The Restoration of a 1968 Delta II

Introduction
Craig Bulman contacted me in 2009 as he was the owner of an original “Red Devils” 1968 Irvin Delta II Parawing. The canopy had been rescued from scrap in 1992, with the ambition to see it once again jumped. Craig warned that it was in need of a lot of rigging attention and, not least, that we needed to learn how to pack the canopy. This last detail was especially important given the lingering reputation of this canopy’s excessive malfunction rate.

Photo by Tony Danbury

                                         



As you can see, Craig got to fulfill his ambition. Because many people helped me and enquired along the way, I’ll record the story here.
This canopy is historically significant as it is one of the very first production models of the Irvin Delta II Parawing. The Parachute Regiment Freefall Display Team “The Red Devils” had jumped in the USA with the Golden Knights in 1967, where they used and learnt about the canopy. In 1969 the first three production models were received by the team in the UK. This caused a lot of consternation within the British Parachute Association as gliding parachutes for parachute displays were regarded as unnecessarily dangerous and very progressive.


The Golden Knights flying their Delta II Parawing's

The Red Devils with their Delta II canopies

Joe Greig

(Kiwi) David Sansom

The Red Devils over Newcastle upon Tyne 1970's, photographs courtesy of Dave Waterman

Cover page from a Red Devils brochure 1970's showing the Wing in flight and a page from inside the brochure showing the performance data of the Irvin Delta II Parawing.

The Red Devils flying the Delta II on various displays photos taken during the 1970's

Kerry Noble at Sunderland Air show 1970. Photo courtesy of Kerry Noble		Joe Greig of The Red Devils at East Kilbride display. Photo courtesy of Bill Miller

I already had a Delta II in my vintage canopy collection, very kindly placed with me by Ian “Wobby” Robertson when he retired from parachuting and rigging in 2008. Wobby had jumped these in the 1970s, and later in his jumping career would occasionally jump one to give us a flying history lesson of where the sport had come from. Very importantly, his meticulous approach to packing the Delta II resulted in some detailed packing lessons for the canopy. Nonetheless, it took me a long time to be able to understand certain features of the canopy. I packed and analysed the canopy on and off for about 9 months. It is odd to have lines from the front of the canopy going to the rear risers, and conversely, lines from the front risers going to the back of the canopy. This made it easier to understand why the Delta II could have malfunctioned so frequently – there are a lot of odd or unique features to confuse any jumper who didn’t take the time to investigate and respect this parachute.

Wobby jumping a Delta II in the 1970's.
Photo courtesy of Ian Robertson

Follow the lines on this picture to see some lines from
front / back of canopy going to the back / front risers.
 Photo courtesy of Tony Danbury

Repairs and Rigging
When Craig’s canopy finally arrived with me in Spring 2009, I realised that packing it was the least of my concerns. On inspection I judged the canopy needed at least 9 patches, a full reline as all the lines had been cut off to prevent it ever being jumped again (!) , new line attachment tapes, a new Opening Shock Inhibitor, a new OSI rip line, and a new upper OSI.

		Pictures of canopy as received, with missing lines, various holes and damage indicated by the yellow tags.

As well as the damage I found, there were even some areas with metal staples in the fabric. This was explained when Craig sent me the following picture of a Red Devils reunion where the canopy is stapled to the wall in the background as a decoration! This canopy had certainly suffered some abuse since it retirement!

Canopy stapled to the wall as decoration at a Red Devils' reunion 1989.
Sgt Les Sedgebeer R.I.P.

 I set to work on the canopy and patched all the damaged fabric areas and line attachment tapes.

		Patching and line attachment tape repairs

Building the Opening Shock Inhibitor was next, and unsurprisingly the OSI material is no longer available. It was originally thick cotton webbing, which was some 6 inches wide. For this I chose to use more modern Kevlar instead, for its heat resistance and strength. I utilised tandem drogue Kevlar bridle stitched to match the size of the OSI. The OSI is subject to an enormous amount of heat friction and the Kevlar was hopefully going to be good at absorbing that.

OSI and reel of line

The OSI completed and attached.

The line material however was still available from Paragear – 1000lb Type 5 nylon line, so I purchased a complete roll of 100 yards. Andy Cowley of Airborne systems advised that the original coloured material as used by Irvin was no longer available at the factory either – some adventure between him, Ian Marshall and some paragliders had long since used the last of it. Since the colours are significant to the packing, I applied coloured threads at the stitched portions of each line for reference as well as some coloured marker pen at useful points.

Finished line set with coloured stitching and labels

The line trim information was crucial too. And, just to confuse things further the UK canopy had a different set of measurements to the USA ones. However the relative trim was the same.

For reference here are the lengths used –

Line	Colour	Trim versus Red L/R5	Overall length
K1 nose	Blue	74	279
K2	Blue	72	277
K3	Orange	71	276
K4	Green	74	279
K5	Gold	59	264
K6	Red	33.5	238.5
L/R1	Blue	62	267
L/R2	Orange	52	257
L/R3	Green	42	247
L/R4	Gold	23.5	228.5
L/R5	Red	0	205
Key: K – Keel Lines ; L Left Lines ; R – Right Lines
All measurements in inches with lines under 30lbs of tension

 Line sequence and Steering Panels

To illustrate the prior mentioned confusion about line sequencing, here is a diagram of where how the various lines route to the risers from the sides and middle of a triangular parachute –

A similar diagram illustrates the panels of the canopy. The shaded panels in the middle are the control panels. This is different to a modern square and also to later Parawings, where the steering lines attach simply to the rear of the canopy to control the direction of flight. The control panels on the Delta II are an extra panel beneath the single top skin of the canopy. The steering lines pull down on the rear of these panels and alter the direction of the canopy flight.

Following the fitting of the lines, the canopy was flown as a kite at Langar on a windy day to determine the line continuity and assembly and the basic aerodynamics before it could be jumped.

Flying as a kite. Photographs courtesy of Gary Wainwright

Packing and Jumping the Delta II
Getting close to jumping the Red Devils canopy I continued to practice packing the Delta II from Wobby and then put a few jumps on that one. I also jumped another one belonging to Bill Miller. These two canopies were in exceptional condition, especially Bill’s, all the more so considering they were built nearly 40 years ago. The jumps were a success, with the canopies opening completely as unexpected. To keep things simple I utilise a modern rig for jumping all my vintage gear, finding that a Telesis container built for 280-300 square feet modern mains is just about big enough for these older canopies. This means I am jumping familiar systems with a BOC main deployment, RSL and ram-air reserve. The performance is certainly much less than a modern ram-air canopy, but it was plain to see that they had more glide and speed than the high performance round canopies that were used at the time. Landings are certainly harder than modern canopies, but these kinds of hard landings are not a surprise if you prepare for them with a good PLF position. The feeling of relief when they open was quite marked, the greatest shock at first being to see the OSI slowly unfurl. Given that I was expecting a malfunction it was a surprise that this was just the canopy opening properly.

I have spent a bit of time discussing Delta II packing with other vintage gear jumpers and also considering it from my own limited experience. I feel that a prime cause of the high malfunction rate is that the canopy arrived in an era when people were unfamiliar with gliding canopies. The actual packing is similar in a lot of way to a ram-air flat pack, which is quite normal to the modern jumper. This would have been completely alien to round jumpers back in the day, even with the help of a manual describing it. So too the OSI system, which is unique to this day. If the OSI is packed in the wrong sequence, around the wrong lines, or closed the wrong way, then complications, damage and even complete failure of the opening are easily achieved.

Jumping Wobby’s and Bill Miller’s Parawings at Langar Autumn 2010. Photographs courtesy of Tony Danbury

Finally, one day at Langar with suitably light winds, a paper WDI streamer recently thrown to indicate the exit point, and a couple of other Delta II jumps already, it dawned on me I couldn’t find any more excuses not to jump the Red Devils canopy. With a bit of concentration to control the doubts, fears and questions as to why I was doing this, I got myself on a load. On the way to the ‘plane, Ally Milne offered to tell me one of his dad’s stories about the Delta II. I impolitely declined his offer until after the jump. I can remember passing through the door of the aircraft on exit thinking that in about 10 seconds I would know that it had not worked. To my astonishment, it did open, fly correctly and land safely. Under-promised and over-delivered! There was a huge sense of satisfaction at having come to the end of this journey successfully.

	The canopy gets jumped for the first time in over 30 years. Photographs courtesy of Tony Danbury

Tony Danbury took some fantastic pictures of this historic jump. Later that day I emailed one to Craig, with no other explanation, having kept the final progress of the project quiet. It didn’t take long before a rather excited Craig was on the phone and we were arranging a repeat for the next weekend at Langar. Joe Greig came along to watch too and Craig jumped Bill’s model first for reference. Finally he was on his own Delta II, after some 18 years of waiting, and about 35 years after having seen the Red Devils use it on a display he watched a young boy in 1975.

Craig’s first jump on a Delta II Parawing, canopy courtesy of Bill Miller. Photos courtesy of Tony Danbury
In light winds a PLF is usually required.	(L to R) Craig Bulman, Joe Greig, Andrew Hilton at Langar, December 2010

Video by Joe Greig ex Red Devil and Delta II jumper.

Craig finally jumps the Red Devils Delta II Parawing. Photographs courtesy of Tony Danbury

Video by Joe Greig ex Red Devil and Delta II jumper.


The End
The Irvin Delta II Parawing enjoyed a brief period of popularity in the sport in the early 1970s. At this time ram-air canopies had yet to reduce in bulk, or gain in reliability or performance. Round parachutes still had a reasonable popularity based on their lesser pack volume and a proven track record. Of course, ram-air canopies eventually took over and are universally accepted nowadays. The parawing design was utilised by other canopies such as the ParaDactyl in the 1970s, which was also available in a dual keel model. This was reliable enough to be used as a student canopy by some operations, such as Perris Valley in Southern California. The ParaDactyl was even available as a reserve canopy known as a Safety Dactyl. The Russians also developed a reserve canopy using a Parawing design – known as the PZ-81, which was still being manufactured in the late 1990s. Nowadays, Parawing paraglider emergency canopies are still made.

Single Keel ParaDactyl Black canopy. Photo courtesy of John Williamson
Dual Keel Paradactyl. Photo courtesy of Jim Wilson	Pz-81 Reserve. Photo courtesy of Jim Wilson
Para-glider emergency parachute – the Guided Mayday

Craig, several others and I continue to jump vintage gear when conditions allow. I compare it to driving a vintage car – under the correct conditions it’s extremely enjoyable and interesting and helps maintain a connection to our history. There are several collectors of vintage gear in the UK and worldwide, and if you have any questions or comments feel free to get in touch.

Craig Bulman on the Delta II, Andrew Hilton jumping a Competition Paracommander
and Richard Wheatley on a modern square.
Photograph courtesy of Tony Danbury

 Thanks for reading. Andrew Hilton 2012  

Acknowledgements 
Craig and I extend our gratitude to the following people for their help along the way with the Red Devils Irvin Delta II Parawing restoration and jumps – Ian “Wobby” Robertson for invaluable packing and flying advice as well as the donation of his canopy to my vintage collection.
Bill Miller for the use of his canopy.
Dave Hickling and Richard Wheatley for allowing us to use such equipment at British Parachute Schools, Langar, Nottinghamshire.
Jim Wilson of Canada for his advice and the use of some of his photographs.
Joe Greig, original Red Devils Delta II Parawing jumper, for advice and support.
Dean Fisher for some decent old fashioned spotting.
Tony Danbury for the magnificent photography.

------------------------------------------------------------------------------------------------------------
Aerial footage and photos by Steve Murfin
Delta II flown by Craig Bulman