Test Review

Aerodynamics

Aerodynamic forces

Bernoulli's principle

• The relationship between the velocity and pressure exerted by a moving liquid is described by the Bernoulli's principle: as the velocity of a fluid increases, the pressure exerted by that fluid decreases.

What is this an illustration of?

THE LAW OF INERTIA

• A body will preserve its velocity and direction so long as no force in its motion's direction acts on it.

• For example : a package thrown out of an airplane will continue to move at the speed of the airplane on the horizontal axis (in the direction of the airplane's movement). Since the law of gravity acts on the package (a vertical downward axis), the package will gather speed along the vertical axis, but on the horizontal axis its speed will remain equal to that of the airplane.

Angle of Attack

• The angle of attack is the angle at which relative wind meets an airfoil. It is the angle that is formed by the chord of the airfoil and the direction of the relative wind or between the chord line and the flight path. The angle of attack changes during a flight as the pilot changes the direction of the aircraft. It is one of the factors that determines the aircraft's rate of speed through the air.

Dihedral

Stall

• when the climb is too steep for the available power, the nose of the plane will quickly drop, this is known as a “stall”. As the plane dives and picks up speed, most likely it will pull up from the dive and climb again until the plane stalls again.

The First Aeromodeling Clubs

• The first model airplane clubs started in the New York City area as early as 1907. Balsa wood was not used in model planes until around 1911, so models were constructed of materials such as bamboo, pine, and spruce. 

The Influence of Charles Lindbergh on Aeromodeling

• Charles Lindbergh’s historic flight from New York to Paris in 1927 was the driving force to skyrocket the popularity of aeromodeling. Before Lindbergh’s flight only around a dozen model airplane kit manufacturers existed and within a year of the flight there were over two thousand.

3 degrees of freedom

Engines

• Turbofan -

• Turbojet

• Turboprop

Turbojet

• Most modern passenger and military aircraft are powered by gas turbine engines, which are also called jet engines. The first and simplest type of gas turbine is the turbojet. Turbojets consist of an air inlet, an air compressor, a combustion chamber, a gas turbine (that drives the air compressor) and a nozzle. The air is compressed into the chamber, heated and expanded by the fuel combustion and then allowed to expand out through the turbine into the nozzle where it is accelerated to high speed to provide propulsion

Turbojet

Turbofan

• Incoming air is captured by the engine inlet. Some of the incoming air passes through the fan and continues on into the core compressor and then the burner, where it is mixed with fuel and combustion occurs. The hot exhaust passes through the core and fan turbines and then out the nozzle, as in a basic turbojet. The rest of the incoming air passes through the fan and bypasses, or goes around the engine, just like the air through a propeller. The air that goes through the fan has a velocity that is slightly increased from free stream. So a turbofan gets some of its thrust from the core and some of its thrust from the fan.

Turbofan

Turboprop

• The turboprop uses a gas turbine core to turn a propeller. Propeller engines develop thrust by moving a large mass of air through a small change in velocity. Propellers are very efficient and can use nearly any kind of engine to turn the prop (including rubber bands!). In the turboprop, a gas turbine core is used.

Turboprop