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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34
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2answers
9k views

Why do helicopters have windows near the pedals?

What is the purpose of the clear windows in some helicopters in the floor of the nose, right where the pilot's feet and pedals are? For example, here's a Huey with windows clearly visible: Airbus ...
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3answers
100 views

Autorotation: Positive Pitch during descent phase possible?

I was wondering if a rotorcraft, that descends very slowly compared to its nominal rotor rotation rate (for example an RC Helicopter vertically autorotating with 3m/s descent rate and 2200RPM on the ...
-3
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1answer
138 views

Did NASA just broke the world record for fastest aircraft by going over 10 times faster than the previous record?

The current world record is held by the Lockheed SR-71 Blackbird. In 1976, this aircraft reached a top speed of 3,529.6 km/h, according to Wikipedia. Fast forward 44 years, and NASA just launched the ...
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2answers
315 views

Is there other option than a Chinook to transport 2 cars simultaneously?

If a civilian wants to fly between homes several hundred miles apart AND carry 2 cars with him what are the options other than a chinook?
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0answers
105 views

Are there any true aerobatic helicopters that aren’t built around the Bo-105?

I know that some aerobatic maneuvers have been performed (legally or otherwise) in many different models of helicopters. However, to my knowledge, I have only heard of Bo-105s being specifically ...
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0answers
32 views

What are the expected vibration frequencies in a co-axial rotor system with contra-rotating propellers?

I am trying to understand the frequency spectrum of a co-axial rotor system. Form now i have a RC helicopter with two sets of three gear systems arranged in parallel, The number of teeth are 7,23,27) ...
3
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3answers
243 views

Is PVC tubing a good material for helicopter airframes?

Been thinking of getting into the hobby of building ultralight helicopters, and would PVC tubing be a good choice to build the overall airframe?
3
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1answer
120 views

CH-37 Mojave Helicopter decibels

What was the decibels level for the Sikorsky CH-37 Mojave Helicopter? 1956 --1959. I need this information for the VA, to process my hearing claim. I was a crew chief in the Army.
6
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3answers
296 views

What is the helicopter in the background of this image of the V-22 Osprey?

I found a photo of a V-22 Osprey alongside an unknown helicopter on the left corner:
3
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1answer
132 views

How does a bearingless rotor work on a helicopter?

I have read about some helicopters now using a mechanism referred to as a "bearingless rotor". From what I've seen online, the system involves a flapping hinge. What I struggle to get my ...
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1answer
280 views

What were those two military helicopters that I recorded?

I have recently recorded two military helicopters. Here is a screenshot of it:
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2answers
136 views

Helicopter retreating blade stall: Increasing the fwd speed decreases the tip speed on retreating side and angle of attack. So why limit on V_n.e?

On Retreating side: Speed of wind over blade tip = blade rotation speed - forward speed. So, with an increase in forward speed, the speed of the wind over tip is getting reduced. In airflow diagram, ...
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3answers
3k views

Why do helicopter operations avoid IFR?

In almost any airplane commercial operation, unless you’re doing something very short haul daytime ops, an Instrument Rating is all but required with airplanes(it’s even in the FARs). Generally the ...
5
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0answers
111 views

How to say the name of this approach clearance: COPTER RNAV (GPS) 027°

JFK has this approach: https://aeronav.faa.gov/d-tpp/2006/00610COPTERR027.PDF How is this approach said on frequency? Is it the "copter RNAV zero two seven approach" or the "copter RNAV zero two ...
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2answers
409 views

What was this helicopter photographed on a Chinese aircraft carrier?

I've read this twit Chinese carrier got photographed by a satellite. On the nose you can find a helicopter and several people around it. What helicopter is that?
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2answers
156 views

Was flying a helicopter below building height against FAA regulations? [duplicate]

I'm referring to this incident: https://twitter.com/Dacheslow/status/1267638389421072384 Some people were saying it was illegal under FAA rules to fly that low and close to a crowd, and also to use a ...
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1answer
43 views

What are the applications, advantages and limitations of Gyrodyne rotorcraft?

Gyrodyne is a VTOL rotorcraft. It has ability to power both rotors and propellers for generating lift and thrust. What makes it of lesser popularity than helicopters. Are there any applications of ...
1
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1answer
102 views

Helicopter Basics: How does lead-lag of blades actually help in compensating for increase/decrease in speed due to flapping?

I understand the following - Due to dissymmetry of lift, flapping up and down occurs. Since angular momentum has to be conserved, the speed of blade increases/decreases during flapping up/down ...
0
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1answer
48 views

What does induced flow exactly means on helicopters flight? How is it different from downward deflection of air?

I believe all airfoils deflect air downwards at an angle at a velocity V. What is the difference between the downward-vertical component of the deflected wind and the induced velocity in Helicopter ...
2
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2answers
290 views

Helicopter flight: Does the rotor disc plane and hub plane rotate along axis perpendicular to rotational axis?

In many pieces of literature, diagrams as below are shown to explain the directional flight of Helicopter. I have the understanding that the cyclic input will only change the pitch angle of the blades ...
2
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1answer
103 views

What is this long Bar/Rod on the Boeing MH-47G? [duplicate]

This MH-47G has a thick, long rod at the bottom left front. What's the purpose of this thing?
8
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2answers
1k views

What is the purpose of a freewheeling unit in an helicopter, if a centrifugal clutch is already present?

Some helicopters such as the Bell 47 are fitted with a centrifugal clutch. Centrifugal clutch will engage only at certain engine RPM. If the engine fails, the engine RPM will reduce and the ...
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2answers
127 views

Helicopter Flight: What is the reason for decrease in Induced drag with increase in speed?

As per the figure the induced drag will decrease only if the AoA of the blade is decreased — But in the forward flight, cyclic input increases and decreases the AoA throughout the blade rotation cycle....
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1answer
105 views

Is it possible to start another engine of Mil Mi 8 with one engine started and APU off?

In the 737NG, it is possible to start the other engine without APU if one engine is already started, by routing air from the started engine to the other one. Is this possible in the Mil Mi 8 ...
3
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1answer
133 views

How are pitching and rolling moments transferred from rotor to the body?

When a rotorcraft pilot moves pushes on the cyclic control stick, the swashplate tilts so that angle of attack of the retreating blades increase and of the advancing blades decrease, which creates ...
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4answers
170 views

In helicopter's forward motion, how is the forward pitching moment taken care off?

When the rotor disk is in the position shown by the dashed lines, the net Lift is at an angle. It should produce a forward pitching moment about CG (Center of gravity). That can cause the helicopter ...
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2answers
122 views

Can you use a home built helicopter for solo hours?

I'm curious to know if anyone has heard of or has any knowledge of using a kit helicopter for the FAA required minimum solo hours of flight training.
2
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1answer
153 views

What methods are used for calculating maximum takeoff windspeed of a helicopter?

I would like to calculate the maximum windspeed in which a helicopter may safely take off and safely land, assuming a theoretical wind environment with constant wind direction and no gusts. I ...
0
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1answer
74 views

Are helicopter with coaxial rotors equiped with blade flapping mechanism?

Helicopters with coaxial rotors such as the Ka-27 don't need mechanisms to overcome dissymmetry of lift as there is advancing blades on both sides of the helicopter. A common mechanism to overcome the ...
0
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1answer
93 views

Are there any helicopters with tail rotors where slip-skid ball may be centered even when fuselage is streamlined to the airflow in cruising flight?

In a related answer, I stated "The tail rotor of a helicopter also generates an aerodynamic sideforce. Again, just as with the twin-engine airplane with one failed engine, when the fuselage is ...
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2answers
58 views

How is rotor airfoil analysis different than fixed wing airfoil analysis?

What the is difference between rotor airfoil analysis and fixed-wing airfoil analysis? Intuitively, it seems that the airspeed at the tip of a rotor blade would be more than that at its root. Wouldn'...
3
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2answers
252 views

Does a dual-rotor helicoptor like the Chinook transition from hover to forward flight differently than a single rotor helicopter?

I watched this video of an RAF Chinook taking off vertically and transitioning to forward flight. I'm curious if the method for increasing lift to move forward, controlled by the cyclic in a single ...
2
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2answers
93 views

Are a gyrodyne and a compound helicopter the same thing?

Both the gyrodyne and the compound helicopter are typically rotorcraft with driven rotor, additional stub wings and thrust provision. Are they two terms for the same thing or do they differ in some ...
0
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1answer
71 views

Rotor Tip Speed vs Forward Airspeed - IAS or TAS?

I created this graph to illustrate how the tip speed of the advancing and retreating blades vary with forward airspeed but am confused as to what would be the most correct way to label the x-axis: ...
16
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4answers
5k views

How do “tip jet” helicopters cancel the torque effect of the main rotor?

Some helicopters use "tip jet" on the rotor blades tips such as the McDonnell XH-20 Little Henry and Hiller YH-32 Hornet. How do they cancel the rotor torque (often canceled by the tail rotor)?
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1answer
127 views

Why do intermeshing helicopters use asymmetric airfoils?

I am referring to the Kaman K-max and the Kaman Huskie here. They both use NACA 23012, which is an asymmetric airfoil. Any reason as to why this is? Is there a different mechanic in play when ...
0
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1answer
179 views

Why there is a helicopter sitting north of madras, OR, , above the warm springs reservation every single night? [closed]

Every night I see a helicopter light above the reservation sitting in a spot above my house, but way up that I can't see it closely, just the light. Has to be a helicopter since it sits in one spot.
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2answers
88 views

What angle of deflection / pitch on the rotor blades can the controls generate?

I was wondering, if a pilot uses full input on cyclic and collective, what pitch angle can be achieved for the rotor blades? Is there a mechanical stop to prevent extreme angles of attack? And how ...
0
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1answer
319 views

Helicopter or Airplane, which is the most difficult to fly? [duplicate]

I know it varies from aircraft to aircraft, but I want to know in general, which would be the most difficult aircraft to fly even after years of experience. Helicopter or Airplane ? I tried to fly a ...
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0answers
60 views

Buy an aircraft to train first or after? [duplicate]

I'm thinking about learning to fly. Is it worth buying an R22/S300 or C172/Cherokee to train in then fly afterwards?
28
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3answers
6k views

Can helicopters create contrails?

Can some or all helicopters have contrails? If only some, why only those? If not, why can they not? Pictures would be really helpful. I do know that turboprops and piston props can leave contrails, ...
0
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1answer
86 views

How significant is the static buildup on the blades of the main rotor? And some questions related to this [duplicate]

1) Usually, a static charge is built on the helicopter when it flies through the air. If a person touches the helicopter before it touches the ground can that person get electrocuted because of the ...
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0answers
46 views

Jet Engine Cooling, HTC and cooling calculations

Right now I am working on a project about cooling systems in jet engines. And I don't have a supervisor to ask anything. I would like to know what is the most useful resource (book, analsys programs ...
6
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2answers
339 views

Do helicopter rotors have anti-ice systems like propellers and wings?

Icing disrupts the aerodynamic qualities of wings and props, is there a similar danger with helicopter rotors? Are there de-icing systems to prevent this?
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3answers
488 views

Why does the UH-1 Huey have a hump at the rear of the cabin?

Why does the Huey have this weird hump as shown in the picture? For some system? Why not remove it? https://www.helis.com/h2/uh-1h_seats.jpg
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2answers
264 views

What is the function of the Apache's Strap Pack?

I have recently been reading about the issues with the Apache's (AH-64) strap packs. I've read that the strap pack holds the rotor blades on to the hub. However, it appears the blade also connects ...
16
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2answers
6k views

How do helicopters avoid detection from enemies by using IR suppressors?

no IR suppressor IR suppressor All I know is that it blends the hot air before releasing it How does an IR suppressor help an aircraft avoid detection from a missile? Wouldn’t the entire ...
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1answer
196 views

What are the advantages of dual counter-rotating rotors vs coaxial rotors?

It just seems to me, as though, dual counter-rotating rotors are a much better solution (Chinook) than coaxial and that the center of gravity is offset to allow useful loads to be spread out. Even ...
3
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2answers
298 views

How does the Mi-26 tilt its rotor like this?

I watched this video on YouTube, which shows an Mi-26 taking off with its rotor tilted forward about 45 degrees. Is the video fake or is it real, and if it is real, how does the Mi-26 do such a thing?
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2answers
6k views

Why would helicopters not have black boxes?

Is there a legitimate argument against having a black box on helicopters? I'm assuming there must be reasons beyond financial ones?

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