Weightshift Aircraft

So what are these things?

In Australia, they are generally called trikes or microlights. Other countries use the terms ultralight or ULM (Ultra Léger Motorisé). Some people refer to them as “powered hang-gliders” though this is inaccurate in most cases (like calling a sports motorcycle a moped). Technically they are classed as weight-shift controlled aeroplanes but, whatever the name, we just think they are loads of fun.

Most models are 2 seaters (with the passenger or instructor seated behind the pilot) but there are also single-seat models available. Some models of trikes are capable of speeds as high as 90kts and are designed for mega cross-country trips with an endurance of 6 hours or more. Such trikes have done many long-distance trips (including several circumnavigations of the globe). Other models fly as slow as 40kts and are ideal for property or stock inspection as well as the sheer pleasure of local flying.

Airborne XT-912 Tourer

Some trikes are “naked” (the structure of the trike and the feet and legs of the occupant are exposed to the elements) whereas others have a fibreglass streamlining “pod” around the trike. These are often fitted with larger “tundra” wheels to facilitate landing on rougher surfaces than standard trikes. Trikes can also be fitted with floats or skis to operate from water or ice.

To continue the theme of double-entendres, some trikes are “topless” (there is no structure above the wing to support its weight). As this is intended to improve performance, these would not usually be fitted to “naked” trikes (though they can be).

One design feature of all trikes is the ease with which the wing can be removed and dissembled for transportation. Although most people prefer to keep their aircraft in a hangar if possible, it is entirely feasible for trikes to be kept at home in a shed or garage and transported to an airfield to be rigged for flying. This can be done single-handed (although easier with 2 people) and, with practice, takes around half an hour.

Caboolture Microlights currently operates two Airborne XT-912 with a choice of Merlin, Cruze, or SST wings. This allows students to train on the wing most suitable for the trike they intend to purchase. Students are also able to try the different wings during training. The two school aircraft are available to cross-hire to approved trike pilots who learnt to fly with us.

Airborne Tlite nanolight (1-seat)


A brief history lesson

The origins of the trike can be traced back to the late 1940s when an American aeronautical engineer named Francis Rogallo developed and patented a flexible wing utilising a simple aerofoil which was used for model kites which he built and sold. By the 1950s, the space race between the USA and USSR was driving aviation development. Francis was working for NASA who were busy investigating designs for the recovery of capsules from space. One candidate was Francis’ flexible wing design which was apparently tested at heights of up to 200,000ft and speeds of Mach 3. Ultimately NASA chose conventional parachutes for recovery from space and relinquished the patent of what became known as the “Rogallo” wing.

Airborne Outback “naked” trike

By the 1960s, the design was being used by various experimenters around the world for the development of man-carrying kites, which were typically towed by speedboats. These designs evolved into the modern hang-glider concept, credit for which belongs to an Aussie – John Dickenson of Grafton NSW.

By the 1970s, the sport of hang-gliding was becoming established and people were getting fed up with carrying their wings to the top of hills for launch (particularly in areas where there were no suitable hills). Inevitably, various pioneers began experimenting with engines to self-launch from level ground. With no consensus of the best way to achieve this, the pioneering spirit was not dissimilar to the first days of powered flight. Like then, there were several serious accidents that added to the already dubious reputation of hang-gliding. The bad reputation built up in these earlier years is largely responsible for the reaction to both sports which the media and many people still seem to have today.

Airborne XT912 with Arrow strutted (“topless”) wing

By the 1980s, the layout of the modern trike had become more or less established and a number of designs were available as plans or kits. The growing popularity of trikes (and 3-axis ultralights) in many countries resulted in the attention of the regulators and, consequently, the drafting of legislation to make the aircraft legal and to allow flight training. Australia was the pioneer in this. The new rules established minimum standards for the aircraft which henceforth tended to be produced by a smaller number of aircraft factories (albeit fairly small scale ones).

The availability of reliable engines (predominately Rotax) in the 1990s resulted in improved designs, some of which can still be seen flying today. The increased performance of these models allowed an increasing number of record-breaking flights. The trend for stronger, heavier aircraft which therefore require more powerful engines but have higher performance has continued through the decade and into the 21st century.

It might be argued that the current “top-of-the-range” microlights have lost some of the simplicity of the earliest models in the quest for greater speed and endurance but most of the major manufacturers also still offer “entry-level” models which, whilst much safer and stronger, still provide the simple enjoyment of flight which inspired the original concept.

Microlight on trailer for transportation


Fixed Wing Aircraft

Sling 2

Light-Sport Aircraft (LSA) is a certification category for aircraft designed to the ASTM standards. It originated in the USA and allows manufacturers to self-certify aircraft with a maximum take-off weight not exceeding 600kg. In Australia, the term LSA is often used generically to describe fixed-wing aircraft (including “Primary” category planes) which are heavier with a higher performance than traditional ultralights but are lighter than General Aviation aircraft.

The qualification required to fly them is the same pilot certificate issued by Recreational Aviation Australia that is needed to fly microlight trikes or ultralights. Conversion between the different types of aircraft is not difficult but does require some different training.

Sling Cockpit

The Sling 2 is designed and built in South Africa and cruises in excess of 110kt whilst burning around 18 litres of unleaded car fuel per hour. It features a low-wing, an enclosed cabin with a two-seats-in-side-by-side configuration, fixed tricycle landing gear, and a single 100HP engine.