Designing A Helicopter

Whenever we are about to design a Helicopter we need to focus on few parameters and system that will govern the design. Such as-

Rotor System :-

The rotor system, or more simply rotor, is the rotating part of a helicopter that generates lift. The rotor consists of a mast, hub and rotor blades.A rotor system may be mounted horizontally, as main rotors are, providing lift vertically, or it may be mounted vertically, such as a tail rotor, to provide horizontally thrust to counteract torque from the main rotors.The mast is a cylindrical metal shaft that extends upwards from the transmission. At the top of the mast is the attachment point for the rotor blades called the hub. The rotor blades are attached to the hub. Main rotor systems are classified according to how the rotor blades are attached and move relative to the hub. There are three basic types: hinge less, fully articulated, and teetering; although some modern rotor systems use a combination of these.

 revolutionized the aviation industry, and the turbo shaft engine finally gave helicopters an engine with a large amount of power and a low weight penalty. Turboshafts are also more reliable than piston engines, especially when producing the sustained high levels of power required by a helicopter. The turboshaft engine was able to be scaled to the size of the helicopter being designed, so that all but the lightest of helicopter models are powered by turbine engines today.FlightThere are three basic flight conditions for a helicopter: hover, forward flight and the transition between the two.Forward flightHovering is the most challenging part of flying a helicopter. This is because a helicopter generates its own gusty air while in a hover, which acts against the fuselage and flight control surfaces. The end result is constant control inputs and corrections by the pilot to keep the helicopter where it is required to be. Despite the complexity of the task, the control inputs in a hover are simple. The cyclic is used to eliminate drift in the horizontal plane, that is to control forward and back, right and left. The collective is used to maintain altitude. The pedals are used to control nose direction or heading. It is the interaction of these controls that makes hovering so difficult, since an adjustment in any one control requires an adjustment of the other two, creating a cycle of constant correction.Transition from hover to forward flightAs a helicopter moves from hover to forward flight it enters a state called translational lift which provides extra lift without increasing power. This state, most typically, occurs when the airspeed reaches approximately 16–24 knots, and may be necessary for a helicopter to obtain flight.In forward flight a helicopter's flight controls behave more like those of a fixed-wing aircraft. Displacing the cyclic forward will cause the nose to pitch down, with a resultant increase in airspeed and loss of altitude. Aft cyclic will cause the nose to pitch up, slowing the helicopter and causing it to climb. Increasing collective (power) while maintaining a constant airspeed will induce a climb while decreasing collective will cause a descent. Coordinating these two inputs, down collective plus aft cyclic or up collective plus forward cyclic, will result in airspeed changes while maintaining a constant altitude. The pedals serve the same function in both a helicopter and a fixed-wing aircraft, to maintain balanced flight. This is done by applying a pedal input in whichever direction is necessary to center the ball in the turn and bank indicator.">

Engines

The number, size and type of engine(s) used on a helicopter determines the size, function and capability of that helicopter design. The earliest helicopter engines were simple mechanical devices, such as rubber bands or spindles, which relegated the size of helicopters to toys and small models. For a half century before the first airplane flight, steam engines were used to forward the development of the understanding of helicopter aerodynamics, but the limited power did not allow for manned flight. The introduction of the internal combustion engine at the end of the 19th century became the watershed for helicopter development as engines began to be developed and produced that were powerful enough to allow for helicopters able to lift humans.

Flight controls

A helicopter has four flight control inputs. These are the cyclic, the collective, the anti-torque pedals, and the throttle. The cyclic control is usually located between the pilot's legs and is commonly called the cyclic stick or just cyclic. On most helicopters, the cyclic is similar to a joystick.The control is called the cyclic because it changes the pitch of the rotor blades cyclically. The result is to tilt the rotor disk in a particular direction, resulting in the helicopter moving in that direction. If the pilot pushes the cyclic forward, the rotor disk tilts forward, and the rotor produces a thrust in the forward direction. If the pilot pushes the cyclic to the side, the rotor disk tilts to that side and produces thrust in that direction, causing the helicopter to hover sideways.

HELICOPTER TECHNOLOGY

A is a type of Rotor craft which runs due to rotor and the lift and thrusts are supplied by rotors. And due to this, to hover, and to fly forward, backward, and laterally.The capability to hover efficiently for extended periods of time allows a helicopter to accomplish tasks that fixed-wing aircraft and other forms of vertical takeoff and landing aircraft cannot perform.Helicopters were developed and built during the first half-century of flight, with the Focke-Wulf Fw 61 being the first operational helicopter in 1936. The main components of a Helicopter are shown below -

UAV -Unmanned Aerial Vehicle

They are usually deployed for military and special operation applications, but also used in a small but growing number of civil applications, such as policing and firefighting, and nonmilitary security work, such as surveillance of pipelines. UAVs are often preferred for missions that are too "dull, dirty or dangerous"for manned aircraft.

UAVs typically fall into one of six functional categories :

• Target and decoy – providing ground and aerial gunnery a target that simulates an enemy aircraft or missile

• Reconnaissance – providing battlefield intelligence

• Combat – providing attack capability for high-risk missions (see Unmanned combat air vehicle)

• Logistics – UAVs specifically designed for cargo and logistics operation

• Research and development – used to further develop UAV technologies to be integrated into field deployed UAV aircraft

• Civil and Commercial UAVs – UAVs specifically designed for civil and commercial applications.

Inview UAV for use in scientific, commercial and state applicationBeyond th military applications of UAVs with which "drones" became most associated, numerous civil aviation uses have been developed, including aerial surveying of crops, acrobatic aerial footage in filmmaking, search and rescue operations,inspecting power lines and pipelines, and counting wildlife, delivering medical supplies to remote or otherwise inaccessible regions, with some manufacturers rebranding the technology as "unmanned aerial systems" (UASs) in preference over "drones."
UAV remote sensing functions include electromagnetic spectrum sensors, gamma ray sensors, biological sensors, and chemical sensors. A UAV's electromagnetic sensors typically include visual spectrum, infrared, or near infrared cameras as well as radar systems. Other electromagnetic wave detectors such as microwave and ultraviolet spectrum sensors may also be used but are uncommon. Biological sensors are sensors capable of detecting the airborne presence of various microorganisms and other biological factors. Chemical sensors use laser spectroscopy to analyze the concentrations of each element in the airUAV remote sensing functions include electromagnetic spectrum sensors, gamma ray sensors, biological sensors, and chemical sensors. A UAV's electromagnetic sensors typically include visual spectrum, infrared, or near infrared cameras as well as radar systems. Other electromagnetic wave detectors such as microwave and ultraviolet spectrum sensors may also be used but are uncommon. Biological sensors are sensors capable of detecting the airborne presence of various microorganisms and other biological factors. Chemical sensors use laser spectroscopy to analyze the concentrations of each element in the air
Commercial aerial surveillance

Remote sensing

Aerial surveillance of large areas is made possible with low cost UAV systems. Surveillance applications include livestock monitoring, wildfire mapping, pipeline security, home security, road patrol, and anti-piracy. The trend for the use of UAV technology in commercial aerial surveillance is expanding rapidly with increased development of automated object detection approaches.

Aircraft Design

Designing an

Another important factor that influences the design of the aircraft are the regulations put forth by national aviation airworthiness authorities.Airports may also impose limits on aircraft, for instance, the maximum wingspan allowed for a conventional aircraft is 80 m to prevent collisions between aircraft while taxiing(The movement of Aircraft on the ground in readiness for takeoff or the landing)

Before designing an Aircraft we should be clear about its use i.e will it be a military purpose aircraft or a commercial one. We should be clear about our financial market and investment before designing a aircraft.

Safety equipments to be installed, number of passengers which can travel in that aircraft should be clear enogh before we design an aircraft.

Now the major aspects of an Aircraft while designing them are :- 

Aerodynamics

Propulsion 

Mass

Structure    

Aerodynamics

  Aerodynamics deals with the design of the body and the wings. The geometry of wings should be such that they causes lift force more without consuming more fuel.

 

Propulsion

Propulsion basically deals with the maximum and minimum thrust that an aircraft can give without much consumption of fuel.Engines geometry and its mass is also a major issue which is to be focused .

Weight  

The weight of the aircraft is the common factor that links all aspects of aircraft design such as aerodynamics, structure, propulsion together. An aircraft's weight is derived from various factors such as empty weight, payload, useful load, etc. The various weights are used to then calculate the center of mass of the entire aircraft.The center of mass must fit within the established limits set by the manufacturer.

 

Structure

The aircraft structure focuses not only on strength, stiffness, durability (fatigue), fracture toughness, stability, but also on fail-safety, corrosion resistance, maintainability and ease of manufacturing. The structure must be able to withstand the stresses caused by cabin pressurization, if fitted, turbulence and engine or rotor vibrations.

COMPONENTS OF AN AIRCRAFT

In this post we will be focusing on parts of an :-

1)Fuselage

2) Cockpit

3)Airfoil

4)Spoiler

5)Turbine Engine

6)Wingtip devices

7)Rudder

8)Propeller

9)Elevator

10)Aileron

Functions of different Aircraft Parts:

1)The fuselage is the main body structure to which all other components are attached.content =" The fuselage contains the cockpit or flight deck, passenger compartment and cargo compartment. While wings produce most of the lift, the fuselage also produces a little lift. A bulky fuselage can also produce a lot of drag. For this reason, a fuselage is streamlined to decrease the drag. We usually think of a streamlined sports car as being sleek and compact - it does not present a bulky obstacle to the oncoming wind. A streamlined fuselage has the same attributes. It has a sharp or rounded nose with sleek, tapered body so that the air can flow smoothly around it.

2)Cockpit is usually the front area of an aircraft from where Pilot controls the aircraft. It contains Flight instrument on an instrument panel and the controls that enable the pilot to fly the aircraft. In most airliners, a door separates the cockpit from the passenger compartment.

3)Aerofoil or An Airfoil is the shape of the wing which produces lift. It is designed using laws of aerodynamics. The component of this force perpendicular to the direction of motion is called lift.Airfoil design is a major facet of aerodynamics. Various airfoils serve different flight regimes. Asymmetric airfoils can generate lift at zero angle of attack, while a symmetric airfoil may better suit frequent inverted flight as in an aerobatic airplane.

Terminology Of an Airfoil.

4) Spoilers are used to reduce lift in an Aircraft
Lift dumpers are a special type of spoiler extending along most of the wing's length and designed to dump as much lift as possible on landing. Lift dumpers have only two positions, deployed and retracted, and must not be used in flight as they completely stall the aircraft. Spoiler controls at full extension also act as lift dumpers. Spoilers are different from airbrake as spoilers are responsible for reduction in lift and increase in drag.

 

5) Turbine Engine/ Gas Turbine is a type of Internal Combustion Engine. It has a compressor which sucks air and passes into the combustion chamber and then towards the downstream which is a turbine.

 

6) Wingtip devices are usually used on fixed wings aircraft.Wingtip devices increase the lift generated at the wingtip (by smoothing the airflow across the upper wing near the tip) and reduce the lift-induced drag caused by wingtip vortices, improving lift-to-drag ratio. This increases fuel efficiency in powered aircraft and increases cross-country speed in gliders, in both cases increasing range.

7) Rudder is a device used to steer an aircraft . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the hull or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft's stern, tail, or after end. Often rudders are shaped so as to minimize hydrodynamic or aerodynamic drag. On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be turned by a helmsman. In larger vessels, cables, pushrods, or hydraulics may be used to link rudders to steering wheels. In typical aircraft, the rudder is operated by pedals via mechanical linkages or hydraulics.

 

8) A propeller is a type of fan that transmits power by converting rotational motion into thrust.A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid (such as air or water) is accelerated behind the blade. Propeller dynamics can be modelled by both Bernoulli's principle and Newton's third law.

 

9) Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's longitudinal attitude by changing the pitch balance, and so also the angle of attack and the lift of the wing.The elevators are usually hinged to a fixed or adjustable rear surface, making as a whole a tailplane or horizontal stabilizer. They may be also the only pitch control surface present, sometimes located at front (early airplanes) or integrated in a rear "all-moving tailplane" also called a slab elevator or stabilization.

 

10) Aileron is the hinged part on trailing edge of an airplane wing. It is used to control lateral turns.

AIRCRAFTS

Components Of An Aircraft

An aircraft is a machine that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil,or in a few cases the downward thrust from jet engines.
The human activity that surrounds aircraft is called aviation. Crewed aircraft are flown by an onboard pilot, but unmanned aerial vehicles may be remotely controlled or self-controlled by onboard computers. Aircraft may be classified by different criteria, such as lift type, propulsion, usage and others.

The main Parts of Aircraft are shown above-

 

 The Fuselage is the main body of an Aircraft which is a streamlined design so it produces least possible drag. All the other components of an aircraft are joined together to the fuselage. The fuselage contains the cockpit or flight deck, passenger compartment and cargo compartment. While wings produce most of the lift, the fuselage also produces a little lift.