The simpler the better

[JerryBaumchen 1,238]

Hi folks,

Some just posted this in another thread:  The simpler the better

Over the yrs I have often thought about this.  There is also the KISS principle.  And, the more complex, the greater the potential for failure.

This brings me to my thoughts on the simplest setup:

-  The rig would use a semi-exposed pilot chute [ Jav, Wings ] to reduce the flaps to push away

-  The reserve canopy would be a 26 ft Navy Conical with no diaper - less things to go wrong & a very strong canopy

I know that few of you would agree; so, let's hear your thoughts.

This might be fun,

Jerry Baumchen

 

[Veis 28]

58 minutes ago, JerryBaumchen said:

This brings me to my thoughts on the simplest setup:

-  The rig would use a semi-exposed pilot chute

MARD is loved by the manufacturers of rigs. Because many dropzones began to require RSL for certain categories of parachutists in order to reduce the human factor of fatality. But manufacturers of rigs do not like RSL, because many in recent years have noticed delays in freebag's extract on some sizes and in some flight poses. Semi-exposed PC too. And RSL does not allow us to attribute such a delay to the human factor. MARD is an "RSL without risking the reputation of the manufacturer"... The number of possible reserve deployments where the delay can manifest itself is getting less by MARD etc

58 minutes ago, JerryBaumchen said:

This might be fun

))

Edited June 27 by Veis

[gowlerk 2,070]

No thanks to the round reserve. And I would not have them in my rental fleet either. Many DZs won’t even allow them. 

[pchapman 275]

Stirring the pot, eh Jerry?

Like many sayings, the one about "the simpler, the better" holds true only in some situations.  But you know that too, since you know all the tradeoffs that come with things that are engineered.

While all the modern add-ons can make rigging more complex, I'm not sure many jumpers would want to keep things simple and ditch AAD's (complex electronics and cutter design!) or even MARDs (despite all their slightly confusing variety and some valid concerns about certain rare situations). Added safety balanced against reliability and of course money.

Super strong Navy Conical? Yeah it'll work, but most of us would these days like the tradeoffs that come with complexity. Like ram-air steering since not all DZs are out in big farm fields any more.  Or somewhat reduced weight & bulk would be appreciated -- Doesn't have to be quite as bulletproof (or nylon burn proof...)  if a diaper keeps opening sequences less messy. And ram-air reserves have kind of proven themselves (even if the spectre of a bag-lock has never been entirely removed).  

You sure you'd be OK with a terminal Navy Conical opening? We're not all 20 anymore y'know!
 

[wmw999 2,291]

Well, the absolute simplest is probably a base rig on a high bridge jump. One canopy, enough time to get stable, pull. No obstacles if it’s an ideal world.

That said, I’d go with a square 7-cell main and a square 7-cell reserve. Because part of the simplicity is the same thing you’re used to no matter what. 

While they’re more complex-seeming, squares seem to have a better track record on not malfunctioning than rounds. 

Wendy P. 

[JerryBaumchen 1,238]

32 minutes ago, wmw999 said:

Well, the absolute simplest is probably a base rig on a high bridge jump. One canopy, enough time to get stable, pull. No obstacles if it’s an ideal world.

That said, I’d go with a square 7-cell main and a square 7-cell reserve. Because part of the simplicity is the same thing you’re used to no matter what. 

While they’re more complex-seeming, squares seem to have a better track record on not malfunctioning than rounds. 

Wendy P. 

Hi Wendy,

IMO opinion, there is very little data to support that.  Others may disagree.

And, of course, we need to define 'malfunction.'

With side by side problems, I'll take the round to survive the landing.

YMMV,

Jerry Baumchen

[Veis 28]

Square reserves are reliable enough, but only when there are no triggers and retarders between freebag and PC.

I had a Rogallo-type (like Para-dactyle) reserve, and I didn't have complete confidence in him. Firstly, because of the large internal air volume. Secondly, because of the deployment and slowing down system.

[SCS422 24]

All 7 of my reserve deployments were with a navy 26 except one and that was a 26 lo-po, i liked it  I think only 2 were terminal though and the opening dang sure wasn't any worse than when i jumped Hanks Piglett, there is a whole 'nuther story there.

[Iwan 44]

Excepting round shape reserve I agree. I can't see nothing complicated with square shape reserves. I prefer normal fabric not LPV. 

[riggerrob 598]

Hi Jerry,

Good point about the exposed reserve pilot-chute.

The most complex reserve deployments involve internal pilot-chutes which look pretty and are difficult to snag accidentally.

A Vector loop needs to clear 5 grommets before the pilot-chute can launch. If the AAD gets scared, it still needs to clear the 5 grommets, plus one more in the inner bottom flap. To launch the free-bag requires clearing a total of 9 grommets plus a cutter.

A single-pin Mirage requires the pilot-chute to push 5 grommets aside before it can a launch. Launching the freebag requires clearing a total of 7 or 8 grommets plus a cutter.

A Racer pilot-chute needs its loops to clear 12 grommets plus a pair of cutters. Yikes!

A single-pin Teardrop may look the same as a Racer - from a distance - but it only has 7 grommets plus a cutter. If the AAD gets scared, the loop still needs to clear 7 grommets to launch the pilot-chute.

Reflex has an exposed, single-pin pilot-chute, but the loop still needs to clear 6 grommets plus a cutter to launch the pilot chute. If the AAD gets scared, the loop still needs to clear 5 grommets.

To summarize: most Pop-Tops fit your criteria of fewer grommets above the pilot-chute, but loop(s) still need to clear ALL of the grommets before the pilot-chute can launch.

The semi-exposed pilot-chutes found on Javelin, Dolphin and  Wings only require pushing 3 grommets aside to launch a pilot chute and 6 to launch the free-bag. Even a dud cutter cannot interfere with deploying a Javelin reserve because the cutter is mounted below the free-bag.

The ADVANCE container was basically a simplified Javelin minus the reserve side flaps. Launching an ADVANCE reserve pilot-chute only required pushing aside 3 grommets. Launching the free-bag require clearing a total of 4 grommets.

The basic problem is that most piggyback containers were designed back when bulky, 26' Navy conical reserves were the height of fashion. Since then they have just built smaller and smaller versions. Not all the components scale down gracefully. For example, most reserve pilot-chutes are still based upon the MIL SPEC MA-1 pilot-chute with a 6 inch crown. That 6 inch crown does not scale down graceful to the narrower containers that are fashionable today.

After a few Mirages suffered reserve pilot-chute hesitations, I concluded that the fewer grommets the better.

So I challenged myself to build a container with the fewest grommets possible. My first prototype had only 2 reserve flaps and 2 main flaps. It had an exposed, single-pin pilot-chute. There has no hard (aluminum or composite) cap and no grommets set in the pilot-chute. The reserve ripcord cable laid against the jumper's spine (ala. Racer Reflex and Teardrop). During ripcord deployment, the closing loop only had to clear 2 or 3 grommets plus slide through a sleeve. Then the loop still had to clear one more grommet plus the cutter to launch the free-bag. If the AAD got scared, then the loop had to clear a single grommet and slide through a sleeve to launch the pilot-chute. An AAD deployment still required the loop to clear all 3 or 4 grommets.

My main container only had 2 side flaps.

[Veis 28]

The loop is only one problem. There are other problems that are no less important:

1. The energy of the PC should be maximum. To do this, the PC hat must be heavy and/or the upper coils of the spring are larger.

2. The freebag path should not limit overlapping parts, including corners.

3. But at the same time, the geometric shape of the container must remain stable during operation, especially the loop axis.

4. The density near the spring should not change after packing, so that the position of the parts does not change. Ideally, the spring should not stand on reserve fabrics.

etc.