3 ms·

Besides the extra weight, what is the difference between a skydiver and someone wearing a jetpack when deploying a parachute?

ratsbane 17y ago
In the case of the jetpack the parachute is launched upward with rockets. This takes extra time: the time it would take for the operator or system to detect engine-out and initiate parachute launch, then the time it would take for a rocket(s) to launch the parachute up to where it could be, then the time for the uprush of air to catch the canopy. Here's a link to an article about the ballistic parachute fitted to Cirrus SR20/22 aircraft. http://www.cirruspilots.org/content/CAPSHistory.aspx http://www.cirruspilots.org/content/CAPSHistory.aspx There's one mention of a low-altitude parachute deployment: "one activation occurred at too low an altitude to fully inflate the canopy (witnesses report 200 feet above ground), and another activation where the rocket took an unusual trajectory resulting in a failure to open the canopy."
nfg 17y ago
Well isn't the extra weight pretty significant in this case? The jetpack obviously can't be jettisoned.
bonsaitree 17y ago
I'm not sure I understand your question. A skydiver is transitioning (abruptly) from unpowered free-fall into unpowered, albeit greatly slowed, descent. The jetpack user is transitioning from powered, controlled horizontal flight (with its characteristic 6 degrees of freedom) into unpowered descent. A back-up chute for the skydiver has essentially, but not quite, the same flight characteristics and initial deployment conditions as a main. Parachutes in a stable flight configuration are incredibly safe and reliable, but it's GETTING that 6-axis dynamic flight-body INTO that stable flight configuration that's the real challenge. It's relatively easy to design a system for even extremely large, static, dead-weights (such as cargo or even battle tanks) to be safely launched, arrested, and landed via parachute. It's an entirely different problem when your safe chute deployment must take into account the wide variance in airspeed, pitch, yaw, altitude, and environmental influences which powered free flight allows. Imagine a worse-case scenario where all power was lost just after a major inadvertent yaw maneuver (it appears to be designed to minimize yawing). That's a sticky-wicket to solve repeatedly and reliably.

ratsbane 17y ago

In the case of the jetpack the parachute is launched upward with rockets. This takes extra time: the time it would take for the operator or system to detect engine-out and initiate parachute launch, then the time it would take for a rocket(s) to launch the parachute up to where it could be, then the time for the uprush of air to catch the canopy. Here's a link to an article about the ballistic parachute fitted to Cirrus SR20/22 aircraft. http://www.cirruspilots.org/content/CAPSHistory.aspx http://www.cirruspilots.org/content/CAPSHistory.aspx There's one mention of a low-altitude parachute deployment: "one activation occurred at too low an altitude to fully inflate the canopy (witnesses report 200 feet above ground), and another activation where the rocket took an unusual trajectory resulting in a failure to open the canopy."

nfg 17y ago

Well isn't the extra weight pretty significant in this case? The jetpack obviously can't be jettisoned.

bonsaitree 17y ago

I'm not sure I understand your question. A skydiver is transitioning (abruptly) from unpowered free-fall into unpowered, albeit greatly slowed, descent. The jetpack user is transitioning from powered, controlled horizontal flight (with its characteristic 6 degrees of freedom) into unpowered descent. A back-up chute for the skydiver has essentially, but not quite, the same flight characteristics and initial deployment conditions as a main. Parachutes in a stable flight configuration are incredibly safe and reliable, but it's GETTING that 6-axis dynamic flight-body INTO that stable flight configuration that's the real challenge. It's relatively easy to design a system for even extremely large, static, dead-weights (such as cargo or even battle tanks) to be safely launched, arrested, and landed via parachute. It's an entirely different problem when your safe chute deployment must take into account the wide variance in airspeed, pitch, yaw, altitude, and environmental influences which powered free flight allows. Imagine a worse-case scenario where all power was lost just after a major inadvertent yaw maneuver (it appears to be designed to minimize yawing). That's a sticky-wicket to solve repeatedly and reliably.