The Operating Environment and Aircraft Performance
Aircraft Icing
The environmental effect I chose to research was how aircraft icing effects the aerodynamics of fixed wing aircraft. As a pilot we learn that icing can occur only when these 2 factors are present. The first is an Outside air temperature that is below 0 Celsius ( 32 degrees fahrenheit.) The second factor is visible moisture, this could be clouds, rain, fog, or snow.
When an aircraft begins taking on ice it severely effects the performance. As an aircraft takes on ice onto its wings it changes the camber and shape of the wing. This causes the smooth laminar airflow over the wings to become unstable. As the aircraft continues to take on more icing the angle of attack will need to be continually increased. As a pilot we need to be able to identify when the aircraft performance changes and correct it. If we fail to do so we will continue to raise the angle of attack until we reach the critical angle of attack resulting in a stall occurring. Another negative effect of icing occurring is the weight of the aircraft. As we take more and more ice the aircraft becomes heavier causing the aircraft to lose altitude. As our aircraft propeller takes on ice the amount of thrust it can produce decreases as well. Lastly, drag on the aircraft will be increased as ice continues to build on the aircraft. This will also cause the aircraft to lose airspeed and lose altitude as well.
As mentioned above we can tell that icing is extremely detrimental to the aircrafts performance. This is especially true for aircraft that do not have any anti-ice systems. Think of a plane like a Cessna 150/172. It’s critical we do not enter areas identified as known icing.
How do we mitigate icing?
For most training aircrafts there are usually no anti ice systems except for pitot-tube heat. More complex airplanes have anti-ice systems in place. This is usually due to their mission. Complex planes usually fly at higher altitudes and are more at risk of icing occurring. Some different kinds of anti-ice systems include: Thermal, mechanical, and chemical. For thermal systems think of windshield heating, propeller heating, or wing heating that prevents too much ice from forming. Mechanical anti-ice systems usually include wing “boots” ; these systems are designed to change the leading edge of the wing causing the ice to break off. Lastly, chemical anti-ice systems include the use of chemicals to be released onto the wing that help melt ice. This is done through microscopic holes on the airplanes’ leading edge of the wing that allow this chemical to melt the ice.
