USPA Absolute Altitude State Record for Illinois Claimed

[michaelmullins 79]

 

 

Edited September 20, 2022 by michaelmullins

[pchapman 275]

Well, congrats. What can I say? Nice that you got things sorted out with the aircraft & bailout oxygen system and in-aircraft procedures THIS time....

 

Edited September 20, 2022 by pchapman

[dudeman17 308]

I guess those other pesky issues are securely under the rug. Press on!

[anomie168 16]

 well, this post explains the video that just went up in incidents

[2pac 6]

On 9/20/2022 at 11:59 PM, michaelmullins said:

 

 

Wooohoooo....awesome guys! Well done! 

 

[rdufokker 6]

With those temps and altitude, the next incident will be from a premature deployment still above 25,000 and either the canopy is in pieces or the jumpers aorta is in pieces.

[skypilotA1 67]

Rdufokker, you are incorrect, sir. There have been several deployments above 25,000 feet in the past. Most have been planned. There is no hard opening, no damage or injury. I believe you are confusing true airspeed in freefall with indicated airspeed in freefall.  Even at 41,000 feet, it still feels like you are falling at about 120 MPH. The opening shock at 25,000 is no different than at 4000 feet.  A few years ago, during the solar eclipse, we made multiple jumps and openings at and above 25,000 feet. These are called HAHO jumps. They are regularly used by the military for insertion into a neighboring hostile area, open high and drift across the border. I am happy to discuss any of the procedures, conditions or effects of any of these HALO oxygen jumps privately, in detail.

Edited September 27, 2022 by skypilotA1

[Coz999 0]

5 hours ago, skypilotA1 said:

Rdufokker, you are incorrect, sir. There have been several deployments above 25,000 feet in the past. Most have been planned. There is no hard opening, no damage or injury. I believe you are confusing true airspeed in freefall with indicated airspeed in freefall.  Even at 41,000 feet, it still feels like you are falling at about 120 MPH. The opening shock at 25,000 is no different than at 4000 feet.  A few years ago, during the solar eclipse, we made multiple jumps and openings at and above 25,000 feet. These are called HAHO jumps. They are regularly used by the military for insertion into a neighboring hostile area, open high and drift across the border. I am happy to discuss any of the procedures, conditions or effects of any of these HALO oxygen jumps privately, in detail.

My god….you just continue to spread misinformation. Yes, opening higher DOES increase G load and puts additional stress on the harness, chute and jumper. It’s unbelievable that people still trust you with their life. Here’s just a few references… 

https://uspa.org/Discover/News/hard-openings-and-how-to-avoid-them

https://chinese.skydivewanaka.com/wp-content/uploads/2011/09/high-altitude-jumps-1.pdf

 

 

 

 

[pchapman 275]

As for the side discussion of "how hard are high altitude openings", I'm guessing the answer is somewhere in the middle. So let's not be too harsh on each other.

We civilians don't know much about it. Standard references like the USPA say to watch out, but aren't there to provide background evidence.

Certainly for standard round parachutes, there's good technical, scientific evidence about much harder openings at high altitudes. True airspeed (for terminal velocity) at 40,000' will be twice what it is at sea level. So there's four times as much energy to dissipate. (Kinetic energy proportional to velocity squared). And maximum opening forces ended up being four times as great too.  And for 25,000', maybe somewhat more than twice as hard an opening. The lower air density also provides less restraint to the parachute filling out sideways and thus 'opening' faster.   This was all in the US military tests reported in the old, classic Theo Knacke book on aerodynamic decelerators. And probably well verified by modern computer models of parachute openings.

BUT THAT DOESN'T FULLY APPLY TO US... We have REEFED parachutes with sliders, and sliders are a well known way to vary the duration of the opening sequence, depending on the speed & pressure of the airflow. The military must have some data out there, but I haven't seen it.

SkypilotA1 provides some personal experience -- although I bet his HAHO square parachutes were probably rather unlike our small ZP sport parachutes. 

So I'm betting "Yes our parachutes will tend to open harder at high altitude so be careful... but not as massively harder as classic round parachute data tells us... but we don't have a lot of good evidence in the civilian world about whether the openings would be tolerably hard or dangerously so." 

Many of us might have had some opening on a regular jump where the opening was harder and maybe we hadn't slowed down enough from say some small-way freefly, so we kind of have a feeling that extra airspeed can make the G loads less comfortable.

(The New Zealand 'discussion paper' - thanks that's interesting.  That's on high altitude tandems and provides some graphs of G loading vs opening altitude, but unfortunately they give no source - other than 'US military' - and no info on types of parachutes, whether or how it was tested, or if they were simulations. The graph lines are all perfectly smooth and idealized. They make the point that one has to be ready for both main or reserve openings, and the hard openings skydivers occasionally get, and how those loads may push up against or cross the types of G loads and thus strengths the systems are tested & certified to.   HOWEVER, I WON'T TAKE THOSE GRAPHS AT FACE VALUE -- they make it sound like every tandem main canopy opening even at 3000' is 5 G, and every reserve opening at terminal is 8G, with loads of 4000 lb on the harness in the latter case if at say 500lb max load for the tandem. Certainly one has to look at the limits -- like a max weight passenger and a bad, hard, asymmetrical reserve opening. But their graphs seem too pessimistic with no quoted source of what the data really applies to.) 

Edited September 27, 2022 by pchapman
Changed my "So I'm betting..." conclusion to be more precise.

[Coz999 0]

3 minutes ago, pchapman said:

As for the side discussion of "how hard are high altitude openings", I'm guessing the answer is somewhere in the middle. So let's not be too harsh on each other.

We civilians don't know much about it. Standard references like the USPA say to watch out, but aren't there to provide background evidence.

Certainly for round parachutes, there's good technical, scientific evidence about harder openings. True airspeed (for terminal velocity) at 40,000' will be twice what it is at sea level. So there's four times as much energy to dissipate. (Kinetic energy proportional to velocity squared). And maximum opening forces ended up being four times as great too.  And for 25,000', maybe somewhat more than twice as hard an opening. The lower air density also provides less restraint to the parachute filling out sideways and thus 'opening' faster.   This was all in the US military tests reported in the old, classic Theo Knacke book on aerodynamic decelerators. And probably well verified by modern computer models of parachute openings.

BUT ... We have REEFED parachutes with sliders, and sliders are a well known way to vary the duration of the opening sequence, depending on the speed & pressure of the airflow. The military must have some data out there, but I haven't seen it.

SkypilotA1 provides some personal experience -- although I bet his HAHO square parachutes were probably rather unlike our small ZP sport parachutes. 

So I'm betting "Yes our parachutes will tend to open harder at high altitude so be careful... but we don't have a lot of good evidence in the civilian world about how much." 

Many of us might have had some opening on a regular jump where the opening was harder and maybe we hadn't slowed down enough from say some small-way freefly, so we kind of have a feeling that extra airspeed can make the G loads less comfortable.

(The New Zealand 'discussion paper' - thanks that's interesting.  That's on high altitude tandems and provides some graphs of G loading vs opening altitude, but unfortunately they give no source - other than 'US military' - and no info on types of parachutes, whether or how it was tested, or if they were simulations. The graph lines are all perfectly smooth and idealized. They make the point that one has to be ready for both main or reserve openings, and the hard openings skydivers occasionally get, and how those loads may push up against or cross the types of G loads and thus strengths the systems are tested & certified to.   HOWEVER, I WON'T TAKE THOSE GRAPHS AT FACE VALUE -- they have

Good points but how about the current civ canopies aren’t TSO’d for higher openings, as well as, reserves? Aren’t there warning labels regarding these?

[pchapman 275]

6 minutes ago, Coz999 said:

Good points but how about the current civ canopies aren’t TSO’d for higher openings, as well as, reserves? Aren’t there warning labels regarding these?

Good point. Can't check now but yes PD is one company that has made some estimates on their data panels. Not sure of their source but they aren't dumb either. (And they also deal with not just say tandem reserves, but military tandem reserves, where higher altitudes may be more of a "thing".)  Maybe someone has a pic to post.

[kleggo 143]

On 9/20/2022 at 2:59 PM, michaelmullins said:

 

 

 

not me, thanks