Unmanned Systems Technology 036

to longer resident operations, however, it is not a one-size-fits-all situation. “If you have a vehicle that lives in a docking station and has other facilities around it so that you can bring it up immediately, if something goes wrong you can use the same sort of designs we have now. If on the other hand you plan to ‘garage’ it under the ice in the Arctic, say, and leave it there for a year then obviously you will have a very strict set of requirements for configuration, testing and quality control before you get to that point.” One of the most serious problems faced by the Sabertooth, and any vehicle involved in drilling support operations, is the ingress of fine silt into areas and components where it can cause damage. “Some of those particles are magnetic, which helps them to find their way into bearings and seals; if you don’t take care then naturally that will seriously affect your vehicle,” Siesjo notes. “We therefore carry out a fair amount of testing on thrusters, for example, running them in tanks with quite a nasty mix of abrasive and corrosive stuff in them.” The most common watertight seals used on the vehicle are O-rings, which form static seals for lids and electrical connectors, for example, with ceramic rotating seals used on thrusters and any other shafts that pass from inside to outside the vehicle. The latter are lubricated by water, and have a very long service life. “If you try to do that with lip seals, you quite often get into trouble with wear on shafts, for example, because of the abrasive particles in the environment,” Siesjo says. The most frequent maintenance operations involve simple flushing with clean fresh water, visual examination and function checks. The next level involves examining and if necessary replacing O-rings and other seals, in thrusters for example. The frequency of that depends on the nature of the operations for which the vehicle has been used. Current vehicles are built to the high-end ROV standard, but for longer resident operations it is not a one-size- fits-all situation Fly Smarter Introducing the smartest family of products for UAVs on the market The Future of Electric Propulsion Beautifully designed propulsion motors from 1kW to 20kW for different voltage ranges available with corresponding air motor controllers. Intelligent Power Systems from 500W to 12kW Starter Generators from 500W to 12kW Electronic Engine Starters from 500W to 6kW For the most comprehensive line of products for UAVs visit: www.ePropelled.com/ust