when does a parachute have to open after the jumper jumps from the airborne plane .?

Answer 1

Before he hits the ground.

Answer 2

Think about the physics involved. The parachute works by creating a huge drag, providing resistenct to the gravity by using fluid friction of the air to slow the fall. If the parachute were open, it would fill rapidly at high speed and providing it is strong enough for the aircraft flight speed to remain intact, would then jerk the jumper out of the doorway and since the tail is behind the jumper, could simply drag the jumper into the rear stabalizer. Not good. Parachutes are folded the way they are so they open and fill relatively slowly to reduce the jerk, rapid decelleration, on the jumper because of the decelleration from falling speed to open parachute reduced speed of the fall. Terminal velocity is about 120 MPH for a limp human body and is achieved about 4-5 seconds after the jump starts. Parachutes are designed to take this speed, of terminal velocity, but not the higher speed of some flying aircraft, like jets. Small planes fly at slow enough speeds that you could deploy the parachute immediately, but you risk being dragged into the stabalizer, so the thing to do is fall a bit first to insure you clear the tail of the plane before deploying the parachute. Look at the movies of parachute troops during WWII. They used a tag line to pull the ripcord automatically at a short distance below the plane to insure they cleared the tail section.. Since it takes a couple of seconds to deploy, and the jumper in freefall is travelong at about 170 feet per second, it would be safe to assume something above about 5x170 feet ot at a minimum of 850 feet or so. Personally, I would pull the ripcord much earlier so I would have time to see something was wrong and still pull the reserve above 850 feet... My estimates of 850 feet and 170 feet per second are approximate, ball park, figures. The problem comes down to accurately knowing your alititude to insure you allow enough time for the parachute to fully deploy and slow the fall enough that you will survive the impact with the ground, which gravity says you will surely do...

Answer 3

It depends on the type of jump. In a free fall, the time of descent is determined by the altitude at which you leave the airplane. At 12,500 feet, a 185 pound man should have a free fall of about 50 seconds before deploying his chute. If he falls at maximum velocity (some skydivers can deploy a drogue to slow their fall if they are training) he will have about 50 more seconds to delpoy his reserve chute if he needs to. This is not a lot of time to realize there is a problem use your cord cutter, and deploy the reserve.

Skydivers that do not free fall use a static line. The parachute is deployed almost immediately after the jumper clears the plane. Because static line jumpers usually jump at extremely low altitudes, they have far less time to deploy at reserve, and some military static line jumpers are so low they don't even carry reserves because by the time they deploy it they've died...from "deceleration trauma".

Answer 4

umm well i think its300- 500 feet to get slowed down enough to not break your legs or worse. but if your talking airborne as in military, the chute opens as soon as they jump out of the plane. unless they do a HALO (high alt. low opening)

Answer 5

High enough off the ground so that the chute can fully deploy, and reduce the chutist's velocity to the terminal velocity. A thousand feet is ordinarily considered safe.

Answer 6

It depends on the initial jump elevation, speed, landing area, wind and a few other variables. If you don't know you shouldn't be jumping. These are things that you are taught before you ever get off the ground.

Answer 7

Before they hit the ground I hope

Answer 8

At least 100' before touching ground.