore turn in opposite directions with a 'free' 2:1 reduction. Problems with unequal drag of the stalled rotor-blade and that of the counterweight.

Perhaps the propeller has cyclic and collective while the rotor only has collective. (90º).

May be better to have a 2-blade rotor and bring the blades together for 'parking'.

Concerns:

Swinging the proprotor and motor from hover to cruse relocates the longitudinal CG. Idea ~ Locate the wing's center of lift further ahead then the hovering rotor's center of lift.

How to design the 'variable diameter', variable speed, variable pitch rotor.

How to work around Sikorsky's patents.

Slow the large rotor down significantly during part of the transition; to minimize the centrifugal forces.

Initially displayed: November 13, 2008 ~ ~ Posted on Rotary Wing: November 14, 2008 ~ Posted on PPRuNe: November 14, 2008 ~ Last Revised: November 16, 2008

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 it. ~ 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.