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Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories)

 

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NovaTTT  (D 17887)

Feb 25, 2011, 8:56 AM
Post #76 of 107 (1766 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

I don't know the test-jump results, Paul, and I'm not sure this scenario has been tested on any MARD system.

I suppose the RAX would release if the reserve PC "overpowered" the cutaway main.

Like any component it has benefits and risks. Of the three MARDs I've seen I like this one best for its simplicity, use of common materials and straight-forward function. FWIW.

I put a photo of the device on my FB page if anyone wants to see it. Jerry, if you prefer I not post that photo, please let me know and I'll remove it.

RAX Device


riggerpaul  (D 28098)

Feb 25, 2011, 9:21 AM
Post #77 of 107 (1755 views)
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Re: [NovaTTT] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:
I don't know the test-jump results, Paul, and I'm not sure this scenario has been tested on any MARD system.

I suppose the RAX would release if the reserve PC "overpowered" the cutaway main.

Like any component it has benefits and risks. Of the three MARDs I've seen I like this one best for its simplicity, use of common materials and straight-forward function. FWIW.

I put a photo of the device on my FB page if anyone wants to see it. Jerry, if you prefer I not post that photo, please let me know and I'll remove it.

RAX Device

Tested or not, we know that Skyhooks can release when we didn't expect they would.

We have been told that only way for that to happen is "if the reserve PC overpowered" the departing main.

It would seem that "overpowered" is not the correct term, since nobody really believes that the reserve pilot chute can generate more force than a partly deployed main(please, possibly excluding bag-locks). But, if you insist on saying "overpowered", then you've got to admit that some reserve pilot chutes apparently overpowered some mains when there was no expectation of such.

If you cannot count on the device speeding up your reserve opening, what's the point of having it at all?

To me, if we cannot come up with a system that will absolutely use the main in the event of a main cutaway, we've really gotten nowhere at all.


riggerpaul  (D 28098)

Feb 25, 2011, 9:27 AM
Post #78 of 107 (1750 views)
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Re: [NovaTTT] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

can you just post the photo?

Believe it or not, not everybody does Facebook.


andyhughes

Feb 25, 2011, 9:28 AM
Post #79 of 107 (1749 views)
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Re: [NovaTTT] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

re your photo... so the RAX is like the attached diagram except that is anchored to the container?
Attachments: mard.png (15.6 KB)


NovaTTT  (D 17887)

Feb 25, 2011, 9:47 AM
Post #80 of 107 (1738 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

To clarify, I say "overpowered" to mean, exerted a force necessary to release the device, such force in that moment acting greater than the force exerted by the MARD.

But the force might not be greater; it might just be in a different direction (vector). It might just take a split-second of the bridle in an unloaded state for the skyhook (or other MARD) to disconnect due to force pressure from the RPC.

I don't know if testing to identify this problem is viable. Once or if the cause(s) is(are) discovered, it would be very expensive to repeatedly test the condition against possible improvements to the MARD system.

And in the case of the Skyhook, all that testing is against a system that works correctly (guesstimate here) 98%+ the time.

It's one's choice in re benefit vs risk and I don't think we'll ever get something that absolutely will work every time. Not a complete rig, AAD, altimeter, Dytter or MARD.

That margin of uncertainty is an aspect of the sport. BSBD


pchapman  (D 1014)

Feb 25, 2011, 9:56 AM
Post #81 of 107 (1744 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

Here's a screencap of the facebook pic plus description.

(NovaTTT I trust you don't mind.)

Edit: And yes we all have to understand that the "overpowering" only needs to be briefly, early in the sequence, before the RSL/main can apply much force.

Guess we need lousier reserve pilot chutes to fix that.Crazy


(This post was edited by pchapman on Feb 25, 2011, 9:58 AM)
Attachments: rax w description.jpg (135 KB)


NovaTTT  (D 17887)

Feb 25, 2011, 9:59 AM
Post #82 of 107 (1741 views)
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Re: [andyhughes] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

@Paul:

Sorry I can't post the photo - it's too large for Dizzy. I think it's available to any web-connected computer, facebook or no. I'll send you it on Gmail.

@Andy:

The RAX is not similar to that image. The pin on the RAX is attached to the device, which resembles a steering toggle. The white loop, which is attached to the bridle, comes through the grommet and is secured by the pin.

The ends of the device are secured in two pockets - one on the bridle, one on a reserve flap. A length of suspension line leads from the device to the RSL and to the reserve ripcord.

In that photo you can see the portion of the device that extends to the right and is tucked under the flap. I think that was for the aesthetics of the photo. That is where the suspension line is attached and it can be seen in the photo running up along the right riser next to the closing flap.


riggerpaul  (D 28098)

Feb 25, 2011, 10:01 AM
Post #83 of 107 (1740 views)
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Re: [NovaTTT] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:
To clarify, I say "overpowered" to mean, exerted a force necessary to release the device, such force in that moment acting greater than the force exerted by the MARD.

But the force might not be greater; it might just be in a different direction (vector). It might just take a split-second of the bridle in an unloaded state for the skyhook (or other MARD) to disconnect due to force pressure from the RPC.

I don't know if testing to identify this problem is viable. Once or if the cause(s) is(are) discovered, it would be very expensive to repeatedly test the condition against possible improvements to the MARD system.

And in the case of the Skyhook, all that testing is against a system that works correctly (guesstimate here) 98%+ the time.

It's one's choice in re benefit vs risk and I don't think we'll ever get something that absolutely will work every time. Not a complete rig, AAD, altimeter, Dytter or MARD.

That margin of uncertainty is an aspect of the sport. BSBD

So then, what it is that a MARD does for you?

If you cannot count on it to get your reserve open quicker, then it is really not much better than any traditional RSL.

Oh yes, except that it cost a significant amount, and required significant modifications to rigs to install it.

We have at least one case now where the introduction of the Skyhook was the basis for another SB to fix riser cover tabs.

So, it costs more, introduces the need for other fixes, and it doesn't necessarily work in the scenario where we would like it to work best - under something spinning the shit out of you down low, like after a canopy collision.

Please remind me why I am supposed to want one.

If it worked BETTER than a traditional RSL, then at least there would be some room for discussion.

But why, when it doesn't really do anything that much better, and might not work when you need it most, do so many people think this is the hot ticket?


KellyF  (D 13826)

Feb 25, 2011, 10:13 AM
Post #84 of 107 (1734 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:
It's a simple and elegant device which is made completely of common materials.

Sorry, Jerry, if my explanation stinks. Angelic
A couple of things about the history of RAX- I built a VERY rough prototype of an idea that I had and shared it with Jerry and a couple of other manufacturers/designers (on the right in the first pic, one of Jerry's samples on the left). Jerry really liked the concept and asked me if he could develop it further. Not having any time myself, I told him to go ahead so he made up some samples and sent them around for opinions and had some test jumps done. He also named the system and added the pocket on the bridle which makes things a little neater when packing, but is completely unnecessary (he and I have gone back and forth on this). The pocket tries to prevent the RAX interlock from rotating around the loop on the bridle when the PC takes over during a high speed mal like a baglock and can result in a bent pin.

OK, now I'll try to take a stab at an explanation with a couple of pictures. The system consists of essentially 4 parts and 3 steps to assemble it while packing. The reserve bridle would have a loop of Ty-2A (or any other line type deemed appropriate), and the interlock has two legs, one with a #0 grommet and pocket for the tip of the pin, and the other with a stiffened section with the pin secured at the base. The last part is the pocket sewn onto the reserve container. During packing, the rigger would FIRST put the tab into the pocket, then put the loop on the bridle through the grommet, then put the pin through the loop and into it's pocket. The third picture shows the system completely asembled (on Jerry's mock up that I have).

In reply to:
But (and do please correct me if I am wrong), it still suffers from the same deficiency as the Skyhook - that being, if the reserve pilot chute gets enough air from the side, it would release the pin when you would still like it to remain attached to the main.

Paul, once the RSL has initiated deployment, and pulled tab out of the pocket, the reserve bridle is locked to the RSL (see the second picture). I consider this a "mechanical" MARD, and consider the Skyhook (and most others I've seen- Sorcerer being an exception) to be "aerodynamic" MARDs. Meaning that aerodynamic forces cause the system to lock or unlock, and can cause the system to release prematurely during a cutaway. The ability to "change it's mind" in the middle of a deployment was one of the design elements for the Skyhook (horsehoe mal, RSL entaglement, etc.), but I believe it creates VERY diffecult design challenges if you want to prevent premature releases AND license the system to other manufacturers that use a different reserve pilot chute with different drag characteristics (and I'm not sure I agree that it's a "requirement").

The only way I see RAX releasing prematurely during a live cutaway is if the reserve pilot chute somehow launches out ~5' and pulls the loop off of the pin before the RSL covers the distance from pulling the pin to pulling the tab out of the pocket.

Of course like everything else, RAX can be rigged improperly, so I'm constantly trying to come up with ways to prevent that (and I think the required rigging is pretty damn simple). But in the end, is the additional complexity (in rigging and use- and anyone that says they don't add complexity for the user is WRONG) of a MARD REALLY needed? This is one of those situations where I feel we have time to wait and see how things shake out, and if the demand really IS there, we can offer the BEST system to our customers, not just the "FIRST" Smile
Attachments: IMAG0284 [1600x1200].jpg (273 KB)
  IMAG0285 [1600x1200] [1600x1200].jpg (284 KB)
  IMAG0286 [1600x1200].jpg (205 KB)


riggerpaul  (D 28098)

Feb 25, 2011, 10:44 AM
Post #85 of 107 (1721 views)
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Re: [KellyF] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:

Paul, once the RSL has initiated deployment, and pulled tab out of the pocket, the reserve bridle is locked to the RSL (see the second picture). I consider this a "mechanical" MARD, and consider the Skyhook (and most others I've seen- Sorcerer being an exception) to be "aerodynamic" MARDs. Meaning that aerodynamic forces cause the system to lock or unlock, and can cause the system to release prematurely during a cutaway. The ability to "change it's mind" in the middle of a deployment was one of the design elements for the Skyhook (horsehoe mal, RSL entaglement, etc.), but I believe it creates VERY diffecult design challenges if you want to prevent premature releases AND license the system to other manufacturers that use a different reserve pilot chute with different drag characteristics (and I'm not sure I agree that it's a "requirement").

The only way I see RAX releasing prematurely during a live cutaway is if the reserve pilot chute somehow launches out ~5' and pulls the loop off of the pin before the RSL covers the distance from pulling the pin to pulling the tab out of the pocket.

Of course like everything else, RAX can be rigged improperly, so I'm constantly trying to come up with ways to prevent that (and I think the required rigging is pretty damn simple). But in the end, is the additional complexity (in rigging and use- and anyone that says they don't add complexity for the user is WRONG) of a MARD REALLY needed? This is one of those situations where I feel we have time to wait and see how things shake out, and if the demand really IS there, we can offer the BEST system to our customers, not just the "FIRST" Smile

Thanks, Kelly, for the explanation/correction.

I see now why RAX is different from other systems I have seen, and I agree that this fixes the unintended release mode of the Skyhook.

But still, this system has the negative aspect that should the jumper manage to pull on the RSL enough to get the tab out of the pocket on the flap, the device will not release in a situation where the jumper pulls the reserve ripcord.

Maybe that won't happen very easily.

But the failure mode, where the MARD failed to release even though the main was not chopped, is why I don't like the idea of a Skyhook with a latching gate for the red lanyard. It just isn't ready if the jumper can make it malfunction.

One solution might be to somehow route the closing loop right through the tab in the flap pocket. Then you could not pull the tab out of the pocket while the reserve pin is still in place.


NovaTTT  (D 17887)

Feb 25, 2011, 11:22 AM
Post #86 of 107 (1705 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:
Thanks, Kelly, for the explanation/correction.

Ditto.

Will we see the RAX in the Infinity anytime soon?


KellyF  (D 13826)

Feb 25, 2011, 11:23 AM
Post #87 of 107 (1702 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:
But still, this system has the negative aspect that should the jumper manage to pull on the RSL enough to get the tab out of the pocket on the flap, the device will not release in a situation where the jumper pulls the reserve ripcord.

Maybe that won't happen very easily.
One solution might be to somehow route the closing loop right through the tab in the flap pocket. Then you could not pull the tab out of the pocket while the reserve pin is still in place.
You're right, this is one of the issues that I was categorizing under "misrigging"- not so much the RSL getting pulled far enough to dislodge the tab, (ideally, the ripcord pin should get pulled first), but the idea of riggers doing steps 2 and 3 and not doing step 1. Just pull the snap shackle tab, right? lol

I like your concept of anchoring the tab to the closing loop, and will explore that, but it would require different placement than my current ideas.....


JerryBaumchen  (D 1543)

Feb 25, 2011, 11:52 AM
Post #88 of 107 (1695 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

Hi Paul,

If you would like to see/handle/study a mockup of the RAX system, just drop me an email with your address & I'll send one out to you with the instructions. I will want it back.

A couple of things;

1. The RAX system does not use a Pull-Out pin, it uses a longer pin supplied by Square1 and they call it a Toggle Pin.

2. Kelly & I disagree on the need for a pocket, on the bridle line, for the tab with the pin inside of it. Well, we disagree on some other things also but those are other stories.

3. By having the tab with the pin inside of it put into a pocket on the bridle it will cause this pin to bend if you use it when faced with a bag-lock. This is because, due to the higher speeds with a bag-lock, the reserve pilot chute takes over & begins to pull after everything is out and going away. You can see it here if you slow it down:

http://www.youtube.com/watch?v=aqxjHOSKTT0

4. I do not concern myself with what happens after things are long gone during the sequence of MARD activation. By then, you will be under your reserve and the 'junk' will be well away from you. As for a bent pin on the system, it is very easy & quick to just replace that portion of the system & you are good to go once again. The cost of replacing it is minimal ( IMO ), but I am biased.

One manufacturer who is using it asked me about this because they experienced a bent pin during their bag-lock tests. I informed them to consider just including a 2nd device at the time of sale; it is of minimal cost to build.

5. Once you have cutaway, your main canopy ( and anything else that might be attached to it, such as a MARD system ) will flip & flop around in the sky. During one test I spent a fair amount of time just watching the main and was quite taken with what all it was doing. Due to this flip/flop, during one test of the RAX system, it actually became disconnected from the main canopy/RSL; but so what, you're under your reserve. Yes, I know that it would be nice to keep everything together to locate later but that would add complexity that I don't want.

I did talk with one person at the Mirage booth in Reno, and he indicated that they should have their DRX on the market soon; time will tell. He did say that they have developed an alternate system/device to use instead of the Collins Lanyard and that they would be licensing that to anyone who might want to use it. If this actually happens, then I think that you will see many of these current MARD designs to begin to appear on sport gear. But that is just my thinking.

From what I know of all current MARD designs at this time, the RAX system is the only one that will release/disconnect ( when faced with a total malfunction ) with zero force from the reserve pilot chute; it just slips of with no req'ment to break any tacking. As I said, I am biased.

JerryBaumchen

PS) Nova TT & pchapman - excellent descriptions of the RAX system; thank you.


NovaTTT  (D 17887)

Feb 25, 2011, 3:01 PM
Post #89 of 107 (1664 views)
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Re: [JerryBaumchen] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

I tried to describe it, Jerry. But I didn't remember the pin locks to the bridle when the flap pocket is cleared. Crazy I popped that into my notes about the device so I learned, or relearned, something today!

I'd like to know, if you don't mind sharing some of the information, what the pros/cons are of the bridle pocket about which you and Kelly don't agree. And if it's not breaking privacy, I wonder what other aspects are in . . . well, gentle dispute?

I see that without the pocket the bent pin on baglock isn't an issue - but what other issues concern you? Has the positional durability been tested? Meaning, will the RAX remain in place for 180 days of typical rig use if there is no bridle pocket?

I'm a fan of the device, as I think you know, and the only "real" problem I've had with it is the missing Collins Lanyard (or equivalent) - that and the fact that it's not available! Angelic


drewcarp

Feb 26, 2011, 11:25 AM
Post #90 of 107 (1602 views)
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Re: [airtwardo] Skyhook Activation Stories [In reply to] Can't Post

I have a Vector 3 with a skyhook in stalled on the way to my house (first rig) I have been going back and forth about leaving the skyhook hooked up. Initially the skyhook seems like a great idea but what it boils down to is two things..

Everyone who's anyone says they wouldn't rely on it so, I'm not going to change my EP's to where I would cut away at 500 feet if I need a new canopy based on having a skyhook. I have an audible to tell me when I hit 1k feet and every time I hear it I tell myself if anything happens I go straight to silver for more fabric. Adding a reserve to a collapsed/re-deploying main is pretty much just like a 2 out right? 9/10 times they deploy re/deploy together just fine so what good is the skyhook if you aren't going to cut away low? What scenario provides a good reason to use the skyhook? I can't think of any, you will always be better off adding the reserve, right? And the skyhook could cause a problem when I don't need it, which happens to be my most likely cutaway scenario, cutting away high. Which brings me to my next point..

The simpler your reserve system is the better. I understand a standard reserve, pull pin, spring fires, pc pulls canopy...I need to understand how the skyhook operates better before I'm comfortable with it. It hooks up too much shit to my last chance and there are lots of new failure modes that probably haven't even been discovered yet as it's still relatively new.

So..

Unless I am thinking about changing my do not cut away below altitude to count on the skyhook why add failure modes and complexity? Granted I plan on getting some hands on explination from my rigger so hopefully I understand it enough to be comfortable with it but for now I'm skeptical, if it had been out longer and could be relied upon maybe not so much.

Fair assessment? What am I missing?


david3  (D 21297)

Feb 26, 2011, 1:25 PM
Post #91 of 107 (1594 views)
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Re: [drewcarp] Skyhook Activation Stories [In reply to] Can't Post

http://www.youtube.com/watch?v=z-WBBLAgE_s

YMMV


JerryBaumchen  (D 1543)

Feb 26, 2011, 1:36 PM
Post #92 of 107 (1586 views)
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Re: [NovaTTT] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

Hi Nova,

Quote:
what the pros/cons are of the bridle pocket about which you and Kelly don't agree.

I don't think that is anything 'pro vs cons' as I just like things very neat & orderly.

By having a pocket on the bridle ( see the attached photo ), it just keeps things in place until they are needed for useage.

JerryBaumchen
Attachments: 113_1301.JPG (73.7 KB)


KellyF  (D 13826)

Feb 28, 2011, 8:02 AM
Post #93 of 107 (1502 views)
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Re: [NovaTTT] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:
I'd like to know, if you don't mind sharing some of the information, what the pros/cons are of the bridle pocket about which you and Kelly don't agree. And if it's not breaking privacy, I wonder what other aspects are in . . . well, gentle dispute?

I see that without the pocket the bent pin on baglock isn't an issue - but what other issues concern you? Has the positional durability been tested? Meaning, will the RAX remain in place for 180 days of typical rig use if there is no bridle pocket?
Jerry would like to see the tab tacked in place with seal thread, I don't see it as necessary, but wouldn't cause any functional issues. As far as "positional durability", I think it comes down to where it is installed in the reserve container, but I don't think there would be significant movement once the container is closed. I would like to point out that this is just a concept at this point as far as VSE is concerned and we haven't installed one in an Infinity at this point.

In reply to:
I'm a fan of the device, as I think you know, and the only "real" problem I've had with it is the missing Collins Lanyard (or equivalent) - that and the fact that it's not available! Angelic
UPT won't license the Collin's Lanyard separate from the Skyhook, and while there are other ways to accomplish the function, UPT pretty much has the simplest solution. That said, I've never heard anyone say that they would jump a standard RSL "if only it had a Collin's Lanyard", so why one and not the other?


NovaTTT  (D 17887)

Feb 28, 2011, 10:58 AM
Post #94 of 107 (1460 views)
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Re: [KellyF] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

Thanks for the feedback, Kelly.

Quote:
That said, I've never heard anyone say that they would jump a standard RSL "if only it had a Collin's Lanyard", so why one and not the other?

I'm sorry - I think I didn't express myself well or make myself clear in that other post. When I said "it's not available" I meant the RAX, not the Collins lanyard, and when I said "real" and used the Angelic I was implying that there isn't a problem with the RAX - other than it not being available!

I know UPT won't license the CL, which is the KISS solution to the other riser concern. Some of us, though, consider the other riser concern to be not as important as the cutaway-no pull concern. So while the CL would be nice, I don't consider it or its equivalent a necessary aspect of a MARD system.

But I don't use an RSL anyway! If I did, and wanted a MARD, I would choose the RAX (with or without the CL) if it were available.


(This post was edited by NovaTTT on Feb 28, 2011, 11:22 AM)


ruthers  (D 4468)

Jun 16, 2011, 3:35 AM
Post #95 of 107 (1307 views)
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Re: [JerryBaumchen] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

Just reread this thread, if anyone is still interested to discuss: is the RAX pin disconnect sensitive to the direction which the pc/bridle pulls?

I'm not sure what would happen if the jumper has a total (caused for example by being unstable and getting main pc bridle wrapped somewhere), pulls their reserve ripcord, the reserve pc launches but again due to instability the first pull on the bridle pulls to the right, pulling the tab out of the pocket. Would the bridle now be locked to the RSL, which is stuck to the risers and hence container since the main is still closed?

Perhaps I misunderstood the sequence of the RAX opation.

Cheers,
Hamish


riggerpaul  (D 28098)

Jun 16, 2011, 5:59 AM
Post #96 of 107 (1265 views)
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Re: [ruthers] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:
Just reread this thread, if anyone is still interested to discuss: is the RAX pin disconnect sensitive to the direction which the pc/bridle pulls?

I'm not sure what would happen if the jumper has a total (caused for example by being unstable and getting main pc bridle wrapped somewhere), pulls their reserve ripcord, the reserve pc launches but again due to instability the first pull on the bridle pulls to the right, pulling the tab out of the pocket. Would the bridle now be locked to the RSL, which is stuck to the risers and hence container since the main is still closed?

Perhaps I misunderstood the sequence of the RAX opation.

Cheers,
Hamish

Looking at Jerry's picture, notice that there is ample slack in the red webbing that if the pilot chute is pulling, the pin will slip from the loop, regardless of the direction of the pull. To be clear, the pilot chute, missing in this photo, would be attached to the end of the white bridle that goes off to the left.

Pull to the left, and the tab will clearly stay in the pocket (on the flap), pull to the right, and the pin will release before the red webbing "unfolds" to put tension on the tab in the pocket.

This photo is not the latest version of the design. In the design that I recently saw in mock up, the tab has a ring at the end, I believe a steering line guide ring, that is pushed though the pocket. The bottom of the pocket is open. This ring will lay over the grommet of the flap with the tab pocket, and the closing loop will go though the ring as a matter of course. This mechanism will ensure that the tab cannot be pulled from the pocket until the reserve container has opened, eliminating the possibility that rough handling of the rig would do that. But the ring also makes the pocket even more secure as well, meaning that more force will be needed to extract the tab from the pocket. It still slips out readily when it should, but it takes far less force to slip the pin than to extract the tab.

Let me know if this description is clear or not. I'm happy to try again if needed.

-paul


ruthers  (D 4468)

Jun 16, 2011, 8:27 PM
Post #97 of 107 (1131 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

Paul, thanks for the explanation.

At first when I read your post, I was thinking that having the ring around the closing loop could mean the closing loop could get broken by a pull on the RSL (such as from a failure of the RSL side riser/3 ring), releasing the reserve into what is potentially still a mess. But then I realised that of course the RSL pulls the reserve pin anyway, which is why there is the need for a Collins Lanyard type of function.

Will be interesting to see how the new Strong Tandem system's MARD works, as that has been advertised but I haven't seen details yet.


JerryBaumchen  (D 1543)

Jun 16, 2011, 8:51 PM
Post #98 of 107 (1124 views)
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Re: [ruthers] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

Hi ruthers,

Here is a photo of the latest version showing how the Locking Loop will pass through a RW-4 on the end of the tab, which then will keep everything secure until such time as the ripcord pin is pulled.

The Locking Loop shown in the photo is just what I had laying there when I needed the photo; it is not something I would use in the real world.

I hope the photo is sufficiently large enough for you to see everything; this site has a photo size restriction that I had to conform to.

JerryBaumchen
Attachments: RAX-127.jpg (41.1 KB)


riggerpaul  (D 28098)

Jun 17, 2011, 5:44 AM
Post #99 of 107 (1070 views)
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Re: [ruthers] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

In reply to:
Paul, thanks for the explanation.

At first when I read your post, I was thinking that having the ring around the closing loop could mean the closing loop could get broken by a pull on the RSL (such as from a failure of the RSL side riser/3 ring), releasing the reserve into what is potentially still a mess. But then I realised that of course the RSL pulls the reserve pin anyway, which is why there is the need for a Collins Lanyard type of function.

Will be interesting to see how the new Strong Tandem system's MARD works, as that has been advertised but I haven't seen details yet.

The necessity for a Collins Lanyard function is disputed. Most existing RSLs do not have a that functionality.

In addition, the Collins functionality is patented and has not yet been licensed except in conjunction with the Skyhook.

ETA - I have resized Jerry's photo. It is bigger, but the resolution is about the same, so the quality is a bit lower. But I hope it is still easier to look at.

In this photo, the green disk on the left represents the pilot chute. The reserve bridle is black, not the traditional white. What used to be the tab pocket is now a channel, and it is canted towards the closing loop grommet to allow the closing loop to go through the ring.


(This post was edited by riggerpaul on Jun 17, 2011, 5:54 AM)
Attachments: RAX-127 RESIZED.jpg (49.9 KB)


ruthers  (D 4468)

Jun 17, 2011, 4:09 PM
Post #100 of 107 (976 views)
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Re: [riggerpaul] Pros & Cons of M.A.R.D (Was: Skyhook Activation Stories) [In reply to] Can't Post

what happens if a situation as may have happened with the tandem fatality a while ago, where on a low pull, the cypres cut the loop, and the main opening shock may have ejected the reserve freebag and back loaded the skyhook? i.e. if the pull on the reserve bridle is from the freebag side and not the pilot chute side, will the pin disengage or will the pin perhaps get bent?

A convoluted sequence I guess, but Murphy's law has a habit of lurking. Without a collins lanyard, the above would mean that the reserve freebag would not be released from the RSL, which is still attached to the (not yet cut away) risers. Perhaps that's a better outcome than a 2 out anyway?


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