This past week, sUAS News had a first hand look at the new ALTi Transition hybrid VTOL UAS. Duran De Villiers, founder and owner of Steadidrone, a well established multirotor UAS manufacturer based in South Africa's Western Cape province, invited me to join him and his team on a flight testing day. I happily accepted Duran's invitation to get a closer look at their recently announced ALTi Transition UAS, the first aircraft to emerge from his newly formed company, ALTi UAS.
ALTi UAS claims that that the Transition can achieve flight times of up to 6 hours in forward flight. Many folks, including myself, are skeptical by default of manufacturer-claimed endurance figures when it comes to UAS, but after spending the day with the ALTi UAS team and seeing the aircraft fly for 6 hours myself, I can safely say that ALTi UAS's claims are based on actual performance and it is not just a figment of some marketing department's imagination.
For those who are not familiar with the terminology, VTOL stands for Vertical Take-Off and Landing. The term is mostly used to describe fixed-wing aircraft that have the capability of taking off and landing without the use of a runway.
In the case of the ALTi Transition, this vertical takeoff and landing capability is achieved through the use of four electrically powered brushless "quadcopter" motors fitted with 18 inch carbon fiber propellers. A 15 inch tri-blade pusher propeller fitted on an internal combustion engine at the back of the aircraft then powers normal fixed-wing forward flight after the electric motors have lifted the aircraft vertically into the air.
This configuration then allows for launching and recovering the aircraft from areas where normal fixed-wing takeoff and landing rolls are not possible, and at the same time achieve longer endurance flights than would be possible with electric only propulsion. The horizontal takeoff and landing phases of flight are generally also the riskier phases of fixed-wing flight, which a VTOL configured aircraft then removes from the equation.
On the test day, while the aircraft was performing auto circuits around the field for 6 hours, the weather conditions varied from calm and sunny to overcast and windy. A crosswind (in relation to the up and downwind legs of the circuits being flown) of around 10 to 15 knots was blowing for most of the day and became quite gusty at times. The aircraft seemed to handle these conditions quite well.
The field elevation where the flying took place was around 800 feet above mean sea level and we calculated a density altitude of around 2600 feet.
Upon closer inspection, once the aircraft was back on the ground, the Transition appears to be of high build quality with a lot of time and research having gone into the design of the aircraft.
ALTi Transition has a wing-span of 2.76 meters (or ~109 inches for those of you still in the dark ages of measurement standard), a length of 2.5 meters (~98 inches) and a height of 0.49 meters (~19 inches).
The Maximum Take-Off Weight (MTOW) of the aircraft is 15 kilograms (or roughly 33 pounds) and maximum payload weight of one kilogram (2.2 pounds).
Duran also mentioned that ALTi UAS will be offering all-electric versions of the Transition, although it is likely that with an all-electric version, horizontal flight times won't reach the 6 hour endurance mark that the liquid fuel powered version does.
Here are some of the selling points of the platform according to ALTi UAS:
"With a large payload bay area, open to fit and mount a huge range of cameras, sensors and other equipment, the system offers amazing flexibility and does not limit the operator or mission scope. With advanced sensors becoming smaller and lighter, the need for heavy payload capacity is no longer a concern.
As the needs and requirements of our clients vary greatly, along with the wide range of uses, payloads and sensors, we offer custom built and designed ground control systems per order to suit.
The airframe features incredibly efficient aerodynamic design, including dihedral, washout, winglets and quick release connectors for assembly.
From short range basic control systems to long range, vehicle mounted data telemetry, control, video link and payload control systems, as well as IP rated weatherproof hardware and flight cases.
Ultra bright, fully programmable navigation LED and strobe system, as well as a landing light underneath the airframe, with the ability to remotely turn the lighting on or off, as well as enable the landing light, special lighting features and more."
Electric VTOL Endurance: <10 Min
Fuel Fixed Wing Endurance: Over 6 Hours
Endurance based on actual real world flight tests.
ALTi Transition VTOL hybrid
electric/fuel UAS flies for 6 hours
16 sUAS Guide / Q3 Update, October 2016
BY TIAAN ROUX