The Magnum light aircraft has an all composite hydraulic fully retracting tricycle undercarriage, 30% Fowler flaps with low drag cruise setting, 160 kts continuous cruise on 100 hp, 1000 nautical miles range, 200 kg crew, 50 kg baggage, room for skiis, 21:1 L/D ratio, and a max 21 deg alpha

Stall: 45 kt / 52 mph / 83 kmh
Cruise: 137 kt / 158 mph / 254 kmh
VNE: 155 kt / 178 mph / 287 kmh
Climb Ratio: 800 ft/min / 4 m/s
Glide Ratio: 21:1

After mixed results with the MicroLight prototype, carmaker Lotus still wanted to build a business for the ultralight canard pusher, and when the arrangements with Rutan didn’t work out, they sought backing to continue alone. When that wasn’t approved, Lotus went looking for partners and teamed up with the Eipper company, a big ultralight builder in those days (now no longer in business) to distribute it in the USA, while Malcolm Lawrence’s Aviation Composites of Thatcham in Berkshire, was to distribute it in the UK and Europe.

Lotus originally planned to build the basic structure themselves, with Aircraft Composites finishing and distributing it. It was then decided that the materials (epoxy glass) and the quality control techniques were not part of the Lotus core business, and Aircraft Composites agreed to take over the development and build, with the help of Peter Jackson’s Specialised Mouldings (a well-known firm in motorsport).

Since Lotus was struggling to cope with the aftermath of Colin Chapman’s death, Aircraft Composites moved into taking over the whole project. Instead, Aviation Composites used the design’s features as a basis for a different aircraft. The company employed VariEze builder Ivan Shaw, and built a similar but much heavier version, the two-seat Mercury prototype (G-INAV c/n AC001).

The Mercury featured an all-composite canard configuration with a four-cylinder Magnum pusher engine. The Mercury incorporated various modifications from the Rutan design and Shaw had several problems with it. First of all, it apparently exhibited some not-so-attractive flight characteristics, and its development program suffered a number of developmental problems, among them, the failure to obtain an acceptable engine. When the Magnum engine proved unsatisfactory, and a 40 hp Norton rotary engine was fitted instead. However, testing the brand new aircraft engine of a motorcycle company on an airframe that hasn’t yet been properly flight-tested was not a good idea.

Initially, the aircraft was to be available by February 1986 and Aviation Composites intended to obtain UK certification in the motor-glider category before introducing the type to the US market. However, these setback seriously compromised the fledgling company’s chances to offer a proven model on the market any time soon. Aviation Composites therefore approached Scaled Composites requesting developmental help. While assisting Ivan Shaw, now the company’s production manager on the program, with flight testing (the plane was test-flown by Douglas B. Shane, one of Rutan’s own test pilots), Scaled discovered a poor spin recovery characteristic, and found out the virtue of using of engine power to aid in recovery from a deep stall in a canard pusher-type, using this successfully on several occasions during high angle of attack testing of the Mercury.

Once Aviation Composites realized that changes would be necessary to obtain adequate spin recovery characteristics, the next step should have been to equip the aircraft with a spin recovery parachute and to develop an appropriate aerodynamic fix for the problem. Instead, they discontinued support of the flight testing and further development, and sued RAF for all of their expenses to date—allegedly amounting to several million dollars—claiming that they should have more thoroughly tested the Model 97 in 1983 to find a possible flaw in spin recovery.

The case was scheduled for trial in federal court during January ’91. Burt Rutan best summed up the situation when he declared: “there seems to be no basis, however, these exercises have an enormous effect on our time and distract from our ability to concentrate on things more productive and enjoyable.” The case dragged on (way beyond Lotus being taken over by GM in 1986) and was eventually dropped. The backers disappeared, and Aircraft Composites went into bankruptcy. As for the original MicroLight prototype, it was lost in an accident in which the owner and test pilot of the aircraft were killed, giving some credence to Aircraft Composites’ claim that the design was faulty.

Engine: Norton 40 hp
Maximum speed est: 87 kt
Range est: 290 nm
Seats: 2