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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 ...

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1answer
191 views

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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1answer
160 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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0answers
17 views

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 ...
5
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1answer
203 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 ...
3
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1answer
111 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 ...
7
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1answer
400 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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0answers
177 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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0answers
71 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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2answers
66 views

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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2answers
183 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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0answers
42 views

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, ...
4
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1answer
184 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 ...
4
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2answers
329 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 ...
2
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1answer
148 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
281 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 ...
7
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1answer
306 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
170 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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3answers
287 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
262 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 ...
1
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1answer
124 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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1answer
215 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 ...
15
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2answers
4k views

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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0answers
51 views

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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2answers
334 views

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
211 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 ...
3
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1answer
380 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
228 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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3answers
150 views

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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0answers
104 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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0answers
91 views

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
160 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 ...
2
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1answer
93 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 ...
3
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1answer
196 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 ...
9
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2answers
147 views

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
145 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 ...
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1answer
83 views

How do you orientate the helicopter at night? [closed]

How do you orientate the helicopter at night?
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1answer
66 views

What to do when moisture forms on the helicopter's canopy in a weather front?

Moisture has condensed on the canopy of your helicopter as you fly through a weather front – what should you do?
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2answers
149 views

Why do we not have autonomous helicopters? [closed]

We see a lot of fixed wing autonomous UAVs. What is preventing this in the case of helicopters? I know the helicopter flight dynamics are complicated. But what exactly is the complication in this ...
3
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1answer
152 views

What is a compounding wing and how does it increase helicopter performance?

The US Army is developing a list of enhancements for the next generation Apache attack helicopter. Among them this was mentioned: Topping the list of major changes is re-engining with the 3,000-shp ...
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0answers
135 views

Why don't helicopter rotors use curved blades? Curved from the top view. [duplicate]

I'm studying blade element analysis and I tried applying it to curved rectangular blades instead of straight ones. It doesn't really show any significant changes in the inflow ratio computation. Why ...
55
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9answers
17k views

Can this helicopter/wrecking ball combo remain airborne?

I just ran into this meta-answer which includes this image: My initial guess is that the wrecking ball is far too heavy for the helicopter to lift, but I'd be interested in the numbers to see just by ...
1
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2answers
279 views

Can someone identify these two Bell helicopters seen in the Czech Republic?

I would like to ask you for help with identification of two particular airframes. On Sunday 13 May 2018 around 11.45 local time, I took a picture of two Bell UH-1s south of Brno, Czech Republic. I ...
2
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1answer
208 views

Does the cyclic in a helicopter re-center automatically?

Just wondering if the cyclic in a real helicopter re-centers like a joystick for a computer? I'm pretty sure the controls in a fixed wing re-centers due to natural physics if the plane is in ...
6
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2answers
450 views

What are the limitations to adding wings with engines to a helicopter?

I've probably seen this in science fiction and cartoons but never in real life. Rotor wing aircraft (helicopters) have numerous advantages over their fixed wing counterparts, and vice versa. For ...
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2answers
234 views

How is the speed of a helicopter controlled?

How is the speed of a helicopter controlled? Does the pitch of the blade vary for speed while rotor blade moves at a constant speed as with turboprops? Or is there a throttle mechanism for varying the ...
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1answer
177 views

Why do electric versions of helicopters need four rotors, or: why are they quad copters? [closed]

Why do electric versions of helicopters need four rotors, or: why are they quad copters? Could it be that their motor do not have enough torque? Then again electric motors have much more torque ...
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1answer
233 views

What are the guidelines and regulations for building a helipad for multiple aircraft?

Are there any guidelines and regulations governing the ownership and construction of a multiple aircraft type helipad in a) the USA b) Europe?
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0answers
23 views

How to properly estimate induced flow

Good day. I am currently in a group that is projecting a rotor that when launched must enter in autorotation. The estimated velocity of descent is $V_z=1.29$ $m/s$ which is approximately the same ...
3
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3answers
783 views

Are there disadvantages of coaxial rotor on attack helicopters?

My question stems from the fact that, although this is a very fierce looking, and formidable aircraft with a very powerful engine, Ka-52 Alligator has not seen many export success. Its export is very ...
0
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1answer
88 views

What are the minimum hours required for private instrument fixed-wing plus commercial helicopter?

I want to get my private pilot plus instrument rating in fixed-wing aircraft for personal use. In addition to that I want to get my private and commercial in helicopters to start a career in flying ...