Following a successful outcome in the development of a flight safe throttle actuator for the Herti UAV drone, BAe Systems were then confronted with some similar issues when upgrading the flight control surface actuators. As previously determined, the physiology of the aircraft was not able to be changed so space and weight were once more limiting factors. The actuator had to be powerful enough to produce consistently peak torque rates together with exceptionally fast response rates and meet the stringent safety requirements required of a non-military UAV.
The flight safety regulations ensured that the actuator would have to perform to within just one degree of accuracy of rotation and qualify to the stringent DO178 and DO254 software and hardware requirements respectively. The only available installation space would have to be within the skin of the existing wing profile leaving room for only 1mm of clearance.
For the installation to be a success, the desired power output would demand exceptional performance from a unit that would be so limited by size and weight.
The OTMS design team were able to draw on the experience gained from developing the throttle actuator to derive an understanding of what the end product would look like and to establish that it was possible to design and build a working solution.
The OTM design team came up with a solution that not only ticked off all the outstanding requirements but was also able to produce 40% more power than any available commercial off the shelf (COTS) solution. From a unit of this size and a weight of just 1.25kg, this is an exceptional result.
It works to a positional feedback accuracy of 0.2 degrees which exceeds the safety desired standards by a factor of four.
The units were successfully installed and fully operational on the Herti drone. Although this simplex actuator was developed for use in primary flight control surface actuation, it has also proved its worth in secondary functions such as braking and steering without having to undergo major re-design. Despite the unit being tailored to a very specialised functionality within the limited space of the aircraft wing, the OTM plug and play technology proved itself versatile enough to be put to equally good use in other applications.