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LearningTOfly

Deployment velocity versus opening speed

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Here's a thought I've been wondering about recently:

With regards to hop and pops- the speed that the jumper is falling at when they deploy during a h&p is usually much less than terminal (say 80 mph). Now I havne't done many hop and pops (or at least enough to get my own 'average')... but on one recent hp I do remember the opening being a little 'brisker' than normal- and this was with no intentional variation in packing.

I do recall reading- and this is a thought that, taken for granted, would make sense- "a slower deployment speed (on the part of the jumper) would mean that the speed at which the canopy opens should be slower.

After my h&p, though, I was thinking- shouldn't it be opposite- a slower deployment speed means that less 'lift' is generated by the slider to retard the opening, and thus the canopy will open, in general, quicker than it would in freefall? ..hence a little more opening 'shock'

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From personal experience after doing 4 Hop and Pops at the end of my AFF then doing a full height jump straight after, the full height felt like a harder opening.
But I certainly don't have the experience to provide you with an answer.

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After my h&p, though, I was thinking- shouldn't it be opposite- a slower deployment speed means that less 'lift' is generated by the slider to retard the opening, and thus the canopy will open, in general, quicker than it would in freefall? ..hence a little more opening 'shock'

Depending on design, some sliders will make a canopy snivel a long time at high speeds, due to the air holding the slider up. One of the canopy designers could give you all the reasons and equations. I've simply observed it. With that said, if you're going slow, the opening is usually slow and the opening shock light. There are other variables that will affect this, so it's not a hard and fast rule. I find my slowest openings are when I'm in freefall really close to the ground. Must be the thicker air.:D:D:o

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I had a rather brisk opening on a hop 'n' pop too. I originally thought it might have been the packer. All I know is that cobalt owners say that if they deploy at normal speed the often get a hard opening. Its only when they deploy at speeds faster than 120 that the designed slow opening happens. Maybe is kinda the same thing with deploying a 'regular' canopy at slower than usual speed.

?

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I have come down off of hopnpops surprised to find my shoes still on my feet...... and had equally hard openings from terminal... on a canopy that is predominantly known for slow soft openings....

there are a lot of variables that determine opening shock.......

good luck trying to quantify all of them.... some of them include, packing-line trim-and body position.

Roy

PS: any canopy.... irregardless of design can inflict a severe opening shock.
They say I suffer from insanity.... But I actually enjoy it.

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I do recall reading- and this is a thought that, taken for granted, would make sense- "a slower deployment speed (on the part of the jumper) would mean that the speed at which the canopy opens should be slower.



noob question - isn't the point more the fact that YOU are being slowed down less from sub-terminal than at terminal, so the shock feels less?

I've only done 2 H&Ps (not counting my SL jumps cos the packjob is different) - the second was so slow i started wondering whether i was having a mal! (I loved it :D opening shock is the only part of any skydive that i hate!)
Skydiving: wasting fossil fuels just for fun.

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isn't the point more the fact that YOU are being slowed down less from sub-terminal than at terminal, so the shock feels less?



You're initial speed is less, and your final speed is the same, yes, but the other big variable is the time it takes for the decceleration. The time it takes is controled by quite a few factors, including the design of the canopy and how it reacts at the different air speed.
Remster

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Remember to consider the speed of the plane.

Horizontal speed is no different than vertical speed, when it comes to opening a parachute on the hill.

Some airplanes (like King Airs or Caravans) will fly faster, some planes (like Otters) will fly slower. Faster planes may be flying as fast as 120 knots. 120 knots is 138 MPH - meaning a faster than normal airspeed.

Don't assume that just because you're pulling on the hill your deployment speeds are slow.

_Am
__

You put the fun in "funnel" - craichead.

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Some airplanes (like King Airs or Caravans) will fly faster, some planes (like Otters) will fly slower. Faster planes may be flying as fast as 120 knots. 120 knots is 138 MPH - meaning a faster than normal airspeed.



Not sure who was flying the caravan you were in, but as our pilot last summer said: "it's a cessna...fly it like one." For bigger RW groups, we started complaining about the 85 knot jump runs as you didn't have much control for the first few seconds after exit.



I got a strong urge to fly, but I got no where to fly to. -PF

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True... I was figuring that most hop and pops would be done from smaller aircraft types- 182, 206, 208 sure maybe an otter- all relatively slow- between 80 and 100 mph. The KA- of course- picks up the pace a little in order to stay afloat.

The number of variables going into the problem are relatively many- I was looking to see if anyone out there had run into this also- and discovered anything interesting about deployment speeds.

Thanks for the responses all -blue skies.

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