Is that Airplane Wearing Pants?
The Pitts Special, unlike most of the other aircraft in the museum, places a high emphasis on speed being an aerobatic airplane. To squeeze all of the performance out of the design as it can, the wheels on the main landing gear are covered with streamlined fairings which in this country are commonly referred to as “wheel pants.” In England these same items are called “spats.”
Wheel pants, by eliminating the air turbulence around the tire and wheel assembly, reduce what is called “parasite drag” on the airplane. Parasite drag is that resistance to moving through the atmosphere that is caused by the parts of the airplane that do not contribute to the lift of the airplane. The wing itself on airplanes generates drag, but that drag is known as “induced drag” or drag resulting from the parts of the airplane that create lift.
By installing pants on an aircraft it is possible to increase the speed of the
airplane by about three to five miles per hour while using the same amount of engine power. That means that when pants are installed an airplane can fly a greater distance on the same amount of fuel, therefore, wheel pants save on fuel costs to operate an airplane!
The photo above illustrates the difference in the wheel/tire profile when wheel pants are not used.
Of course there are some disadvantages to using wheel pants. They cost more initially due to extra time installing and the material cost, if operated from airports that do not have paved runways and taxiways they can collect mud, snow and ice with the rare possibility of the wheel freezing in place at altitude which can result in landing with a locked wheel. In addition, while the pilot makes their pre-flight inspection it is more difficult to examine the condition of the tires as a major part of the tire is hidden in the enclosure. Some pilots will roll their aircraft on its wheels during pre-flight in order to inspect the entire tire. Lastly, novice pilots sometimes use the streamlined fairings as a stepping point which can cause damage to the units!