PSS in SA 
John Lightfoot
Notes and pictures from Donald Flint
and Vic Hoxley (Port Elizabeth),
Simon Nelson and Pete Milne (Durban)
and Steve McCarthy (Cape Town)

PSS, or Power Scale Soaring, has really caught the interest of modellers in recent years . . . more precisely, since about the mid-eighties, but what provoked glider pilots to try hurling models which bore no resemblance to gliders off suitable hills in the first place?

There was probably a certain frustration at the fact that a wonderful range of potential scale models was effectively closed to aspiring builders because of the lack of suitable power sources.  Even today, when the miniature gas turbine is a reality and becoming more readily available, it remains a messy, noisy and often heartbreakingly unreliable option.

How could the beauty of jet aircraft be enjoyed without the need for an engine?  No engine? . . . glider! . . . high wing loading? . . . slope soaring!

The first time I came across the idea of a jet flying as a glider from a slope (long before the term PSS was coined) was when I read that a Chance-Vaught Cutlass had been flown by a New Zealander by the name of John Crump — it featured briefly in the January 1975 issue of RCM&E, so it probably flew in 1974.

This was what gave me the idea for a novel form of slope model.  I have never been keen on what I have called ‘ordinary-looking' models — aircraft with straight wings and conventional tails — I wanted something different, and I looked at the early generation of jets . . . when jet fighters were still real flying machines, as opposed to guided engines!

The DH-110 (heading picture), a development of the DH Venom which followed the DH Vampire, immediately caught my eye as a model which looked different and had a decent wing area.

The fuselage was 3mm balsa planking over about ten formers, shaped according to an RCM&E three-view, glass-fibre booms created in moulds taken from a balsa plug and balsa- sheeted foam wings.  The twin tailcones were glass-fibre moulded in Tupperware containers!

It first flew on a blustery afternoon on Signal Hill in August of 1977.  There is a video of the first flight, converted from the 8mm film on which it was originally recorded, showing a nearly unrecognisable slope site, with trees lashing in the wind and our last-year's Chairman (my son, Andrew) about waist-high!

John Beer followed with a Mirage III in SAAF camouflage, which flew on Kanonkop in 1978.  John also produced a small Vulcan which didn't see that much air-time but which got Andrew Anderson, a dedicated Vulcan fan, all fired up and ready to create one.  I'm fairly certain he still has a set of foam cores which I helped him cut, lurking in the roof of his garage!  From time to time he mutters about "returning to the fold" –– what a project that would make with which to stage a comeback!

PSS isn't restricted to jets either —  Ken Alrick took the propellor off his Spitfire and flew it in the 1981 Soaring Nationals in Cape Town, with the motor still under the cowling to provide ballast and keep the CG in the right place!

But was the New Zealand Cutlass the first recorded model of a jet to fly as a slope soarer?

It would seem not . . .

In 1972, Vic Hoxley built a Canberra bomber
and a mate of his, the late John Haviland, built
(and if this isn't another piece of deja vu,
I don't know what is) a DH-110, which they flew from the dunes at Maitland River Mouth, west of PE!

Amazingly, both the Canberra, held by Vic, and the DH-110, with current owner, Hermi Hertel, still exist 28 years later!

Fuselage construction was rolled balsa on a
polyurethane plug which was removed after drying by slitting the fuselage and then removing the plug.  Wings were balsa-sheeted foam.  Finish was paint straight on to the balsa.

Both flew extremely well, and this set off a passion for scale hitherto impossible to achieve, as Vic had no inclination to fly power models.

To the best of my knowledge, these two were the first examples in the World of what became the now-popular PSS — Power Scale Slope — models.

The Canberra was followed by the Victor bomber, which was completed in 1975, although this was not as successful.  The problem was a characteristic which was apparently initially shared by the full-sized version — a sudden dropping of the tail in normal straight and level flight!  It was thought to be associated with the fact that the airflow over the wing involved a corkscrew vortex off the tips, which flowed in towards the fuselage, creating a sudden low pressure beneath the tailplane, resulting in the rear end suddenly being sucked down!  These problems were however overcome with the addition of ‘carrots' (scale) on the wing and small tip fences (not scale).  "Carrots" are chord-length bulges, rather like tip-tanks not at the tip.

At about this point, Vic started taking an interest in aerobatics, so jet bombers were out and fighters were in.  The SAAF were flying Impalas, or more exactly, the Aermacchi 326, so this was the obvious choice, helped by the fact that his son-in-law had a few years previously been shot down in Angola in an Impala.  This particular aircraft was his next project, and with it he won the S.A. PSS Slope Nationals in 1989, but finally wrote the aircraft off flying too late in the evening and the camouflage worked a bit too well against a thunder-cloud backdrop!

His son-in-law was then a member of the Silver Falcons, the SAAF aerobatic team, so the Mk I he was flying became the next project. With this aircraft Vic again won the S.A. PSS Slope Nationals, both in 1990 & '91 — and in fact he's still flying it — seen here being launched from Rotary Drive above Hermanus.

World war 2 aircraft were now  the ‘in' thing and a Spitfire Mk XIX (the fastest mark of the Spit — an unarmed photo-reconnaissance aircraft) was built from Brian Taylor plans, and flown off the Maitland slope.  Both fuselage and wing were of built-up construction and fully-sheeted balsa, with scale split flaps — where the lower surface of the wing drops down leaving the upper surface in place — they slow the plane down very well.  Wing loading achieved was 16 ounces per square foot but the model still suffers from wetted area drag of the large fuselage and it likes a bit of a blow.

The most recent model to emerge from the Hoxley stable is a Mosquito PR XVI also from plans by Brian Taylor.  Again a built up balsa model, fully sheeted.  This too was an unarmed photo-reconnaissance aircraft which was the fastest aircraft of the second world war at the time.  The model has been finished in SAAF 60 Squadron markings, prompted by the fact that the flight engineer, Doc Hoskin, who collected this aircraft from the factory at Hatfield during the war and then flew most his ‘ops' in it, is living conveniently some 5km from Vic. Flying characteristics are good but it is quick and requires strong lift, possibly due to the 24 ounce wing loading.

The next project?  Who knows, maybe a
Tornado with swing-wing --- perhaps
another World War II aircraft.

Andrew Lightfoot entered the arena, following my lead of going for the unusual, with a Saab Viggen, which flew very well on its maiden flight (unpainted) but once painted, never lived up to early promise.  The complex camouflage, in matt paint, introduced incredible drag!

As "design consultant" I had to experiment with canard settings and CG positions.  Since no one could offer firm advice on this unusual setup, I assembled a tiny 15 cm span version out of foam egg-box sheet, which enabled us to set up angles and balance so well that they needed no adjustment after the first flight!

Mark Lochner (the pioneer of egg-box foam as a building material) built a BAe Hawk, whose tail was far too small for stability in the model, but which flew well with an enlarged stab.

There was a lull in PSS in the Cape, until the
formation of the Atlantic Flying Club and the
appearance of two of the most enthusiastic
local scale soarer pilots, Dietmar Wesemann and Anton Benning, who between them produced an impressive variety of models, including the then ubiquitous Impala, which appeareed in a variety of colour schemes — this one showing off an unusual "Gannet" effect.

Other models flown by this very productive pair include
a C-130 Hercules in Safair colours . . .


        . . . a Mirage F1 . . .    . . . an FW-190 . . .


      . . . a Puccara . . .            . . . a Sabre . . . 


. . . and a B-52, seen here against Robben Island and Blouberg.

Although I have never seen it fly, I discovered this Mig-15, built by Dietmar, on the AFC web page.  I hate to think of the airflow around that huge intake — or does it flow straight through?

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The concept of PSS found fanatical supporters in the UK and the US, (not much heard from other centres — lack of interest or lack of communication?) where the ready availability of kits or glass fuselages intended for power scale offer a veritable mine of possibilities, but there were still some original works of art . . . like the huge B-29 Superfortress, whose fuselage started as a length of plastic drainpipe, and of course, the biggest PSS of them all — the monstrous Antonov An-225, carved from foam by Simon Cocker, and big enough for his small son to crawl into the fuselage!  It took three people to launch, two radios to fly, and is currently in the Guiness Book of Records as the largest radio controlled glider in the world.

Brown paper stuck onto foam cores, the result filled, sanded and painted, became a widely- used building medium in the face of the expense of huge areas of balsa, glass and resin also playing a useful role.

There is an active PSS element at present in AFC — models seen at Hermanus recently have included an A-10 Thunderbolt ("Warthog") by Bernhard Goetz, in a (to my mind) rather unattractive although effective desert camouflage, and an F-7 Corsair and an F-16 Falcon by Mervin Eagles.  Unfortunately, the only pictures available of these models do them less than justice.

SteveMcCarthy has produced a SWOS (Stand-Way-Off-Scale) BD-5, for which I was able to offer him a three-view showing the BD-5G, a stretched-wing glider version of the BD-5J (jet), although I don't think he's built that wing yet — maybe this will provoke him . . .

. . . and an impressive P-51 Mustang,
which has seen a lot of air-time, at
Hermanus as well as off Blouberg hill.


mmmmAlex Selkirk has built an unusual Horten IX
mmmmflying wing, which flies well but is far from
mmmmeasy to see when it's edgewise on!


The discovery of EPP (expanded poly-propylene) lead to a rash of ‘combat' PSS, very roughly-finished Spitfires, Me-109's, P-51's etc, (the foam was covered with packaging tape and some of them used corrugated cardboard for tail-feathers!) which chased each other all over the slopes, bouncing fairly effectively when there was a mishap, and doubtless they served their purpose — giving their pilots the desired adrenalin-rush.  More than once I winced to see one of these models slung by a wing-tip into the back of a trailer — but they can't in all honesty be classed as PSS, which is essentially a serious scale business!

Of about the same size, but beautifully detailed and finished, was the tiny and highly responsive Me-109 which Dave Greer bravely allowed me to fly at Hermanus '98 —
here about to be launched by Lance Cranmer.

For many years, slope soaring was virtually confined to the coastal centres — the Cape, Port Elizabeth and Durban, and while there is currently an increase in slope activity in the area north of Lesotho, supported by Natal and Highveld fliers, it doesn't seem to include much in the way of PSS.

The pursuit of PSS requires a dedicated and specialist approach — not one which would involve a lengthy trip to a decent slope every time one wanted to fly.

There is, however, a prolific source of PSS models in Durban, where Peter Milne turns out a regular procession of immaculately finished models.

Pete is reported to have started modelling in about 1940, with rubber-powered free-flight before graduating to control line flying and playing a major role in C/L team racing in this country.

He only started building scale soarers in the early eighties but has certainly made up for any lost time once he got going!

He's unusual in that he seems to sell models almost as fast as he builds them — he received offers for his Bell X-1 on its first outing at Bulwer last year!  His current stable contains only five models — two Spitfires, a Hurricane, a Tomahawk and a Bell X-1 (the Chuck Yeager sound-barrier-breaker), although I have photos of at least three Hurricanes, four Spitfires and a Vampire, so many have passed on to other owners over the years.

Pete's philosophy on PSS —
"It's a real thrill to see a really accurate scale model drawn, designed, built and then thrown off a good hill — a touch of trim and away she goes.  That's what it's all about — a scale model flying like the real one!"

Pete is a professional artist, and it shows both on the walls of his home, hung with numerous paintings, mostly of aircraft, and on his models.  Apart from being meticulously accurate in structural detail, the painting is out of this world.

On the slope at Port Elizabeth I once put out a finger to touch the retracted wheels on his Spitfire — I had to, to convince myself that they really were painted, and not real wheels in real wheel-wells!

His work is neatly summed-up by Simon Nelson's description —
"When Pete turns up at the slope with a new scale model, one can get an understanding of the work involved by keeping an eye on Dave Greer's face . . . all screwed up and muttering, "Oh God, he's not really going to chuck that artwork off the hill?"

This pale-blue-all-over Spitfire is the famous K-5054 — the prototype, with Pete and his painting of the original.

With the exception of the X-1 and the Vampire, which were built from scratch, all the others (huge by slope standards) started as kits with glass fuselages, but were modified, often almost beyond recognition, to get the detail just right
The size — usually almost 2-metre span — stems from the fact that Pete, a keen surfer with an extensive collection of trophies, suffered a surfing accident which cost him an eye, and he claims the size makes them easier to see!

Pete's obvious fascination with Spitfires probably stems from the fact that, as a lieutenant in the SAAF, he flew the original of this one at Stamford Hill in 1947.

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