On Oct 22, 9:27 am, Dan G wrote:
In fact we even tried towing with a Rotax Falke -
only 100hp or so, but very efficient.

"As a tug, the SF25C Rotax Falke seems to perform very well, climbing
with heavy two-seaters at 400ft/min. This is marginally slower than,
say, a Robin DR400, but this Falke uses only half as much fuel and the
noise pollution is much less. In Germany, official analysis of
comparative tug noise estimates a single tow in a Robin DR400 type tug
equates to 4.8 tows in a SF25C Rotax Falke. Glider-tug speed
compatibility, similar wing loadings and aspect ratios, and reduced
wake turbulence, mean the motorglider aerotowing option offers
significant safety features.

The manufacturer's fuel consumption figures are 16-18 litres (c 3.5
gallons) an hour, hardly thirsty for tugs. Taking into account all the
costs of operating the Falke, including an engine rebuild every 2,000
hours, insurance, fuel and maintenance costs, a Falke is estimated by
its makers to tow at about 60 per cent of the cost of today's
conventional tugs."

http://www.fffoundation.co.uk/SGart.html