Three-sixty degree appraisal (my flying 1976)
This page continues from Simple versus complex (my flying 1975 part 2).
I took this photo of Winklebury hill from the car park at Berwick St John village fête in June, 2013. The aspect reminds me of a trivial event in early 1976, when this was our only north-west site. (Bell Hill had not yet been discovered.) I was at the farm at the bottom, watching one of two flying brothers on approach to the landing field (nearer the hill than where this photo was taken). Flying seated in a Waspair Falcon IV, framed by the hill and some low trees (out of view in the photo) he went right round in a 360-degree turn with little loss in height. He then levelled out and landed normally. That was the first 360-degree turn in a hang glider I had seen.
Doesn’t sound like much, but it was most impressive for those times. However, the pace of advancement was so rapid that, by the end of that summer, 360 degree turns were considered almost routine.
To take this photo I used a step ladder. Notice my hnd holding the fir tree bent over out of the way.
This design suffered from an unfortunate pitch characteristic that aerodynamicists term phugoid motion. The camber curve of the sail changed shape as the angle of attack changed, which amplified my pitch control inputs—after a brief delay. On one test flight, that positive feedback mechanism* sent me into a series of pitch oscillations. Fortunately, it happened to be leveling out from a dive when I touched down in the dusty bottom field at Monk’s Down and I got away with a sprained ankle.
A more advanced V-tail flex-wing hang glider designed and built in the USA appears under Developments 1978-9 in Hang gliding 1978 and 1979 part 1.
* Positive feedback mechanism?
“You engineering types are so confusing. Positive feedback is good! We want more positive feedback! It tells use we are doing things right! And why don’t you smile?”
In engineering terms, as distinct from corporate HR arts graduate terms, positive feedback is a runaway response that causes instability; an out-of-control situation. Negative feedback is where the mechanism tends to damp out excursions from the required control setting. The Watt governor of the first successful steam engines is an example I learned in CSE engineering at secondary school.
“The what governor?”
Oh, never mind…
I contracted out the construction of my sails to a local hang glider sailmaker (who, at age 17, had built his own Skyhook IIIA from plans) but I built the airframes myself. My hang gliders all flew — eventually. However, I was always at least two steps behind the state of the art.
Notice the absence of an emergency parachute at this time. This version had a larger control frame to accommodate flying prone. I also did away with the double side flying wires of the first version.
On a later version of this glider, I created the deflexor cables as a single wire running through a pulley (or equivalent device) at the nose so that the tension on each side would always be the same. It just seemed like a good idea at the time. On a flight test, the glider flew normally and I was about to land it, avoiding wet ground, when the horizon whipped round and, still in the prone position, I was dumped onto the ground — actually into a couple of inches of water — with the glider and me facing the opposite direction of my approach.
Some time later, when I was away from home, my mother took a call from Steve Hunt of Hiway Hang Gliders (then based in Brighton on the Sussex coast) who heard about the incident. When I next saw Steve, a year or so later, I had forgotten all about it. I will never know what insights he might have provided.
To see what became of this airframe, see under Simulator in Aviation computer-based training.
Mean Machine 1 was the first of three swallowtails built by Martin O. It is flown here by Chris S. Note the scallop — removal of sailcloth from the trailing edge in a curve — and reduced billow compared to a standard Rogallo. Martin flies paragliders nowadays (2019). I have photos of Chris flying a powered ultralight in 2019 on my page Defying Newton, powered ultralight operations at Newton Peveril in Dorset, England.
As well as stretching the Swallowtail concept, the Firebird, made by Birdman of Marlborough, Wiltshire, England, was said to be so quick to rig it opened like an umbrella. At that time Birdman contracted out their sail-making and, according to one expert insider, the Firebird suffered from a ‘rattly’ sail. (The one I saw flying at Monk’s Down looked impressive, but the sail certainly fluttered more than did that of the Swallowtail, for instance.)
During the long hot summer of 1975, Birdman made Roly the sail-maker an offer he could not refuse, so in about July 1976 he left Kestrel Kites of Poole, Dorset, to join Birdman in Wiltshire. Their premises, former chicken sheds, had no sail loft initially. As well as leading the creation of the Birdman sail loft, Roly added a second batten each side to the Firebird, in the style of late Swallowtail types such as the Hiway Cloudbase. The two battens each side largely eliminated the ‘rattle.’
Ron’s green glider (in the photo) also seems to be a Firebird with the extra battens. Roly informs me that several Firebird owners brought their gliders back to the factory to have the sail modified with the new batten layout.
So what if it’s freezing cold in the north wind on a bare hillside in the middle of nowhere with a swamp for a landing field — or is that slush and snow? We’re going flying anyway!
See my threads page Birdman of Wiltshire, England.
In 1976 I was a hang gliding instructor, first teaching beginners informally at my local site, then working for a hang gliding school in south Wales.
I first saw a Chargus Midas in late 1976 when its pilot, together with his extraordinarily attractive girl friend with long brown hair (I remember her clearly to this day!) visited the hang gliding school in south Wales where I was instructing. (How was I to obtain a girl friend like that? I had no idea, but I soon concluded that hang gliding instructing was not the way.) Compared with the primitive Rogallos I flew at the time, the Midas appeared almost extra-terrestrial. As one university student put it the following year (when I too was at college, where surely there were unattached girls…) the Midas was “just a pair of leading edges.”
The Midas, designed by Martin Farnham, was manufactured by Chargus of Buckinghamshire, a few miles north-west of London, England. Chargus was run by former Royal Navy marksman and motor racing engineer Murray Rose. I encountered Murray in 1980 testing a flex-wing powered ultralight with an experimental 3-blade carbon fiber propeller, in which he climbed out from the airfield despite a down-draft and turbulence caused by wind curling over from the forested edge of the runway. By the early 1990s, he was at Solar Wings in Wiltshire using finite element analysis to compute stresses and strains through the compound curves of flexible wings and airframes. (By then the Solar Wings factory was part of Pegasus Aviation, which made powered ultralights.)
As of this writing in 2019, Murray Rose is a successful thriller writer using the name Walter Gunn. (Info source: SkyWings, August 2018.)
See also my threads page Chargus of Buckinghamshire, England.
One day teaching beginners on a low slope, we found that those who flew one particular glider (the sole example of the type that we used) kept nosing in hard shortly after launching. We determined the correlation with the incidents and the specific glider only gradually. Why did Fred Bloggs nose in just now when he was OK two minutes ago. And why has Joe Soap just nosed in? Eventually one young fellow, a student at the nearby Polytechnic of Wales, was winded so badly in a hard impact he was unable to breathe. He just lay on the ground curled in a ball for a minute. I thought we were witnessing a fatality. However, in a few minutes he was up and about and able to describe his experience. My relief was short lived.
“Everard, take that glider up and find out what’s wrong with it.” Mike, the chief instructor, was a former RAF pilot, glider pilot, and scuba diver.
I launched with plenty of speed (for safety) and was settling into the short period of level flight afforded by the low grass-covered slope when the glider slowly, but unstoppably, pitched nose-down and gathered speed, in much the same way as in stall recovery, but I was nowhere near the stall. I ‘pushed out’ on the control bar for maximum rearward weight shift (equivalent to hauling back on the control stick in a conventional glider or airplane) and it levelled out and flew normally from then on until I landed (for a total flight time of no more than thirty seconds).
“That glider is grounded,” said Mike. No explanation from me was needed; everyone saw what I did and what the glider did.
I do not know why it behaved like that or why the fault had not been discovered earlier, or whether the problem was inherent or the result of incorrect adjustment. (The type had been in use for about a year by then.)
We kept the gliders in a disused cinema at the back of rambling premises in Merthyr Tydfil. ‘Rambling’ isn’t strong enough. It was like another dimension. Looking out one window onto a vertical hole between structures, there was a river flowing underneath… Late in the year, we instructors were all issued with identical red and white winter jackets and I recall us striding up the Merthyr main street, about 10 feet tall. I half expected to bump into a local girl whose song Lost in France was climbing the pop charts. In retrospect, the people in that street likely thought were were a bunch of English fools and I never did get to meet Bonnie Tyler. (One pop star I did meet through hang gliding is Elkie Brooks, but that was in the early 1990s.)
Mike had immigrated from Russia with his mother — who barely spoke English and lived in rooms in the back of the sprawling building (which included a disused cinema/movie theater). Fronting onto the High Street, was a junk shop.
He said that the barrel rolls were sudden and unexpected and that they occurred as one maneuver. He hit his head on part of the kite but had zero Gs and positive Gs intermittently, but no negative G forces. As quickly as the rolls started they then stopped, and Bob was again flying straight and level with no damage…
— George Worthington in Hang Gliding, September 1978, describing Bob Thompson being barrel-rolled in a competition in the Owens Valley, California
Mike sometimes had friends round and I overheard them discussing how much money they had made the day before. Then, barely pausing, switching to the subject of hang gliding, one of them described how turbulence had rolled him upside-down a few days earlier. (This was in a Birdman Firebird — see Firebird earlier on this page — and it was before we adapted emergency parachutes for hang gliding.) He was lucky to be alive. These were kick-ass people with a kinda strange background. Mike had flown for the RAF in his younger days.
This topic continues in My flying late 1970s and early 1980s.
Whisky Kilo Two Eight tells all, my review of Trailblazers, Test Pilots in Action by Christopher Hounsfield, 2008
The Fight to Preserve South Wales’ Jewish History in the Jerusalem Post