A painted history of hang glider design
In 1983 and ’84 I took up painting again. (I had started in the late 1970s, mainly painting Spitfires and the like.) This time, I created large paintings of hang gliders mainly based on small photos, often black and white, in hang gliding magazines. (It seemed like a good idea at the time.)The Eipper-Formance Flexi Flyer was a ‘standard Rogallo’ hang glider of 1973. It was designed by Dick Eipper and based on the principle developed by Francis Rogallo of NASA, John Dickenson of Australia, G.D. Wanner, and others, whereby the air flowing over and under the sail keeps its aerodynamic shape.
The nose angle of the standard Rogallo was a boat-like 80 degrees.
Ground Skimmer (the title of this painting) was an early incarnation of the USHGA magazine (now USHPA Pilot).
Incidentally, the standard Rogallo hang glider was invented by Australian John Dickenson. Rogallo’s 1948 patent was for a bi-cylindrical design with no stiffening of the leading edges or keel. In contrast, the ‘standard Rogallo’ hang glider was bi-conical, stiffened with tubes at the leading edges and keel, and, crucially, it was controlled by pilot weight-shift against a fixed triangular control frame. However, Rogallo worked for NASA and that organization put millions of dollars into researching the bi-conical flexible wing as an alternative to round parachutes in spacecraft recovery, among other applications. Partly because of that, Rogallo’s name became synonymous with the early hang gliders.
The preceding historical information is drawn from research by Mark Woodhams, one time editor of the British hang gliding magazine, and Graeme Henderson.
The Seagull III (and the British equivalent, the Waspair CB240) had parabolically curved leading edges, which improved the efficiency of the wing.
The painting is of a glider that Tony Beresford flew at the British Championship competition in Wiltshire in August of 1975. It had unusually thick sailcloth (for the time). I recall that it did not ripple (visibly and audibly) as many sails did, but the trailing edge had a distinct wobbling motion.
The Ultralight Products Dragonfly of 1974 (and the Hiway Boomerang) had truncated tips supported by chord-wise tubes attached to the tips of the leading edges.
The handling of the Dragonfly embodied a yaw characteristic that imparted a uniquely graceful motion in the air. Apparently always under perfect control, yet always curving to the right or left…
After the truncated wing tips, there still was 20 feet of leading edge, while the keel was only 11 feet long. And yet, his and the other two designs all responded amazingly well to weight shift control.
— W.A. Allen describing Roy Haggard’s Dragonfly at the 1974 US nationals in Wings Unlimited, February-March 1975
The Dragonfly was designed and built by 19-year-old Roy Haggard and it performed so well that Pete Brock of Ultralight Products agreed to manufacture it. (Five years later, Roy Haggard of UP made another major contribution to hang glider design.)
Roy designed the ubiquitous Dragonfly, test-flying it for the first time on October 27, 1974. He surprised everyone (maybe “shocked” is a better word for it) when he appeared out of the obscurity of Visalia, Calif., as a relative unknown to come in a strong 7th at the 1974 U.S. Nationals… and with such a weird-looking design.
— Rich Grigsby (I assume) writing in Ground Skimmer, June 1976
One of the two designs that Bill Allen refers to in his quotation is the short-keel, low billow, and spiky-looking Windlord IV. It was designed, built, and flown by US Navy F-4 Phantom pilot Rich Finley. By a series of refinements, it led to the popular (and less spiky looking) Electra Flyer Cirrus 3, of which there is a photo in Hang gliding 1976.
Although the Wasp Nova first flew in 1976, I first saw it in November 1975 at the annual general meeting of the British hang gliding association. It still had some top rigging wires waiting to be swaged.
It had an S-curved keel tube and tip fins braced by tubes, brackets, fasteners, and cables.
The Sport Kites Inc. Wills Wing Swallowtail of 1974-5 had a 90 degree nose angle as well as less billow than the standard Rogallo. It also had a large amount of sailcloth removed from the trailing edge, which took on a helical curve. Later, a small ‘roach’ was added near each tip, supported by a radial batten (and later a double roach with two radial battens).
The lanky leading edges were braced by short wingposts projecting outwards from the junction of the crosstubes and the leading edge tubes, which supported deflexor wires from the nose to the tips. Even with that added hardware, the Swallowtail was generally regarded as providing good performance and handling (by the standards of the time) with reasonable simplicity.
Here is a snippet of conversation between Wills brothers Bob and Chris, their mother Maralys, and Chris ‘Ramsey’ Price when they were designing and building the prototype that would become the Swallowtail:
After the others had left one night, I said to Ram, “You and Bobby and Chris sure argue a lot.”
He gave me one of his impish grins. “Yeah, we do. But we’ve got this theory about ourselves: If any one of us can convince another he’s right about something, then those two have the answer and the third has to go along. It works every time.” He laughed. “Together we’re a genius.”
— from Higher than Eagles, the Tragedy and Triumph of an American Family by Maralys Wills and Chris Wills, 1992
The Swallowtail featured in the 1976 movie Sky Riders starring James Coburn, Susannah York, Robert Culp, and Charles Aznavour. Its main feature was the removal of sail area that added much to aerodynamic drag and little lift. The designer needs to be careful with that approach, however. If you keep on removing the least efficient parts of the wing, you would eventually end up without any wing!
One of the dangers of the standard Rogallo, which needed a positive angle of attack to maintain its lift-generating shape, was the ‘luffing dive’. This unrecoverable situation could develop if you stalled the wing and, if you then added nose-down pitch input as it self-recovered by diving, the glider could end up flying with the air flowing parallel to the sail, which would flap uselessly. With the sail creating no lift, the pilot had no control. Flexwing hang gliders (then, as now) are controlled by pilot weight-shift, which requires a lift force to react against. Today’s flexwings have additional bracing to automatically pitch the glider nose-up in such a situation.
However, the makers of the Swallowtail claimed that it was unluffable (because of its reduced billow, I think). See the movie Sky Riders for a demonstration of its resistance to luffing. See Paint it black—my overview of the 1976 movie Sky Riders.
The purple near the tips in this 1984 painting has faded over the years. The glider, a Hiway Cloudbase of 1975, was based on the Wills Wing Swallowtail.
The principal variant of the Superswallowtail had a 100 degree nose angle, a fancy trailing edge cut, and the three battens outboard each side were aligned with the chord. Because those chord-wise battens prevented you from furling the sail, they had to be inserted as part of the rigging procedure and removed for de-rigging. Additionally, there were two deflexor wires on each leading edge; one horizontal and one vertical. Things were starting to get complicated.
I no longer have this painting so I cannot take a better photo. This is an old and very small print.
‘Soaring windows’ of transparent Mylar were built into some sails to improve upwards visibility. That is a problem with hang gliders still (2010).
Seagull retained their curved leading edges into the late 1970s.
Note the parachute container mounted on the chest of the harness.
The Raven was designed by Jim Debauche and flown in about 1979 by Eileen Debauche. I created this digital painting in 1996. It uses 16 colors and the original was 640 x 480 pixels. Because I based it on a black and white photo, I have no idea whether the colors are correct.
Like most of my hang glider paintings, this is a copy of a small black and white photo in the USHGA magazine Hang Gliding and the independently produced broadsheet Glider Rider. Unless I had further information, I made up the colors.
The Ultralight Products Mosquito of 1979 was an extraordinary design. It is described in detail by 101st Airborne Division ‘Nam veteran, computer programmer, and hang gliding expert Richard Cobb on this page of his web site, Wind Drifter.
The Electra Flyer Floater was one of a new crop of flexwing which, in 1978 or ’79, omitted the draggy and complex deflexor cables and instead used stronger leading edge tubes.
The Ultralight Products Comet of 1979, designed by Roy Haggard (who designed the 1974 UP Dragonfly) was the first really successful double-surface hang glider, where a battened undersurface (not visible from this aspect) encloses the crosstubes. Modern flexwing hang gliders fly better, but they look much the same.
There is a real Comet in a screenshot in Mid-day lightning in Vermont, my review of the Francis Freedland documentary film 1978 Pico Peak International Hang Gliding Meet. (That scene was filmed in 1980 and was apparently included in the documentary by mistake.)
The Southdown Sailwings Lightning, although it first appeared in 1980, was not really a Comet clone. It was a (slightly) different shape, it omitted the stand-up keel pocket, and its king post was raked backwards to form the leading edge of a shark fin. I saw the prototype on Mill Hill, near Shoreham in Sussex, UK, and pointed out to its designer, Ian Grayland, that the nose angles of the sail and the airframe were mismatched. He had not noticed it before, but I believe that he (or his sailmaker, whose name I do not recall at the moment) re-stitched the sail before its next outing.
My original painting, which I no longer have, had a photographic feel to it, partly I think because the paper I used for the blue backdrop was flecked with brown, similar to photographic ‘grain’. I photographed it in 1990 using a Vista-TIPS video camera and digitizing system at work. I scaled the image to 640 by 350 pixels and 16 colours, and I used the result in my 1991 computer-based training program Hang Gliding Ground School.
This Comet painting was simply an enlarged copy of a black-and-white magazine photo.
I no longer have the original painting from which this photocopy was made.
I have no record of when I drew these images and I cannot be sure of their accuracy, but I believe them to be about right.
The Manta Fledgling was a ‘semi rigid’, which actually means a rigid wing using drag rudders for turn control, but made of aluminium tube, polyester sailcloth, and steel cables, much as flexwings are made. Although its wing was efficient, all the extra cables that held it together generated much drag, so its performance advantage over the top flexwings of the time was not huge. In addition, it was more difficult to transport and more complex than a flexwing.
The Super Scorpion, made by Hiway of Abergavenny, Wales, was said to be based on the Moyes (Australia) Maxi.
Note that the Southdown Sailwings Sigma has a very wide nose angle. Instead of crosstubes to brace the leading edges, it uses a bowsprit and cables.
As mentioned earlier, the Comet was not the first flexwing hang glider to enclose its crosstubes inside the sail. However, it is not much of an exaggeration to say that the UP Comet’s blend of performance, simplicity, and handling rendered all other hang gliders scrap when it appeared in 1979.
Flying squad, a short history of the east coast U.S. hang glider manufacturer Sky Sports
Luff in the time of cholera, about the ‘luffing dive’ thought by some to be a danger inherent in the design of the standard Rogallo
Skyhook Sailwings, a short history of the early hang glider and powered ultralight manufacturer based in the north of England
Space flight and hang gliding including early NASA Rogallo wing aircraft