Our mission is to ensure Airlander will be efficient and environmentally friendly in every way. Noise pollution is one of the factors we take into consideration. While a maximum noise level is not typically a legal requirement for aircraft like Airlander, we are considering noise from the outset of Airlander’s design. Countries like Germany and Switzerland already include take-off and landing noise in their fee structure for the use of airports and we expect that other countries and regulators will follow.
Less power equals less noise
A large proportion of Airlander’s lift is generated by the helium-filled hull, so Airlander requires much less power to fly than an equivalent aeroplane and even less compared with an equivalent helicopter. This means Airlander requires much less powerful engines for the same useful load, burning less fuel and generating less noise energy as a result.
Engine and motor technology
Electric motors are of course very quiet, but what about the engines that are used in the hybrid-electric configuration, and in the all-combustion configuration that we expect to be used for some time in surveillance roles?
Alongside the lower power requirement, we use highly efficient, state-of-the-art turbocharged piston engines. A turbocharger extracts waste energy from the exhaust gases, recycling it to make the engine more efficient. This also reduces the exhaust noise by slowing down the exhaust gases.
Airlander’s engines are similar to medium size truck engines, compared with the massive turbine engines of an aeroplane. Turbine engines rotate at 10,000 rpm or more, while Airlander engines rotate at 4,000 rpm or less. The lower rotation speed also reduces noise levels.
When Airlander is in a hybrid-electric or all-electric configuration we can expect the noise output to be even quieter, just like the reduced noise from an electric car.
Aerodynamic noise is created by airflow around the surfaces of the aircraft. This is especially loud when flying at low altitude and high speeds. Airlander flies more slowly than a conventional aircraft and therefore generates significantly less aerodynamic noise.
Approach to land
On approach Airlander is very quiet, firstly due to a landing speed that is about one quarter that of a large aeroplane. Secondly, on a conventional aeroplane there are features on the wing that are used to create more lift and more drag to help the aircraft fly at a slower speed. That extra drag creates noise, just like when you open your car window while driving. Airlander does not rely on this technique to slow down and land, eliminating those noises.
Keeping a light footprint
Airlander will be quieter than the conventional aeroplanes we are used to in many ways; the low noise and low vibration will make the journey more enjoyable for those onboard. The design of Airlander also means the noise is quieter for those on the ground - aircraft noise is usually a key environmental concern for communities impacted by aviation operations. In the UK, over one million people are exposed to aircraft noise above levels recommended for the protection of health. Airlander will not introduce significant new noise pollution, which will be especially pertinent around built-up areas and transport hubs.