Page 12 - World Airnews Magazine April 2021_intro

HELICOPTERS

AERODYNAMIC ROTOR

HEAD CASING MAKES

HELICOPTERS FLY FASTER

By Petra Wiemayer

ertical take-off and landing

Vhelicopters are indispensable in
places that cannot be reached by road and
where no runways are available for aircraft.

This is the case in mountain rescue

operations, on oil platforms, for medical
care in remote areas or after accidents.

In such instances, helicopters are usually
used, but unlike airplanes, they not only
consume more energy but are also able to
reach lower speeds in forward flight.

This is because the rotor generates high

air resistance in flight. However, the heli-

copter needs the rotor to take off vertically

and maintain a stable position in the air.
With the Airbus demonstrator RACER

(Rapid And Cost-Effective Rotorcraft), an

international team of scientists now wants

to develop an aircraft that can reach a
speed of 400 kilometres per hour in for-

ward flight and is at the same time quieter
and more environmentally friendly than

conventional helicopters.
That’s why the RACER not only has a
rotor, but also wings like an airplane. This
allows it to generate lift in an aerodynami-

cally efficient manner and reduces the load

on the rotor.
SAVING ENERGY THROUGH OPTI-
MAL ROTOR SHAPE

At a flight speed of 400 km/hour, the

helicopter’s aerodynamics are essential.
That’s why researchers at the Technical This gives rise to both so-called attached methods. However, they do not rely on

University of Munich (TUM) have joined flow, which follows the contour of the ob- technology alone.

forces with Airbus Helicopters (AH) in ject - as is the case, for example, on a wing

the FURADO(Full Fairing Rotor Head in cruise flight - and so-called detached “There are many setting variables in flow

Aerodynamic Design Optimization) project flow, which has a particularly high drag, the simulation, and these must be chosen correct-

to develop an aerodynamic fairing or researchers explain. ly to get a reliable result. This requires both

covering for the rotor head. expertise and experience,” said Breitsamter.
“Detached flow occurs when, for exam-

“The components that cause the most ple, the contour of the body is cut off with Patrick Pölzlbauer was able to design the

drag in helicopters during cruise flight an edge, as in the case of a blunt vehicle shape of the rotor head in such a way that

are the fuselage and the rotor head,” said tail on a car,” said TUM professor Christian only small turbulences occur, as the flow re-

Patrick Pölzlbauer, a research associate Breitsamter. mains attached there for as long as possible.

at the Chair of Aerodynamics and Fluid He has also developed an “optimisation

Mechanics. “Then the flow detaches and there is chain for the aerodynamic design of

Geometries have already been developed turbulence. This leads, for example, to dirt geometries” that can theoretically be

for the fuselage that cause as little drag as particles landing on the tail.” Such blunt applied to the development of fairings for
edges also exist in the rotor head area at
possible. However, since the aerodynamics the interface with the rotor blades. other rotor models.
of the rotor are very complex, an aerody- “The plan is to manufacture the devel-
namically optimized full fairing for the rotor NOVEL AERODYNAMIC ROTOR oped rotor head fairings and test them on

head is a greater challenge. That is because HEAD FAIRING the flight demonstrator,” Pölzlbauer said.

the rotational motion of the rotor leads to a The researchers perform simulations of These first flight tests of the RACER will

permanent change in the inflow conditions such complex aerodynamic processes using show whether reality and results from the
at the rotor blade. advanced software and computational simulator match up. Q

World Airnews | April 2021
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