Raven Dash-MZ Reserve

[bwilling 0]

Anybody know anything about the Raven Dash-MZ reserves? It's a ZP version of the Dash-M, but a quick serach of the forum bought up nothing, so I wondered if anybody's had any experience (good or bad) with these reserves... the fact that Precision is the only mfg that uses ZP in a reserve make me wonder... if it's such a good idea, why don't all the mfg's do it? Then again, when square reserves first came out, LOTS of people continued to jump round reserves for many years afterwards...

"If all you ever do is all you ever did, then all you'll ever get is all you ever got."

[Sonic 0]

I know there was a service bullitin out of all of the pre april (99?) ones.

-----------------------------------
It's like something out of that twilighty show about that zone

[weid14 0]

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Anybody know anything about the Raven Dash-MZ reserves? It's a ZP version of the Dash-M, but a quick serach of the forum bought up nothing, so I wondered if anybody's had any experience (good or bad) with these reserves... the fact that Precision is the only mfg that uses ZP in a reserve make me wonder... if it's such a good idea, why don't all the mfg's do it? Then again, when square reserves first came out, LOTS of people continued to jump round reserves for many years afterwards...

I *think* it's a zpo top skin, and a 0-3cfm bottom skin, it never really took off, the only folks that would really benefit from it were the CRW dogs, definately not a rigger! there is really no advantage for the extra struggle to pack them.

Round reserves, BTW, are more advantageous in certain circumstances than squares.

[Jessica 0]

Personally, I DON'T think they're good ideas. I've watched someone pack one, and it took him twice as long as an F-111 reserve, and there was sweat pouring down his face as he tried to control the ZP fabric. Packing reserves requires a lot of precision, which is difficult to get with ZP. Do you really want to make packing your reserve that much more tricky for your rigger?

I just don't think there's any point using ZP for a canopy that's only going to see a few uses (one hopes). The porosity just won't be affected to the point that ZP fabric would be a benefit.

That said, there have been a few discussions on them, but the search function isn't working right, so you might have to browse the threads for them.

Skydiving is for cool people only

[PhreeZone 20]

ZP on reserves just increases the usubility life of the reserve. The only need for this is if you are a test jumper or plan on using your reseve a lot. Normal reserves are good for quite a few jumps, ZP just makes it last longer.It makes it a pain to repack the reserve thats got a top skin of ZP.

Most -M's (-MZ's too) have had the service applied to them on the bulliten already, PA has a search engire to see if a used reserve is on the list.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[Jimbo 0]

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ZP on reserves just increases the usubility life of the reserve.

Doesn't ZP, when it rips, rip all the way to the seam regardless of any rip-stop technology that may be incorporated into the fabric? That's what I've been led to believe, of course I've also been told that F111 does not exhibit this rather nasty characteristic. ZP on a reserve, no thanks.

-
Jim

"Like" - The modern day comma
Good bye, my friends. You are missed.

[weid14 0]

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ZP on reserves just increases the usubility life of the reserve.

Doesn't ZP, when it rips, rip all the way to the seam regardless of any rip-stop technology that may be incorporated into the fabric? That's what I've been led to believe, of course I've also been told that F111 does not exhibit this rather nasty characteristic. ZP on a reserve, no thanks.

-
Jim

not sure about that, the specifications in the little book DuPOnt puts out have them very close in all areas. I would think they would exhibit the same tear tendancies. (ever notice it is hard to get a tear going in material, but once it goes, it rips easily -- just a thought).

[councilman24 37]

My current take on that from hearing various sources... "WARNING, UNSUBSTANTIATED OPINION FOLLOWS"... is that is NOT a characteristic of the fabric, but more due to the higher loads placed on the fabric in general. In other words, ZP is usually loaded higher (higher pressurization, faster air speads, higher opening shocks) so when it goes it goes farther. 0-3 cfm fabric would do the same if loaded to the same level when it fails.

I'm real glad nobody has asked me to pack a MZ.

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

[weid14 0]

on the other hand, though the old "F-111" canopies open "briskly". the newer canopies are a little more forgiving in that area. I've seen them both blow up. It is amazing, though to watch a canopy disintigrate that was sitting in the weather for a year.

[Mtt481 0]

Actually the use for the zp topskin is to allow longer life and less breakdown of the fabric due to repacking of the reserve. They are a bigger pain to pack, and offer no flight advantages over f-111. I do have an mz in my rig, though I have never had to use it knock on wood, but it took one rigger all day to TRY to pack and a different rigger one time to pack. But I will not purchase another mz with my next rig due to the horrible experience that I gave my rigger.

[lummy 4]

Slightly off topic, but aren't the flaring techniques different for an F111 and a ZP canopy?
I seem to recall that F111's would need to be flared a little higher whearas a ZP is more a two step process, First step to level out, second to bleed off speed.
Assuming I'm correct, how would a an MZ flare given that is is a ZP topskin?

I promise not to TP Davis under canopy.. I promise not to TP Davis under canopy.. eat sushi, get smoochieTTK#1

[weid14 0]

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Slightly off topic, but aren't the flaring techniques different for an F111 and a ZP canopy?
I seem to recall that F111's would need to be flared a little higher whearas a ZP is more a two step process, First step to level out, second to bleed off speed.
Assuming I'm correct, how would a an MZ flare given that is is a ZP topskin?

new "f-111" would flare the same as a Zpo canopy, it's when it starts to get porus where the differences really show, and you'd have to replace the reserve by then.

[riggerrob 643]

I have packed a few Raven -MZ reserves. Yes they take a little longer to pack, but by the time I have all my clamps, molar strap, etc. wrapped around the canopy, there is not much difference in technique. You just have to be patient enough to let the air seep out before doing the next step in the packing process.
New ZP and F-111 fabric fly about the same, so I do not expect much difference in flare characteristics. Any reserve that has more than 20 jumps should be taken out of service.
I suspect that the main reason Precision started building reserves with ZP fabric was to gain some experience before F-111 disappears from the market. And trust me, as soon as the military figures out that ZP fabric is a better investment, F-111 fabric will disappear.
As for tearing characteristics, I have only seen two torn reserves. The first was on an over-weight (360 pounds), over-speed (205 knots) drop test. A human would have survived the landing.
The only torn reserve I have seen occurred when an over-weight, over-speed, jumper was unstable when he scared his Cypres. If you are going to make that many mistakes, then you run a high risk of tearing any canopy. He survived with multiple fractures.

[MrHixxx 0]

I have heard the same thing, in that making the material zp makes it lose its ripstop characteristic. F111 fabric tears a few squares then takes 90 turn and stops. Zp fabric blows out from nose to tail. I am certain that Ed Cummings wrote an article on this in Skydiving or Parachutist several years ago. You might drop him an e-mail...

-Jon

[billvon 2,991]

>I have heard the same thing, in that making the material zp makes
> it lose its ripstop characteristic. F111 fabric tears a few squares then
> takes 90 turn and stops. Zp fabric blows out from nose to tail.

Not according to the manufacturer. From George Galloway:

This is a common misconception, even among many high time jumpers,
unfortunately.

F-111 was a particular brand of parachute fabric which has not been produced
in the last decade. Today's fabrics are much better than the old F-111, but
no parachute fabric has ever been particularly strong in the Tear Resistance
category.

The tear strength for brand new "Reserve Canopy Material" is only 5 lbs,
even right off the roll. If you take the same roll of fabric and put a ZP
coating on it, the tear strength goes up to about 18 lbs, so in that regard
the ZP fabric is more than 3 times as strong as the uncoated fabric.

The term "Rip Stop" has more to do with the weave pattern of the fabric than
its tear properties. The term "Ripstop" has been misunderstood for a long
time. Although a rip in a parachute is difficult to initiate (due to the
high Tensile Strength of the fabric) once a tear does get initiated, it will
usually travel along the grain of the fabric with very little effort to the
first seam. In the evrnt of catastrophic failure, the tear will then turn
downseam or upseam to the nearest reinforcement tape, but will seldom
"cross" a seam. Never say never.

[weid14 0]

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I have heard the same thing, in that making the material zp makes it lose its ripstop characteristic. F111 fabric tears a few squares then takes 90 turn and stops. Zp fabric blows out from nose to tail. I am certain that Ed Cummings wrote an article on this in Skydiving or Parachutist several years ago. You might drop him an e-mail...

-Jon

here's a website, take a look for yourself. Tensile strength is the important part. http://www.perftex.com/ exacta-chute is the "F-111" and the Soar Coat is the Zpo. you'll notice a significant difference in tear resistance -- the zpo is mush higher.

[MrHixxx 0]

Thanks for the link. Perhaps this explains why it does go from nose to tail when it fails, because three times the force has to be neccessary to initiate damage.
I would still like to hear PDs take on this. They chose their materails carefully after quite a bit of research and I don't see them with a zp reserve on the market.

-Jon

[MrHixxx 0]

I heard back from PD on the material issue. The short aswer, F-111 material is stronger as the speed of the tear increases... The manufacturer tests at 12" a minute where PD tested fabrics at 150" a second (more like a catastrophic failure). This is why PD considers F-111 a superior fabric for reserves. I'll post the entire e-mail when I get to a PC that I can cut and paste with (shitty coffee shop PC).

-Jon

[MrHixxx 0]

Here is the answer I received from PD Marketing Rep...

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Why don't we use ZP fabric in our reserves?

First, the tear strengths listed in the specs are very misleading, for
two reasons. The tear strength is measured at a specific tearing speed,
measured as a certain distance per unit of time. When you tear things
relatively slowly, the tear strengths are quite high. However, when you
increase the speed of the tearing motion, the actual forces required to
keep the tearing motion progressing actually go down. The tear spec is
measured at a standard 12 inches per minute, a rate at which the ZP
fabric looks superior to the standard fabric. However, this tear speed is
not very realistic compared to the way a canopy would really tear.

Because of this, we have created our own testing machinery that can
measure tear strengths at up to 150" per SECOND. When you measure the tear
strength at a high tearing speed more like what would happen in
reality, the tear strengths go way down, to the 3 to 7 pound range. The
standard fabric actually has a higher tear strength at these speeds than the
ZP fabric torn at the same speed.

So to cut it short, the tear strength of the ZP fabric is lower than
that for the F-111 style fabric when the tear speeds are up where things
would be in an actual failure mode.

When a ZP canopy fails, it is typically pretty catastrophic, with tears
going every which way in unusual patterns. On F-111 type canopies, the
damage is typically more localized.

Other reasons to not use the fabric? The benefit of ZP fabric is
partially the fact that is stays low porosity. If that is an issue on your
reserve, you are using it way too much. Another benefit is the presumed
aerodynamic advantage. In reality, the aerodynamic performance is due
to other aerodynamic issues such as better airfoils, aspect ratios,
trim, etc. These items aren't suitable for reserve designs, due to opening
issues. When you use good reserve aerodynamics, but throw the ZP fabric
in there, you don't really get an improvement in landing performance.
An example of this can be seen by comparing the ZP lightning crew canopy
to a ZP Spectre. The two canopies are designed to do separate things.
The Lightning lands well for a CRW canopy, but is relatively tricky to
land compared to the Spectre, even though both canopies have ZP fabric.

-Jon