Just as wood can float on water, so too does helium on air. Primarily, it would be practically impossible to build a helium balloon to reach these altitudes. There are several limiting factors to this question. The question then becomes, why not jump from even higher? Why not jump from the true edge of space at 100km? The increasing drag around Baumgartner – due to the thicker atmosphere closer to the surface – will eventually slow him below the speed of sound as he continues his descent, until eventually he deploys his parachute at subsonic speeds. The shock will be maintained constantly in the cone around Baumgartner, keeping fairly consistent pressures and no longer being as chaotic.Īs long as he keeps all of his limbs within the shock cone, Baumgartner should not experience too much difficulty in continuing to fall supersonically. If he accelerates past Mach 1.2 Baumgartner will no longer be in transonic flow. EPA/Balazs GardiĮventually, the drag will balance Baumgartner’s weight and he will reach terminal velocity. At this point, Baumgartner will have truly become supersonic.īaumgartner’s trip to the stratosphere will take just under three hours. At these speeds, the air in front of Baumgartner cannot avoid his body until it passes through the shock, an extremely thin layer where pressure, temperature and density increase dramatically. If he reaches the speed of sound (Mach 1), a bow shock will form in front of his head and in a cone around him. This mixture of flow speeds can result in a loss of control and Baumgartner may be buffeted around due to dramatic changes in pressure. That is, Baumgartner’s body will be surrounded by air currents travelling a range of speeds, from Mach 0.8 to the speed of sound and beyond. The air in front of his head will become more compressed as it is no longer able to move as quickly around his body.Īt roughly 80% of the speed of sound (or Mach 0.8) shock waves will begin to form around his body as the flow becomes “transonic”. The problem is that at such high speeds, more extreme effects will begin to take place.Ī test dive from an altitude of nearly 22km was a great success.Īs Baumgartner approaches the speed of sound, he will experience more and more drag. Will Baumgartner reach this velocity and become supersonic?

In the stratosphere, the speed of sound is approximately 1,100km/h. Since Baumgartner will be jumping from much higher in the atmosphere, where the air density is less that 1% of that at ground level, his terminal velocity will be more than 1,000km/h. Due to this limitation, conventional skydivers jumping from altitudes of less than 5km can’t reach speeds greater than 200-300km/h.īut the amount of drag depends on the density of the surrounding air – the more air flowing over the skydiver, the higher the drag. But as they speed up, the drag from the surrounding air reduces their acceleration until they reach terminal velocity.Īt this point, the drag balances the gravitational (or weight) force, and they can accelerate no more. As skydivers fall towards Earth, they are accelerated by gravity.

AAP Image/Red Bullīreaking the speed of sound is a challenge for several reasons. The mission will be streamed live ( almost) on various websites, including the Red Bull Stratos site.īaumgartner prepares to exit the capsule at an altitude of 22km in his March 16 test jump. Once at an altitude of 120,000 feet, Baumgartner will exit the ascent capsule and free-fall back towards Earth. The balloon will provide the necessary buoyancy to lift Baumgartner above the previous world record of just under 35km, held by his mentor, retired US Air Force Colonel Joseph Kittinger.

If laid flat, the fully inflated balloon would cover more than 40 acres (roughly 160,000m 2 ). While not at the technical boundary between the Earth’s atmosphere and space, at 100km of altitude (known as the Kármán Line), Baumgartner’s remarkable feat will still take place in near vacuum.Īt roughly 11.30pm tonight (AEST) Baumgartner will ascend in his capsule to the stratosphere pulled upward by a balloon filled with 850,000m 3 of helium. Austrian skydiver Felix Baumgartner will attempt to make history early tomorrow morning (AEST) when, weather permitting, he jumps from a capsule at an altitude of 120,000 feet (more than 36km).Īll going well, Baumgartner will become the first person to break the speed of sound in free-fall.

Speed of sound at altitude