1.2 Classifications of Aircrafts .1 General.1General
1.2.5 Rotorcrafts (Rotor-Wing Aircrafts)
Rotorcraft, or rotary-wing aircraft, uses a spinning rotor withaerofoilsection blades (a rotary wing) to provide lift. Types as depicted in Fig.1.37include powered and unpowered groups.
Unpowered are mainly rotor kites. Powered group includes three main sub- groups, namely,helicopters, autogyro, and gyrodyne.
1.2.5.1 Powered Rotorcrafts
1.2.5.1.1 Gyrodyne
Agyrodyneis a rotorcraft with a rotor system that is normally driven by its engine for takeoff and landing – hovering like a helicopter and its forward thrust is obtained from a separate propulsion device (usually two propellers mounted in tips of short or stub wings) rather than from tilting the rotor. Being able to fly in
autorotation gives the gyrodyne all of the advantages and simplicity of a gyroplane.
Figure1.38illustrates the famous UK gyrodyne Rotodyne powered by turboprop engines and having a capacity of 44 passengers and speed of 200 mph.
1.2.5.1.2 Autogyro
An autogyro (sometimes called gyrocopter, gyroplane, or rotaplane) utilizes an unpowered rotor driven by aerodynamic forces in a state ofautorotationto develop lift, and an engine-poweredpropeller(mostly piston), similar to that of afixed-wing aircraft, to provide thrust (Fig.1.39).
1.2.5.1.3 Helicopter
Helicoptershave powered rotors (single or dual). The rotors are driven (directly or indirectly) by engine(s) that push air downwards to create lift. Rotors are driven by the engine(s) throughout the flight, to allow the helicopter to take off vertically, hover, fly forwards, backwards and laterally, as well as to land vertically. The first
“helicopter” flight dates back to 1907. The Frenchman Paul Cornu took off with a Fig. 1.36 Firefighting C-130 aircraft dropping water
helicopter and hovered at a height of 30 cm for approximately 20 s. Continuous developments in helicopter industry lead to the extended list of helicopters. Heli- copters have several different configurations of one or more main rotors. Each main rotor has a number of blades between two and six.
Classifications Based on Rotor Single Main Rotor
Helicopters with one driven main rotor require some sort of anti-torque device such as atail rotor,fantail, orNOTAR, except some rare examples of helicopters using tip jet propulsion which generates almost no torque. Twin rotor has two rotor discs which usually rotate in opposite directions, so that no tail rotor or other yaw
Rotorcraft (Rotary-Wing Aircrafts)
Powered Unpowered Lift (Kites)
Single Rotor
Dual Rotors
Inter-meshing
Tandem Coaxial Transvers
Gyrodynes Autogyros Helicopter
Tail Ducted
NOTAR (No Tail Rotor)
Tip
Fig. 1.37 Classification of rotorcrafts
Fig. 1.39 Autogyro rotorcraft Fig. 1.38 Gyrodyne rotorcraft
stabilizer is needed. The two rotors are arranged intandem (one in front of the other), transverse (side by side), coaxial (one rotor disc above the other), with concentric drive shafts orintermeshing (where the rotor discs may be arranged to pass through each other).
Tandem Rotor
Tandem rotorhelicopters have two large horizontal rotor assemblies mounted one in front of the other [16]. Tandem rotor helicopters use counter-rotating rotors. This configuration is used for large cargo helicopters like CH-46 Sea Knight, CH-47 Chinook, Boeing Model 234, and Boeing Model 360.
Transverse Rotors
Transverse rotorsare mounted on the end of wings or outriggers, perpendicular to the body of the aircraft and uses differential collective pitch. This configuration is found on the Focke-Wulf Fw 61 (powered by radial engine) and Focke-Achgelis Fa 223 (powered by radial engines), as well as the world’s largest helicopter ever built, the Mil Mi-12 (powered by turboshaft engines). Figure1.40illustrates both tandem rotor (CH-47 Chinook) and transverse rotor (Focke-Achgelis Fa 223) helicopters.
Coaxial Rotors
Coaxial rotors(Fig.1.41) are a pair of helicopter rotors mounted one above the other on concentric shafts, with the same axis of rotation, but that turn in opposite directions. This configuration is produced by the Russian Kamov helicopter design bureau.
Fig. 1.40 Tandem rotor (CH-47 Chinook) and transverse rotor (Focke-Achgelis Fa 223)
Intermeshing Rotors
Intermeshing rotors(sometimes referred to as asynchropter) are a set of two rotors turning in opposite directions, with each rotor mast mounted on the helicopter with a slight angle to the other so that the blades intermesh without colliding. The Fig. 1.41 Kamkov KA32 Coaxial rotor helicopter
Fig. 1.42 HH-43 Huskie with intermeshing rotors
arrangement allows the helicopter to function without the need for a tail rotor.
Figure1.42illustrates HH-43 Huskie helicopter with Intermeshing Rotors.
Early helicopter designs utilized rotary engines, but these were soon replaced by more powerful automobile engines and radial engines. Next, during the first half of the twentieth century, helicopters used the compact flat engine. Later on, turbine engines revolutionized helicopter industry, where turboshaft engine gave helicop- ters an engine with a large amount of power and a low weight penalty.
Civil Helicopters
Helicopters activities are daily increasing both in civilian and military disciplines.
In civil world, helicopters are used in transportation, training, construction, remote sensing, search and rescue as well as firefighting (Fig.1.43).
Transport
Helicopters are used as transport vehicles for commercial purposes.It includes commercial transport, tourism, and aerial photography. Thus it may transport employees say for oil search companies, isolated locations, or offshore sites.
Moreover, many tourism companies use helicopters for sightseeing like those in Pyramids’area in Giza, Egypt, and Las Vegas, USA. Moreover, equipped helicop- ters are used in aerial photography. It is used also for transporting cargo and
Civil Helicopters
Transport
Search and Rescue
Firefighting (Helitack) Construction
(Aerial
Remote Sensing
Commercial
Tourism Aerial Photography
Mining and Energy
Sea MEDEVAC
Air
Police Dept Training
Cargo
Agriculture
Fig. 1.43 Classification of civilian helicopters
equipments. All helicopters are powered by turboshaft engines, except small types which are powered by piston engines.
Training
Training helicoptersare mostly single engine including MD500E, MD600, Bell 206 JetRanger, and Robinson R22 BetaII. All are powered by turboshaft engines except for the last one.
Aerial Cranes
Aerial cranes or skycranes are used to lift heavy loads. Figure 1.44 illustrates Sikorsky Skycrane S-64 (powered by turboshaft engine) carrying a house. Helicop- ters were first used as aerial cranes in the 1950s, but attained its popularity in the constructionfield in the 1960s.
The most consistent use of helicopters as aerial cranes is in theloggingindustry to lift large trees out of rugged terrain. Other lift services to the construction industry cover: HVAC removal and/or installation, steel tower construction, powerline construction, marine salvage, remote area operations/high-rise buildings, and congested areas and erect, remove, and replace all types of antennas and antenna towers.
Fig. 1.44 Sikorsky Skycrane S-64 carrying a house
Remote Sensing
Helicopters employed in aerialremote sensingfor several reasons including: time flexibility in measurement, high maneuverability, surface sampling, fills gap between satellites and ground station, and satellite sensor calibration with helicop- ter sensors. Typical helicopter for remote sensing are Hughes/MD 500 and BK 117, both are powered by turboshaft engines.
Search and Rescue
Search and rescue helicopters have many duties as sea or coast guard, aerial ambulance, mining, and energy as well as police departments. Typical helicopters are Sikorsky series H-19, HH-52A Sea Guard, S-70, HSS-2, and CH-53. All are powered by turboshaft engines except for Sikorsky H-19, which is powered by radial engines.
Figure1.45illustrates Sikorsky HH-52A Sea Guard, which has the ability to land on the water.
Agriculture
Agriculture helicoptersare used in crop spraying and dusting, seeding and spread- ing fertilizer, frost patrol, and insect eradication. These helicopters are equipped with special removable gear for spraying, fertilization, and generation of aerosols.
Examples are Ka-15 M and Mi-1.
Fig. 1.45 Sikorsky HH-52A sea guard
Aerial Firefighting
Aerial firefighting is the use of aircraft and other aerial resources to combat wildfires. Aircraft may be fixed-wing or helicopters. Helicopters may be fitted with tanks or carry buckets. Buckets are usually filled by submerging in lakes, rivers, reservoirs, or portable tanks. Popular firefighting helicopters include variants of the Bell 205 (Fig. 1.46) and the Erickson S-64 Aircrane helitanker, which features a sea snorkel for filling while in flight. Both are powered by turboshaft engines.
Military Helicopters
A military helicopter is a helicopter that is either specifically built or converted for use by military forces. A military helicopter’s mission is a function of its design or conversion. The most common types of military helicopters are transport, attack, training, experimental, search and rescue, UAV, maritime, tactics and operation, and finally observation (Fig.1.47).
Attack
Attack helicoptersare armed helicopters used in theantitankandclose air support roles.
Fig. 1.46 Firefighting Bell 205 dropping water
Weapons used on attack helicopters can include autocannons,machine-guns, rockets, and guidedmissilessuch as theHellfire. Today’s attack helicopter has two main roles: first, to provide direct and accurateclose air supportfor ground troops, and the second, in the anti tank role to destroy enemy armor concentrations.
Examples are Mi -24P and Kamov Ka-50, Westland WAH-64 Apache, Boeing AH-64A Apache, Bell 209/AH-1 HueyCobra, Boeing/Sikorsky RAH-66 Coman- che, Z-10, Eurocopter Tiger, Augusta A 129 Mangusta, and Denel AH-2 Rooivalk.
All are powered by turboshaft engines (Fig.1.48).
Trainer
Trainer helicopter is used for air education. An example for this category is HH-60G Pave Hawk helicopter, which is powered by turboshaft engine.
Transport
Transport helicoptersare used in places where the use of conventional aircraft is impossible. It lands easily in any area. Transport helicopters are operated in assault, medium, and heavy classes. Examples for this category are Aerospatiale SA 231 Super Frelon, Eurocopter Puma/Cougar, Eurocopter Dolphin/Panther, NH Industries NH 90, HAL Dhruv, PZL Swidnik W-3 Sokol, Mil Mi-8 Hip, Mil Mi-26 Halo, Westland Lynx, Sikorsky S-70A/UH- 60 Black Hawk, and Boeing Helicopters CH-47 Chinook. All are powered by turboshaft engines.
Military Helicopters
Multi- Mission
and Rescue
Trainer
Observation Tactics
And Operation Maritime
Attack
Low Intensity Warfare High Intensity Warfare
Transport
UAV Experimental
Fig. 1.47 Military helicopters
Experimental
Experimental helicopter as mentioned earlier is anaircraftthat has not yet been fully proven in flight. As an example, X-49A “Speedhawk”, Eurocopter X3, Kamov Ka-50, Mil Mi-X1, and Sikorsky S-97. All are powered by turboshaft engines.
Search and Rescue (SAR)
Multi-mission and rescue, or Search and Rescue (SAR)which is sometimes iden- tified asCombat Search and Rescue (CSAR)are helicopters that perform search and rescue missions in land and sea. The main objective is to use of available resources (personnel and facilities) to assist persons, ships, or crafts in potential or actual distress and provide for their initial medical or other needs, and deliver them to a place of safety. Examples are CH-118 Iroquois, CH-149 Cormorant, CH-146 Griffon, CH 53GS, HH 60/Pave Hawk, and HH-52A. A sub-group of this category isMedical evacuation(MEDEVAC). TheUS militaryhas recently employedUH- 60 Black Hawk helicopters to provide air ambulance service. Also coast-guard helicopters like HH-65A Dolphin – which used in saving hundreds of lives since introduction in 1987 – belongs to this sub-category. All are powered by turboshaft engines.
Fig. 1.48 Attack helicopter Mi -24P
Maritime Helicopters
Maritime helicoptersoperate from ships, destroyers, cruisers, and battleships. It may act as anti-submarine warfare (ASW), anti-shipping, transport, SAR, and reconnaissance roles. It must have enhanced protection against salt water cor- rosion and protection against ingestion of water. Examples are Royal Navy AgustaWestland EH101 Merlin anti-submarine warfare & medium-lift trans- port/utility helicopter, LAMPS SH-60B Seahawk, and Kamov Ka-27 (Fig.
1.49).
Tactics and Operations Helicopters
This category of helicopters gives a force multiplier that maximizes their impact in a combined arms approach. It is employed both ashigh- and low-intensity warfare.
High-intensity warfare is characterized by large arrays of conventional armed forces, like Cobra helicopters, which armament included anti-tank missiles, such as theNord SS.11, and3M11 Falangamissiles. Concerninglow-intensity warfare, helicopters are used in counter-insurgency (COIN) warfare. It is powered by turboshaft engines.
Fig. 1.49 Maritime helicopter LAMPS SH-60B Seahawk
Observation
Observationhelicopters were initially limited to visual observation thus featured rounded, well-glazed cockpits for maximum visibility. Today, they include low light level television and forward looking infrared cameras. Often, these are mounted in a stabilized mount along with multi-function lasers capable of rangefinder and targeting designators for weapons systems.
Examples are Gazelle, OH-58 Kiowa, Kawasaki OH-1, and Tiger ARH. All are powered by turboshaft engines
UAV
UAV rotorcraft also flies without a human crew on board similar to fixed wing UAV. They are powered by a jet or reciprocating engine. In addition to conducting intelligence, surveillance, and reconnaissance, it successfully could achieve new goals. Boeing’s A160T Hummingbird UAV has the ability to resupply frontline troops in rough terrain (Fig.1.50). Northrop Grumman Corporation’s RQ-8 Fire Scout unmanned air vehicle (UAV) can successfully fire two rockets and has the ability of vertical landings on a moving ship without a pilot controlling the aircraft.