Sonic boom: The science behind the bang
When planes fly faster than the speed of sound – around 761mph – a sonic boom is created.
Travelling at this speed, also known as Mach 1, the aircraft displaces the air and creates pressure waves that become compressed and then released in a shock wave.
Sonic booms have been heard on numerous occasions in the UK.
In early March, a sonic boom was heard over Leicestershire as RAF fighter jets were scrambled to escort an aircraft which had lost communications.
A Ministry of Defence (MOD) spokesperson said: "Typhoon aircraft from RAF Coninsgby offered assistance to a civilian aircraft and were authorised to fly supersonic."
They also confirmed that the "civilian aircraft was directed to Stansted Airport and landed safely".
The RAF maintains a pool of quick reaction alert Typhoons at readiness 24 hours a day, 365 days a year to respond to any potential threats.
"A significant part of the RAF's primary role [is] to defend the UK and UK interests overseas", the RAF said.
In 2021, a sonic boom was heard across areas of London, Cambridgeshire and Essex, with doorbell camera footage capturing the sound of the event.
The science behind the boom
Firstly, when travelling at subsonic speed – anything below 767mph – pressure waves move away from an aircraft in all directions.
At the speed of sound, 767mph, the waves compress to form a shockwave.
When the speed of an aircraft exceeds the speed of sound, as NASA explains on its website, the air reacts like a fluid.
As a supersonic object moves through the air, molecules are pushed out of the way with huge force, creating a shockwave – like a boat creating a wake in the water.
These molecules, or waves, then merge into one single shockwave cone of pressurised, built-up air molecules which move in all directions and extend all the way to the ground.
And it is the release of pressure, after the build-up of a shockwave when the sound of the sonic boom is heard.
According to the US Air Force, an aircraft will continuously create shock waves, producing sonic booms along its flight path.
They also state that "from the perspective of the aircraft, the boom appears to be swept backwards as it travels away from the aircraft".
If an aircraft was to sharply change direction or pull up, the sonic boom would then strike the ground in front of the aircraft.
There are multiple factors which may influence a sonic boom, including the weight, size and shape of an aircraft.
The larger an aircraft is, the more air it must displace and the more lift it must create to sustain flight so, the larger the aircraft, the larger the boom.
Additionally, altitude, attitude, flight path and weather or atmospheric conditions can also affect the size of a sonic boom.
Related topics
Join Our Newsletter
