Delta II Opening Shock Inhibitor (OSI)

With the nice responses to the Volplane hydraulic reefing device thread, I decided to do another on the Delta II Opening Shock Inhibitor (OSI). In addition to the OSI, I will give a brief history of the Delta II which will help to later describe the differences between the American and Canadian versions of the parachute.

The Delta II came about life through development from another parachute known as the Irvin Eagle and Steve Snyder. The Irvin Eagle came before the Delta II and to my knowledge wasn't fully released to the public. It was a slightly different parachute but similar in many ways. Both were parawings and had a very similar layout. The front sections of the parachutes are the same. There were three main changes that occurred to transform the Eagle into the Delta II: the addition of stall panels for steering, removing of the back section of panels to reduce the parachute's size and the addition of the OSI to stage the openings. With this the Delta II was born.

This background on the development of the Delta II will distinguish a Canadian Delta II and an American Delta II. The American Delta II was a parachute that was produced as a Delta II. A Canadian Delta II was actually a conversion from the Eagle parachutes that Irvin Industries still had to the Delta II design. You can see the data panel restamped on the Canadian Delta II in the picture. While the Canadian and American Delta II’s are similar, they are also slightly different. Most notably is the reinforcing that the Canadian Delta II had which lead to a little bit different shape in the nose panels. This reinforcing was necessary on the Irvin Eagle because it had no way to stage the opening. So as a result the parachute was reinforced to take the stronger openings. Since the American version was actually designed as a Delta II with the OSI in mind, it didn’t require as much reinforcing and was never added to the parachute. The parachute in the pictures and video describing the OSI is a Canadian version. I have posted a two ads of the two parachutes and a couple of photos of the Canadian Delta II’s front and side section (sorry I don’t have any in flight photos yet) and two in flight photos of an American Delta II. From these photos you should be able to see the difference in reinforcing and even though the Eagle ad is drawn, you can count that it had one additional section that the Delta II doesn’t have.

How the OSI operates is quite simple, it wraps around the lines of the parachute from back to front and separates different line groups of the parachute. The first set of the lines to be wrapped in the OSI is the three tail lines, the next set is the six lines from the next two sections and control lines, then the next three and so forth. The OSI is closed by a piece of Velcro that is peeled back off it when the parachute inflates. The Velcro lanyard is attached to a piece of tubular nylon that runs through a couple of rings along the center rib or keel of the parachute. When the Parachute starts to inflate, the tubular nylon gets pulled through the rings and peeled off the OSI. Once the Velcro lanyard is free from the OSI, it will start to unravel and allow the parachute to fully inflate from front to back. A cross sectional diagram from the Delta II manual should help form a better picture of how the lines are wrapped in the OSI.

I made a brief video on the OSI and how it works. Unfortunately, I didn’t realize that I had the mic blocked so I had to raise the volume via software. You can still hear it but it is not as clear as it could have been.

http://youtu.be/kdwnUWIu_VQ

I am still thinking of topics for a seminar at the PIA next year. If there are any thoughts or suggestions let me know. I am still a little stumped what to focus on. It is over a year away but I would like to figure out a direction to go fairly soon.

More pictures for the post.

Fantastic write!

And great pics...I'd forgotten how much tape was on those things!

Great post Jim! Always great to read and see more about this amazing canopy.

The OSI in your post is some 20 inches longer than I am used to seeing on those canopies that are in the UK. This is likely to be something that people reduced in length as they came to understand....or mistrust....or dare to experiment with the OSI and is reflected in the variation of the packing instructions too - in the attachments here there are different numbers of turns of the wraps around the lines and different placements of the lines within the OSI.

There is some scope for variation, though the same basic order of the lines into the pack job and then into the OSI would remain the same - hence the colour coding of the lines to help aid packing and understanding.

One picture I have attached here shows a simplified OSI where the velcro is simply attached to the nose line which was placed on a very short OSI - about 12 inches total - and as always this required the direction of the OSI closure velcro to be considered. Get that wrong and the wrap would remain closed.

As well as the Canadian and US versions there was also a UK version made over here by Irvin. It was stamped as a UK one on the cotton logo panel on the outer edges. The two UK ones which I have seen, both dated around 1971, are very similar to the US ones, but have a lighter fabric which helps with packing bulk. Of course all this is relative - any Delta 2 with lighter fabric, and less reinforcement still packs about one and a half times as big as a modern tandem main.

There are more Delta2 pictures available here -

http://www.flickr.com/photos/vintageparachutegear/sets/

http://www.flickr.com/photos/vintageparachutegear/sets/72157629894844058/

http://www.flickr.com/photos/vintageparachutegear/sets/72157625240508274/

http://www.flickr.com/photos/vintageparachutegear/sets/72157622741872232/

Thanks again Jim for your post.

Here's some Irvin adverts and pictures of the forerunners to the Delta 2 - the Eagle and Hawk. Like Jim said I don't know whether these were on the market at all, or if they were it was for a very short time.

Those ads are interesting. Both of them have inaccuracies. The Eagle Hawk ad has an eagle that has been modified with the back section removed. There should be five sections and the nose. If you compare it to the other photo of the Eagle you will understand what I mean. They may have been already starting to experiment with it.

The Eagle ad actually has a Hawk in the photo.

Hi andrew,

The Eagle Hawk ad mentions that it is a TSO'd canopy.

It was in 1967 that J. Scott Hamiltion made a few jumps on it and wrote an article about it in PARACHUTIST magazine.

You two guys should contact Dan Poynter & see if you can get him to make a copy of that article for you.

JerryBaumchen

I've got that article somewhere and can post a copy if anyone else is interested.

Thats a good write about the Delta II. I probably used my American Delta II on more demos than any other chute, exzcept for the Para Commander for low openings. Both Gary Freeze and I had American Delta II canopies, and they worked like a charm. One must remember when wrapping the lines in the OSI, the last blue line to the center of the nose should NOT be wrapped with the other blue lines. I found the canopy always opened, and it was a soft opening. I was give a dozen or so Canadian Delta II canopies, and they were all over the sky, a mal was almost guaranteed. I gave them all away to guys I jumped with. The comparison between the American and Canadian Delta II canopies was like night and day. I loved the canopy, and you sure could chop the sky in pieces with it. I presently have my old Delta II in the back of my car. I repacked it, and noticed someone did a hatchet job of " rigger" on various things, like the velcro tab, the rear blue lines which had been stitched by hand with the guts of a piece of 550 cord. I dont know who did it, but they sure ruined a great flying parachute. I have been mulling it over in my mind, and I believe the chute has been rigged for a malfunction, and there is no way to know what has been done to how many lines. I don't think it will fly like before. I doubt I will bother to jump it in the Spring, but what a shame....what a great canopy, wasted by some self styled rigger.

Beatnik

I am still thinking of topics for a seminar at the PIA next year. If there are any thoughts or suggestions let me know. I am still a little stumped what to focus on. It is over a year away but I would like to figure out a direction to go fairly soon.

With regards to a PIA seminar, the 2 threads you've started recently sure seem to me to be a good start to developing something. The history of deployment systems is amazing--the thought and engineering that has gone into the various devices is impressive (and a little frightening sometimes). It would be pretty cool to get some slow motion video (rear/up facing camera?) of the various devices and systems in action. Just my .02--I really appreciate the effort you've put in for this community!

Some of my DeltaII pics

Hi Chuteless
Are you saying that all Canadian Delta2's were more malfunction prone than the American ones - or just the dozen you were given? Any particular reason that you know of?
As for the one you have, I'm sure someone would be willing to restore it back to the proper configuration - I certainly would do it for you with pleasure.

Thanks for rekindling fond old memories. I put 350 jumps on my black and gold Delta II (with no malfunctions) before Snyder talked me into a Para Plane. It had a unique feel in flight, like no other canopy I have ever jumped. OSI openings were soft, but two problems I remember: 1. No flare, and 2. If you pulled down a single turn panel too quickly, it would often turn in the opposite direction.

Hi Beatnik

I wanted to tell you how much I enjoyed your delta 2 presentation.

The origional ad was priceless, we were located in kansas the last to find out.

Some of the locals at the tip of the speer like Matt Farmer, and Jim Garrision, and the only golden that would jump it, experienced a unacceptable malfunction rate. In the boonies I can assure you the rush was not on.

After reading the origional ad I was laughing so hard the tears blinded my vision.

When people like Mr Booth: 350 lumps and zero mals, and chuteless say they had zeo mals I have no reason to doubt what they say. They are men of honor.

IMO The addition of the color coded strips to the Osi went a long way to reducing the malfunction rate.

Thanks beatnick your the man if you say it I believe it. Thanks for preserving the history of the sport.

R

Thanks everyone for the kind remarks to this thread. Like the Volplane thread generated this one on the Delta II, this one gave me the idea of another topic. Bill Booth mentioned his old Para-Plane. I just happen to have a Para-Plane that I saved a few years ago. The previous owner did some strange short lining work and really butchered the deployment bag. With the help of a couple of people on here (one of which was the man that designed the deployment bag) and some pretty heavy geometry on every photo of the Para-Plane I could find, I was able to restore the parachute.

The deployment staging on the Para-Plane is really something else. All you can think of is bag lock when you see it. I will try to get some photos, video, writeup, etc. together for sometime next week but no promises.

Thanks again everyone and I am glad you are all enjoying the threads as much as I am sharing them with all of you.

Beatnik

Thanks everyone for the kind remarks to this thread. Like the Volplane thread generated this one on the Delta II, this one gave me the idea of another topic. Bill Booth mentioned his old Para-Plane. I just happen to have a Para-Plane that I saved a few years ago. The previous owner did some strange short lining work and really butchered the deployment bag. With the help of a couple of people on here (one of which was the man that designed the deployment bag) and some pretty heavy geometry on every photo of the Para-Plane I could find, I was able to restore the parachute.

The deployment staging on the Para-Plane is really something else. All you can think of is bag lock when you see it. I will try to get some photos, video, writeup, etc. together for sometime next week but no promises.

Thanks again everyone and I am glad you are all enjoying the threads as much as I am sharing them with all of you.

Hi Mr Beatnick

Are you talking about the ropes and rings with the half hitch?

Just like the Delta 2, in the sticks, center of the country, all we had to go by was the instruction manual. No internet, no cell phones, long distace calls were $,
We didn't even have a phone on the dz.

Not whining just the way it was, but we still had fun. It was a adventure.

Can't wait to see the restored paraplane,

Be well
R.

R.

I do think all Canadian Delta II canopies were prone to malfunction. Don't ask me why, all I know every Canadian canopy was a mal waiting to happen. The American Delta IIs like mine and Gary Freeze's, were the perfect flying machine. Soft openings, , no extra modifications, and you couldnt ask for a better chute.
As for mine, it was in a box at the Baldwin Hangar, and someone got hold of it, claiming it ass their own. Somewhere along the way someone did some very poor rigger work on it. They shortened the velcro tab, tied two pieces of 1/2 inch tubular to activate the release of the OSI, and stitched by hand some of the rear lines....what for, I have no idea. They have ruined a great canopy with some of the worst rigger work Ive ever seen.. A jumper who claims he got the canopy from someone on a dark night, has loaned it to me for one last jump. I think the stitching of the lines tells me someone has perhaps shortened them, and I don't think I could trust it like I used to. I told this guy he can have the canopy, although I certainly question the legality of anyone but myself owning it. I had quite a history using mine, HALO jumps, demo jumps, and everything in between. It was heartbreaking to look at it in its new configuration, and I cannot understand why anyone would do that to a great chute. It sure is a puzzle. Thanks for your offer anyhow....but I guess for some reason, I dont own it anymore, and for the life of me, I don't know why I don't. When someone takes a chute that doesnt belong to them and claims it, that has several titles in police work, like theft, maybe fraud, and I'll admit, I am sorry that great canopy ended up like it has.

Jim: I might have missed it, but your description of the opening sequence : One should remember NOT to wrap the OSI around the line to the nose. With it unwrapped, the nose if first to catch the air, and that is what causes the velcro to come off the OSI. If that nose line is wrapped with the others, you can almost count on a malfunction.

Bill Cole

The spreading of the canopy is what causes the tubular nylon attached to the hook velcro to peel back from the OSI. Some manuals have the centre nose line outside of the OSI and some have it inside. I personally don't believe that either configuration really makes a difference to if the canopy will malfunction.

I know someone that jumped his Delta II with the centre nose line wrapped up for years without any issues. Now this is an extremely small sample size and really can't be considered as fact to the canopy opening without a malfunction or not. But if you look at the mechanics, design, slope of the Delta II it really wouldn't seem to cause a malfunction. Even with the centre line wrapped, it there is such a great opening for an air channel to start inflation of the parachute. The velcro lanyard is attached to the line after the centre line nose line. So the nose inflating in itself really has little effect on the lanyard tightening. I can simulate this on the ground by pulling up on the nose and the OSI won't release until the next section of canopy starts to spread. Leaving the nose line outside of the OSI wrap tends to produce more on heading openings as it can inflate a little less restricted and the nose is straighter.

Jim I sent you a message re Delta II . Please reply when able.

Bill Cole

Hi Jim: I recently sent my Delta II ParaWing to a United States
( USPA ) rigger, for some major repairs. I got the canopy from Peter Chapman, and although I packed it, I wasn't happy with it, because there was so many things that had been damages, and supposedly rigged, and I felt the chute was no longer safe. I will let you know later this summer, when I get it back, and perhaps you would take a look at it, and let me know your opinions on it ( and several other things ).
I have never in my 50 + years of skydiving seen so much damage to a canopy, and I have taken some photos of thew chute before I sent it to the guy in the USA, and you can see the extremely poor rigging. I believe someone had shortened the two rear blue lines, and it certainly was not the safe canopy that I had been using for many years. I don't know the full extent of repair costs, but I may sell the canopy to someone, after I put a couple of jumps on it. I can tell how it
flys, and then I'll decide if I keep it or sell it. It should never have ended up in anyone's hands unless they had made a deal with me, but it appears some people dont mind taking a canopy that wasn't theirs, and when I saw the damage and rigging on it, I decided I would get it back into top shape, and then either keep or sell it. Take care, maybe see you sometime this summer.
Bill Cole

Hi Bill:

Sure thing. When you get it back, let me know and I would be happy to check it out for you. I have a few other Delta II's that we can use as a comparison for.

Cheers!

Hey Jim: I just thought I would bring you up to date on my Delta II rebuild. It should be ready to fly by the end of May, give or take a week or two. Its been quite a job, but the rigger says he has run into several difficulties, but its a time thing. I told him to do what he had to do. I do not want to get it back with a single thing wrong with it. I may make a few jumps on it, and then sell it. It will likely be costly, but if it doesnt sell for what I will ask after paying so much to get it fixed right, then I will just keep it.

I hope to see you sometime this summer., but can't say when or where. I guess it will depend on your schedule, and my willingness to drive any distance

Take care...talk at ya later.
BILL

I had a Delta 11 back in 1976, did about 80 jumps on it, never had a mal, but they were regarded with suspicion by just about everyone. It seemed to me most of the mals were caused by wrapping all the lines inside the OSI. I always left one nose line out.

I lent it to a guy one day who had sold his Delta 11 after lots of chops, he packed it, and of course chopped it as well, due to packing it with all the nose lines in.

A mate decided to take the OSI off his Delta 11, and put on a slider type device, basically 2 x 6 inch rings connected by a short piece of webbing. He asked me to jump it (without telling me what he'd done) which I did. The canopy came out of the bag, the rings fell down the lines and hit me on the head a nano second before the explosive opening nearly knocked me out.

2 grand under canopy still seeing stars, I looked down to see him driving at speed out of the airfield gates. Didn't catch up with him for about a week. Thats mates for ya!!!.

He modified his "slider" a couple of times and came up with a workable system. I think his idea was simply to save a bit of weight and bulk, because the OSI was quite bulky.

Being rather solid, I got quite good performance out of my wing, some of the early Strato Stars were just coming onto the market, and I could usually stay with them when the PC's and cheapos were being left behind on long spots.

I liked that canopy, mainly because everyone was scared of it and loved telling me every load that I was going to have a mal, but it proved them wrong every time. No one ever asked to jump it.

Eventually sold it and bought a Strat.

Is anyone still on this thread who can talk to me about the Delta II?