The microlight Cinderella
Tony Unwin explains something to the author before flight.
Although still in the minority with some 50 examples, around one percent of the 4869 total of all types currently on the New Zealand civil aircraft register, autogyros are losing their novelty aspect and showing signs of acceptance among recreational pilots.
All pilots who know them well agree that the type is just about the safest way of taking to the air, given its inherent stability and slow takeoff and especially landing speeds. Even more than with the average microlight, a pilot has to be unusually hamfisted or determinedly inept to come to serious grief in one of these machines — once the basics have been learned under the guidance of the right sort of instructor.
That last point is vital, highlighted by inappropriate takeoff and show-off techniques by one or two teach-yourself tyros who are no longer with us.
The only real point of debate among rotary wing aficionados is what to call them. The CAA groups them under gyroplanes, but they are also widely known as gyrocopters and autogyros, the latter designation confused slightly by being taken up as company name AutoGyro by a prominent German manufacturer.
The late Kenneth Wallis, who did more than perhaps any other single person to raise the profile of these aircraft in the UK, had this to say on the subject: “This class of aircraft should have only the one truly generic name — ‘Autogyro’. That is technically correct in that it implies ‘self turning’ whereas ‘Gyroplane’ and ‘Gyrocopter’ mean ‘turning wing’ and so could describe a helicopter.
“‘Autogiro’ spelled with an ‘i’ instead of a ‘y’ was used as a copyright trade name by Juan de la Cierva for his autogyros. If a world record is achieved by this class of aircraft and officially recognised by the Federation Aeronautique Internationale, it is in the ‘Autogyres’ category.”
And he should know. Ken Wallis broke or set 14 speed, altitude, distance and endurance records over 30 years from 1969, flying autogyros of his own design and build. Only machines of greater or turbocharged power have later broken his records.
The dream of vertical takeoff and landing occupied the minds of many early inventors, all of whom recognised the need for rotary wings of some sort. Even Yorkshireman Sir George Cayley, one of the most notable pioneers of manned flight, worked out a means of controlling vertical and horizontal flight with contra-rotating rotors and fans plus pusher propellers and rudders in an 1842 design. As with all those early efforts, however, potential success came up against the lack of a suitable power source.
Aero engines came of age during WWI and so the dream of the helicopter started to be realised not long afterwards, leading to its own specialised branch of aviation. The autogyro, although bearing a superficial similarity to the helicopter, had rather different and earlier origins but with some technical cross-fertilisation.
Juan de la Cierva was born in Madrid in 1895 and demonstrated an aptitude for aeronautics as early as 1911. While still at the Madrid Civil Engineering School, in 1918 he designed a bomber biplane with 80ft wingspan, but it was destroyed on its maiden flight during a low-level turn at low airspeed.
Recognising that the pilot, who survived with cuts and bruises, could have recovered control from a greater height, Cierva started investigating means of making aeroplanes stall-proof. One way of achieving that was to make the wing move through the air always at optimum speed, soon leading to a rotary wing design driven purely by airflow reaction. After work with flexible blades and flapping hinges, success came in January 1923 with Cierva’s fourth machine, a converted Hanriot Scout with Le Rhône rotary engine, and the Autogiro phenomenon began.
Cierva designs were also built under licence in other countries, some with pre-rotators to dramatically shorten the takeoff run, but a major advance came with the Cierva C30’s direct control rotor head, allowing the entire rotor disc to be moved relative to the rest of the airframe on a sort of universal joint. That led to the deletion of the elevator and stub wings with ailerons for control, at the same time dramatically increasing control at low speeds, and all subsequent designs have followed the same principle.
Prewar Autogiros tended to be on the large side with aeroplane-type fuselages, and a still-born postwar foray into a multiple passenger-carrying type went one further. The Fairey Gyrodyne of 1947 used an Alvis Leonides radial engine to provide rotor power for takeoff, hovering and landing, plus a propeller on one stub wing to counteract yaw and provide thrust in level flight when the lift was taken by the free-rotating rotor. It set a helicopter speed record of 123.4mph in June 1948.
More ambitious was the Fairey Rotodyne with a boxy fuselage with rear clamshell doors for loading vehicles or freight and seating for 45–50 passengers. First untethered flight was in November 1957 and just over a year later the prototype achieved an average speed of 190mph for a new 100km closed circuit speed record.
The Rotodyne used two Napier Eland turboprop engines on short wings. Compressed bleed air was fed through the four 90ft diameter rotor blades to pressure jets at the tips, where jet fuel was introduced and the mixture ignited in a form of afterburner.
Despite much interest from airlines and possible manufacturing licence agreements from Kaman in the USA, uncertainties surrounding the British government’s 1959 reorganisation of the entire aviation industry meant the chance to overcome noise and other technical difficulties was missed, and the project was cancelled in February 1962.
The second, and continuing, generation of autogyros emerged in the mid-1950s. Igor Bensen, who had flown a prewar Kellett autogyro and also the unlikely-looking wartime military Hafner Rotachute, set up his own company and produced gyroglider plans and kits for towing behind cars. That led directly to a powered version with 42hp two-stroke engine, wooden teetering rotors and overhead control stick, and in 1957 the Bensen B-8M gyrocopter was offered to an eager public.
Many others have followed, most of them with engines in similar pusher configuration, and the current list in New Zealand covers a wide range of manufacturers and builders. They come in a spread of shapes, generally pushers and mostly powered by Rotax and Subaru, single-seat open and enclosed, two-seat tandem or side-by-side and also open and enclosed. Two-blade rotors keep things simple and make autogyros by far the easiest aircraft to tuck away in hangars.
Aviation News recently accepted the invitation of Tony Unwin of Gyrate NZ and travelled to Tauranga to try this unfamiliar (apart from a rear-seat passenger flight with Bill Black two years ago) form of aviating.
Tony’s autogyro experience goes back some 20 years, with his first training machine being VPM M16 G-YRAT in, well, distinctive pink colour scheme. Italian VPM (Vittorio Pietro and Vittorio Magni) made its first proper two-seater in 1992 (the one-plus-one M14 had the rear occupant perched above and behind the pilot, with legs outboard and feet tucked into slots in the fairing), powered by the 125hp four-cylinder two-stroke Arrow engine which proved unpopular and was often replaced by Rotax or Subaru.
VPM became Magni in 1996, and to date has made somewhere around 1000 autogyros. Expanding rapidly since its start in 1999 and with a production of some 1500 to date is AutoGyro of Hildesheim, Saxony, Germany. It makes a range of basically three models, with country variations of each — the open-cockpit tandem MTOsport replacing the MT03 Eagle; enclosed tandem Calidus; and enclosed side-by-side Cavalon. All have composite fuselages and pusher Rotax engines, either the 100hp 912ULS as standard or the turbocharged 115hp 914UL.
Gyrate NZ is the local distributor for the AutoGyro range and so the hangar is mostly occupied by machines from that stable. Before introducing me to the hardware, Tony gives a full preflight briefing and goes through the paperwork.
“The gyroplane is very much the Cinderella of microlights,” he explains. He retired from commercial aviation, flying fixed wing aeroplanes from Aztec to Airbus (“I gave up long-haul flying when sectors started getting more than 10 hours”), and came to New Zealand with his wife Sue in 2005, starting the business at Tauranga the following year.
Even more thorough, if possible, is the walkaround of MT03 Eagle ZK-RGG, the company’s standard trainer. Without a cowl the engine is easy to inspect, and particular attention is paid to the controls, also in full view. The prior explanation of the combined pre-rotator and rotor brake system now makes sense, turned by a belt-driven shaft next to the propeller hub with its own right-angle gearbox and universal joints to take the drive to the rotor head. But that comes later.
Starting is standard Rotax, and the only instrument not seen in the usual microlight is an extra tachometer for rotor rpm, which makes up for the lack of turn-and-slip, taken care of by a useful piece of cotton taped to the windscreen.
Taxying to the far end of Tauranga’s grass runway 02 is done carefully, keeping in mind shock loadings on the stationary rotor head bearings. With stick held forward, the switch below the altimeter is turned to Flight, releasing the rotor brake and starting the flight sequence with a button on the stick to power up the pre-rotator.
At Tony’s gentle coaching over the excellent intercom from the back seat, at around 120rpm rotor speed I release the button and turn into wind, Tauranga’s usual late-afternoon sea breeze, and watch the rpm increase a little.
Then, with stick held back, the Rotax is encouraged to full noise. Soon the nosewheel lifts, and the temptation must be resisted to keep it high in an effort to coax more rotor rpm. That has been the downfall (literally) of many an inexperienced autogyro pilot who has gone off the far end of the airstrip still not airborne.
Think of the rotor as a big wing. Keep the nose of a fixed wing aeroplane too high and it will create drag, not lift, and the same thing happens here.
Lower the nose to keep the wheel just off the ground, and everything accelerates smoothly. RGG flies off when it’s ready, so lift the nose to 60mph (“Everything happens at 60, just like a Tiger Moth,” says the intercom) and we climb away. Satisfyingly steeply.
Open-cockpit flying is like none other, although the helmet and visor with chin flap prevent any wind in the face and so wind noise is non-existent, making communication a breeze. Gyrate’s jackets, incorporating flotation just in case, keep out the wind chill while the low cockpit sides, offering a sense of exposure at first, don’t trouble even this serious and determined acrophobe.
We head out to The Mount and the harbour entrance for some gentle exercises, keeping a watchful eye on any parapenting activities but not distracted by any need or wish to stare at glass panels inside the cockpit. This is a strictly VFR machine, and anybody who likes instruments should go and find something else to fly.
Throttling back just enough to maintain height shows utterly minimal groundspeed but full control, something that would take a lot of getting used to, and steep turns take up a minimal amount of sky with rotor speed increasing with G loading. Control response is excellent, but movement should never be abrupt, especially in the pitch. A rapid push-over can stop the relative airflow up through the rotor disc, and therein lie things you don’t even want to think about.
Flight is not as smooth as in a fixed wing aeroplane as the rotor sets up its own vibrations which have nothing to do with air currents, but that’s autogyros.
Returning to the airport past a cruise ship, just to make them wish they’d done something interesting such as going flying during their day in port, we want to fly some circuits, a normal sort of thing to do in a new aircraft. Permission denied, however, for some unexplained and unfathomable reason. Perhaps the complete lack of other traffic at Tauranga is too much for the controller. Who knows?
So we make a full-stop landing, gradually reducing speed throughout short final approach until, at the right height, I keep the stick coming back to hold off and we touch down gently with near-zero forward speed. That’s the theory, anyway. Practice, practice.
Stick forward to kill any possible lift, I taxi back to the holding point, muttering about air traffic controllers, then take off again, this time heading down Papamoa way along the beach. More turns, more pointing at landmarks (there’s no better aerial platform for such activity) and it’s back to runway 02.
“This time maintain 1000ft until we’re over the threshold,” says Tony, about the time I’m starting to plan a careful right base.
Oh yes, this will be interesting, I think, and against all those fixed wing instincts I’ve been carefully accumulating for more than 40 years.
But I soon realise that it’s a ploy to land further down the runway to avoid an excessively long taxi back to the hangar. Certainly the approach is steep, but it’s far from disconcerting and everything feels completely under control.
By the end of 40 minutes’ flying I’m persuaded that the autogyro/gyroplane/gyrocopter is indeed a legitimate member of the aviation machine fraternity, and it’s little wonder that converts to the invisible wing can become just a little fanatical. Its 80mph cruise is not necessarily ideal for long cross-countries, but for the sheer fun of flying a highly controllable aircraft, right out there and being part of the air you’re flying through, it is indeed hard to beat an open-cockpit autogyro.
But if you want to stick your head in the cockpit to watch instruments, go and find something else.
Aviation News thanks Tony Unwin and Gyrate NZ for this introduction to an interesting facet of aviation.
- Report by John King, photographs by Dorothy King and Gyrate NZ.
» Summer success at the Walsh
» The luxury of living in the Ivory Tower
» Comper moves swiftly
» UAV usefulness increasing
» Woodville’s even dozen
» 60th birthday party for ZK-BNL
» New airline MRO facility
» Hands across the Southern Alps
» Praise earned in tough place