If you've ever flown on an Airbus A220, you may have noticed a distinct sound that the aircraft produces, particularly during ground operations and on approach. This sound has been affectionately dubbed the "whale noise," and it's a topic of interest for aviation enthusiasts and passengers alike. In this article, we'll take a closer look at what causes this sound and why it's unique to the A220.
First, let's start with some background on the Airbus A220. Originally designed by Bombardier as the C Series, the aircraft made its first flight in February 2015 and entered service with Swiss Air in July 2016. In October of that same year, Airbus acquired a majority stake in the C Series program and rebranded it as the A220. The aircraft currently has two variants, the A220-100 and A220-300, with rumors of a stretched A220-500 version in the works.
Both the A220-100 and A220-300 use Pratt and Whitney PW1500G Series engines, which are a type of geared turbofan engine. While other aircraft, such as the A320 Neo series, use geared turbofan engines from the PW1000 family, the whale noise is most prevalent on the A220's PW1500Gs.
So, what causes the whale noise? According to Pratt and Whitney's VP and Regional Jet GTF Engine GM, Graham Webb, the noise is a low-power transient combustor tone caused by pressure changes against the combustion structure. The resulting effect and sound is similar to blowing over the opening of a bottle. Webb also suggests that all engines have a combustor tone, but the quiet nature of the PW1500G makes this noise more noticeable on the A220.
But why is the PW1500G so quiet in the first place? The answer lies in the design of the geared turbofan engine itself. In a traditional turbofan engine, the fan is connected to the turbine via a shaft, so they must turn at the same speed. However, turbines are more efficient at high speeds, while the fan is more efficient at a lower speed. With the design of the geared turbofan engine, the fan is geared to turn at a relatively slower speed than the turbine. This allows both the turbine and the fan to spin at two different speeds where they are both optimal for efficiency. The reduction in fan speed also reduces engine noise from the fan itself, which is why the PW1500G is so quiet compared to other engines.
In conclusion, while the whale noise of the A220 may sound strange, it's actually a byproduct of the quiet and efficient geared turbofan engine that powers the aircraft. So, the next time you fly on an A220 and hear that distinctive sound, you can rest assured that it's just the sound of an efficient and innovative engine at work.
Images in this postAirBaltic A220-300 at DUS (Photo: Paul Buchroeder) via plnspttrs.net
PW 1500G Engine (via flightglobal.com) via cloudfront.net