79
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. ...
- 61.3k
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 ...
- 230k
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 ...
- 230k
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 ...
- 61.3k
37
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 ...
- 27.4k
28
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 ...
- 281
27
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....
- 16.5k
26
votes
Accepted
Is it possible to fly with counterbalanced single blade engines?
Both Bo-102 and 103 were experimental aircraft, with Bo-102 more of a jig than an actual aircraft. They were used a testbed for various technologies and the single blade rotor is only one of them , ...
- 100k
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
- 6,011
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 ...
- 72.8k
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 ...
- 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 ...
- 4,201
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 ...
- 3,671
15
votes
Can a helicopter carry a large airplane?
One of the purposes of the Sikorsky CH-54 was to transport aircraft.
Carrying a Chinook:
Lifting a Caribou:
- 1,120
14
votes
Accepted
How are folding wings managed?
The wing folding mechanisms (in aircraft) and rotor folding mechanisms (in helicopters) are different. The V-22 Osprey falls somewhere in the middle.
In case of aircraft, the wing folding mechanism ...
- 100k
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 ...
- 11k
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 ...
- 61.3k
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 ...
- 17k
13
votes
Can you help me to identify this helicopter?
The helicopter is a S-65C-3 Yas'ur (Albatross). It is a CH-53D version similar to USAF HH-53C Pave Low. Here is a photo of the same.
The identification is based on the following:
Six bladed main ...
- 100k
13
votes
Accepted
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 ...
- 61.3k
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 ...
- 230k
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 ...
- 11.9k
12
votes
Is it possible to fly with counterbalanced single blade engines?
The number of blades determine the solidity ratio of a propeller. If you need to limit tip speed and propeller diameter, the propeller will have a high solidity ratio by using many, short blades. Take ...
- 230k
12
votes
Accepted
What are the uses of gyroplanes?
Gyroplanes have quite a few applications, but the problem is that anything they can do, others (helicopters/fixed wing aircraft) can do better.
The main advantage of a rotorcraft is that they can ...
- 100k
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 ...
- 61.3k
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 ...
- 11k
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 ...
- 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 ...
- 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 ...
- 56.2k
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. ...
- 81
Only top scored, non community-wiki answers of a minimum length are eligible