Mono tiltrotor
Encyclopedia
The Baldwin Mono Tiltrotor project is a research effort into a tiltrotor
Tiltrotor
A tiltrotor is an aircraft which uses a pair or more of powered rotors mounted on rotating shafts or nacelles at the end of a fixed wing for lift and propulsion, and combines the vertical lift capability of a helicopter with the speed and range of a conventional fixed-wing aircraft...

 aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 that uses only one rotor. Like other tiltrotor configurations, the mono tiltrotor combines the vertical lift capability and structural efficiency of a helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

 with the speed and range
Range (aircraft)
The maximal total range is the distance an aircraft can fly between takeoff and landing, as limited by fuel capacity in powered aircraft, or cross-country speed and environmental conditions in unpowered aircraft....

 of an fixed-wing aircraft
Fixed-wing aircraft
A fixed-wing aircraft is an aircraft capable of flight using wings that generate lift due to the vehicle's forward airspeed. Fixed-wing aircraft are distinct from rotary-wing aircraft in which wings rotate about a fixed mast and ornithopters in which lift is generated by flapping wings.A powered...

.

Development

Work on the Mono Tiltrotor (MTR) was initiated in 2004. A concept study was performed under an Office of Naval Research
Office of Naval Research
The Office of Naval Research , headquartered in Arlington, Virginia , is the office within the United States Department of the Navy that coordinates, executes, and promotes the science and technology programs of the U.S...

 contract
Contract
A contract is an agreement entered into by two parties or more with the intention of creating a legal obligation, which may have elements in writing. Contracts can be made orally. The remedy for breach of contract can be "damages" or compensation of money. In equity, the remedy can be specific...

 and this study concluded that the MTR, if technically realizable, would be half the size and one-third the weight of legacy helicopter concepts for a 1000 nautical miles (1,852 km) mission.

In 2005 and 2006, design of the 9400 pound gross weight MTR Scaled Demonstrator (MTR-SD) was performed under a United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 contract. This work included the following tasks: engine
Engine
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...

 selection; transmission
Transmission (mechanics)
A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...

 design; hub, controls, and blade preliminary design; comprehensive performance and aeroelastic
Aeroelasticity
Aeroelasticity is the science which studies the interactions among inertial, elastic, and aerodynamic forces. It was defined by Arthur Collar in 1947 as "the study of the mutual interaction that takes place within the triangle of the inertial, elastic, and aerodynamic forces acting on structural...

 analysis; analysis of critical stress concentration
Stress concentration
A stress concentration is a location in an object where stress is concentrated. An object is strongest when force is evenly distributed over its area, so a reduction in area, e.g. caused by a crack, results in a localized increase in stress...

s; conceptual design of the fixed wing and cargo pod; wind tunnel
Wind tunnel
A wind tunnel is a research tool used in aerodynamic research to study the effects of air moving past solid objects.-Theory of operation:Wind tunnels were first proposed as a means of studying vehicles in free flight...

 testing of wing deployment; and longitudinal static stability
Longitudinal static stability
Longitudinal static stability is the stability of an aircraft in the longitudinal, or pitching, plane during static conditions. This characteristic is important in determining whether an aircraft will be able to fly as intended...

 analysis from hover through cruise
Cruise (flight)
Cruise is the level portion of aircraft travel where flight is most fuel efficient. It occurs between ascent and descent phases and is usually the majority of a journey. Technically, cruising consists of heading changes only at a constant airspeed and altitude...

. This work resulted in a definition of each component's and each subassembly's weight, moments of inertia
Moment of inertia
In classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an object's resistance to changes to its rotation. It is the inertia of a rotating body with respect to its rotation...

, location on the aircraft, and aerodynamic drag. The predicted range and speed were derived from this aircraft design data.

In 2007 and 2008, demonstrations
Scientific demonstration
A scientific demonstration is a scientific experiment carried out for the purposes of demonstrating scientific principles, rather than for hypothesis testing or knowledge gathering ....

 and validations
Verification and Validation
In software project management, software testing, and software engineering, verification and validation is the process of checking that a software system meets specifications and that it fulfills its intended purpose...

 of the MTR-SD design were performed under an Army contract. The three unprecedented hardware mechanisms of the MTR were demonstrated in small scale flight tests: 1) the aerodynamically
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...

 deployed wing panels; 2) the pitch axis suspended cargo pod; and 3) the tilting centerline rotor. Furthermore, a 7 feet (2.1 m) diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...

 rotor remote control
Remote control
A remote control is a component of an electronics device, most commonly a television set, used for operating the television device wirelessly from a short line-of-sight distance.The remote control is usually contracted to remote...

 MTR Functional Demonstrator (MTR-FD) that integrates these three features was designed, built, and hover tested. Bell Helicopter Textron
Bell Helicopter Textron
Bell Helicopter is an American rotorcraft manufacturer headquartered in Hurst, Texas, near Fort Worth. A division of Textron, Bell manufactures military helicopter and tiltrotor products in and around Fort Worth, as well as in Amarillo, Texas, and commercial rotorcraft products in Mirabel, Quebec,...

 used proprietary methods for advanced concept design and analysis to validate the 25 feet (7.6 m) rotor MTR-SD design. Bell Helicopter's assessment resulted in validations of the MTR-SD vertical lift capacity, engine power required and power available, cruise thrust and propulsive efficiency, aircraft weight, and airplane mode cruise lift. Bell Helicopter also generated and reported MTR-SD flight dynamics
Flight dynamics
Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...

 data. A computational fluid dynamics
Computational fluid dynamics
Computational fluid dynamics, usually abbreviated as CFD, is a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Computers are used to perform the calculations required to simulate the interaction of liquids and gases with...

 drag assessment was performed, and in combination with the Bell Helicopter assessment this validated MTR-SD projected drag and aircraft cruise range performance.

In early 2009, a Concept of Operations
Concept of Operations
A concept of operations is a document describing the characteristics of a proposed system from the viewpoint of an individual who will use that system. It is used to communicate the quantitative and qualitative system characteristics to all stakeholders...

 (CONOPS) video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...

 was produced showing the MTR-SD performing the missions specified in the United States Marine Corps
United States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...

 - Cargo Unmanned Aircraft System - Universal Need Statement (USMC Cargo UAS UNS) and in the Office of Naval Research – Cargo Unmanned Aircraft System – Request for Information (ONR Cargo UAS RFI). In early 2010, under a multi-year contract with the Office of Naval Research (ONR), the CONOPs and aircraft design were refined for Navy shipboard compatibility.

On October 2, 2010, the first full conversion between helicopter and airplane modes of flight was achieved using a revised Mono Tiltrotor - Functional Demonstrator (MTR-FD), 4 foot diameter, small-scale remote control model.

A hybrid of a mono tiltrotor and a tiltwing has been successfully test flown on the sub scale. Evidence of the flights can be found on the youtube channel called "tiltrotorcoaxialheli", the coaxial tilt wing project is separate from the mono tilt rotor project.

See also

Further reading

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