Ice builds up on aircraft either through precipitation on the ground or by formation of ice during flight, which is very dangerous. Ice can add significant weight, which requires more fuel and potentially makes the aircraft too heavy to fly. Additional weight also changes the aerodynamics of the surfaces of the aircraft, adding drag and reducing lift. Any of these concerns can result in cancelled missions.
The Federal Aviation Administration (FAA) requires that all aircraft that have ice build-up on their wings and fuselages, have it stripped off before takeoff.
Icing on UAVs is a relatively new field of research. This has been unfortunate since icing has been identified as one of the most hazardous weather phenomena for manned aircraft.
Ice tends to build up on an aircraft in various areas such as:
- The leading edge of the wings and stabilizers, propellers, and sensors.
- Frozen water on wings increase their weight, which reduces lift and can cause an aircraft to stall.
- Ice on a propeller can increase drag and reduce thrust.
- Ice on sensors, which can lock up, interfering with the autopilot’s ability to gauge speed and altitude.
Heated hangars are the solution for de-icing for many airports, though some of the smaller airports may not have such an option. Heated hangars make it possible to use one of the most common methods of de-icing an aircraft, which is to heat it up. Heated hangars can be kept at a temperature that melts ice, which only requires a wiping of the aircraft with a towel. A thin coating of a fluid depressant at freezing point is applied to the wings of the aircraft to prevent ice from forming again during takeoff and flight.
Aircraft covers that are designed to shield the wings and other components are vulnerable to ice build-up. These covers also have the advantage of being easy to store, and relatively inexpensive. Because icing can still occur between the time of taking the covers off and the time of departure, applying FPD liquid may still be necessary.
Spray equipment that applies FPD liquids to the plane is the most common method for de-icing aircraft. Most airports provide portable spray equipment, like pressurized containers and spray wands, to apply de-icing liquid, which consists of ethylene glycol and propylene glycol.
As the FPD melts ice it mixes with the water and dilutes it. It may be necessary to apply additional coatings of FPD if the aircraft is on the ground for extended periods of time and waiting for takeoff. Because glycol is also toxic, similar to the antifreeze in automobiles and refrigeration equipment, safety precautions must be taken to prevent exposure.
Inflatable boots can be attached to the wings and the stabilizers. When ice accumulates on the boots, they can be inflated to break it up.
Continuous or intermittent electrical heat is used on propellers, sensors, and other components.
An autonomous electrothermal system is one of the solutions to icing and is preferred by many because it can be lighter than mechanical and chemical de-icing systems.
De-icing of Drones
It is not surprising that drones, just as with larger aircraft such as airplanes, have the same problem with the accumulation of ice during flight on the wings, propellers, and tail, which can make it hazardous to fly.
The electrothermal panels can be embedded in the wing of a UAV during the manufacturing process or attached to existing wings, and the panels are activated when the system detects deviations from the expected aerodynamics of the UAV, indicating that ice is forming on the wings.
A high-conductivity, carbon nanotube heating coating is the technology Battelle’s HeatCoat™ uses, that conforms to the existing skin of the aircraft and utilizes intelligent sensors and controls to reduce ice accumulation without compromising flight performance. Direct spray or laminate film options allow flexible designs for all types of aircrafts. Many believe that HeatCoat’s significant size, weight and power advantages, over alternatives, means more mission payload, range and persistence and that their technology, enabling the aircraft to fly higher and farther under icy conditions than traditional de-icing and anti-icing technology allows.*De-cing by drones is definitely safer than conventional approaches when workers would need to climb aircraft and it is estimated that using drones to de-ice planes presents a massive cost-saving compared to using climbers to do the job, more specifically, $1,000 vs. $5,000.