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Questions tagged [helicopter]

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 does a circulation control helicopter work

This essay describes that this helicopter uses circulation control of the rotor for cyclic and collective control, but not how circulation control works. https://ntrs.nasa.gov/archive/nasa/casi.ntrs....
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Is autorotation possible in a tandem rotored helicopter?

I just wonder, whether a synchronized autorotation is possible in case of turbine failure (one or both gas turbine engines). All Gearboxes obviously must turn not to desynchronize -> lethal
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What happens when you apply full cyclic + collective?

Can a helicopter apply full cyclic and then full collective at the same time? Would'nt the blades on one side (opposite of the intended tilt direction) have already maxed their aoa, resulting in a net ...
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Will Thrust on Rotor (Main) increase with altitude?

Can some one please let me know,if the thrust required on the rotor head increases with the increase in altitude in an Helicopter or decreases with increase in Altitude?. Thanks in advance, Pawan
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Phoenix Area Helicopter ATC: What is “Hee-lah” (Gila?) One, and what is the 101 transition?

I've been listening to the Phoenix Tower LiveATC feed, and I hear references to "Hee-lah" (Gila?) One and the 101 transition with helicopters (see audio files below): Angel-Five TV-3 TV-15 Does ...
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Are there attempts at fly-by-wire servo flap controlled rotor?

Reading this question and then this document about servo flap controlled rotor I was wondering if there has been any attempt at building one fixed hub helicopter with twistable blades hosting at 75% ...
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Are helicopter searchlights fixed or movable?

Can the helicopter crew move the helicopter searchlights or are they always fixed at a specific location on the helicopter? They are used by rescue helicopters mostly but I am not sure if crew can ...
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1answer
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Does the commercial helicopter training in 61.129(c)(3)(i) require a CFII?

For the commercial ticket in a helicopter you need 5 hours of hood time. Can any CFI provide this training or does it require a CFII? 14 CFR 61.129(c)(3)(i): Five hours on the control and ...
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How is static droop achieved in mechanical governors

The Bendix power turbine governor in the Bell 206 is just simple flyweight arrangement which controls a pneumatic signal to the FCU. How is static droop achieved in this type of system?
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147 views

What do I need to get my pilot license? [closed]

I am thinking of getting my pilot license, I would love to fly a helicopter or a small plane, but I don't know where to start. What do I need to get a pilot's license? Things like: How much does it ...
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1answer
50 views

Does the HAL LCH have fly-by-wire?

Is Automatic Flight Control System (AFCS) the same as Fly-by-wire? If not what's the difference? India’s Hindustan Aeronautics Limited (HAL) has carried out the first flight of a Light Combat ...
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Wheel or skid? Which advantages does each one have when used as the landing gear system compared to the other one?

I would like to discuss this topic in depth, as I have not found a clear answer yet. Which are the advantages of using skids instead of wheels (or viceversa) for the following considerations?: -As ...
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Where can I find official information about a recent crash in Mexico?

I have heard about a helicopter crash involving an Agusta A 109 in Mexico, that seems to be causing some turmoil due to the deaths of a newly-elected governor and her husband. Is there any info about ...
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3answers
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From which rating would it be easier to transition to an Osprey? Fixed-wing or rotary-wing?

If the future of flight was to be on aircraft that were a hybrid of fixed-wing and rotary-wing (for example the Osprey), assuming they had similar technical abilities and the same number of flight ...
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1answer
110 views

How can you calculate the vertical speed of an helicopter during auto-rotation?

How can I calculate velocity of a helicopter when it falls with autorotation when the engine fails, given all the parameters such as mass , height , wing size etc.
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Black aircraft at night no lights with helicopter following - is this a stealth aircraft? [closed]

I have just seen a dark long aircraft fly over my car followed by a long helicopter. I am not an expert at this but it is 8pm, i am on a hill with a few houses, there is a little street light on the ...
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212 views

Do Military Turboshaft engines have a distinctly different sound from Civilian ones?

I live in India, and near an airbase so there are a moderate amount of helicopters flying overhead. My friend claims that he can distinguish between a civilian helicopter or a military one based on ...
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How is the inflow velocity distributed of a tilted and trimmed rotor in hover?

I'm wondering of how the inflow velocities per blade look during one revolution of a real-life helicopter in hover (no inflow velocity into the rotor plane) with a tilted rotor plane about 20 deg. Is ...
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1answer
233 views

Why are autorotations to a full touchdown not practised any more?

What is the history behind a decision to discontinue helicopter autorotations all the way to ground contact? In the 1960s, our Army flight program directed full ground contact for any and all ...
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1answer
142 views

How do typical ground marshaling signals differ for helicopters?

There are common hand signals used by ground crew for fixed wing aircraft like 'taxi forward', 'spin up engine #1', 'turn right', or 'stop', for example: At most airports, general helicopter traffic ...
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482 views

What is the name of this vintage helicopter trainer?

I am curious about the tiny training helicopters that can be seen from the second 0:10 in this vintage video about the Cuatro Vientos helicopter school, near Madrid. ...
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194 views

What is the heaviest payload ever carried by a single main rotor helicopter?

What is the most heavy payload ever carried by a single main rotor Helicopter?
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161 views

Would increasing rotor disc diameter increase efficiency in a helicopter by reducing disc loading?

Despite the obvious drawbacks of a larger rotor diameter would the reduced disc loading increase efficiency during hover and forward flight?
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In an articulated hub rotor craft, what could cause the blade to flap negatively?

For example in forward flight what could cause the blade to flap lower than parallel to the CF at the front of the aircraft ?
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202 views

Benefit of a deswirl vane for a turboshaft helicopter engine

I am trying to understand the benefit of deswirl vanes on a turboshaft helicopter engine. For these type of engines, the kinetic energy of the exhaust stream is essentially wasted energy. Also, ...
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Where to find information on weight breakdown for helicopters?

I would be interested in information on the weight breakdown for the different components of a helicopter. How much of the maximum gross weight is related to the airframe, engine, gearboxes, ...
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1answer
257 views

What are the fins near the tail of a helicopter called?

My young sons are very enthusiastic about helicopters and I am repeatedly asked to name parts of their model aircraft. I would like to do so correctly, but my research has not always given definitive ...
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2answers
399 views

Why is this type of rotor hub so rare…?

I wonder why is this type of helicopter rotor hub so rare... It is a very simple construction, having no flap or lead-lag hinges. A universal, constant-speed joint leaves the rotor free to find his ...
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1answer
159 views

What is the rod attached to the top of the Bell UH-1N's rotors?

So, I was looking at an image of a Bell UH-1N, and noticed that the top if the rotor has a little stick or rod What is this rod for? I also see this rod on a RC helicopter.
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3answers
350 views

Why are helicopters less efficient than planes?

At higher speeds, advancing helicopter blades will operate at velocities approaching mach 1, reducing efficiency. But what about lower speeds? A helicopter is basically a wingless plane with a giant ...
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1answer
378 views

What factors govern the placement of a helicopter's tail rotor (left or right)?

An image search for 'helicopter' indicates that there isn't a consensus on whether to place the tail rotor to the left or the right of the tail boom, although I'm believe there may be a bias for left. ...
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1answer
209 views

How much thrust could a 400 mm EDF produce?

there's a 195mm EDF from Schübeler that produces 25 kg of thrust at a peak power consumption of 15 kW: https://www.schuebeler-jets.de/de/produkte/hst Now, my question is: How much thrust could you ...
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304 views

Who controls airspace and time in my area on helicopters?

I live in Newport Beach which is located in Orange County, California. I recently moved to an area where helicopters fly once in a while at 2-3 am above my house. Since I live on a hill, the sound is ...
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2answers
650 views

How to become a helicopter pilot? [closed]

I once had a dream of becoming a helicopter pilot. Then life happened: married young, kids, school, career, etc. I'm working in a good career while finishing a Ph.D. in engineering. But still, I find ...
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1answer
162 views

Is ATC clearance or permission required to fly helicopter routes and transitions in the Los Angeles area?

Skyvector has Los Angeles helicopter charts here and here. Are pilots required to obtain ATC clearance or permission to fly helicopter routes and transitions?
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225 views

Do military tactical transport flights provide seatbelts for all occupants?

In several movies I have watched recently, the temporary bench style seats of tactical transport aircraft such as the C-130 do not show seat-belts. I would not be surprised that some instances of seat ...
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Are there any reported cases of noise from helicopters causing damage to property?

In the Netherlands, three cases have been reported of Chinook helicopters' rattle noise (low frequency sound) damaging solar panels. The Dutch defense ministry recognises this problem and the lawyer ...
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How does the number of blades affect the static thrust of a propeller? [duplicate]

Since I couldn‘t find an answer to this question I thought I‘d ask you guys! By which factor does the thrust of a propeller increase if I double the number of blades, the motor being powerful enough ...
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How do CH-47 pilots lower the tail during a pinnacle landing?

(thedrive.com) Given the recent rescue of a climber on Mt. Hood by a Chinook, how are the pilots able to lower the tail in this situation? Is this just the natural angle during a hover, or are there ...
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1answer
220 views

Why have helicopter top speeds not increased much over time?

With advancements in technology why there isn't much increment in helicopter top speeds from what they were in the 1980s? We have newer designs like the Eurocopter X3 which is a hybrid, but the speed ...
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1answer
632 views

What‘s the thrust of two stacked propellers?

Let‘s say that you have two identical propellers and each is powered by their own motor and together they produce a thrust of 1 kN. How does the thrust change if instead of operating them side on side ...
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1answer
354 views

Why don't helicopter change altitude based on variable rotor RPM as opposed to the collective? [duplicate]

AFAIU, helicopter rotors turn at constant RPM and changes lift based on the collective. Why no have a variable RPM heli?
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What is the autorotative rate of descent for a Bell 47-H?

I would like to estimate the amount of time a pilot would have before a forced landing after suffering engine failure in a Bell 47-H at 1,000ft. This is for purposes of understanding a historical ...
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1answer
210 views

When helicopters are instructed to air-taxi direct to an airport location, are they allowed to pass above other aircraft and people?

When helicopters are instructed to air-taxi direct to a location at the airport, are they allowed to pass above other aircraft / people / road traffic?
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Where can I find more details about how ornithopters work?

I learnt about the special helicopter-ornithopter which was put forward by Delft University. Its principle is different from a common helicopter and it doesn't need a tail rotor. But there is very ...
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3answers
208 views

Can a Stewart Platform be used instead of a swash-plate assembly in a helicopter? What are the pros and cons? [closed]

https://en.wikipedia.org/wiki/Stewart_platform Also, are there any helicopters in service that use this mechanism? I was thinking along the lines of using it instead of the part of the swashplate ...
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1answer
95 views

What are the pros/cons of low/forward powerplants on helicopters?

(Original) The double-decker Westland Wessex has a pair of side-by-side Gnome turbines low and forward (blue rectangle above). What are the pros and cons compared to the center-high more typical ...
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1answer
238 views

By what angle does the rotor disc change with max. cyclic input?

If maximum longitudinal/lateral cyclic blade pitch input is given, by how many degrees does the thrust vector (or rotor disc) change? Is the magnitude in the order of $\pm5^\circ$ or more in the order ...
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Relationship between flapping and lagging frequency

In my rotorcraft module at university, we were told that blades leading/lagging is as a result of blade flapping. To conserve angular momentum, an upward flapped blade (CG moves toward rotor hub) will ...
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1answer
194 views

Can a helicopter enter Vortex Ring State In Auto Rotation? [see qualifiers]

If you are in a vertical descent [no wind] with rotor at max RPM Auto, and you abruptly pull full collective, the momentum of the blades will drive air down creating down wash. Now obviously this is ...