The Stemme S10 motor glider in the Dubai 2005 static park was delivered to its owner in Saudi Arabia only recently but he readily agreed to bring it to the show to allow visitors to see an aircraft with a remarkable performance. Although powered by a single Rotax engine driving a retractable two-blade propeller, the S10 can climb to high altitudes and glide for long distances.

Five years ago an S10 was used to set an FAI-certified world record of 1,330 nm in the longest distance category for soaring flight. But as well as being a fun aircraft to fly, the Stemme S10-VTX variant has been developed in collaboration with Sagem to function as high altitude platform for surveillance sensors.  

Dubbed the Busard Project, the working system was demonstrated at the Paris Air Show earlier this year, when real-time images were transmitted from the high-flying S10 to the Sagem chalet at Le Bourget. Delighted with the performance of the aircraft, Sagem decided to collaborate with Stemme on developing of the S6 sport motorglider into a long endurance UAV. It will be marketed as the Patroler UAV for use in a wide spectrum of roles, from military surveillance to homeland security and maritime patrol.

The Patroler will be offered as an optionally piloted vehicle as well as a full UAV system with a 20-hour endurance carrying a 440-pound payload. Supercharging can enhance the performance of the Rotax engine but eventually a diesel engine may be offered with greater power.

But, meanwhile, the Paris demonstration resulted in an order from Russia for the S10-VTX, with a further 10 to be supplied next year in support of the Ministry for Emergencies.  

Although the S6 and S15 Patroler have a shorter wingspan than the S10, their wings have a more modern airfoil developed by Professor Boermans of Delft University in the Netherlands and recognized as the leading guru on glider design. Their performance is similar to that of the S10 with its much higher aspect ratio wing.