Gyroplanes are making a comeback, which has led to one US specialist launching a sleek, 21st century version, sporting a range of cutting-edge technology. Stuart Nathan reports.
Gyroplanes are an oddity in the aerospace field. Sharing the characteristics of a helicopter and a light aircraft, they have been around since the early 1920s, but are probably still best-known for the cameo appearance of the rocket-and flamethrower-toting Little Nellie, battling helicopters over a Japanese volcano in the James Bond film You Only Live Twice.
But gyroplanes are making a comeback, according to Oregon engineer Jim Vanek, whose company, SportCopter, is about to launch a new range of machines on to both the military and civil markets.
Because the planes have a big rotor on the top, they’re often thought of as miniature helicopters, but there are important differences between the two.
In a helicopter, the rotor is powered, and it generates lift as it is forced through the air. In a gyroplane, the rotor spins freely, while a propellor, often but not always at the back of the craft, generates thrust. Gyroplanes don’t take off vertically either. the main rotor is pre-rotated — sometimes by hand, sometimes by the engine — and then the propellor pushes the aircraft along a short runway.
The main rotor is tilted backwards slightly, and spins faster as the plane accelerates. Once this is spinning fast enough to generate sufficient lift, the aircraft takes off. Tilting the main rotor forward and back in flight makes the craft climb and dive; tilting it from side to side makes it roll which, combined with a rudder in the tailplane, steers the craft.
Combining helicopter and aircraft characteristics gives the gyroplane some important properties, explained Vanek. ‘Basically, you fly like a plane, but you’re very manoeuvrable at low speeds.’ Gyroplanes don’t stall, he claimed. ‘They can fly at very low speeds, and they’re very safe and recoverable.’ This is because, as long as the rotor is turning, the craft is still generating lift. ‘We can land our craft at 0-20mph,’ he added.
Because of this manoeuvrability and low-speed performance, the most common use for gyroplanes has been for reconnaisance. The German navy, for example, carried unpowered gyroplanes on U-boats during World War II. Then, when it surfaced the planes would be towed behind the sub, much like kites, to spot enemy shipping. Here they were used to calibrate coastal radar stations during the Battle of Britain.
Since then, they have fallen out of favour with the military, but are still popular among enthusiasts as leisure vehicles. Tending to have a lightweight construction with the pilot often exposed to the elements, they can be compared to ‘motorbikes of the air,’ said Vanek. ‘Because of the extremely manoeuvrable way they fly, it feels like you’re on a motorbike, cutting your own trails through the air,’ he said.
Moreover, gyroplanes are easier to fly than helicopters, added Vanek. ‘There’s a lot less workload. You don’t have to watch rotor rpm and engine rpm,’ he explained. The only hand control is the cyclic, which tilts the whole rotor, unlike helicopters, which have a second hand control called the collective, which rotates the rotor blades along their axis to change the angle at which they meet the air.
The relatively low-cost, easy flying, stability, safety and convenience of gyroplanes is beginning to make them more popular again, said Vanek. ‘People realise you can fly them in high winds, and you can remove the blades and tow them behind a vehicle.’
This increasing demand has led Vanek to design a new gyroplane range, rather different from his existing models. While his older craft have adhered to the ‘less is more’ philosophy — single-seaters with open cockpits and exposed struts — the new SportCopter II is a sleek insectoid shape, powered by a Subaru car engine, with an enclosed bubble cockpit similar to a helicopter’s.
It is a two-seater, with pilot and co-pilot or passenger sitting side-by-side in leather-upholstered comfort, and it has a range of instrumentation options including glass displays similar to the most up-to-date airliners. According to Vanek, it’s the fastest gyroplane on the market, as well as being the only one with a fully-enclosed cockpit and engine.
‘There was a definite market need for an enclosed version,’ said Vanek. ‘For years, we’ve had people asking us for military applications, for surveillance and spotting.’ The enclosed design gives reconnaisance personnel the safety and security they need for the task, and the flight characteristics of the gyroplane allow them to fly slowly for detailed observations.
‘It’s safer than a plane, because you’re always in autorotation, so you can land it in very tight situations,’ said Vanek. To help with this, he designed in a wheeled undercarriage with a robust suspension. ‘It can take a very high rate of sink, which basically means you can just stop it in the air and kerplunk it down on to the ground without a lot of precision to land it.’
The SportCopter II can be flown in high winds, and the blades can be removed to enable the craft to be towed behind a vehicle
The low cost of the craft is a major attraction for military reconnaisance. ‘Rather than paying several times the cost of this for a UAV, they can afford to put people in it, with all the advantages that gives it, for much less money,’ said Vanek. A basic SportCopter II costs in the region of $100,000 (£50,000) although more sophisticated instrumentation adds to the price.
Vanek is proud of the sophistication of the engineering in the SportCopter II, which is well beyond the level his small company has ever attempted. The cockpit bubble, for example, combines the strength of its monococque composite shell and a backbone airframe. ‘We’re relying on the skin’s strength and the core strength of the fuselage, whereas before, we’d typically build a strong airframe, and the body would just hang off that for wind resistance. We’ve also got a more sophisticated dual-control system, and the flying services are designed for higher speeds. Everything on the craft is an advancement.’
The new range led Vanek to embrace computer-aided design to a degree he hadn’t done before, using the SolidWorks package to design many of the components and systems. ‘We got to looking at how you could possibly make optically perfect windows, and decided that we had to go to computer cutting.’
The benefits weren’t just in accuracy. Switching to CAD allowed Vanek to halve design times and reduced prototyping times by a factor of ten. ‘We’ve evolved from making scale models using wooden sticks to test geometry in 3D CAD, and it’s proved to be much more affordable in the long run than filling the shop with dust and resin.’
The company uses contractors for CNC work. ‘You can cut these complex parts by hand, but it takes a very talented person and a lot of tooling to carve something so perfectly. Today, there are 5D mills that can cut the shape for you, perfect every time, and lots of places will do that for you. But you have to speak the language, and that means CAD.’
Vanek said he has had a great deal of interest in the SportCopter, from civil and military markets. ‘We’re finding that many people are more interested in this more sophisticated type of machine, with the good instrumentation and the leather interior — it’s up to the level of a light aircraft, but you can tow it behind your motorhome.’
The company is already working on the next generation of the SportCopter II. ‘We’re building a law enforcement version with dual screens and a thermal camera — there’s a large demand for that,’ he said. ‘And we’re also putting together a more powerful version, with an aircraft engine rather than the engine we currently use. That’ll give us a benchmark power-to-weight ratio. We’re also doing a float version, for take-off and landing on water, and we’re considering a version that could use hydrogen as part of its fuel source.’
James Bond would be proud of how far Little Nellie has come. And he might well be putting in an order.