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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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Is it plausible that helicopters are safer than cars?

For some reason there is a lot of talk on helicopter safety online at the moment, and one fact that keeps coming up is "helicopters are safer than cars", supported by this article "Are ...
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Can a wind gust below the rotor affect the lift force in a helicopter?

If a helicopter is hovering and a very strong, narrow and focused wind gust comes from the front and passes few feet below the rotor blade without touching the fuselage or any part of the aircraft for ...
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Why do American Helicopters not have ejection seats or some form of ejection system?

In Russia there is the Kamov Ka-50 which is a helicopter with a ejection seat that blows off its rotors before the pilot ejects. I was wondering why here in America we Don't have some form of similar ...
Jordan Stephan's user avatar
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Helicopter attitude during take-off and landing (wheels, not skids)

Helicopters with wheels can take-off and land in a level or nose-up attitude (nose wheel off with main wheels on the ground). For example, the pilot of a VIP helicopter might want to take-off in a ...
user9251544's user avatar
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Do helicopters have to pay landing fee?

Is there a landing fee for helicopters? I ask because since they usually don't use the runway hence doesn't cause maintenance costs for the airport I would imagine they have at least a different fee ...
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What is the arrangement of flapping, drag, and feathering hinges on a fully-articulated rotor hub?

Every diagram I have seen puts the flapping hinge closest to the rotor hub, but there seems to be variation whether the feathering comes next followed by the drag/lead-lag, or vice versa. For this CH-...
Rekov's user avatar
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What exactly are these two cones on top of this Sikorsky S-61 helicopter?

Haven't notice this thing on the Sikorsky, what is it? Another picture from another angle:
Gabe's user avatar
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Can a single-bladed rotor with cyclically varying torque emulate a swashplate?

Instead of a swash-plate cyclically varying the pitch of the rotor blade(s), could a similar effect be generated by cyclically varying the thrust of the motor on a fixed-pitch single-blade rotor? The ...
Albeit's user avatar
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why does the rotor could head (Nr) "overspeed" if the collective is lowered suddenly, what is the Physics behind it

I know that in helicopters the N2 and Nr are coupled. I would appreciate a physical explanation leading to the cause of how the rotor blades could overspeed if collective (power) is lowered suddenly I ...
YamchaAviator's user avatar
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Have there been attempts to break Jean Boulet's 1972 helicopter records? (highest altitude and longest unpowered descent)

So this is the incredible photo of a man accidentally setting a world record. In 1972 a French pilot named Jean Boulet set out to break the world record for the highest altitude ever reached in a ...
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How to calculate fuel burn rate in Model BK117 helicopter

I am confused which parameters we are use, I have fuel quantity, fuel flow, fuel weight and speed etc is there so how to using and which parameters using the Endurance time calculate in helicopter
Manju MLA's user avatar
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How to identify a NDB on a garmin 430W or GTN650?

I have a Garmin 430W and a GTN 650 interfaced with a G500H in my aircraft. I can program either to go direct to an NDB. The question comes as to whether or not I can identify the navaid. Reading ...
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Gyroscopic Precession in Coaxial Helicopters

I'm trying to understand gyroscopic Precession in the case of coaxial helicopters. Obviously the effect still exists. But if gyroscopic Precession is a result of counter torque. Shouldn't the effect ...
Slartibartfast's user avatar
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My ceiling fan preference is to have 5 blades because it's quieter. Do helicopters ever have 5 rotor blades. Why?

My home ceiling fans have 5 blades to reduce the wopwop sound in a quiet room. It probably also moves air more efficiently at a lower spin rate. Can a helicopter operate properly with 5 blades?
Lenny C.'s user avatar
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What is the downwash speed on a typical helicopter?

On a typical 2 or 4 seat helicopter like a Robinson R22/R44, at full throttle at 20ft ASL, if you put a Wind Speed Meter/Anemometer about 10ft below the blades and halfway along a rotor blade's span, ...
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H145 helicopter type rating trainings

There are different variants of H145 helicopter (BK117), there are BK117, BK117 C2, BK117 D2 and BK117 D3 helicopter. So if you finish type rating training for example for BK117 D2, and you want to ...
cirica's user avatar
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Can you identify this helicopter seen near Boscombe Down?

Please can you identify this helicopter seen near Boscombe Down (near Amesbury, Wiltshire, England) in January 2024?
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Autorotation Trajectory Datasets?

I was looking for works/datasets on autorotation trajectories. Now, I have found works like this: Aponso et al, Dalamagkidis et al, Abbeel et al or Nonami et al (Chapter 6). However, I have a hard ...
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Do coaxial rotor helicopters have a size limit? [duplicate]

Why haven't there been heavy helicopters like the CH53 with coaxial rotor configuration? Is there any physical limitation inherent to the concept? I recall someone at Sikorsky saying that their new X2 ...
Can Tosun's user avatar
5 votes
1 answer
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Why single engine turbine helicopters can operate on higher altitudes than multi engine helicopters?

Probably you knew the example where H125 landed on Mount Everest (8848 m), and H145 highest landing was on Aconcagua (6962 m), almost 2000m difference.
cirica's user avatar
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What are the main changes in CAP437 rev 9 from a Helideck Monitoring perspective?

CAP437 rev 9 was first published Edition 9 February 2023. In particular, what should a Heliops operator conducting operations on a "moving" helideck be made aware of. What training would an ...
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How does a helicopter rotor keep spinning in the same direction when autorotating without reversing the pitch

I have read that if helicopter's engine fails, you set the pitch to minimum but not reverse pitch. The rotor would have to be tilted back to provide an angle of attack on the blades so it glides like ...
Peter R. McMahon's user avatar
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Deriving Accurate Exit air velocity of rotor

My goal is to derive the equation for exit air velocity as a function of: Pitch angle RPM Rotor Radius Constants like ρ Assumptions: Vc is relative velocity of air upstream, and is = 0 Inflow is ...
Luke-McDevitt's user avatar
3 votes
2 answers
339 views

Is blade flapping "fully automatic"?

I have a rather simple question just to "double check" if I understood blade flapping right. So, I understand that a helicopter, in forward flight faces an asymmetric lift. Blade flapping is ...
Clex's user avatar
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17 votes
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Why are there no helicopters with the rotor mounted on the bottom?

Downwash from the rotor of a helicopter creates drag on the helicopter body acting against the lift force of the rotor. Why are there no helicopters with the rotor under the main body of the ...
Andreas Pichler's user avatar
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136 views

Why is there variation in helicopter autorotation maneuvers?

Why are there some different autorotation techniques? For example, on light helicopters, like the Airbus Helicopters H125 or Aérospatiale Gazelle, you do not flare too much: at 70-100ft AGL adjust ...
cirica's user avatar
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What are the effects of whiteout (snow) and brownout (sand/dust) on helos?

Is there any other effect besides low visibility? Both seem to show very similar conditions.
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For transporting 4000kg of cargo via Mi-17 helicopter for 54 km, how much maintenance cost per flight hour will be incurred?

In a disaster response case study, I am using Mi-17 helicopters for relief supplies transportation in a challenging logistics environment. Regarding this, I want to check my estimates with the actual ...
Engr. Moiz Ahmad's user avatar
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224 views

How much fuel cost will be incurred for transporting 4000kg of cargo via Mi-17 helicopter for 54 km?

I am working on a logistics case study in which I am using Mi-17 helicopters for transportation of relief to the affected areas in a disaster. In this regard, I want to check my estimates with the ...
Engr. Moiz Ahmad's user avatar
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171 views

What differences would a helicopter designed to withstand many negative Gs have compared with a normal one?

There are a few helicopters that are able to take negative G's, and to this day only one can actually perform aerobatics (ie. Chuck Aaron's BO-105). The BO 105 is a rigid rotor helicopter that has ...
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1 answer
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What type of helicopter is this?

Wondering what kind of aircraft this is. Military or commercial? Photographed nearing island HK (possibly near Wanchai) an hour or two ago.
Spehro Pefhany's user avatar
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Humidity and its effect

We know that humidity degrades engine performance. Is there any charts or tables which quantify effect on engine performance due humidity? The question is specific to helicopters.
Vikas Singh's user avatar
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2 answers
172 views

Can vortex ring state (VRS) be solved by shaping the blades so that the vortexes they produce are weak enough not to form a vortex ring?

Vortex Ring State is one of the hazardous states a helicopter can find itself into. VRS happens when a helicopter has low airspeed (and usually hovering OGE) and is descending. If the helicpoter is ...
BanzaiFighterbomber's user avatar
2 votes
1 answer
1k views

Helicopter V speeds explanation

I am reading Cat A heli procedures, and there is Vtoss speed, so what is the difference between Vx(best angle of climb speed) and Vtoss(take off safety speed) ?
cirica's user avatar
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Can the use of wide-chord supercritical airfoil blades in a helicopter with coaxial counter-rotating rotors solve retreating blade stall?

The problem with retreating blade stall is that it limits the VNE and the overall top speed of helicopters. Retreating blade stall is basically the tip of the retreating blade having too much AoA at a ...
BanzaiFighterbomber's user avatar
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Helicopter autopilot

Is there any video or explanation how parallel actuators work on 4 axis helicopter autopilot ? I am familiar with beep trim and trim release buttons, but want to know how it all works in the ...
cirica's user avatar
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Rotor system Weight of a Helicopter

I was wondering whether there is a "rule of thumb" or some kind of estimate (ideally with a source) that states how heavy a rotor system (blades, swash disk, actuators) typically is as a ...
Clex's user avatar
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2 votes
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accelerated turns in helicopter

In flight Manual of Russian Mi-17 helicopter, it is give that ”max bank permitted in accelerated turns is 45 deg up to 1km altitude”. At the same time it also mention max bank permitted is 30 deg up ...
Vikas Singh's user avatar
5 votes
1 answer
439 views

Does the CH-47 Chinook generate differential yaw as a side effect of generating differential lift?

I have been reading up on the controls of the CH-47 Chinook. I understand how yaw movement is created not by counter torque but by opposite cyclic on the front and back rotors. What I'm wondering ...
tavis's user avatar
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Adding fixed wing CFII SEL to helicopter CFII rating

I am a CFII, and have just been asked to assist a Helicopter pilot who has FIH (CFFII-Helicopter) and a Commercial fixed wing (SEL) certificates to obtain a CFII SEL rating. My research to date ...
Warren Bishop's user avatar
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109 views

How much power and lift margin do helicopters have for hover?

Suppose you are designing a helicopter and trying to size the rotor system for hover and flight. Your helicopter has a certain gross weight at sea level, standard atmosphere. How much additional lift ...
Gerry's user avatar
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Helicopter induced velocity

I found this on one book I am now reading, and I dont uderstand how induced velocity is decreasing whyle climbing? And what is the difference between induced velocity and inflow velocity ?
cirica's user avatar
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Does a cyclic in a helicopter essentially control rotor attitude?

So the basics of helicopter control as I understand it, at least, in terms of roll and pitch, are as follows: A helicopter is caused to move through space by means of tilting the main rotor disc, ...
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Why is the helicopter rotor brake easily accessible?

According to this article, a rotor brake is dangerous to use in-flight, yet it's easily accessible and the pilot's reaction indicates that it would've deployed mid-flight. Why is the brake so easily ...
Ahmed Tawfik's user avatar
4 votes
4 answers
360 views

What, if anything, could actually cause one helicopter blade to be more eroded than the others?

Does this scenario in which one blade is more eroded then the others commonly occur with real helicopters? Even if it does, Julio's explanation is obviously wrong; what actually causes it?
Someone's user avatar
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Why phase lag on helicopter blade is sometimes 90°, and sometimes less?

On semi rigid rotor head, phase lag is 90°, and also the advance angle between pitch link and coresponding blade. But of fully articulated rotor the phase lag is less then 90°, and also the advance ...
cirica's user avatar
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2 votes
2 answers
375 views

Helicopter blades flapping with the cyclic – can you help with the explanation?

I am now reading books about helicopter aerodynamics. And I have one question about blades flapping. If you push forward on the cyclic, the swashplate will tilt forward and will set the maximum pitch ...
cirica's user avatar
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Would military aircraft jam TV signals?

Various military aircraft just flew overhead on their way to the Trooping of the Colour in London. At the same time, my Television's signal went completely dead, and then restored once they had gone. (...
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What is the approximate lifespan of H125 helicopter

What is the lifespan of the Airbus H125 helicopter used by law enforcement agencies?
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Why do heli PC2 operations require highest obstacle clearance

In designing a helipad I notice that the Australian requirements (AC139.R-01) for obstacle clear gradients specify that the slope category (12.5% slope) generally applies to PC2 operations, whereas ...
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