Advantages and disadvantages of single-rotor and coaxial helicopter schemes

In the USSR, there were simultaneously two schools of helicopter engineering: Mil and Kamov. The followers of Mikhail Leontievich Mil are sure that the best scheme for a helicopter is a single-rotor one. At the same time, the students of Nikolai Ilyich Kamov consider the coaxial design to be more preferable.

By the way, the first stories the helicopter (if that device can be called that) was built exactly according to the coaxial scheme, which for a long time was considered the only one suitable for rotorcraft. However, in 1939, Sikorsky's single-rotor apparatus took off, ushering in an era of rivalry between adherents of each of the above schemes.

To this day, both types of helicopters are produced and operated in Russia. At the same time, it is difficult to say which scheme is better - single-screw or coaxial. Each of them has its own advantages and disadvantages.

So, helicopters with two propellers experience increased drag. In addition, such a machine runs the risk of crashing due to overlap (this happens) of the propellers. Finally, the absence of a tail rotor contributes to the helicopter's lesser stability and worse yaw control at low altitudes.

However, the absence of a tail rotor is also an advantage of machines built according to a coaxial scheme - they are more compact, which makes them ideal helicopters for fleet.

At the same time, the presence of a tail rotor is the main disadvantage of single-rotor machines. Firstly, the long tail boom increases the weight and dimensions of the helicopter. Secondly, the tail rotor takes about a fifth of the engine power. Thirdly, the failure of the tail rotor makes the car uncontrollable and ends with an inevitable crash.

The material is presented in the Video section. Information about variants of schemes for helicopters - in the video:

Comments

[Mavrikiy]

Advantages and disadvantages of single-rotor and coaxial helicopter schemes

Thank you, very informative.

[tolancop]

About nothing. Extremely empty material. The author was even too lazy to dig in the net, otherwise he would have found that the tail rotor scheme is Yuryev, and not Sikorsky.

[Bad_gr]

In addition, such a machine runs the risk of crashing due to overlap (this happens) of the screws .....

And helicopters with one main rotor sometimes cut off their tails.
In a single-rotor scheme, a fenestron can be installed instead of a simple tail rotor. For example, the Kamov Ka-60 Kasatka helicopter (also the Ka-62)

When creating the Mi-24, they tested it the same

The MD 520N helicopter of the American company McDonnell Douglas Helicopter on its helicopter used a fan with a NOTAR jet device to compensate for the reactive moment of the main rotor.

The NOTAR system consists of a rotatable, lattice-nozzle jet rudder mounted at the end of the tail boom. Air is supplied to the jet rudder through a channel inside the tail boom, pumped by a single-stage fan driven from the main gearbox. Fan speed 5388 rpm. The jet rudder can be rotated to balance the main rotor jet joking moment and directional control as well as longitudinal control. In addition, there are longitudinal slots in the tail boom through which part of the air blown by the fan is blown out. The air flow thrown by the main rotor blows around the tail boom, and interacts with the air flowing out through the slots due to the well-known Coanda effect, creating a lateral aerodynamic force on the surface of the tail boom, which also helps to balance the reactive torque and reduces the total power consumption for balancing the reactive torque. The NOTAR system has been extensively tested on experimental and prototype helicopters, demonstrating high reliability and low noise levels.

In the Mil design bureau there was a single-rotor helicopter without a reactive moment from the main rotor (Mi-7). The rotation of the main rotor due to jet engines at the ends of the blades. The tail rotor is only for taxiing.

Quite an interesting scheme of a helicopter with overlapping rotation of the blades (syncrocopter). She, like the Kamovskaya, does not need a tail rotor.

[dfk-80]

The case when the comments are much more useful than the article itself.

[mat-vey]

Quote: dfk-80

The case when the comments are much more useful than the article itself.

Uh .. they took it off the tongue

[Sergei N 58912062]

Quote: dfk-80

The case when the comments are much more useful than the article itself.

I agree with you.

[dmiitriy]

And how is the synchrocopter in terms of reliability? In principle, if the blades have a common drive, then there should be no problems, and if they clashed, then this is a consequence of more serious problems.
But why aren't they widely used? The compactness of a coaxial, but without complicating the shaft to a screw and swashplates.

[ailcat]

1. Increased vibration level and reduced fuselage life due to resonant loads on the fuselage (note how the modern - yellow - synchropter is compressed).
2. Extremely high complexity of the swashplate and transmission (more difficult than on coaxials - while the synchropter implements only part of their advantages).
3. Almost complete impossibility to land on an inclined platform (and without stopping the propellers, passengers cannot be disembarked due to propeller disks close to the ground).

[vovochkarzhevsky]

What the hell is this video? The coaxial scheme was proposed by Lomonosov back in 1754.
And in general, here it is the first really flying helicopter, 9 years before Sikorsky.

[Buyan]

And I have a book autographed by Sikorsky's son and co-author ... curious material ... it's a pity that the revolution squeezed Sikorsky's talent out of Russia. By the way, Ilya Muromets is also his creation

[mat-vey]

"However, in 1939, Sikorsky's single-rotor apparatus took off" -
However, in 1912, Yuryev built his own helicopter with the help of the student circle of the Technical School. And its swashplate is used to this day. And on the first and subsequent Sikorsky machines, including ..

[Sergei Kazarin]

3 types of attack helicopters and in reality all three are obsolete.
Without long-range missiles, everyone is useless

[Sergei Kazarin]

Everything except the Mi-28 is scrapped without wasting resources.

[Buyan]

Quote: Sergey Kazarin

Everything except the Mi-28 is scrapped without wasting resources.

Why?

[Sergei Kazarin]

Why is it needed without an overhead radar

[Realist58]

Guys, didn't you recognize the voice of the author of the video? Yes etozh ukromraz mark corned beef. Russophobe, anti-Soviet, and just an extremely vile henchman of Tan.

[Raymond]

Quote: mat-vey

"However, in 1939, Sikorsky's single-rotor apparatus took off" -
However, in 1912, Yuryev built his own helicopter with the help of the student circle of the Technical School. And its swashplate is used to this day. And on the first and subsequent Sikorsky machines, including ..

L'inventeur du pilotage "cyclique" (variation continue du pas des pales) est l'ingénieur Pescara. Et Juan de la Cierva est l'inventeur du pilotage "direct", après avoir inventé "l'axe de battement vertical".

[Alexandre]

The Ka-52 has a very strong vibration. This is also due to the coaxial screw.

[ailcat]

Key:
"coaxial" hangs well (less prone to slip and the formation of a vortex ring),
"classic" flies well (less drag and higher directional stability).
The rest is trivia.

[JPD]

I would like to know what the author has to do with the published topic? It seems that the text is typed from the study of technical popular literature ... Both products are good for their specialized application. Read Isakson or Volodko, maybe expand your horizons of knowledge ...