The MD520N is a variant of the MD500 helicopter which was originally designed in the 1960s by Howard Hughes (Hughes Helicopters) for the US Army.
Building on the proven design of the MD500, the MD520 introduced a revolutionary design with its NOTAR (NO Tail Rotor) system, which was added in 1990, replacing the conventional tail rotor, to create a safer and extremely quiet aircraft. The MD520 is now used by law enforcement, training schools and for private ownership worldwide due to its low noise footprint and high reliability.
Our MD520 looks fresh in its recently-received coat of paint, and is in the process of a number of avionics upgrades. The 5 bladed fully-articulated rotor system means the helicopter is incredibly smooth, very manoeuvrable and exciting to fly! It’s available with ICE Helicopters for private hire and type ratings.
How does the NOTAR work?
Replacing a conventional tail rotor, the MD520 is equipped with a different type of anti-torque solution called the NOTAR.
It was designed by Hughes Helicopters and uses a large fan at the forward end of the tail boom to push high velocity air towards the rear. Some of this air ejects out of two long & thin slots (venting downwards) on the right hand side of the tail boom, and some comes out of a nozzle (directionally controlled by the pedals) at the end of the boom.
The air coming out of the side of the boom is fast moving and therefore low pressure; this causes the [also fast moving] downwash from the main rotor to hug the tail boom, providing enough of a pressure differential on the tail to counter most of the torque effect from the rotor system. Think of how a wing or rotor blade can be seen as having a lower pressure on the top side, causing lift in that direction – now imagine it sideways.
This force is then supplemented by the rotating jet nozzle at the back, which helps provide variable directional control, as well as the vertical fins which are mainly for ‘balance’ during forward flight.
A system which is still very ahead of its time!