Hang gliding 1975 part 2
This page continues from Hang gliding 1975 part 1.
The best pilots were starting to fly in prone harnesses, which created less drag and allowed much greater range of pitch control, enabling steeper coordinated turns. This is my a cobbled together modification of my Skyhook seat harness worn the wrong way round! Although it might look as though the rope goes around my neck, those lines went all the way to the thick plywood seat (worn on the front, however).
I flew it at Monk’s Down and I was shocked at the way the glider just climbed. How was I ever going to land in that tiny field at the bottom!
The piece of fabric stitched between the rear rigging wires by the keel, visible in the preceding two photos, was my half-hearted attempt at a device known as a sail feather. Standard Rogallos were thought by some to become unstable in pitch in a steep dive because, with the air flowing parallel to the airframe, the sail deflated and ceased to provide lift, which is essential for control in a weight-shift controlled aircraft. Several fatalities in the USA had been ascribed to luffing dives. The idea was that the fixed sailfeather, small though it was, would act as an up-elevator, preventing such an extreme situation developing.
For more on this subject, see Luff in the time of cholera. (Sorry!)
I was one of about 300 competitors flying for the crowds and television cameras at the British championships at Mere, Wiltshire, in August 1975. When I launched, I concentrated on keeping the landing target in view and, when I felt it appropriate, I turned left only to discover that I had been hovering in one place and was still right next to the hillside. The crowd in front of me scattered as I hurtled towards them and there was a shuddering as one of my glider’s tube ends furrowed the grass. I thought it was the left wing-tip, but if it had been, it would have turned me into the hill, so I was puzzled yet relieved when the shuddering stopped and I flew away from the hillside. When I landed and unstrapped from my harness, I found dirt and grass sprouting from the rear end of the keel tube. I did not make the cut to the final. I consoled myself that I had at least scored higher than Brian Wood, the reigning British champion, but so had many others.
See Appliance of statistics for an accident at this competition and incident reporting then and now.
Pilot was (and is) Britain’s main light aviation magazine. The March 1976 edition featured hang gliding and it included this photo of me taken by Len Gabriels, the brains behind Skyhook hang gliders, at the British championships in August 1975. (Coincidentally, long time Pilot editor James Gilbert watched me and my comrades hang gliding on the Spanish island of Lanzarote in the early 1990s.)
The highest scoring pilot at the 1975 British Championships was American Bob Wills flying an all-black Sport Kites Inc. Wills Wing Swallowtail. Examining the glider from under its expanse of sailcloth I noticed that the sun highlighted brownish streaks criss-crossing the fabric. Wills explained that the sails of these gliders were originally white (or multicolored in some cases) and they were painted black for an upcoming movie which they had just filmed in Greece. The film was Sky Riders, starring James Coburn, Susannah York, Robert Culp, and Charles Aznavour. It was in cinemas/movie theaters the following year. (See Paint it black–my review of that film.)
While most hang glider pilots flew standard Rogallos in 1975, in the USA several people attempted to improve on the basic idea. One was the Wills Wing Swallowtail with its reduced billow, cut-out trailing edge, and (in later versions) tip roach supported by radial battens. Other engineers tried different approaches to achieving improved performance.
The Cirrus was actually the Windlord 4 created by Rich Finley. Like most Rogallos, it had no sail battens.
Chord-wise battens took extra time to rig and de-rig, but they reduced aerodynamic drag caused by sail flutter. This is the production Electra Flyer Cirrus.
The Cirrus II and Cirrus III (of 1976) had the improvement of roached wing-tips supported by radial battens. The Cirrus III was a hugely successful and popular hang glider. While most were built by Electra Flyer in Albuquerque, New Mexico, they were also manufactured under licence in Britain by Scot-Kites.
Nineteen year-old Roy Haggard designed, built, and flew the Dragonfly. When Pete Brock of Ultralight Products saw it perform at the 1974 U.S. nationals, he agreed to manufacture it. The prototype is the relatively scruffy white and red one in the following image. The other, with an aerodynamically cleaner sail, is a production UP Dragonfly. The Daragonfly’s fixed tip struts apparently made it resilient to the luffing dive problem. As I understand it, Charlie Baughman obtained Roy Haggard’s prototype, so it is likely that he is flying it (the lower one) in the photo and Roy Haggard is flying the upper example, made by Ultralight Products.
British hang glider manufacturer Birdman, of Marlborough in Wiltshire, brought two (I think) Dragonflies and a Red Tail (Ultralight Products’ easier to fly wing) from the 1975 world championships at Kössen, Austria, back to Britain. I saw the Dragonflies flying at Mere in Wiltshire in the summer of 1975. The yaw characteristic of those gliders imparted a uniquely graceful dynamic in their flight. I assume that Birdman intended to build the Dragonfly under licence, but my information is that they did not do so. However, they took on board UP’s slick hardware and the entire Birdman range was soon unequaled in quality of finish and slickness of fittings. As I understand it, Pat Fry, who I had flown with on occasion, obtained a Dragonfly, but his one flight in it scared him so badly he never flew it again.
In the Hawaii image, notice other hang gliders specking out behind the Dragonfly.
You might be able to make out the truncated tips (more aerodynamic than those of the Dragonfly) and side flying struts instead of wires, which obviated the need for top rigging with its attendant drag, cost, weight, and set-up time. Donnita’s aeronautical engineering talents were well in advance of most others at the time, yet she was content to let her partner Dave Kilbourne receive the lion’s share of the publicity, mainly for his daring flying achievements. I guess the media understood heights and distances better than they understood the technology.
While the Rogallo offered the advantage of simplicity, its one-piece airfoil (two, if you regard both halves as separate) that combined the functions of generating lift and providing control and stability, compromised those individual needs heavily. Conventional aircraft, including gliders (sailplanes) employ separate wing and tail surfaces to provide those separate functions. That results in greater efficiency, but at the cost of complexity. Several hang glider designers around the world created hang gliders with separate wing and tail surfaces. Some were entirely rigid, with conventional control surfaces, while others used sailcloth with a some airframe flexibility in an attempt to retain the simplicity of pilot weight shift as the control method. Foremost among practitioners of the latter, in Britain at least, was Miles Handley. His first glider, which owed almost nothing to any predecessor, was the Gulp.
I seem to recall that this photo of the Gulp, which its designer and constructor Miles Handley (who had no formal education in aerodynamics) sent me as a print, was of the second flight of the prototype.
The original Miles Wings Gulp had no battens, but — extraordinarily — the thick sailcloth maintained an airfoil section, as if by magic, even when the wing was rigged flat on the ground. It had just enough dihedral (and the sail was cut precisely) that span-wise tension together with the curved join of the two semi-spans at the root ensured its 3-D form. Nevertheless, the Gulp was reputed to be hard to turn, a problem likely magnified by that dihedral.
I heard also that it suffered from a minor pitch control problem (a phugoid) because the changed airflow at different pitch angles (so-called angle of attack) caused the high point of the airfoil curve to move forward and back, countering the pilot’s control inputs. To resolve that problem (which struck my own later experimental glider more seriously) the next version of the Gulp featured chord-wise airfoil shaped fixed battens spaced evenly across its entire span.
Brian Wood, the first British hang gliding champion, did not do as well as expected in the 1975 competition, but he demonstrated the Miles Wings Gulp 130 monoplane flex-wing one calm evening. Having launched from the ridge top, instead of gliding down to land at the bottom like every other hang glider, he flew straight out, losing barely any height until he touched down in a field far out from launch.
…the late, great low-speed aerodynamicist, Dr. Paul MacCready, once told me that he felt the hang gliding design evolution had progressed further through a semi-educated trial-and-error process than what would have been achieved in the same time span by classically educated aerodynamicists.
— Lt. Col. Mark Stucky USMC (call sign Forger) in Hang Gliding & Paragliding, January 2008
Brian Wood, incidentally, was the first and only British hang gliding superstar, often appearing on radio, television, and press. Previously, like his American counterpart Bob Wills, he rode moto cross.
For a comparison of the Wills Wing Swallowtail with the British Miles Wings Gulp, see Simple versus complex. That page also describes my own first experimental hang glider.
Meanwhile, both Bob Wills in California and Miles Handley in Britain were working on new developments, one an extension of previous design improvements and the other so radical it took a few years to come to fruition.
And other manufacturers forged ahead combining short root chord, fixed tips, and battens. The Cumulus VII was made by Dick Eipper’s company Eipper Formance Inc. (Say it out loud…)
Flying squad, a short history of the east coast U.S. hang glider manufacturer Sky Sports, which I include here to avoid imparting the impression that Bob Wills and Miles Handley were the only people creating significant developments
Miles Handley photo gallery on British Hang Gliding History
Miles Wing Gulp photos by Don Liddard on flickr