Skydiving
Red Bull Stratos: Breaking the barrier of sound
Is it really possible for a human being to break the speed of sound in freefall?
3 min
Red Bull Stratos : The science behind
Check out the latest news about the Red Bull Stratos, mission to the edge of space!
Here’s what the experts on the Red Bull Stratos team face as they attempt to write a new chapter in aerospace history.
What would happen to a human falling to Earth faster than the speed of sound? Would a spacesuit provide sufficient protection? Would GPS equipment function? Could a drogue parachute provide adequate stabilization?
Worldwide, the answers to such questions are vital. Like any transportation system, high-altitude flights need safety procedures; but currently, researchers don’t know if it’s possible to bail out from ultra-high altitudes.
Aviators and astronauts look to extend the boundaries of their exploration and – with the opening of facilities like SpacePort America – the day when everyday people can become space tourists is on the horizon.
The mission’s findings may point the way toward developing escape systems for the space tourists of the future, as well as for the pilots and astronauts who already need suborbital systems today.
What does it mean to “break the speed of sound”?Breaking the speed of sound refers to catching up with – and surpassing – the speed at which sound waves are produced in the air. The speed of sound is affected by temperature: where the air is colder, sound travels more slowly. At about 30,480 metres above sea level, Felix will need to accelerate to about 1,110 kilometres per hour to match the speed of sound, known as Mach 1.
Is there really a sound barrier? No, it’s a figure of speech. The concept stems from the mid-20th century, when early high-speed aircraft sometimes experienced extreme instability, and even broke up, as they neared the speed of sound. Today we know that such instability is caused by shock waves that build up in the “transonic” zone – the range of speeds approaching the speed of sound. Once an object passes through that imaginary “sound barrier” to catch up with and surpass the speed of sound, flight is smooth.
What other hazards will Felix face as he attempts to break the speed of sound? The list includes temperatures well below freezing, too little oxygen to breathe, the tendency to spin uncontrollably and air pressure so low that without protection blood is said to “boil” with vapour bubbles.
What will protect Felix from these hazards? Strategies include intensive training to prepare him for possible instability: the team has developed a test program in which he jumps from successively higher outdoor altitudes, as well as a choreographed step-off from the capsule so that he achieves a streamlined position. Equipment is also important: an innovative full-pressure suit and helmet provide oxygen, protection and pressurization, and a special drogue parachute is available for stabilization if necessary.
Why won’t Felix reach terminal velocity before he breaks the speed of sound? Terminal velocity, a concept familiar to skydivers, refers to the point at which a falling object stops accelerating. Drag, or resistance, is one of the key factors causing terminal velocity. Bailing out at a very high altitude, where the air is thin, should enable Felix to break the speed of sound before reaching more dense air that will create drag and eventually result in his terminal velocity.
What can be learned by breaking the speed of sound in freefall? The data gathered about the effects of supersonic freefall can provide valuable tools for researchers looking to develop safety procedures for the pilots and astronauts of today and tomorrow. Proof that a human can break the speed of sound in freefall could provide support for the development of sub-orbital bailout procedures that currently don’t exist.