Can a commercial airplane break the speed of sound?

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Can a commercial airplane current breaking the sound speed barrier? We answer this question, Your answer is more interesting than you imagine.. Photo by SevenStorm JUHASZIMRUS

In recent days there have been several publications and comments on social networks where it is claimed that several commercial aircraft due to wind currents "they broke the sound barrier", a statement that generated hundreds of surprised comments and likes, but reality is not as simple as you think.

Can a commercial airplane fly faster than the speed of sound?

In general terms, no, A commercial airliner cannot break the sound barrier.. The speed of sound is approximately 1.235 km/h at sea level, and most commercial airliners have a maximum cruising speed of around 900 km/h.

There are two main reasons why a commercial airliner cannot break the sound barrier.:

Design

Commercial airplanes are not designed to fly at supersonic speeds.. Its aerodynamic design, Materials and systems are not capable of withstanding the extreme forces and temperatures generated by exceeding the speed of sound..

• Aerodynamics: Aircraft aerodynamics change dramatically at supersonic speeds. Shock waves form around the plane, which increases resistance and makes control difficult. Commercial airplanes are not designed to withstand these conditions..
• Materials: The materials used in the construction of commercial aircraft are not strong enough to withstand the high temperatures and stress generated by flying at supersonic speeds.. Special materials are needed, such as titanium alloys, which are lighter and heat resistant.
• engines: Commercial airplane engines are not powerful enough to propel the plane to supersonic speeds.. Special motors required, such as afterburning turbojets, that generate additional thrust.

Efficiency

Efficiency: Flying at supersonic speeds is extremely inefficient. A large amount of fuel is required to overcome air resistance at such high speeds., making supersonic flight prohibitively expensive.

• fuel efficiency: Flying at supersonic speeds is extremely inefficient. Fuel consumption increases exponentially as the speed of sound approaches.. This makes supersonic flight prohibitively expensive..
• Environmental impact: Supersonic flights generate a loud sonic boom that can be annoying to people on the ground.. What's more, Supersonic planes emit more pollutants than subsonic planes.
• Regulations: Supersonic flights are prohibited over many populated areas due to sonic boom. Aeronautical authorities also impose restrictions on the altitude and speed of supersonic flights.

Nevertheless, there are some exceptions:

• The Concorde: The Concorde It was a supersonic commercial airliner that operated between 1976 and 2003. It could reach speeds of up to Mach 2,04 (2.179 km/h). Nevertheless, The Concorde was a very expensive plane to operate and only 16 units.
• military flights: many military aircraft are designed to fly at supersonic speeds. These aircraft are usually used for combat or reconnaissance missions..

Speed ​​of sound and how to calculate it

It is mistakenly believed that if a plane shows a speed equal to or greater than the 1.235 km/h, this one already broke the speed of sound, but as we are going to demonstrate, this value is not fixed and depends on many factors., what's more, There is a difference between indicated speed and ground speed..

The speed of sound is the distance that a sound wave travels in a given medium during a given time.. It is defined as the square root of the elastic modulus of the medium divided by its density..

In mathematical terms:

v = √(E/r)

Where:

• v is the speed of sound (m/s)
• E is the modulus of elasticity of the medium (Pa)
• ρ is the density of the medium (kg/m³)

Modulus of elasticity is a measure of a material's ability to resist deformation. Density is a measure of the mass of a material per unit volume.

In air at 20°C:

• Modulus of elasticity (E): 1,42 x 10^5 Pa
• Density (r): 1,2 kg/m³

Substituting these values ​​into the equation:

• v = √(1,42 x 10^5 Pa / 1,2 kg/m³) = 343 m/s
• The speed of sound in air at 20°C is 343 m/s.

Factors affecting the speed of sound:

• Temperature: The speed of sound increases with temperature.
• Pressure: The speed of sound increases with pressure.
• Humidity: The speed of sound increases slightly with humidity.
• Half: The speed of sound varies depending on the medium. It is greater in solids than in liquids and in liquids than in gases.

Therefore, a commercial airplane flying at a speed greater than 1.235 km/h is not necessarily breaking the sound barrier if the air temperature is above 20°C.

Indicated speed and reference to the terrain

To go even deeper into the matter, We must know that there are different measurements to know the speed of an airplane, these are:

• indicated speed (IAS): It is the speed shown on the airspeed indicator (BUT) of the airplane. It is measured in knots (kts) or miles per hour (mph). The IAS is the speed of the plane with respect to the air around it..
• Ground speed (GS): It is the actual speed of the plane over the Earth's surface.. It is measured in knots (kts) or miles per hour (mph). The GS is calculated taking into account the IAS and the wind speed.

differences:

• Reference: IAS is measured with respect to air, while the GS is measured with respect to the terrain.
• Wind impact: The IAS is not affected by wind, while the GS does. Headwind reduces GS, while the tailwind increases it.
• Importance: The IAS is important for the control of the aircraft during flight, while GS is important for navigation and flight planning.

Example:

An airplane is flying to an IAS of 100 kts with a headwind 20 kts. The GS of the aircraft will be 80 kts.

In summary, Although it is possible for a commercial airplane to break the sound barrier, It's not something I can do regularly or efficiently..

I close with some interesting facts I found about the sound barrier:

• The sound barrier was broken for the first time in 1947 by pilot Chuck Yeager in the Bell X-1 experimental aircraft.
• The Concorde was the first supersonic commercial airliner to enter regular service..
• Supersonic flight produces a loud sonic boom that can be annoying to people on the ground.
• Supersonic flights are prohibited over many populated areas due to sonic boom.

What did you think of this reading?? I read them in the comments…

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