Ever wonder how airplanes prevent ice from building up on propeller blades? When flying at 30,000 feet above sea level, airplanes are exposed to very cold air — typically about minus 40 to minus 70 degrees Fahrenheit. At these temperatures, any superficial moisture on an airplane’s fuselage, propeller or other exposed parts will instantly freeze. Fortunately, however, there are deicing solutions that protect propellers from freezing over so that they can spin and function as intended.
Electric Heating Element
One of the most common deicing solutions for propellers is an electric heating element. It involves the use of wires that produce heat as electricity flows through them. Electric heating elements consist of “boots” with embedded wires. They are found on both inboard and outboard propellers. When ambient temperatures begin to drop, the boots will activate. Electricity will then flow through the embedded wires, thereby heating up the propeller.
Glycol-Based Solution
Some airplanes use a glycol-based solution to protect their propellers from ice buildup. Glycol, such as ethylene glycol or propylene glycol, is the same stuff found in automotive antifreeze. It has a much lower freeze point than plain water. As a result, many automobiles and airplanes use glycol to protect various parts from ice buildup.
In airplanes, a pump forces a glycol-based solution through strips along the leading edge of the propeller. The solution essentially flows through small holes. This creates a thin layer over the propeller that protects it from ice buildup.
Alcohol-Based Solution
While some airplanes use a glycol-based solution, others use an alcohol-based solution. Alcohol has an even lower freeze point than glycol. The alcohol-based solution is discharged from small nozzles around the propeller, which allows it to coat the propeller blade.
It’s important to note that many airplanes use both glycol and alcohol to protect their propellers from ice buildup. The combination of these two substances allows for maximum protection against ice buildup.
Why Propeller Ice Is a Concern
When left unchecked, ice buildup on propellers can cause several problems. First, ice changes the propeller’s pitch. The pieces of frozen ice alter the propeller’s shape, which in turn changes the angle at which the propeller cuts through the air, which is the pitch.
Ice buildup creates drag. Drag is the force that opposes an aircraft’s motion. The more drag an airplane has, the more energy it will have to spend to continue moving. Ice buildup makes airplanes less aerodynamic while subsequently increasing drag.
