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80 votes
Accepted

Do helicopters use more fuel when hovering?

Yes it is correct that helicopters use more fuel when hovering: the engine needs to apply more power to overcome drag. Here is a graph of the engine power required for different airspeeds, from J. ...
Koyovis's user avatar
  • 61.8k
50 votes

Can a helicopter carry a large airplane?

If you look more closely, this "airplane" is only the husk of a Tupolev Tu-134, a rather small airliner, and the helicopter is a Mil-26, the heaviest helicopter ever to go into production. Not only ...
Peter Kämpf's user avatar
42 votes

Do helicopters use more fuel when hovering?

Yes, it is correct, if the helicopter doesn’t fly too fast. A helicopter will produce the necessary lift most efficiently at a moderate forward speed. In a hover all the airflow which is available ...
Peter Kämpf's user avatar
38 votes

Would a helicopter with the blades on the bottom fly the same, if at all?

Yes that is possible, like the Hiller flying platform demonstrated. It had two counter-rotating propellers inside a shroud and the pilot controlled his craft by shifting his body weight, like on a ...
Koyovis's user avatar
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36 votes
Accepted

Can a helicopter really fly with rotors going this slow?

It's an illusion that the blades appear to be going slowly. It's actually a well known effect called the wagon wheel effect. Essentially the rotor is spinning at close to an even multiple of the ...
ratchet freak's user avatar
30 votes

Do helicopters use more fuel when hovering?

Yeah, I'm not a physics student, but I work on Black Hawks. If you conceptualise a helicopter as just a main rotor disc producing lift, then Peter Kampf's answer about mass-flow through the rotor disc ...
James's user avatar
  • 301
26 votes

Why does a turbine helicopter need to spin a tail rotor?

Well, that’s complex. Where should I begin? The main job of the tail rotor is to use its long lever arm and directed force/thrust (horizontal lift) to counteract the torque of the spinning main rotor....
Dean F.'s user avatar
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25 votes

Would a helicopter with the blades on the bottom fly the same, if at all?

We spend all our weekends mowing lawn with these guys. Courtesy: Helifreak.com You can find thousands of Youtube videos showing how comfortably they can do that
Hanky Panky's user avatar
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20 votes

Do you know the exact model and use of this rotorcraft?

It's a Bell TH-57, most likely a TH-57C, which is the Navy's variant of the Bell 206 JetRanger. It's used for VFR and IFR helicopter primary flight training for the Navy and Marine Corps. Most ...
Romeo_4808N's user avatar
20 votes

Do helicopters use more fuel when hovering?

The concept is known as "translational lift". When moving in forward flight, a helicopter's rotor disc acts a lot like an airplane's wing - it has a significant lift-to-drag ratio. The required ...
pericynthion's user avatar
  • 4,640
17 votes

Can a tiltrotor fly safely with one engine?

Short Answer: yes. If they could not, they'd likely not get certified One engine can drive both prop rotors. After digging into an old version of the V-22 flight manual, I find a whole pile of tables ...
KorvinStarmast's user avatar
16 votes
Accepted

How do the Kaman K-225 rotor "planes" work?

These are a form of servo flap, commonly found on Kaman designs, but also on at least one early helicopter (namely, a coaxial rotor aircraft built by d'Ascanio (shown below): As opposed to ...
Marius's user avatar
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14 votes

Would a helicopter with the blades on the bottom fly the same, if at all?

One of the first helicopters that really flew (c. 1918) was the 'Petróczy-Kármán-Žurovec', intended to be used by the Austro-Hungarian Army as a tethered observation platform. The observer stood above ...
xxavier's user avatar
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14 votes

Why do helicopters typically have blades at the top?

Yes the answer is that simple, that mincer needs to be out of the way so it doesn't chop peoples' head or feet off, or slashes into a bit of concrete and shatters into 100 pieces scattered around like ...
Koyovis's user avatar
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14 votes
Accepted

Can a tiltrotor fly safely with one engine?

This concern was one of the major design challenges in the development of tilt-rotor VTOL craft. In every flying example I'm aware of, it was solved one of two ways: either the engines were embedded ...
Zeiss Ikon's user avatar
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13 votes
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What is the reasoning behind Kamov twin-rudder design?

It's kind of a hard one. It looks like in this helicopter directional stability is a challenge because: the tail arm is quite short; there is no tail rotor, which provides directional stability just ...
Koyovis's user avatar
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12 votes

Is it more efficient to have many or a few rotors?

The problem with many propellers is that more of the propeller slipstream will flow around wings and tail. The higher local flow speed might be beneficial if you want blown flaps, but for regular ...
Peter Kämpf's user avatar
12 votes

Is it more efficient to have many or a few rotors?

Rotors need something to power them and the current generation of aircraft (once you get bigger than model size) burn hydrocarbons to get that power. If you want twelve rotors, then you either need ...
David Richerby's user avatar
12 votes
Accepted

Why do helicopter rotors have constant section and angle of attack?

Helicopter blades do have twist. The relative air speed increases from blade root to blade tip, and therefore on an untwisted blade lift would increase quadratically from root to tip. Or going the ...
Koyovis's user avatar
  • 61.8k
10 votes

Would it take 7 to 10 times more energy to lift a turbofan-helicopter?

Helicopter rotors are very large precisely for that reason. Lift from a rotor (or thrust from a propeller or fan) is obtained by accelerating a given mass of air m to a velocity v. The thrust obtained ...
xxavier's user avatar
  • 11.1k
10 votes

Do helicopters use more fuel when hovering?

When in a hover, the air has more time to setup into an induced wash from further upwards that translates into higher down flow speed by the time the induced wash reaches the plane of the rotor. When ...
rcgldr's user avatar
  • 504
9 votes

Can a helicopter really fly with rotors going this slow?

Life is full of illusions and many things give similar illusions. Strobe lights are popular with dance and and other entertainment venues. One game was to adjust the strobe timing so a spinning wheel ...
Gilbert's user avatar
  • 191
8 votes

Why are RC rotor blades different from helicopter blades?

If the rotor was mechanically strong enough to lift the desired weight It wouldn't be. Because of the square-cube law, lift and mechanical strength grow with second power of linear size, but weight ...
Jan Hudec's user avatar
  • 56.3k
8 votes

Why does a turbine helicopter need to spin a tail rotor?

The turbine output is very hot and therefore needs to be shielded in some way if it is to be routed through any part of the helicopter. This shielding adds cost and weight, so it's generally avoided. ...
Roger Lucas's user avatar
7 votes

How does a helicopter hover?

A helicopter can hover without the CoG being directly underneath the rotor hub, because the rotor hub can apply hinge moments: Fully articulated hubs with a hinge offset and fixed hubs apply direct ...
Koyovis's user avatar
  • 61.8k
7 votes
Accepted

Helicopter mast bumping in low g condition

The answer is yes it could be used in that flight profile as the pilot of that AS300 was never in a low G condition with the rotor unloaded during those maneuvers. Once he dropped the concrete, ...
Romeo_4808N's user avatar
6 votes
Accepted

Is there a disadvantage to the "fan in fin" design seen for the tailrotor on many Eurocopter helicopters?

The fenestron is a lot heavier than a free tail rotor. This is probably the main disadvantage; helicopters are more sensitive to extra mass than aircraft. At the time Eurocopter was produced by ...
Peter Kämpf's user avatar
6 votes

Would it take 7 to 10 times more energy to lift a turbofan-helicopter?

A turbofan helicopter must also take off by producing at least the thrust equal to the TO weight. With turbofans, the static thrust at zero speed is very much determined by the bypass ratio. You're ...
Koyovis's user avatar
  • 61.8k
6 votes

Do helicopters use more fuel when hovering?

Another point to consider is whether helicopter has supplemental wings. Rather famous example is Mi-24 family of attack helicopters, where weapon pylons works as wings. "At high speed, the wings ...
Severin Pappadeux's user avatar

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