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Strong DHT - design flaws, safety hazards, maitenance hazards

 

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Zahry  (D 698)

Jul 20, 2009, 12:01 AM
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Strong DHT - design flaws, safety hazards, maitenance hazards Can't Post

MOVED from discusion forum about another fatality related to DHT equipment.

http://www.dropzone.com/...6;page=unread#unread

I would like to encourage all people reading my posts if you agree and even more if you dissagree with my opinions to COPY and PASTE the texts as it is or a link to this forum to an email and send it to EVERY TM and RIGGER you possibly know.

We have a freedom of speach and the right to know what's really going on .

Is Strong deliberately diverting our attention from real problems?

Is Strong covering up dangerous design flaws?

Is Strong DHT certified according to the present standarts?

Is Strong DHT high maintenance demand reasonable workload or unjustified hazard?

Why Strong DHT doesn't have a lot safer reserve system yet?

>>> moved from previous forum<<<
In reply to:
I don't know you but you OBVIOUSLY have an ax to grind. In my opinion Strong Enterprises is one of the most reputable companies in the industry. The SET 400 is a very reliable system that by design has a lot of redundancy. I am a rigger and like most systems maintenance is key. To try and even suggest some of the things in your statement is hiding from the truth. Truth - The proper maintenance and training wasn't done. Truth - The manufacturer's approved canopies were not used.

Regarding this incident the two truths stated above were both huge factors in this fatality and anyone with common sense would not try and argue differently.

For what its worth I saw first hand an unapproved smaller canopy being used in a SET 400. This incident happened at Titusville around three years ago. The reason I remember the incident is because on deployment 1/2 of the reserve container was ripped away when the main canopy lines didn't deploy correctly.

There is a big reason why ALL the manufacturer's recommend using a properly sized container for sport parachutes. Of course under your logic only Strong Enterprises is wrong when they suggest that some canopies are too small to be used with a SET 400 system.

Hi, are we speaking here about the THRUTH in meaning I BELIEVE it is a THRUTH or are we talking about thruth based on facts?

It looks like Strong is trying to carefully divert the attention and they are trying to cover something up.

Here we have a few facts based on my experience as a packer, rigger and tandem master ...
(done about 10K - 20K + packjobs, 6 years of maintenance on daily basis (fulltime job on busy NZ dropzone), done about 1000+ reserve packjobs and about 4000+ tandems on DHT):

Strong DHT is a HIGH maintenance system with many design flaws, weak points and many mods and mods of mods. Surprisingly not too many people has died yet - I guess the main credit goes to the tandem masters well aware of the dangers related to DHTand riggers maintaining the systems rather than Strong Enterprises.

About the accused main canopy problem. There is a difference in size but there is very small difference in packing volume. If Strong realy mean it serious with the volume of the packjob beeing main contributor of the accident, than ALL DHT systems should be rendered UNSAFE and grounded IMMEDIATELY. Simply - packing volume can change significantly in dependance on humidity, packjob, age of the canopy and so on and there is no guaratee the packjob will have the correct volume for the system to work properly even with approved canopy.
Blaiming the difference in sizes of the canopies to be the cause of the problem is bit suspicious and smells with something dirty. The difference in volume is very small.

Lets draw the attention to the more "hot" subjects.
Who has a DHT please gab it and check following examples:

- above mentioned improperly secured hard housings on main risers - bottom of the housing is free to twist and is very common for the housing to twist out during the approved period of jumps and stretch - potentialy jamming 3 ring system. During the packing inspection it seems for the packer there is a huge gap between the housing and the 3 ring system. That's when it is lying flat on the ground - if you bend it back (when you place the risers into container) the gap disapears (no point to argue - it's geometry - try it :-) ) in that stage the loop can hook up on the housing and once the canopy is deployed the housing can either slip out fromn the trap or get stucked there and jam the 3 ring system. If you need to cutaway you'll have a bad day.

- above mentioned ripped off reserve corners - not so many TMs know whats the real cause of the problem. Mostly they blaime it on packers and risers. True but the cause is somewhere else. If you don't believe grab a rig and have a look into reserve compartment and focus your attention on the construction of the reserve corners. Without too much difficulty you should be able to find (unless the rig has been modified by rigger) the corners are held just by a few fairly weak stitches. There is a gap in stitching allowing through cypres cables. Mostly - this weak point is over the period of time more and more weaken by deploying risers and eventualy it is bound to let go. (it happened on almost EVERY rig we have here regardless of the canopy and packing volume of the canopy)

- drouge release system is a chapter for itself and unless I want to start writing a book I have to take it very briefly.

Housings are easily damaged and has to be changed frequently otherwise jamming cables inside.

Flexipins have to be checked frequently because of the damage caused by kinks in the housings and the sharp edges of unproperly finished housings (I'm talking about those infamous plastic covers for the ends of the housings which has to be frequently checked and replaced regulary otherwise the sharp edge gets exposed and than the circus begins). It can jam the cable or the cable can snap by the base resulting in drogue in tow.

I'm going to mention just briefly the drogue release cables wich can jam in damaged housings or get stucked on those sharp edges on housing ends when the plastic gets bit tired. In most cases you get just scratched cable but time to time the housing cuts into the cable and than you have to hope for the odds that's not gonna happen on the secondary as well.

Also, there has been numerous problems with hard cutaways realted to cutaway cables, the geometry of the 3 ring system and the top attachement points. The 3 Ring can be pushed/bent away from or into TMs shoulder in dependance on passengers possition (just like a seasaw). It quite changes the forces applied through the loop to the cutaway cable and the geometry. Feel free to grab a rig and discover this interesting feature yourself - it is very interesting - the possibilities are endless.

There is more but I don't want to write a book on How To Survive Jumps on DHT. That's a job for the boys from SE.

All those things are VERY BAD and there in NO EXCUSE why it hasn't been redesigned and fixed - BUT you can get away with it by carefully inspecting the rig before each jump and GOOD MAINTENANCE. It is the same principle like walking throuh long mine field with a map :-) - Once you can get use to it it's quite safe (just don't forget the map ;-)

The ONLY thing you CAN'T do ANYTHING about is the RESEVE... If you can call it so ...

Open up the reserve compartment and have a look inside. For those who has seen reserve and freebag before but haven't seen what's inside DHT there might be a nasty surprise. Why? Have a look how the lines are stowed in shock cord loops and tightly locked in by plastic chokers - this is done on purpose to slow down the line deplyment on high speeds. Without it opening reserve on tandem terminal would be a suicide - MR425 hasn't been intentionaly designed as a reserve (as far as I know it used to be a main and it was opening pretty hard and from what I've heard not really reliably) and the kevlar lines used (who knows why?) are transfering full force of the opening shock directly into harness and back to canopy - not the best feature if you need to slow down quickly on short distance (to make the opening bearable the MR425 has to be flat packed and the nose is rolled/folded in - if you don't believe me do a standart reserve packjob and jump it. BUT ON YOUR OWN RISK!!!)

Anyway back to the PROBLEM NO1: Lines stowed in SHOCK CORD loops choked byPLASTIC CHOKERS on RESERVE deployment bag.
It it doesn't sound like a major problem consider this:

Q: Can you get a bag lock on DHT reserve? (Hint - the lines are not free stowed and there is no running loop)
A: Of course - just like on any other deployment bag where the lines are held in by ruber bands or - in the worst cases - by shock cord. (don't believe me? change your rubber bands on main canopy dbag for shock cord with plastic chokers or just a shock cord. BUT DON'T FORGET - IT IS ON YOUR OWN RISK!!!)

I'll skip the sharp edges on the plastic chokers (easy to find) and I'll cut to the chase.

WHAT IS THE POTENTIAL KILLER HERE:

Imagine this scenario:

Scenario No1: You have a spinning malfunction, you manage to cutaway easy and just when you are about to deploy the reserve your freakt out customer starts kicking (quite familiar - isn't it?) time is ticking or maybe the RSL already kicked in as well and you are rolling just as the reserve pilotchute leaves your back. Sudenly you find yourself with reserve pilotchute bridle wrapped on some part of your body. What is the possible outcome? (hint: it is a classic horseshoe malfunction the same as on main canopy - the lines are NOT freestowed and there is NO running loop). More likely you end up with heap of mess above your head instead of good canopy

Scenario 2: What if the reserve bridle or pilotchute will get caught on drogue in tow on hanged up canopy?

Scenario 3: what if the chokers slow down line deployment and the reserve line will tangle with drougue in tow or canopy hang up?

Ted and Tom - How can you justify such a HUGE design flaw on reserve system? What is the excuse for this?


Zahry  (D 698)

Jul 20, 2009, 12:04 AM
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

>>> posted by [divnswoop] - moved from previous forum<<<<

In reply to:
Wow, That is a lot.
Kinda scary that you have all these issues, but have 1000+ Reserve pack jobs and 4000+ jumps on the system. Why do you continue to pack/ jump the system if it is such a "death trap"?

Quote:
BUT you can get away with it by carefully inspecting the rig before each jump and GOOD MAINTENANCE

Good idea, I think the tandem manufatures should adopt this.

Quote:
How can you justify such a HUGE design flaw on reserve system?

While the Dual Hawk may not be the most modern system, It passed the same testing process as every other system.
You can sit and pick out flaws/ scenario's in every system out there.


Quote:
Skydiving is natural segregation of heroes and idiots ;-)

...and those who will pack anything for a dollar...


Zahry  (D 698)

Jul 20, 2009, 12:05 AM
Post #3 of 98 (4410 views)
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

>>> moved from prev forum <<<<

In reply to:
Quote:
Wow, That is a lot.
Kinda scary that you have all these issues, but have 1000+ Reserve pack jobs and 4000+ jumps on the system. Why do you continue to pack/ jump the system if it is such a "death trap"?

Funny you assuming I had all those issues. Learning is an interesting process and I found out good education and observation is sufficient substitute for my own cockups. I know the symptoms, I know the causes so why do you think I'll be waiting for the consequences? Long story short - why should I repeate mistakes someone has done before me in past?

And why I pack it and maintaining such a death trap? Because I have a job to do and responsibility to the TMs. I want to give them the best chance they'll go home on the end of the day and I don't want to see anyone going home in a coffin. I'm well aware of the dangers of DHT and I have the knowledge I've got from riggers I've previously worked with - and they had to learn all of that the hard way (thanks Dave and Dave). That, in my opinion, is giving me the best chance to cheat the odds in this game of russian roulette.

Long story short - if i'll quit someone else will come and it might be as well new unexperienced rigger who doesn't have a clue about the maintenance demads of DHT. And than you have a dead bodies walking to work every day. They just don't know yet.

Unless SE will be forced to redesign and recertify their DHT to comply with safety standarts (hopefuly just because of good arguments not because of too many fatal accidents) there is nothing much going to happen except sometimes we will have to clean up the mess.

The DZ owners don't want to or can afford to replace the gear because of the huge cost, SE don't want to admit there is anything wrong because redesign the system or recalling all the systems back to the factory would kill their company for good - plus there will arise the legal responsibility as well. And in middle of that you have a lot of confused people and riggers who have to deal with the pressure from both sides and take the punishment for someones greed, lack of good judgement and no sense of responsibility -

I reckon now is the time to push back.


Quote:
Quote:
BUT you can get away with it by carefully inspecting the rig before each jump and GOOD MAINTENANCE

Good idea, I think the tandem manufatures should adopt this.
everyone who does anything with DHT has to remember that - but good maintenance doesn't fix the reserve system problem.

Quote:
Quote:
How can you justify such a HUGE design flaw on reserve system?

While the Dual Hawk may not be the most modern system, It passed the same testing process as every other system.
You can sit and pick out flaws/ scenario's in every system out there.

THIS STATEMENT IS NOT TRUE. Exactly as you wrote - the DHT is NOT a modern design. It is one of the OLDEST systems (first i believe) on the market and it has been certified way in PAST when piggybacks and square canopies were still novelty and no one had a clue what can possibly go wrong. It is widely IGNORED FACT!

As far as I know DHT has NEVER been tested to comply with present safety standarts. I couldn't find any records of retesting the whole thing again in recent years. The so called reseve system is a hard evidence it hasn't been done - it is just another main system with disconnected dbag with main canopy in it. Present standart is - the freebag should prevent horseshoe malfunction and baglock on reserve - and DEFINITELY NOT PROMOTE IT. The DHT is NOT up to present minimum safety standart. (and I'm not going into details about opening characteristics of MR425 which never been designed as a reserve in first place! And that's the whole core of the snowballing problems)

If you want to compare DHT to other modern tandems I'm strongly engouraging you to DO SO. Have a look at each element of each system, how it works, why it works like that and compare it to others and ask yourself - what can passibly go wrong with those things. Nothing is just good or bad but as we learn more and more you can make yourself a better picture whats right and what's wrong.

My conclusion is - The DHT is old rusty chain which constantly tries to break brak with no propper backup in place.



Quote:
Quote:
Skydiving is natural segregation of heroes and idiots ;-)

...and those who will pack anything for a dollar...

... unfortunately not those who sell anything for a dollar ...


feuergnom  (D License)

Jul 20, 2009, 1:21 AM
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

IMHO: with this whole arguement you try to divert the discussion from the main cause of the incident which triggered the whole debate: Non-existing maintenance and care

maybe - I am not a rigger, just a strong rated TI, so my opinion is surely biased - DHT's are high maintainance. but maintaining DHT's and keeping them safe, seems pretty easy to me. ever tried to change a kill-line on a vector? this is high maintainance in my eyes. take this as a sidenote, because i have no interest in bashing any manufacturer for how they design their gear like you do

if you really don't like strongs and working with them convince your dzo to buy other gear, this is a free world. until then it is your job as the dz's rigger to keep any tandem equipment in a working and safe condition and stick to manufacturer recommendations and safety bulletins by the book - which the dz where the incident happend failed to do


(This post was edited by feuergnom on Jul 20, 2009, 1:22 AM)


pchapman  (D 1014)

Jul 20, 2009, 6:04 AM
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

Interesting perspective in the original post.

Why would anyone buy Strong tandems any more, with the Sigma out there? I'd guess UPT charges a big premium for their system, and of course DZ's stick with what they already have unless they completely replace all their tandem gear and retrain instructors.

I hadn't previously heard much critique or discussion of the Strong reserve system.

What exactly is the use of Kevlar in the reserve? Not just Kevlar lines but also some reinforcing in the canopy?

I try to keep an open mind on the design. But statistics be damned, I can't help be a little suspicious as I had two friends blow up Strong tandem reserves, with not very reassuring explanations from the company. However, I only heard what others said the company said, and haven't seen any actual report.

In one case, the company suggested the rigger might not have packed the reserve properly, snugging up those chokers correctly, something like that. It is always possible but the rigger was experienced and detail oriented and we had zero reason to suspect she did something wrong.

That accident came after an inadvertent main container opening with the drogue out, leaving the bag spinning around. The speed would have been drogue terminal or maybe more if the drogue were choked off. The video shows that the instructor properly released the drogue & jettisoned the main. A hole blew into the reserve on opening; they only had a few cells open; but got a couple more cells shortly before crashing in a field and incredibly didn't break anything.

In the second case, the instructor had a hard pull on the drogue, couldn't get it out, ended up at tandem terminal, blew up the reserve, with instructor and student receiving serious injuries. The company apparently said the instructor should have pulled the reserve earlier, before ending up at tandem terminal. I can see the point about not screwing around too long but it doesn't give me a warm and fuzzy feeling about their reserves when the advice is basically not to use them at high speed.

So I'm curious whether there have been many other issues or I just hung out with unlucky people!


(This post was edited by pchapman on Jul 20, 2009, 6:05 AM)


ojibwe  (A 36892)

Jul 20, 2009, 8:29 AM
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Re: [pchapman] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

My rigger will only pack Sigmas, cites obvious design safety features. What premium justifies human lives? If you can possibly manage the time, please redesign.


(This post was edited by ojibwe on Jul 20, 2009, 8:43 AM)


RiggerLee

Jul 20, 2009, 8:47 AM
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Re: [pchapman] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

 
I've been packing DHT from strong sence my second jump in 1991. I'd have to go back an count how many reserve packjobs. Absolutely no clue how many hours I've spnt sewing on them. Gripeing about strong tandoms has been a standard pass time in the loft for years.

i can sit here and pick apart any design on the market. I keep saying that one day I'll buld a new tandom rig... but what ever. Are strongs my faverat? No. Do they have flaws? A pile of them. are a lot of your bitches valled? Yes. But haveing said all of that I got to tell you your being a little harsh. There are flaws in every system out there. Strong has a working system. It does work. Lot's and lots of jumps on them out here. They've had fatalities, every body has. It has weeknesses, the reserve canopy is a perfect example, but you cant say it's a death trap not when it's been around as long as it has with as many jumps as it has on it.

Now if you want to set down and brain storm ideas mods and upgrades for improving the strong tandom I think that would be a great thread. But with your wild ravings your comeing off as a borderline lunitic tool.

Lee


riggerrob  (D 14840)

Jul 20, 2009, 8:56 AM
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

"Why Strong DHT doesn't have a lot safer reserve system yet?
... because on deployment 1/2 of the reserve container was ripped away when the main canopy lines didn't deploy correctly.
...
- above mentioned ripped off reserve corners ... look into reserve compartment and focus your attention on the construction of the reserve corners. ... the corners are held just by a few fairly weak stitches. ..."

........................................................................

This problem is not unique to Strong Dual Hawk containers.
I have had to re-sew reserve containers back onto Flexon, Javelin, Sidewinder, Talon, Vector 1, Vector 2, etc. containers.

The problem starts with containers originally designed to be deployed on belly being deployed at a wider variety of angles.
The problem is exacerbated by packers wrapping main risers around the lower corners of reserve containers.
I was able to convince the Sidewinder factory to follow EOS, Atom, Wings, etc. example of sewing trianglar "line guides" to lower corners of reserve containers.
The latest Vector 3 and Mirage use alternative methods to prevent peeling reserve containers off.

That being said, all the Strong Tandems here have a little extra zig-zag stitching in the lower corners of the reserve containers.


riggerrob  (D 14840)

Jul 20, 2009, 9:00 AM
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

" ... drogue release system is a chapter for itself ...

.........................................................................

Most of the other tandem manufacturers also use variations on 3-Ring release, so you would have to start bashing Atom, Next, Racer, Vector 1, Vector 2, etc.


riggerrob  (D 14840)

Jul 20, 2009, 9:06 AM
Post #10 of 98 (4146 views)
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

" ... Flexipins have to be checked frequently because of the damage caused by kinks in the housings and the sharp edges of unproperly finished housings ... "

..........................................................................

This problem is not unique to Strong.

Most of the tandem manufacturers (Jump Shack, Parachutes de France, Strong, United Parachute Technologies, etc.) have issued Service Bulletins reminding us to inspect flex pins on a regular basis.

Flex pins are "high wear items."

If you are not willing to inspect - and replace - high wear items, you should get out of the student business!


riggerrob  (D 14840)

Jul 20, 2009, 9:53 AM
Post #11 of 98 (4112 views)
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

" ... MR425 hasn't been intentionaly designed as a reserve (as far as I know it used to be a main and it was opening pretty hard and from what I've heard not really reliably) and the kevlar lines used (who knows why?) are transfering full force of the opening shock directly into harness and back to canopy - not the best feature if you need to slow down quickly on short distance (to make the opening bearable the MR425 has to be flat packed and the nose is rolled/folded ..."

...........................................................................

Ah!
The arrogance of youth!

Perhaps you are not old enough to have jumped Pioneer Hi-Lifter 370. Performance Designs 360 and Strong 425 as mains.
I jumped all of those canopies back when they were fashionable as tandem mains.
I made 1,500 jumps on F-111 tandem mains before SET-400 was introduced.
Trust me, Strong 425 was the "least of the evils."

Maybe I should relate a phone call from a nearby DZO. "Good news! You got another save - on a Vector Tandem reserve - last week. Bad news! The opening sucked! It was stalling and rocking all over the sky!"

Granted, Strong 425 main canopies only lasted about 600 jumps, but solo main canopies - made of the same materials (F-111 fabric with Dacron lines) - only lasted 600, maybe 800 jumps before retirement. By 800 jumps, most F-111 canopies flare like bag-locks!

ALL F-111 canopies open harder than modern ZP mains.
What is your point?

As for Kevlar lines and reinforcing tapes on Strong reserves ... they were the best materials, with the highest strength to weight ratio available, when that system was certified back in the early 1980s. Granted, kevlar suspension lines only survive a few dozen hard openings - before they start snapping, but reserves are limited to twenty deployments (before retirement), so what is your fuss????

Modern zero-stretch lines like Spectra, Vectran and HMA transmit opening shock to the harness at about the same rate as Kevlar.
What is your point?

Speaking of retiring Strong 425 reserves. Back in the 1990s, after we had 20 jumps on Strong reserves, we used to reline them with Dacron and put another 400 jumps on the, before the fabric wore out.

As for criticising Strong's reserve packing methods ... that packing method was fashionable for mains back when the system was certified. I even used to pack my Strato-Cloud that way.

As for suggesting that Strong Enterprises design and certify a more modern reserve canopy ... do you have nay idea how expensive test drops are?
Hint: solo test drops start at $800 per jump!
A few years back, Strong re-tested their tandem gear at 600 pounds.

That being said, I believe that hanging more than 400 pounds of meat under a tandem is just asking for shoulder and spine and leg problems.


RiggerLee

Jul 20, 2009, 3:15 PM
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Re: [riggerrob] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

 
What year was the reserve originaly "certified". I use the term losely as I recall it was really waver/experamintal program. How dose the testing they did then compare to what we've now established as the standard? Don't have the specs in front of me and don't know what they used before seing as they were makeing it up as they went. They them selves admit that it will blow to hell at tandom terminal. Shurely the TSO c23d is higher then that.

What year did they switch to nilon tapes every where on the maine? As it has a closer streach to the fabric under load, any thing would be better then kevlar, I'd bet it has a higher survivability yet they never upgraded the reserve.

and as I recall TSO c23d does allow the use of free fall bullets or dumbies to test canopies. Just roll it out the back of the plane and let it fall till it's going as fast as you like. No more supper high speed passes with specal aircraft. It's nolonger beyond the doable.

Lee


Zahry  (D 698)

Jul 20, 2009, 5:10 PM
Post #13 of 98 (3936 views)
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Re: [riggerrob] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

Quote:
" ... MR425 hasn't been intentionaly designed as a reserve (as far as I know it used to be a main and it was opening pretty hard and from what I've heard not really reliably) and the kevlar lines used (who knows why?) are transfering full force of the opening shock directly into harness and back to canopy - not the best feature if you need to slow down quickly on short distance (to make the opening bearable the MR425 has to be flat packed and the nose is rolled/folded ..."

...........................................................................

Ah!
The arrogance of youth!

Perhaps you are not old enough to have jumped Pioneer Hi-Lifter 370. Performance Designs 360 and Strong 425 as mains.

I've done some jumps on PD 360 and VS 386 and some things just did their job but their time is way over. I think you agree it is easy and inexpensive to replace main canopy but replacing whole system is incredibly expensive. Question is - How much is too much?

Quote:
I jumped all of those canopies back when they were fashionable as tandem mains.
I made 1,500 jumps on F-111 tandem mains before SET-400 was introduced.
Trust me, Strong 425 was the "least of the evils."

It doesn't change the fact main canopy designed as a main canopy is a main canopy - you are a rigger and a very good one. You know reserves are designed different than mains because there are required different opening characteristics and the same is valid for deployment system on reserves.

Now is year 2009 not 1980. I've heard the same arguments before "If you are complaining jump LoPos, ParaCommanders, Thunderbows" - and I did. It made me appreciate those people who stepped up and stepped over those dead legends and moved us forward. And I bet once you were helping to push the safety level up as well ...

Quote:
Maybe I should relate a phone call from a nearby DZO. "Good news! You got another save - on a Vector Tandem reserve - last week. Bad news! The opening sucked! It was stalling and rocking all over the sky!"

I agree. Breaks set so deep it stalls after opening. It is a cheat how to beat the tests on tandem terminal. There are already more modern and better reserves on the market. But you can't say MR425 is not bad because VS360 is not good - it doesn't make sense

Quote:
Granted, Strong 425 main canopies only lasted about 600 jumps, but solo main canopies - made of the same materials (F-111 fabric with Dacron lines) - only lasted 600, maybe 800 jumps before retirement. By 800 jumps, most F-111 canopies flare like bag-locks!

ALL F-111 canopies open harder than modern ZP mains.
What is your point?

my point is in these days we know more about materials, openings, construction and safety. What's the point to throw it out of the window and ignore it?

Quote:
As for Kevlar lines and reinforcing tapes on Strong reserves ... they were the best materials, with the highest strength to weight ratio available, when that system was certified back in the early 1980s. Granted, kevlar suspension lines only survive a few dozen hard openings - before they start snapping, but reserves are limited to twenty deployments (before retirement), so what is your fuss????

As I wrote before, now is year 2009 not 1980. There are far better materials and technologies now. Kevlar lines worn by constant rubbing on sharp edges of plastic chokers can snap any time without any warning - and unless you know exactly what you are looking for afterwards you'll never find it was exactly on the same place where the plastic choker was sitting before.

Quote:
Modern zero-stretch lines like Spectra, Vectran and HMA transmit opening shock to the harness at about the same rate as Kevlar.
What is your point?

Come on, are you pulling my leg? Try the other one - it has a bell on it :-) - Spectra doesn't stretch? Since when and how that happened? As far as I know spectra lines still shrink and stretch in dependence on heat and weight applied ...

Vectran and HMA - true. It doesn't stretch but have you seen it on reserves??? Those lines are used because designers want to keep the same trim over period of hundreds of jumps to keep the same performance on canopy with 10 jumps as well as 500. Zero stretch lines are for competition canopies to reduce drag and to help keep more constant performance and more constant recovery arch On top of it - Most people don't have a clue how extremely difficult is to design canopy to open reasonably with those lines and how complex is designing the opening.

Tell me, was MR425 thoroughly tested and is it well designed for the purpose it serves?

Was the MR425 intended to be used for hundreds of jumps as a swooping canopy/reserve as well?

Quote:
Speaking of retiring Strong 425 reserves. Back in the 1990s, after we had 20 jumps on Strong reserves, we used to reline them with Dacron and put another 400 jumps on the, before the fabric wore out.

As for criticising Strong's reserve packing methods ... that packing method was fashionable for mains back when the system was certified. I even used to pack my Strato-Cloud that way.

Exactly - it is old way and time has moved on. Don't tell me now you'll let your dentist to do your teeth the same way they did it in 1890 or 1960? Back in the day you haven't had an option and no one knew better - now it is a different story

Quote:
As for suggesting that Strong Enterprises design and certify a more modern reserve canopy ... do you have nay idea how expensive test drops are?
Hint: solo test drops start at $800 per jump!
A few years back, Strong re-tested their tandem gear at 600 pounds.

So what. It costs $800 per jump. Everyone has to pay it - not just SE. If they can afford to make it safe that's bad - it's time to take it of the market than.

Are you saying it is not good to question the safety of DHT because testing it and making it safe would cost money???

On the contrary I'm well aware how expensive and how difficult (and that will be the main issue here) is to pass tests for tandem reserve. Especially if the reserve blows up on one of the 3 required jumps on tandem terminal with full weight on. Or if you find it didn't blew up but it would kill both the passenger and TM as well. Or on the end you find the canopy and people survived but because of those changes the canopy doesn't opens to slow on low speeds or stalls after opening - Does it sound familiar?

Quote:
That being said, I believe that hanging more than 400 pounds of meat under a tandem is just asking for shoulder and spine and leg problems.

I fully agree unfortunately average passenger is now more and more heavy


Zahry  (D 698)

Jul 20, 2009, 6:09 PM
Post #14 of 98 (3910 views)
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Re: [riggerrob] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

In reply to:
" ... Flexipins have to be checked frequently because of the damage caused by kinks in the housings and the sharp edges of unproperly finished housings ... "

..........................................................................

This problem is not unique to Strong.

Most of the tandem manufacturers (Jump Shack, Parachutes de France, Strong, United Parachute Technologies, etc.) have issued Service Bulletins reminding us to inspect flex pins on a regular basis.

Flex pins are "high wear items."

If you are not willing to inspect - and replace - high wear items, you should get out of the student business!

Yes - other systems has a few issues as well. BUT strong DHT has almost the same number of problems as other systems all together that's not just flexipins. Of course you can take a DHT and start pointing on other systems and say "See - this rig has tis problem common with DHT, THAT rig has THAT problem common with DHT". Try to do it the other way. It looks like the DHT has enough problems for all the different systems available on the market.


Lets compare two bigest players in a game in USA. UPT and SE -

UPT started with VECTOR 1 and no drogue and say PD 360. They went through Vector II, Vector III and different main designs (surelly it wasn't for free) and ... NOW THEY HAVE A SIGMA!!! It might have still a few flaws but they proved the will to learn, change and improve. And it is to our mutual benefit.

Lets have a look at SE. Third of century ago they started the whole thing with DHT and MR425 ... and now ... we STILL have the same DHT and MR 425 with a few not really functional mods. And it looks like ALMOST EACH minor mod had to be paid for by human lives.

WHAT DOES IT TELLS YOU?


Zahry  (D 698)

Jul 20, 2009, 6:29 PM
Post #15 of 98 (3895 views)
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Re: [feuergnom] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

In reply to:
IMHO: with this whole arguement you try to divert the discussion from the main cause of the incident which triggered the whole debate: Non-existing maintenance and care

In reply to:
No - it is not. The whole discussion is here to show there is lot more to it than just poor maintenance and care and expose the behavior which seems to me is totaly suspiciousl

maybe - I am not a rigger, just a strong rated TI, so my opinion is surely biased - DHT's are high maintainance. but maintaining DHT's and keeping them safe, seems pretty easy to me. ever tried to change a kill-line on a vector?

In reply to:
:-) yes, I've tried. It is very easy job

this is high maintainance in my eyes. take this as a sidenote, because i have no interest in bashing any manufacturer for how they design their gear like you do

In reply to:
I'm not trying to bash SE down, I'm merely trying to make the old dinosaur to move!!!

if you really don't like strongs and working with them convince your dzo to buy other gear, this is a free world.

In reply to:
I'm trying - and we've got first sigma here and I've got for us one different tandem system for free. And I tell you its not an easy job to change something. Money is the name of the game and lot of pople preffer to close their eyes, cover their ears and shut their mouth instead of doing something


until then it is your job as the dz's rigger to keep any tandem equipment in a working and safe condition and stick to manufacturer recommendations and safety bulletins by the book - which the dz where the incident happend failed to do

In reply to:
Yes, it is a good advice BUT Is it enough?


Zahry  (D 698)

Jul 20, 2009, 6:37 PM
Post #16 of 98 (3888 views)
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Re: [RiggerLee] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

In reply to:
Now if you want to set down and brain storm ideas mods and upgrades for improving the strong tandom I think that would be a great thread. But with your wild ravings your comeing off as a borderline lunitic tool.

Lee

Hi Lee, first step in improving things is identifing if there is a problem, what kind of problem it is and if there is a way how to correct it - That's why I've started the thread.

I'm pulling skelletons out of someones closet right now but it wasn't me who put them in there...


peek  (D 8884)

Jul 20, 2009, 6:46 PM
Post #17 of 98 (3884 views)
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

In reply to:
... unfortunately average passenger is now more and more heavy

Tomas, I'm sorry, I need to comment on the logic of this one. If you follow the manufacturers weight limitations, it doesn't matter how fat we are all getting. If the student is heavier the instructor must be lighter, etc. The weight limitations do not guarantee safety, but they help.

As far as the original thread about the fatalities in the Czech Republic, well, haven't we found that the owners/users of that Dual Hawk did many, many things wrong?

A properly maintained and properly used tandem system from any manufacturer is acceptably safe.


(This post was edited by peek on Jul 20, 2009, 6:56 PM)


Zahry  (D 698)

Jul 20, 2009, 11:11 PM
Post #18 of 98 (3818 views)
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Re: [peek] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

In reply to:
In reply to:
... unfortunately average passenger is now more and more heavy

Tomas, I'm sorry, I need to comment on the logic of this one. If you follow the manufacturers weight limitations, it doesn't matter how fat we are all getting. If the student is heavier the instructor must be lighter, etc. The weight limitations do not guarantee safety, but they help.

In reply to:
yes

As far as the original thread about the fatalities in the Czech Republic, well, haven't we found that the owners/users of that Dual Hawk did many, many things wrong?

A properly maintained and properly used tandem system from any manufacturer is acceptably safe.

Hi Garry, I agree, if you put your hart and soul in it - anything can be maintained and serviced. I'm sorry for beeing harsh but you could use even condom 1000 times if you'll maintain it properly and use it carefuly - but would you do that?

Maintenance was definitely one of the mayor factors of the accident - but not the only one. And don't get me wrong - I'm not trying to apologise them for overlooking the one broken part. That's one link in a chain. Size of the canopy? It looks like their disgusting marketing trick - "buy set400 and you are invincible". It would make me laugh if is wasn't so outrageous - volume is almost the same. Do we have to measure now exact volume of each packjob and readjust closing loop lengths before each jump? It sounds ridiculous

Scary thing is - any of those dozens and dozens weak points and flaws which can go wrong with strong DHT - EACH OF THOSE can start the chain of events resulting in someone DEAD. It's like loaded gun with hundreds of little hidden triggers pointing at people. You can maintain those triggers - I'm not saying it is impossible - I'm doing it every day but once you'll forget one - the gun will fire straight into your face. I have a feeling you know it, right?

long story short: Strongs report is NOT INDEPENDENT and they are hiding, ignoring and twisting impontant facts.


acmik  (C 3875)

Jul 20, 2009, 11:36 PM
Post #19 of 98 (3806 views)
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Re: [peek] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

In reply to:
As far as the original thread about the fatalities in the Czech Republic, well, haven't we found that the owners/users of that Dual Hawk did many, many things wrong?

Well, actually we have not... there is still just SE press release, not final report from CZ legal authority. It's IMHO just one side of the coin so far... Unsure


feuergnom  (D License)

Jul 21, 2009, 4:52 AM
Post #20 of 98 (3727 views)
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Re: [acmik] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

In reply to:
In reply to:
As far as the original thread about the fatalities in the Czech Republic, well, haven't we found that the owners/users of that Dual Hawk did many, many things wrong?

Well, actually we have not... there is still just SE press release, not final report from CZ legal authority. It's IMHO just one side of the coin so far... Unsure

so what will the czech autorities say? that the TI/E did everything right? will the czech authorities stand up and defend that they overruled the manufacturer recommendations, service bulletins and the guidelines under which the rating is to be issued? GIVE ME A BRAKE!

Do you think the outcome would be any different if there had been the same amount of neglect with any other manufacturers gear? and the owner would have cared to come personally to your corner of the world to lead the investigation himself? no? then stop kidding everybody and stop opening diverting battlegrounds.


acmik  (C 3875)

Jul 21, 2009, 5:13 AM
Post #21 of 98 (3717 views)
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Re: [feuergnom] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

In reply to:
so what will the czech autorities say? that the TI/E did everything right? will the czech authorities stand up and defend that they overruled the manufacturer recommendations, service bulletins and the guidelines under which the rating is to be issued? GIVE ME A BRAKE!

I dont know... but I see you have some better information then all of us - would you be so kind and share them? Or is it just a bad feeling?

In reply to:
Do you think the outcome would be any different if there had been the same amount of neglect with any other manufacturers gear? and the owner would have cared to come personally to your corner of the world to lead the investigation himself? no? then stop kidding everybody and stop opening diverting battlegrounds.

Yes, I do think it will be different in some aspects. But even if not, it's quite important for many of us to have independent report to judge the accident.
Do you expect manufacture do blame it's own product? What about giving a brake?

I'm going to wait for final report regardless SE press release. Some other will do the same, some are already decided and don't need it. That's life.


feuergnom  (D License)

Jul 21, 2009, 5:28 AM
Post #22 of 98 (3706 views)
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Quote:
Do you expect manufacture do blame it's own product?

IF the product had been used following all recommendations and guidelines two people still would be living. period. or do you argue the findings on the system owned (or rented/leased/whatever) by the I/E in question?

if you own a vector/sigma or even a MarS and don't keep them in a working order (Regular Ispection & Repack, Repairs as necessary, etc) you'll be fucked sooner or later as well Shocked


(This post was edited by feuergnom on Jul 21, 2009, 5:29 AM)


davelepka  (D 21448)

Jul 21, 2009, 5:38 AM
Post #23 of 98 (3696 views)
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Quote:
Do you expect manufacture do blame it's own product? What about giving a brake?

I'm going to wait for final report regardless SE press release. Some other will do the same, some are already decided and don't need it. That's life.

I'm all for waiting for the report from the czech authorities, but if you look at many of the points in the SE report, they are factual and could easily be proven flase if they indeed were false.

SE would know for sure if the TM was certified to jump a DHT. That's a significant point, and one that SE would know for sure.

Along those same lines, SE is the also the final authority on the 8 year inspections. They would know for sure if they had seen these rigs 8 years after production, and they had not.

If the rigs had reserve repack cards, or there was any proof that the reserves has been repacked on any sort of regular basis (riggers log, etc), I'm sure they would have provided that to Ted during his visit. As it was, Ted saw no proof, and reported as such.

If the rigs been inspected on a 25 jump interval, again, paperwork would have been presented to Ted. Again, no paperwork = no inspections.

The only possibility is that the reserve repacks and 25 jump inspections were performed, but not at the specified interval, so the paperwork was withheld at the time of Ted's visit. Ted's only conclusion was that this work was never performed, when in reality it may have been done at some point at some other interval.

Either way, the reports of an un-certified TM, rigs without an 8 year, and no proof of reserve repacks or 25 jump inspections remain factual. Regardless of what the czech authorities reveal, Ted's report is certainly an eye-opener.


feuergnom  (D License)

Jul 21, 2009, 6:27 AM
Post #24 of 98 (3660 views)
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

Since you put so much effort in your posts Ill give you the credit of being truly concerned and that you want to change something for good. On many points we should (and surely can) agree that we disagree and I have no interest in this developing into a nice pissing contest.

Ill take just a few shots

You say I'm not trying to bash SE down, I'm merely trying to make the old dinosaur to move!!!

Well it comes across totally different. Do you really think that this message will be heard at all? I know theres been much talk about a new design going on and many people wait for it. And I have a bet for you: If they presented a new design within the next month people like you would be outraged why it took the so long to come out with it and why did we have to jump the old stuff for such a long time? YaddaYaddaYadda

Next point - you say tandems are a death trap: Did you, in your long career as a packer and rigger (how many thousand of packjobs have you got?) ever take the time to read the warning label in bright orange on mains, reserves and containers? Bingo! Skydiving is a fucking minefield. Welcome to the real world. And it is your F******* job as a rigger to keep your jumpers safe. If you have worked out how YOU can improve some detail, get in touch with the manufacturer in question. If it is something that hasnt been thought about already and your invention comes in handy, I am sure it will turn up in the next update.

Speaking of updates: You criticise, that DHT-design is just one giant patch. I bet you post this from a computer running on windows. Updating gear in small steps (as being done on DHTs) is _IMHO_ an evolutionary process. You do not have to reinvent everything from scratch over and over again to keep a system and a good team running. Heck I could even cite Bill Booth that with every safety update idiots evolve as well finding new ways to kill themselves (and others) making the whole process nearly worthless

Your other point the MR425 reserve not being designed as a reserve: Can you spell Decelerator or Raven? In the rare case of a malfunction - again IMHO I want my reserve to be as big and strong as possible. I need Kevlar to do this? Fine just use it! If I blow up a cell or two being at terminal or over with a master 425 Ive still got something larger left over than if I jumped a PD 360. And if I go for a reserve-ride I surely dont want the fucker to rock all over the sky stalling and recovering because of setup/trim issues. Thanks Ill stick to Masters!

I am sure someone really clever will come up and state the superiority of the sigmas. Well that was Booths shot to get rid of all the inherent design flaws of the vectors without getting the new design totally free of (possible) bugs. Even the much acclaimed Skyhook had a major fuckup needing a ghetto-fix

You ask if proper maintenance of tandem equipment is enough to keep TIs safe out there: Honestly I dont know. Remember: This is still a minefield. But it is the most vital first step never to be missed.

Still another point: TSOs do your reading and find out if ANY manufacturer has multiple TSOs for one design. AFAIK everybodys just got one. Vector 1 & 2 ran under the original wonderhog TSO (If I am wrong on this, correct me, Ill freely apologise)

I definitely know how hard this whole incident (how I hate that word) must be for everyone directly involved and I can understand that many people want to get the spotlight off the people involved but in this process you blur the lesson: Do what you want and how you feel if you go out alone. But under no circumstances leave the proven path when it comes to taking a student/passenger/punter/peace of living cargo with you

Thats the last post on my behalf in this forum, because I think I have said all I had to say. Maybe someone more knowledgeable than me has more details. Over & out

If it really bugs anybody - PM me


edit:

I just found the following lines posted by riggerrob in this thread


Quote:
We have a GLOBAL STANDARD ... a global standard that most tandem manufacturers and national aero sport organizations agreed on more than a decade ago.

Was it 1993 or 1994 that leading tandem manufacturers told us to install AADs?
It was so long ago that it has became the global standard.

Similarly, it has been 25 years since leading manufacturers said that new tandem instructors must be trained/approved/stamped on the forehead by a factory-approved Tandem Examiner.

Another 25 year old global standard.

Just a little background on why Strong Ent. insists on 8-year inspections. It is a subtle admission that their first eight years of production were ... er ... crude. And they wanted them back to the factory for all the updates.
Just so that it does not sound like I am picking on Strong, the Vector I tandems that I started on were pretty crude too: no AADs, no drogues, etc.

After they got a few rigs back, Strong Ent. started to notice that after they had been jumped hard in the Southern California Desert, some rigs were scrap!
If it sounds like I am picking on Strong ... I told a Vector owner to not send his faded and frayed 14 year old Vector II tandem - to my loft - because I refuse to sew any more patches on it!

Yes, Strong Ent. may have set the toughest inspection standards, but other manufacturers are only slightly looser. This is a marketing ploy.
When you get significantly outside of Storng Ent's inspection guidlines, you are just plain dangerous!

Local laws are insignificant if you ignore global standards.
IOW a judge will ask:"What would a reasonable man/professional instructor/professional rigger have done?"

The bottom line is: if you ignore global standards, you suffer the death penalty!

i guess they speak for themselves


(This post was edited by feuergnom on Jul 21, 2009, 7:48 AM)


RiggerLee

Jul 21, 2009, 8:42 AM
Post #25 of 98 (3597 views)
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Re: [Zahry] Strong DHT - design flaws, safety hazards, maitenance hazards [In reply to] Can't Post

 
Oh my god. I can't beleave you've got me defending SE.

How much is to much?
I don't know any one that doesnt want better gear. Haveing said that there are limits. You can stand up all self ritious screaming that there is no price too high to pay for safty. That is the cry of a nieve child. The only way to totaly insure safety is to stay on the ground. There are limits top what every one will pay. Unless you are independently welthy there are limits to what you will pay. The cost of tandom gear, hell all skydiveing gear, is all ready through the roof. even now it's beyond the reach of many small dz's. A couple of months age a groop came through and baught out all the closets full of old gear there at the drop zone. Shit they had retired be cause we thought it was worn out. And these guys were happy to get it. What's a DHT go for right now? $10,000 rings a bell. Let's say all the manufactores decided to pull out all the stops, fix all the problems, and go for %100 saftey. That would include the doubleing of all prices across the board. you and every one else would be squealing like a little bitch. The industry couldn'ttake it. Skydiveing would end. None of that is an exaguation. It's not just what SE or UPT are willing to spend, it's what you and every one else is willing to pay. So don't put it all on them. Most of there decisions are based on you. If "you", you here being the drop zone industry as a whole, were willing to pay for a fully redesigned system SE would have come forward with it by now. It's not just the manufacteror it's also the market.



You know reserves are designed different than mains because there are required different opening characteristics and the same is valid for deployment system on reserves.

Now is year 2009 not 1980. I've heard the same arguments before "If you are complaining jump LoPos, ParaCommanders, Thunderbows" - and I did.



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Quote
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Maybe I should relate a phone call from a nearby DZO. "Good news! You got another save - on a Vector Tandem reserve - last week. Bad news! The opening sucked! It was stalling and rocking all over the sky!"

--------------------------------------------------------------------------------


I agree. Breaks set so deep it stalls after opening. It is a cheat how to beat the tests on tandem terminal. There are already more modern and better reserves on the market. But you can't say MR425 is not bad because VS360 is not good - it doesn't make sense



For the record SE lopo's are still one of the best pilot canopies out there for the range of speeds for which they were designed. And your optama is not superier for that perpouse. You have to judge things based on what they were designed for. VS360 is a fine example. It was designed to survive opening. Tweeking the breaks isn't some cheep trick. Every manufactor of every canopy does that. It's the easiest way to adjust the opening. And choseing a supper deep setting is a ligitament way of slowing the opening way way down. And that's what you need when your going 180+.

Got to go. I'll pick at your post more later.

Lee


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