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Results tagged with helicopter
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user 21091
A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft would usually not be able to take off or land.
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How are helicopter cyclic and collective jacks connected?
There are three "jacks" providing both collective and cyclic movement to the swash plate, the difference is in how many are moving.
All three are used for collective input: they all move, so the sw …
- 62.9k
6
votes
Can a helicopter stall?
When all airspeed is gone, the helicopter cannot maintain hover at this weight/altitude combination and starts to lose altitude. … Descending vertically, the helicopter descends in its own downwash and enters a dangerous situation called Vortex Ring State. …
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2
votes
What is the relation between a helicopter's length and rotor diameter?
If the helicopter has a main rotor and a tail rotor:
The main rotor is attached very near the centre of gravity. … The tail rotor axis is preferably mounted at the same height in the helicopter as the main rotor - outside the main rotor radius of course. …
- 62.9k
11
votes
Helicopters: why hasn't NOTAR been more popular?
Image from Principles of Helicopter Aerodynamics by J. Gordon Leishman. …
- 62.9k
2
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Accepted
What is the range of amplitude of vibration in a helicopter?
The amplitude of the vibration depends on the frequency and the acceleration: at a given acceleration, only at low frequencies do we get any significant displacement. If displacement is taken as the i …
- 62.9k
2
votes
Accepted
What range or variation should we expect from gyroscope in a helicopter?
A helicopter usually has higher inertia than a car, so sprung frequency should be lower. If you take 0 - 10 Hz as a baseline for the range, you should be safe. … Above graph shows pitch response of an example helicopter, from Prouty, Helicopter Performance, Stability and Control. …
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5
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How is rotor pitch best managed in helicopter autorotation?
The procedure is to lower collective immediately to the full down stop to minimise blade drag, upon which the helicopter will start to descend. The air upflow tilts the local lift vector forwards. …
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3
votes
Will Thrust on Rotor (Main) increase with altitude?
I presume that OP means torque on the rotor, since thrust must always compensate weight to maintain altitude. Thrust T, torque Q and power P equations for momentum theory in the hover:
$$T = C_T \cdo …
- 62.9k
3
votes
Accepted
In a helicopter does forward flight produce a rolling moment?
Gordon Leishman, Principles of Helicopter Aerodynamics:
The picture shows the lateral tilt from longitudinal airspeed, which must be compensated for by tilting the swash plate. … Picture above shows the lateral stick setting as function of airspeed for an example helicopter, which resembles the UH-60. …
- 62.9k
44
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Why do helicopters have skids?
All the above is for wheels, which allow the helicopter to taxi on-ground. … One would not want to land this helicopter without the skids! …
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6
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To operate on Mars, how large would a manned helicopter's rotor blades have to be?
On the Space site it was determined that a manned helicopter flying on Mars would look like a Sikorsky Firefly with the rotor of the Mi-26. …
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3
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Do helicopter rotor blades speed up and down during the rotation?
A helicopter rotor usually has flapping hinges, which lifts the blade up when travelling forward and down when travelling backwards. …
- 62.9k
2
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Do helicopters need to use yaw pedals to fly a coordinated turn?
Fixed wing aircraft that deflect their ailerons experience adverse yaw: the aileron deflecting downwards experiences more drag than the one deflecting upwards, and this creates a yawing moment in the …
- 62.9k
1
vote
What is the lift to empty weight ratio of some popular modern helicopters?
From Prouty: Helicopter Performance, Stability and Control: the example helicopter that is referenced throughout the book, to illustrate the equations used and computations made. … The example helicopter has the following characteristics:
Design gross weight = 20,000 lb
Minimum operating weight = 10,700 lb
Main rotor radius = 30 ft
Blade geometry: chord = 2 ft, airfoil = NACA0012 …
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3
votes
Accepted
What is the typcial descent rate of a helicopter?
I have a flight manual of an older type helicopter, I cannot reproduce the contents, but it shows True Airspeed on the horizontal axis, Rate of Descent on the vertical, and a set of inclined lines for …
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