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RIG for the upcoming supersonic skydive

 

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obelixtim  (D 84)

Apr 5, 2012, 3:55 PM
Post #26 of 38 (1543 views)
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Re: [skydiverek] RIG for the upcoming supersonic skydive [In reply to] Can't Post

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Who knows. I know PD has military reserve canopies that are designed to open for 10 (ten) seconds. Maybe it is similar in this case?

Yeah, not hard to have some sort of reefing system to slow down your openings, but not sure if its a good idea on your reserve if you also want it to open fast if necessary.


ChrisHoward  (D 28490)

Apr 7, 2012, 4:53 AM
Post #27 of 38 (1460 views)
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Re: [obelixtim] RIG for the upcoming supersonic skydive [In reply to] Can't Post

In reply to:
Quote:
Who knows. I know PD has military reserve canopies that are designed to open for 10 (ten) seconds. Maybe it is similar in this case?

Yeah, not hard to have some sort of reefing system to slow down your openings, but not sure if its a good idea on your reserve if you also want it to open fast if necessary.

Not a problem if you adjust your openning accordingly.


obelixtim  (D 84)

Apr 7, 2012, 7:03 AM
Post #28 of 38 (1439 views)
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Re: [ChrisHoward] RIG for the upcoming supersonic skydive [In reply to] Can't Post

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Not a problem if you adjust your openning accordingly.

As I said, the problem Felix faces is an accidental opening, especially if he is at altitude and has a high speed terminal velocity.

Like 800 km/h.


Chris-Ottawa  (A License)

Apr 9, 2012, 7:57 AM
Post #29 of 38 (1338 views)
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Re: [obelixtim] RIG for the upcoming supersonic skydive [In reply to] Can't Post

I think the opening may be one of his worries...but assuming he survives that, what would he do with an open reserve at 100,000ft?

I'm sure he doesn't have enough oxygen to fly down from that altitude and hook knifing the reserve doesn't seem too smart.


Aside from that conundrum, would a reserve opening at 100,000 ft and 800kph necessarily be a concern due to the low air density? Would it not just remain a streamer, would the reserve even deploy?


Premier skydiverek  (C 41769)

Apr 9, 2012, 8:22 AM
Post #30 of 38 (1328 views)
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Re: [Chris-Ottawa] RIG for the upcoming supersonic skydive [In reply to] Can't Post

Reserve can be cutaway by pulling the break-away handle.

What is interesting, if you open the main first, you can cut it away and open your reserve. Then, the reserve can NOT be cutaway.

If you open reserve first, it CAN be cut away, and then you can open the main. Then, the main can NOT be cutaway.

Basically, you cannot cutaway your LAST canopy ("cutaway inhibitor system").

Drogue will deploy if Felix reaches the spin of 3Gs for more than 5 seconds.

Main or reserve can be open with or without the drogue out.

Cypres releases the drogue and opens the reserve.

http://www.youtube.com/watch?v=SErtpdKLsM4

Way to go INFINITY!!!

Cool


(This post was edited by skydiverek on Apr 9, 2012, 8:34 AM)


obelixtim  (D 84)

Apr 9, 2012, 1:40 PM
Post #31 of 38 (1260 views)
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Re: [Chris-Ottawa] RIG for the upcoming supersonic skydive [In reply to] Can't Post

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Aside from that conundrum, would a reserve opening at 100,000 ft and 800kph necessarily be a concern due to the low air density? Would it not just remain a streamer, would the reserve even deploy?

Well I guess he's depending on a drogue to inflate correctly if he needs it, so I guess the same physics would apply to his reserve.

Kittinger had a drogue, it worked fine.


obelixtim  (D 84)

Apr 9, 2012, 1:44 PM
Post #32 of 38 (1259 views)
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Re: [skydiverek] RIG for the upcoming supersonic skydive [In reply to] Can't Post

Quote:
Reserve can be cutaway by pulling the break-away handle.

What is interesting, if you open the main first, you can cut it away and open your reserve. Then, the reserve can NOT be cutaway.

If you open reserve first, it CAN be cut away, and then you can open the main. Then, the main can NOT be cutaway.

Basically, you cannot cutaway your LAST canopy ("cutaway inhibitor system").

Drogue will deploy if Felix reaches the spin of 3Gs for more than 5 seconds.

Main or reserve can be open with or without the drogue out.

Cypres releases the drogue and opens the reserve.

http://www.youtube.com/watch?v=SErtpdKLsM4

Way to go INFINITY!!!

OK, that looks like a good system. I wonder (I assume so) if they've figured out what sort of opening shock he would be subjected to if he did have an accidental opening at altitude.

At 800 mph I wouldn't expect him to be too healthy after such an event..


theonlyski  (D License)

Apr 9, 2012, 4:05 PM
Post #33 of 38 (1214 views)
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Re: [obelixtim] RIG for the upcoming supersonic skydive [In reply to] Can't Post

In reply to:
OK, that looks like a good system. I wonder (I assume so) if they've figured out what sort of opening shock he would be subjected to if he did have an accidental opening at altitude.

At 800 mph I wouldn't expect him to be too healthy after such an event..

I would think the thinner or lack of air would soften the shock a bit.


pchapman  (D 1014)

Apr 9, 2012, 8:32 PM
Post #34 of 38 (1167 views)
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Re: [Chris-Ottawa] RIG for the upcoming supersonic skydive [In reply to] Can't Post

Normally, round parachutes open harder at high altitude. Say, three to four times as hard at 40,000' than low altitude. [Reference: Knacke] It might not work quite the same with reefed ram air parachutes; it might be not quite so bad.

Still I can say:

At high altitude a jumper will take longer to get to the local terminal velocity. (One outside analysis of the planned Red Bull jump suggested 45 seconds to the peak speed.) But once at it, the dynamic pressure at say 800 mph is going to be the same as when the jumper is doing 120 mph or whatever near sea level.

So that's 6.7 times as much actual speed, and thus by squaring it, 44 times as much actual kinetic energy to deal with. (Well, one isn't slowing to a canopy descent rate of zero, certainly at high altitude, but we're just looking at rough numbers here.)

Whether all that energy matters depends on how fast the parachute opens -- it would be no problem only if the canopy takes a lot longer to open, with a long long snivel. On a regular skydive, if a canopy inflates fully in a very short time, the G forces get excessive when at terminal. Don't go slider off at terminal velocity. Deceleration loads are only acceptable when the full inflation starts at lower speed. So normally we need that reefing from the slider so the partially open parachute slows us somewhat before it snaps fully open.

To reiterate, the wind pressure felt on a high altitude jump at high altitude terminal will be like 120 mph down low -- so there's plenty of force trying to open the canopy.

The part of the deployment process where the canopy fills with air is less of a factor for squares than rounds, but in any case that inflation is affected more by the volume of air (even though it is very thin air), than the density. So the tendency, at high speed & altitude, is for much more rapid canopy filling, because there's a lot more cubic feet of air going by every second.

Thus overall you still have plenty of wind pressure like usual, tons more energy, and faster canopy filling. This sounds like it should lead to much harder openings. Unless the slider somehow guaranteed a really long snivel in some manner I don't understand, a high altitude, high airspeed opening would be extremely hard.


Premier skydiverek  (C 41769)

Aug 2, 2012, 1:52 PM
Post #35 of 38 (935 views)
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Re: [skydiverek] RIG for the upcoming supersonic skydive [In reply to] Can't Post

In reply to:
Reserve can be cutaway by pulling the break-away handle.

What is interesting, if you open the main first, you can cut it away and open your reserve. Then, the reserve can NOT be cutaway.

If you open reserve first, it CAN be cut away, and then you can open the main. Then, the main can NOT be cutaway.

Basically, you cannot cutaway your LAST canopy ("cutaway inhibitor system").

Drogue will deploy if Felix reaches the spin of 3Gs for more than 5 seconds.

Main or reserve can be open with or without the drogue out.

Cypres releases the drogue and opens the reserve.

http://www.youtube.com/watch?v=SErtpdKLsM4

Way to go INFINITY!!!

Cool

Great video on the Infinity rig used for the jumps!:

http://www.redbullstratos.com/...20for%20Stratosphere

Cool



jinlee  (D License)

Aug 3, 2012, 12:56 PM
Post #36 of 38 (817 views)
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Re: [blkhwk91b] RIG for the upcoming supersonic skydive [In reply to] Can't Post

In reply to:
Water boils at lower temperatures at lower pressures.

Water will boil at room temperature in a vacum.


Premier Remster  (C License)

Aug 3, 2012, 1:57 PM
Post #37 of 38 (789 views)
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Re: [jinlee] RIG for the upcoming supersonic skydive [In reply to] Can't Post

In reply to:
In reply to:
Water boils at lower temperatures at lower pressures.

Water will boil at room temperature in a vacum.

What's room temperature in a vacuum? Wink


Southern_Man  (C License)

Aug 3, 2012, 2:14 PM
Post #38 of 38 (784 views)
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Re: [jinlee] RIG for the upcoming supersonic skydive [In reply to] Can't Post

In reply to:
In reply to:
Water boils at lower temperatures at lower pressures.

Water will boil at room temperature in a vacum.

My vacuum is also a steam cleaner so that is very convenient.


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