Skydiving Downward Velocity FAQ

So you have the desire to jump out of a perfectly good airplane. Thousands do it every day. But what are the physics behind your jump?

The moment you exit the aircraft, you are immediately slowed down from the speed the plane is travelling by air resistance, and you also start dropping toward the ground, drawn by gravity.

Newton's law of gravity

Sir Isaac Newton was the discoverer of gravity, having made some profound observations, which he wrote down in his Philosophi Naturalis Principia Mathematica.

It was understood that the physics of skydiving were dictated by gravity, as laid down in Newton's law, and for all practical purposes, the terminal velocity of a skydiver was established to be 124 mph.

This figure was arrived at by measurement of a person laying prone, face down while falling, therefore offering the most amount of resistance, or drag. This, however, is where Newton's first law required correction, as his mathematical formulas all assumed that the body falling was a fixed object. The brilliant Swiss mathematician Leonhard Euler found flaws with Newton's law and set out to write a formula that would apply to a falling body that was flexible.

Varying the velocity

A parachutist is not a fixed body, and there are instances where the jumper aligns himself in a head-down position, with arms alongside the body, to offer the least amount of wind resistance. In such an alignment, individuals routinely attain speeds of 200 mph, which is the same as that of a steel ball dropped from a great height.

Terminal velocity is normally attained in a matter of about 15 seconds, and the duration of the thrill of freefall is dependent on the altitude you start out from.

Recently, there have been some new developments in clothing worn by people partaking in the sport, where there are membranes sewn onto the jumpsuit that connect from the lower arm to the hips, acting like wings, allowing acrobatic maneuvers to be performed.

Kittinger's record velocity

The absolute speed and altitude record was set by U.S. Air Force pilot Captain Joseph William Kittinger during aerospace research. He became airborne in a helium balloon over the desert of New Mexico on Aug. 16, 1960, eventually reaching an altitude of 102,800 feet. The purpose of the experiment was to test a new type of two-stage high-altitude parachute that would allow the pilots of the new and coming generations of high-flying aircraft to safely bail out at those altitudes. It was just in May 1960 when the Russians shot down the U2 spy airplane piloted by CIA pilot Francis Gary Powers, so with new and higher-flying aircraft, new life-saving technology was needed quickly.

Kittinger was in freefall for a total of four minutes and 36 seconds, during which time his velocity attained 614 mph. It is highly probable that, if it were not for a drogue chute attached to his main chute, he would have exceeded that speed. Theoretically, he would have exceeded the speed of sound, which is 768 mph at sea level.

His main chute opened at 18,000 feet after free falling for 84,800 feet. His accomplishments have never been duplicated. They stand as USAF records only, because they were never submitted as an official record, due to the sensitive nature of the research being performed.

Attempts using the latest, high-tech equipment may set new records. When ascending to such great heights, the only way to survive the harsh environment is to wear a pressurized space suit.

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