MARD discussion...

[councilman24 36]

I'm on my phone. But go look at breakaway testing. It keeps 300' but adds +2 second to the 4.3.6 requirements since its subterminal. 4.3.6.2 last sentence. It's in the car.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[NWPoul 1]

Quote

Interlock (Eric Fradet): military
DRX (Mirage): sport (secret option for selected customers ;-) )
LES (Basik): sport (used to be?, not any more)
DRD (SWS Rigs): military

DRD from SWS Rigs is avaible to order for sport rig "SWS Fire"

Why drink and drive, if you can smoke and fly?

[skydiverek 54]

Thank you for all the corrections and clarification!

[Deyan 31]

Quote

I'm on my phone. But go look at breakaway testing. It keeps 300' but adds +2 second to the 4.3.6 requirements since its subterminal. 4.3.6.2 last sentence. It's in the car.

You are right Terry and I was wrong.

I knew that 2 seconds delay after cutaway is allowed, but I was not aware that you can add those seconds to the total time when using RSL.

"My belief is that once the doctor whacks you on the butt, all guarantees are off" Jerry Baumchen

[jsaxton 0]

where is the option for I don't want one, I'd rather not introduce any additional complexity in my equipment?

[eric.fradet 17]

Any idea why the LES wsa introduced and then withdrawn? Of maybe it wasn't introduced?
__________________________________________________
I can answer this one since I designed the LES : it was withdrawn because MARD system was found unsafe in sport rigs, what was the case in 96, and it is still true in 2012 (some manufacturers should also not offer it to sale), as I said it could be useful only in case you cuttaway in between 200 feet and 300 feet above the ground ! not a situation you will see in an entire life on a drop zone, besides of that there is a lot of situation where MARD can kill you ! sometime to make the sport safer, you have to make it less complicated

[ShcShc11 0]

Quote

Any idea why the LES wsa introduced and then withdrawn? Of maybe it wasn't introduced?
__________________________________________________
I can answer this one since I designed the LES : it was withdrawn because MARD system was found unsafe in sport rigs, what was the case in 96, and it is still true in 2012 (some manufacturers should also not offer it to sale), as I said it could be useful only in case you cuttaway in between 200 feet and 300 feet above the ground ! not a situation you will see in an entire life on a drop zone, besides of that there is a lot of situation where MARD can kill you ! sometime to make the sport safer, you have to make it less complicated

"is still true in 2012"
even the skyhook?

Cheers!

[Deyan 31]

Quote

"is still true in 2012"
even the skyhook?

Cheers!

What makes you think that Skyhook is an exception ?

"My belief is that once the doctor whacks you on the butt, all guarantees are off" Jerry Baumchen

[ShcShc11 0]

Quote

Quote

"is still true in 2012"
even the skyhook?

Cheers!

What makes you think that Skyhook is an exception ?

Well the poster's assertion is that all MARDs are unsafe even in 2012. I'm assuming he is including the skyhook too?

If that is so, are there any tangible real-life examples (or better yet, statistics) that demonstrate that it is unsafe? As the good ol' folks at ChutingStar once said: "not necessary, but highly recommended".


Hugs & Cheers!
Shc

[Southern_Man 0]

Quote

Any idea why the LES wsa introduced and then withdrawn? Of maybe it wasn't introduced?
__________________________________________________
I can answer this one since I designed the LES : it was withdrawn because MARD system was found unsafe in sport rigs, what was the case in 96, and it is still true in 2012 (some manufacturers should also not offer it to sale), as I said it could be useful only in case you cuttaway in between 200 feet and 300 feet above the ground ! not a situation you will see in an entire life on a drop zone, besides of that there is a lot of situation where MARD can kill you ! sometime to make the sport safer, you have to make it less complicated

Hi Eric,

Thanks for sharing. Was the LES some version of your interlock system or is that a different system?

What was found to be unsafe about it in sport rigs?

"What if there were no hypothetical questions?"

[eric.fradet 17]

Besides the fact I do not like the idea for any sport rig to use any MARD, (in my mind MARD is restricted to the soldiers jumping at 1000 foot high, who are the only skydivers paid to be kill, anyways)
5 reasons to not use any MARD (in fact they are more but it should be enough to convince people)
1) Increasing entanglement on any Type of main horse shoe malfunction
On a MARD equipped rig, the chance having your camera helmet entangled by the reserve travelling on his way is duplicated when you cutaway, in those days everyone jump a camera.
Also if only the non-RSL riser is entangled, the RSL riser will leave and open your reserve container, chance on entanglement is higher.

the MARD may also increase the probability of a main and reserve entanglement after a cutaway, in any type of horseshoe malfunction like foot (feet) in the main lines, main pilot chute trapped in the arm or foot, or main container open while main pc still in his pocket, The situation of a horseshoe (premature container opening with PC still in pouch) is worth looking at to get the picture :

Any type of partial or total malfunction will look like these two little pictures which show the differences in between having a skyhook or not.

Pic 1 shows a PC (without a MARD) trying to blow by the cutaway main that is still attached to a jumper via a stuck pc.
Pic 2 shows the MARD trying to blow by the cutaway main that is still attached to a jumper via a stuck pc.

If the reserve pc with the MARD inflates, it is likely that the reserve will find clear air to inflate in, but not if the reserve pc goes through the lines of the main or something similar.

If the reserve pc with the MARD does not catch air immediately, and is still attached to the MARD wraps the trailing main, then I think that a main-reserve entanglement is almost a certainty. The remaining length of the reserve bridle line may provide enough drag for the reserve canopy to come out of the reserve bag, but maybe not.
You can also get more slack in the reserve deployment (from the MARD point of attachment to the reserve risers) that will allow the reserve (bag and or lines) to flap around and become entangled with the trailing main. At best you could hope for the drag on the reserve lines to pull the reserve canopy out of the bag, even if the bag is attached someplace along the trailing main.
I think this is a failure mode of the MARD that has not been tested, not been explained and kind of glossed over. (I certainly do not recommend asking test jumpers to test this either.)

2)Main bag lock hitting the reserve ( I did experimented it myself) .
All bag locked mains will not miss the reserve canopy, especially when it is a Sigma Tandem., their tandem reserve opens in deep brakes, and therefore doesn't get out of the way as well as a "normally" braked canopy.
Also with a small reserve, there is some damage or entanglement potential issue, especially to have the main lines wrapped around the reserve ones.

3) twisted lines reserve due to the main spinning malfunction momentum :
All very experienced skydivers who experimented a few of this type of scenario have already disconnected their Skyhook (including sponsored team by UPT like world champion Babylon Team and French National Vertical Formation Skydiving team do not use it because of that)
Read this one : it is the worst case I know, but I have other very similar scenario too : A very experienced jumper using a skyhook had a malfunction on a Velocity that had him spinning into line twists while the canopy was spinning. The resulting cutaway with a skyhook had him entangled in the freebag and bridle, he sorted it out but was nearly choked out by the reserve risers caught under his chin. It produced some nasty rash. Severe spinning around your Y axis while spinning violently doesn't seem to be covered on the videos that I have seen

4) increase of reserve shock opening
There are, scenarios where an open canopy can be cutaway and act as a super pilotchute while the jumper is still at terminal.
1. The cutaway handle is accidently pulled on exit or in freefall, the jumper deploys the main, the riser covers hold long enough for the canopy to come out of the bag and partially inflate before separating from the harness.
2. The jumper deploys the main, has a hesitation, goes for the cutaway handle as the pilotchute lifts off, cuts away just as the canopy comes out of the bag. This is a relatively common malfunction.
3. The jumper experiences a baglock. Just on cutaway the canopy comes out of the bag.
In these scenarios the jumper has not been decelerated by the main but it will be at least partially inflated as it lifts off. If there is a skyhook it will act as a super pilotchute with the risk of a catastophically hard opening.
Many people think that once the resreve is out of the bag the speed of the opening is determined only by the slider. The slider is critical for any opening but so is the pilotchute. UPT knows this so their drogues collapse on lift off so as to have just the right amount of snatch to lift the bag at optimum speed. If your kill line shrinks on your sport rig not only do you get slower bag lift off you get slower inflation.
A big pilotchute gives a harder opening because the bag is more rapidly decelerated. At the moment the canopy comes out of the bag the speed difference between the jumper and the canopy will be higher and therefore the load on the lines will be higher. That means the initial snatch will be harder but force on the lines also contributes to the next stage of canopy inflation.
Lets say standard bag lift off takes one third of a second. That suggests the bag is travelling at about 45 feet per second slower than the jumper. 135 ft/s vs 180 ft/s.
A fully open canopy with a suspended jumper has a descent rate of about 15 feet per second. A cutaway canopy with only a reserve freebag hanging under it will have a descent rate somewhere between 135 ft/s and 15ft/s depending on the degree of inflation. It d doesn't need to be inflated much to increase the speed difference between the jumper and the bag by a factor of 2 or 3 and possibly as much as 6 compared to a standard pilotchute.
Surely this creates the possibility of a severely hard opening. The prospect of superhard skyhook openings has not been fully investigated.

5) Short reserve bridle
Some manufacturers have shorten the reserve bridle by 4 feet to make the system work better! This is just as insane than tacking the system with a 4 pounds of resistance cord to the reserve container !
They forgot that there was a good reason to decide in the past to come up with the 16 feet long reserve bridle, like they also forgot that there was a good reason to have a hesitator loop configuration to secure the bridle and holds the reserve bag, with a bite of the reserve bridle to stage/sequence the reserve opening, by locking the container closed under full reserve bridle extension.
For sure we build up devices to make the skydiver a better idiot instead to educate him .. So, I don’t think that there is anything good with putting out a (necessarily) flawed system specially as long the truth is not out there about the weaknesses of the system so people are not informed, having no responsible decisions about whether to use it or not. Downplaying the dangers doesn’t do anyone any good.

I think that problems will always exist in any MARD, there is no perfect system. Furthermore, it is a system which is designed to make up for user stupidity, and therefore could be eliminated if people weren’t being stupid. Still, people want it. Never mind that it could kill them, or that gear is very safe when used appropriately without it. They still want it.
UPT’s story that there have been thousands of Skyhook deployments with no other problems misses the point: that people should fully understand their gear, how it works and how it may fail, so that they can take responsibility for their own safety. They should not be told a fairy tale of perfection, as if skydiving could be made completely safe by better gear.
Too much safety devices kill the safety !
For sure we build up devices to make the skydiver a better idiot instead to educate him .. So, I don’t think that there is anything good with putting out a (necessarily) flawed system specially as long the truth is not out there about the weaknesses of the system so people are not informed, having no responsible decisions about whether to use it or not. Downplaying the dangers doesn’t do anyone any good.

I think that problems will always exist in any MARD, there is no perfect system. Furthermore, it is a system which is designed to make up for user stupidity, and therefore could be eliminated if people weren’t being stupid. Still, people want it. Never mind that it could kill them, or that gear is very safe when used appropriately without it. They still want it.
UPT’s story that there have been thousands of Skyhook deployments with no other problems misses the point: that people should fully understand their gear, how it works and how it may fail, so that they can take responsibility for their own safety. They should not be told a fairy tale of perfection, as if skydiving could be made completely safe by better gear.
Too much safety devices kill the safety !

[GGGGIO 0]

+1

[pchapman 261]

For those who can't easily open Eric's .odt Open Doc file, here's a conversion to PDF, even if this is a bit late to the conversation. It sketches his thoughts on deploying a reserve past a horseshoe, MARD and no MARD.

[JohnSherman 1]

Quote

It keeps 300' but adds +2 second to the 4.3.6 requirements since its subterminal. 4.3.6.2 last sentence.

Sorry Councilman but those numbers are not additive. The opening time is 3 seconds or 300 feet from activation, RSL or no RSL. I know some manufacturers have made the interpretation that it allows 5 seconds but it is an intentional distortion so that they could get their rigs certified.

I sat on the committee that wrote the rule and it was never intended to be interpreted this way. If you don't have an RSL and are trying to get a reserve pull within 2 seconds after cutaway you had better be fast. The non-additive allowance was provided to allow for testing and certification without an RSL.
This has apparantly been clairfied in the latest revision of TS-135

[councilman24 36]

If that's true John the language was not written to reflect that position. It is changed in the new one. It's three seconds from pack opening, rsl or not.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[JohnSherman 1]

Quote

If that's true John the language was not written to reflect that position. It is changed in the new one. It's three seconds from pack opening, rsl or not.

I would agree that the language was poor. However, Everyman Jack, who makes rigs, was on that committee and all knew that the rule was 3 seconds. It was 3 seconds before that version and is 3 seconds in the next version. There was never any discussion about raising it to a longer time.
I don't buy the excuse of mis-interpretation. I don't read the language that way.

[councilman24 36]

I didn't have it in front of me when I replied earlier. I do now.

I don't know any other way to read the sentence.

"Breakaway Drop Tests: Eight drips shall be made by a person weighing not more than the maximum operating weight by breaking away from an open and normally functioning main parachute canopy with a vertical velocity of less than 20 FPS (6.1 m/s) at the time of the breakaway and actuating the reserve pack within 2 s of the breakaway. If a reserve static line is part of the assembly, no less than 4 of the breakaway drops shall be made with the reserve static loin actuating the reserve pack. The parachute canopy must be functionally open withing the time +2 s, or altitude, obtained in 4.3.6 from the time of breakaway."
emphasis added

Sure looks like it gives both the jumper and the RSL 2 seconds to open the reserve pack and then the 3 seconds for the normal opening requirement. Since no standard is given for the first case the last sentence must apply to both manual and RSL. "...time +2 s.." sure looks additive to me. And yes this would effectively allow a reserve to take 5 secs to open using an RSL because pack opening is fractions of a second after breakaway.

I agree this is not what we want to measure and hence the changes in TS-135 to measure both from the pack opening and apply 3 sec.

But we've hijacked the thread and its time to go pick up the kids.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[skydiverek 54]

Quote

Quote

Interlock (Eric Fradet): military
DRX (Mirage): sport (secret option for selected customers ;-) )
LES (Basik): sport (used to be?, not any more)
DRD (SWS Rigs): military

DRD from SWS Rigs is avaible to order for sport rig "SWS Fire"

Looks like it uses Collins Lanyard licensed from UPT, correct?

http://www.swsrigs.com/ru/products/fire/features/drd/

[ChrisD 0]

Quote

For those who can't easily open Eric's .odt Open Doc file, here's a conversion to PDF, even if this is a bit late to the conversation. It sketches his thoughts on deploying a reserve past a horseshoe, MARD and no MARD.

I'm stareing at picture #2 and I'm a little confused, Don't we "complete the sequence," in a horseshoe by releasing the PC? As our first step? And I get the point you guys are trying to make, esp about the UPT Reserve PC, but I have yet to see any PC pointing downward?? (Ya I have seen burbiling PC's, but never pointing downward?)

Someone help me out here?
C

But what do I know, "I only have one tandem jump."

[JerryBaumchen 1,046]

Hi Bartek,

Quote

Looks like it uses Collins Lanyard licensed from UPT, correct?

It has been a few years since I have looked at/read the licensing contract ( which was to be with a 'Parachute Patents' organization ) but it had no provisions for licensing the lanyard only.

The SkyHook licensing contract included the lanyard; at least in the copy that I was given.

JerryBaumchen

[pchapman 261]

Quote

I'm stareing at picture #2 and I'm a little confused, Don't we "complete the sequence," in a horseshoe by releasing the PC? As our first step? And I get the point you guys are trying to make, esp about the UPT Reserve PC, but I have yet to see any PC pointing downward?? (Ya I have seen burbiling PC's, but never pointing downward?)
Someone help me out here?
C

To answer one question, I have seen Vector PCs in a burble be completely inverted or in any attitude, even for a single jumper (not just an AFF 3-person burble). This was for a Vector PC on a main canopy. Maybe it didn't launch quite as well as on a tightly packed reserve, but still this shows it is possible -- see my video at http://blip.tv/pcxstuff/the-secret-life-of-pilot-chutes-3507191.


As for the 2 drawings by Eric Fradet:

I don't know Eric's exact line of thinking but this is what I see:

-- He's talking about the type of horseshoe you can't clear from its entanglement, or you don't notice in time. If you do clear it, then you don't have a horseshoe any more. Great.

-- Now say that you still have the horseshoed main, cut it away, but it is trailing off you at some location. If the reserve PC catches air properly, then it doesn't matter whether you have a Skyhook; the reserve PC is doing the job and hopefully will clear the trailing mess. Everyone takes their chances equally.

-- But he says that if the reserve PC burbles for a moment and doesn't catch air, now instead of a trailing mess and a nearby reserve PC trying to catch air (dangerous enough), you also have the Skyhook lanyard still connecting the flapping, trailing risers, to your reserve bridle.

So now you are pulling the reserve bridle in towards the trailing main canopy mess, especially just as the main risers are cutaway from your shoulders and whip back to wherever the entangled main is trailing.

(Assuming the drag on the risers is enough to peel all that Skyhook RSL velcro in the first place. That has been questioned for some low drag mals like baglocks. Manually clearing risers away by hand has been suggested.)

Is the connection between the main risers and the reserve bridle enough to actually drag the reserve pilot chute into the trailing mess? Will even just yanking some reserve bridle towards the mess be enough to cause problems?

I'm not sure yet either way, but Eric seems to think so, and asks whether any testing has been done to show what the truth really will be for that scenario.

[gregpso 1]

Quote

For a point of reference: Skyhooks have been on the market for 10 years now, and are installed on over 15,000 civilian and military rigs worldwide.

I rest my case 10 years now... proven technology. way to go Bill !!

I tend to be a bit different. enjoyed my time in the sport or is it an industry these days ??

[piisfish 135]

I don't have one, and don't want one for now.

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[JohnSherman 1]

Quote

I'm stareing at picture #2 and I'm a little confused, Don't we "complete the sequence," in a horseshoe by releasing the PC? As our first step? And I get the point you guys are trying to make, esp about the UPT Reserve PC, but I have yet to see any PC pointing downward?

The pilot chute is pointing downward because the "Skyhook" is "Hooked" to the reserve bridle at just above the halfway point. The loading from the horseshoed main canopy is to this point and is greater than the response of the reserve pilot chute. The reserve pilot chute has not had chance to orientate itself. However, it is still dragging but in the wrong way. There are numerous videos where this may be observed. If I remember correctly it is observable on the original promo video.

[ChrisD 0]

Quote

Quote

I'm stareing at picture #2 and I'm a little confused, Don't we "complete the sequence," in a horseshoe by releasing the PC? As our first step? And I get the point you guys are trying to make, esp about the UPT Reserve PC, but I have yet to see any PC pointing downward?

The pilot chute is pointing downward because the "Skyhook" is "Hooked" to the reserve bridle at just above the halfway point. The loading from the horseshoed main canopy is to this point and is greater than the response of the reserve pilot chute. The reserve pilot chute has not had chance to orientate itself. However, it is still dragging but in the wrong way. There are numerous videos where this may be observed. If I remember correctly it is observable on the original promo video.

But isn't the skyhook connected to the right main riser?? And in this picture the risers are still attached??? Let me get this straight, cause im having a brain fart here??? The risers have the power to "outrace" a pilot chute??? So what yoour saying is that the skyhook bridal under these conditions can actually wrap around the trapped main mess and hold down the PC?? As things that don't release correctly have been shown to do...
C

But what do I know, "I only have one tandem jump."