The Aviation Science

Helicopter Structure 🛩️The major components of a helicopter are the airframe, fuselage, landing gear, powerplant/ transmission, main rotor system, and antitorque system. 🛩️The airframe, or fundamental structure, of a helicopter can be made of either metal or wood composite materials, or some combination of the two. Typically, a composite component consists of many layers of fiber- impregnated resins, bonded to form a smooth panel. Tubular and sheet metal substructures are. 🛩️The major components of a helicopter are the airframe, fuselage, landing gear, powerplant/ transmission, main rotor system, and antitorque system. 🛩️The airframe, or fundamental structure, of a helicopter can be made of either metal or wood composite materials, or some combination of the two. Typically, a composite component consists of many layers of fiber- impregnated resins, bonded to form a smooth panel. Tubular and sheet metal substructures are usually made of aluminum, though stainless steel or...

Empennage 🛩️The empennage of an aircraft is also known as the tail section. Most empennage designs consist of a tail cone, fixed aerodynamic surfaces or stabilizers, and movable aerodynamic surfaces. 🛩️The tail cone serves to close and streamline the aft end of most fuselages. The cone is made up of structural members like those of the fuselage; however, cones are usually of lighter construction since they receive less stress than the fuselage. 🛩️The other components of the typical empennage are of heavier construction than the tail cone. These members include fixed surfaces that help stabilize the aircraft and movable surfaces that help to direct an aircraft during flight. The fixed surfaces are the horizontal stabilizer and vertical stabilizer. The movable surfaces are usually a rudder located at the aft edge of the vertical stabilizer and an elevator located at the aft edge the horizontal stabilizer. 🛩️The structure of the stabilizers is very similar to that which ...

Types of Radio Waves 🛩️Radio waves of different frequencies have unique characteristics as they propagate through the atmosphere. VLF, LF, & MF waves have relatively long wavelengths and utilize correspondingly long antennas. 🛩️Radio waves produced at these frequencies ranging from 3kHz to 3mHz are known as ground waves or surface waves. They follow the curvature of the earth as they travel from the broadcast antenna to the receiving antenna. Ground waves are particularly useful for long distance transmissions. Automatic direction finders (ADF) & LORAN navigational aids use these frequencies. ✈️High frequency (HF) radio waves travel in a straight line & do not curve to follow the earth’s surface. This would limit transmissions from the broadcast antenna to receiving antennas only in the line-of-sight of the broadcast antenna except for a unique characteristic. HF radio waves bounce off of the ionosphere layer of the atmosphere. This refraction extends the range of...

Helicopter Flight Control System 🛩️helicopter pilot manipulates the helicopter flight controls to achieve and maintain controlled aerodynamic flight. 🛩️Changes to the helicopter flight control system transmit mechanically to the rotor, producing aerodynamic effects on the rotor blades that make the helicopter move in a deliberate way. 🛩️To tilt forward and back (pitch) or sideways (roll), requires that the controls alter the angle of attack of the main rotor blades cyclically during rotation, creating differing amounts of lift(forces) at different points in the cycle. 🛩️To increase or decrease overall lift requires that the controls alter the AoA for all blades collectively by equal amounts at the same time, resulting in ascent, descent, acceleration and deceleration. 🛩️A typical helicopter has three flight control inputs—the cyclic stick, the collective lever, and the anti-torque pedals. 🛩️Depending on the complexity of the helicop...

Five Major Stresses 🛩️Aircraft structural members are designed to carry a load or to resist stress. Aircraft parts must be planned to carry the load to be imposed upon it. 🛩️The term stress is often used interchangeably with the word “strain.” They are not the same thing. External loads or forces cause stress. Stress is a material’s internal resistance, or counterforce, that opposes deformation. The degree of deformation of a material is strain. When a material is subjected to a load or force, that material is deformed, regardless of how strong the material is or how light the load is. 🛩️Here 5 major stresses to which aircraft is subjected ✳️Tension ✳️Compression ✳️Torsion ✳️Shear ✳️Bending ✈️Tension is the stress that resists a force that tends to pull something apart. The engine pulls the aircraft forward, but air resistance tries to hold it back. The result is tension, which stretches the aircraft. The tensile strength of a material is measured in pounds per square inc...

Lateral and Longitudinal Balance 🛩️Balance refers to the location of the CG of an aircraft, and is important to stability and safety in flight. The CG is a point at which the aircraft would balance if it were suspended at that point. 🛩️The primary concern in balancing an aircraft is the fore and aft location of the CG along the longitudinal axis. The CG is not necessarily a fixed point; its location depends on the distribution of weight in the aircraft. 🛩️As variable load items are shifted or expended, there is a resultant shift in CG location. The distance between the forward and back limits for the position of the center for gravity or CG range is certified for an aircraft by the manufacturer. 🛩️The pilot should realize that if the CG is displaced too far forward on the longitudinal axis, a nose-heavy condition will result. Conversely, if the CG is displaced too far aft on the longitudinal axis, a tail heavy condition results. It is possible that the pilot could not c...

Forces in Turn 🛩️If an aircraft were viewed in straight & level flight from the front & if the forces acting on the aircraft could be seen, lift & weight would be apparent: two forces.If the aircraft were in a bank it would be apparent that lift did not act directly opposite to the weight, rather it now acts in the direction of the bank. When the aircraft banks, lift acts inward toward the center of the turn, perpendicular to the lateral axis as well as upward. 🛩️An increase in airspeed results in an increase of the turn radius, & centrifugal force is directly proportional to the radius of the turn. In a correctly executed turn, the horizontal component of lift must be exactly equal & opposite to the centrifugal force. As the airspeed is increased in a constant-rate level turn, the radius of the turn increases. This increase in the radius of turn causes an increase in the centrifugal force, which must be balanced by an increase in the horizontal compo...