No Tar

7/31/2019 No Tar

1/3

NOTAR

MD Explorer (German police)

The Cierva W.9 showing the long

tailboom from-which the efflux from

the engine-driven fan emerged from a

NOTARFrom Wikipedia, the free encyclopedia

NOTAR is the name of a helicopter anti-torque

system which replaces the use of a tail rotor.

Developed by McDonnell Douglas Helicopter

Systems (through their acquisition of Hughes

Helicopters), the name is an acronym derived

from the phrase no tail rotor. The system uses a

fan inside the tailboom to build a high volume of

low-pressure air, which exits through two slots

and creates a boundary layer flow of air along the

tailboom utilizing the Coand effect. The

boundary layer changes the direction of airflow

around the tailboom, creating thrust opposite the

motion imparted to the fuselage by the torque

effect of the main rotor. Directional yaw controlis gained through a vented, rotating drum at the

end of the tailboom, called the direct jet thruster. Advocates of NOTAR believe the system offers

quieter and safer operation.[1]

Contents

1 Development

2 Concept3 Applications

4 See also

5 References

6 External links

Development

The use of directed air to provide anti-torque control had

been tested as early as 1945 in the British Cierva W.9. During1957, a Spanish prototype designed and built by Aerotecnica

flew using exhaust gases from the turbine instead of a tail

rotor. This model was designated as Aerotecnica AC-14.

Development of the NOTAR system dates back to 1975,

when engineers at Hughes Helicopters began concept

development work.[2]

In December 1981, Hughes flew an

OH-6A fitted with NOTAR for the first time. The OH-6A

helicopter (serial number 65-12917) was supplied by the U.S.

Army for Hughes to develop the NOTAR technology and was

the second OH-6 built by Hughes for the U.S. Army. A more

NOTAR - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/NOTAR

1 of 3 14/04/12 4:04 PM

7/31/2019 No Tar

2/3

directable vent on the left side at the

tip of the tailboom

Diagram showing the movement of

air through the NOTAR system.

1 Air intake 2 Variable pitch fan 3

Tail boom with Coand Slots 4

Vertical stabilizers 5 Direct jet

thruster 6 Downwash 7 Circulation

control tailboom cross-section 8

Anti-torque lift

heavily modified version of the prototype demonstrator first

flew in March 1986 (by which time McDonnell Douglas had

acquired Hughes Helicopters). The original prototype last

flew in June 1986 and is now at the U.S. Army Aviation

Museum in Fort Rucker, Alabama. Soviet manufacturer Kamov made a prototype on their co-axial

helicopter Ka-26 which they called Ka-26SS in 1988 it never went into production.

A production model NOTAR 520N (N520NT) was later produced and first flew on May 1, 1990. It

later crashed on September 27, 1994 when it collided with an AH-64D while flying as a chase

aircraft for the Apache.

Concept

Although the concept took over three years to refine, the

NOTAR system is simple in theory and works to provide

some directional control using the Coand effect.[2]

[3]

A

variable pitch fan is enclosed in the aft fuselage sectionimmediately forward of the tail boom and driven by the main

rotor transmission. This fan forces low pressure air through

two slots on the right side of the tailboom, causing the

downwash from the main rotor to hug the tailboom,

producing lift, and thus a measure of directional control. This

is augmented by a direct jet thruster and vertical stabilisers.

Benefits of the NOTAR system include increased safety (the

tail rotor being vulnerable), and greatly reduced external

noise. NOTAR-equipped helicopters are among the quietest

certified helicopters.

Applications

There are three production helicopters that utilize the

NOTAR system, all produced by MD Helicopters:

MD 520N - a NOTAR variant of the Hughes/MD500

series helicopter.

MD 600N - a larger version of the MD 520N.

MD Explorer - a twin-engine, 8-seat light helicopter.

See also

Cierva-Weir W.9

Helicopter

Tail rotor

Other alternatives to conventional tail rotor

Fenestron

Tip jet rotor

Coaxial rotors


2 of 3 14/04/12 4:04 PM

7/31/2019 No Tar

3/3

MD 900

Aerotcnical AC-14, Ducted exhaust

and rudders detail

MD Helicopters 520N NOTAR

Tandem rotors

Synchropter

References

^ kulikovair.com (http://www.kulikovair.com/Notar.htm)1.

^ ab Frawley, Gerard: The International Directory of CivilAircraft, 2003-2004, page 155. Aerospace Publications PtyLtd, 2003. ISBN 1-875671-58-7

2.

^ NOTAR Technology (http://www.mdhelicopters.com/products.php?id=NOTAR)

3.

External links

MD Helicopters (http://www.mdhelicopters.com

/products.php?id=NOTAR)

Youngcopter (http://www.youngcopter.com/) ,

manufacturer of the neo - a kit helicopter with Wankel

engine and NOTAR-like anti-torque system.

Retrieved from "http://en.wikipedia.org

/w/index.php?title=NOTAR&oldid=476970480"

Categories: Aerospace engineering

Helicopter components

This page was last modified on 15 February 2012 at

07:56.Text is available under the Creative Commons

Attribution-ShareAlike License; additional terms may

apply. See Terms of use for details.

Wikipedia is a registered trademark of the Wikimedia

Foundation, Inc., a non-profit organization.


3 of 3 14/04/12 4:04 PM

No Tar

Documents

Transcript of No Tar