Figure 3-11.  Stabilator components.  Landing Gear  The Powerplant  Figure 3-12.  Types of landing gear: floats (top)  skis (middle)  and  wheels (bottom).  The powerplant usually includes both the engine and the  propeller. The primary function of the engine is to provide  the power to turn the propeller. It also generates electrical  power  provides a vacuum source for some flight instruments   and in most single-engine airplanes  provides a source of  heat for the pilot and passengers.  [Figure 3-13]  The engine  is covered by a cowling  or a nacelle  which are both types  of covered housing. The purpose of the cowling or nacelle  is to streamline the flow of air around the engine and to help  cool the engine by ducting air around the cylinders.  is a rotating airfoil that produces thrust through aerodynamic  action. A high-pressure area is formed at the back of the  propeller’s airfoil  and low pressure is produced at the face of  the propeller  similar to the way lift is generated by an airfoil  used as a lifting surface or wing. This pressure differential  develops thrust from the propeller  which in turn pulls the  airplane forward. Engines may be turned around to be pushers  with the propeller at the rear.  There are two significant factors involved in the design  of a propeller that impact its effectiveness. The angle of a  The propeller  mounted on the front of the engine  translates  the rotating force of the engine into thrust  a forward acting  force that helps move the airplane through the air. A propeller  Airplanes with conventional landing gear are sometimes  referred to as tailwheel airplanes. When the third wheel is  located on the nose  it is called a nosewheel  and the design  is referred to as a tricycle gear. A steerable nosewheel or  tailwheel permits the airplane to be controlled throughout all  operations while on the ground. Most aircraft are steered by  moving the rudder pedals  whether nosewheel or tailwheel.  Additionally  some aircraft are steered by differential braking.  Wheeled landing gear consists of three wheels—two main  wheels and a third wheel positioned either at the front or rear  of the airplane. Landing gear with a rear mounted wheel is  called conventional landing gear.  The landing gear is the principal support of the airplane when  parked  taxiing  taking off  or landing. The most common type  of landing gear consists of wheels  but airplanes can also be  equipped with floats for water operations or skis for landing  on snow.  [Figure 3-12]  3-7  Antiservo tab  Stabilator pivot point 