We carefully evaluated a number of different aircraft and gyrocopters for the project. Gyrocopters were ruled out early in the process due to concerns over vibration, and over acquisition and operating costs. Microlight-class aircraft had many attractions, but the low operating weight limit for microlights presented a problem, given the weight of the equipment we needed to carry. Thus it was decided to focus on identifying a suitable conventional light aircraft.
The chosen aircraft had to have good low-speed performance and handling, both to allow safe circling over a study animal, and also to permit operation from very short airstrips. However, a good power-to-weight ratio would also be required to ensure good take-off and climb performance at the higher temperatures and altitudes experienced (the Okavango Delta sits at roughly 3000 feet above sea level!). As temporary airstrips prepared in the African bush were likely to be rough, it was felt that a rugged “tailwheel” undercarriage would be more appropriate than the more common but less rugged “nosewheel” configuration. All-metal construction would be more robust and would cope better with the high ultraviolet light levels found in Africa, which tends to degrade the fabric of fabric-covered aircraft. We also felt that the chosen aircraft should be well-proven, and that the importer of the aircraft should be of established reputation – the importer being a vital source of help, advice, and manufacturer liaison during the construction process.
After much consideration, we decided on the Italian Gropo Trail aircraft as imported in kit form by Sprite Aviation, equipped with a 100hp Rotax 912S engine. The Trail is an all-metal tailwheel aircraft with excellent low-speed handling, and when paired with the 100hp Rotax engine offers an excellent power-to-weight ratio. Although new to the UK, the aircraft is well proven over many years on mainland Europe and the importer, Graham Smith, has many years of experience in importing and supporting kit aircraft builds, with excellent reputation.
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