Intro to the Helicopter (Chapter One) Flashcards
What is a helicopter rotor system?
It is the rotating part of a helicopter that generates lift.
What is a Tandem Rotor? (sometimes referred to as dual rotor)
Helicopters that have two large horizontal rotor assemblies; a twin rotor system, instead of one main assembly and a smaller tail rotor. Tandem rotor helicopters, however, use counter-rotating rotors, with each canceling out the others’s torque.
What is a Coaxial Rotor?
Are a part of rotors turning in opposite directions, but mounted on a mast, with the same axis of rotation, one above the other.
What is a single main rotor system?
It is a single main rotor assembly with a tail rotor assembly. The main turns in one direction creating torque and therefore the tail rotor assembly needs to be in place to counter act that torque.
What is Newton’s third Law?
Every action has an equal and opposite reaction.
What are the three most commonly used antitorque designs used today?
Traditional tail rotor, Fenesron (also called a fantail), and the NOTAR
What is a Traditional Tail Rotor?
The tail rotor is a smaller rotor mounted so that it rotates vertically or near-vertically at the end of the tail of a traditional single-rotorhelicopter.
What is a Fenestron Tail Rotor?
the Fenestron rotor differs from a conventional rotor by adding several more blades. Whereas a conventional tail rotor seldom has more than four blades, a typical Fenestron includes eight to thirteen blades. Compared to conventional tail rotor blades, the Fenestron blades are also much smaller and spin at higher speeds. Furthermore, these blades are mounted within a shroud that forms part of the vertical tail fin of the helicopter. This configuration turns the rotor into a ducted fan whose blade tips are protected from the external air.
What is a NOTAR Tail Rotor?
NOTAR, short for NO TAil Rotor, is a more unusual torque control system that does away with the tail rotor completely. Instead, the system makes use of compressed air that is forced out of slots inside the tail boom. This jet of air changes the direction of the air flow in the vicinity of the tail boom to create an aerodynamic force that opposes the spinning torque motion. NOTAR is one of the latest methods devised to counteract the torque effect, but it is only used by MD Helicopters in the United States.
What are the Pros and Cons of a Fenestron Tail Rotor?
Pros: Less subject to FO because it is protected by a shroud, less likely to hurt or kill someone, more efficent and has more antitorque than tranditional
Cons: expensive, more complex
What are the Pros and Cons of a NOTAR Tailer Rotor?
Pros: shorter than traditional tail systems along with now tail rotors leaving it subject o FOD or stricking objects, can also get into small areas
Cons: uses more power then other systems, has hovering issues in wind dpeeds above 17 KNOTS, in crusie speed needs extra stablity for yaw control
What does the Tail Rotor Drive System consist of?
Driveshaft powered from the main transmission and a gearbox mounted at the end of the tail boom. The driveshaft may consist of one long shaft or a series of shorter shafts conenected at both ends with flexible couplings.
Flexible Couplings do what?
They allow the drive shaft to flex with the tail boom.
What does the tail gearbox do?
Provides an angled drive for the tail rotor and may also include gearing to adjust the output to the optimum rotational speed typically measure in RPM.
What do Intermediate gearboxes do?
On larger helicopters they are used to angle the tail rotor drive shaft from along the tail boom or tailcone to the top of the tail rotor pylon, which also serves as a vertical stabilizing airfoil to alleviate the power requirement for the tail rotor in forward flight.
