Coaxial Helicopter
From EFlightWiki
A "coaxial" helicopter refers to a helicopter that has two sets of main rotors, one above the other. These rotors spin in opposite directions, while producing lift in the same direction.
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How they work
Coaxial helicopters use two sets of counter rotating blades. The yaw torque from one rotor is canceled by the other so no tail rotor is required. These helicopter usually have a 45 degree flybar on the top rotor similar to the PiccoZ, which makes them very stable (Like the PiccoZ they will hover with no input from the pilot). The lower rotor has a swashplate, which allows the helicopter to move in any direction.
The blades are typically attached to two drive shafts, with one drive shaft running through the center of the other. The lower set of blades is driven by the outer shaft, while the upper blades are driven by the inner shaft.
You may notice that your coaxial helicopter has a horizontal tail rotor. Some models use this rotor to tile the helicopter forwards and backwards to control forward/backward flight. These models do not have a swash plate on the lower rotor and cannot fly sideways.
Advantages
As stated above, this design stabilizes the helicopter automatically. Also, coaxial helicopters can lift a greater payload at the same engine power than a single rotor of the same diameter.
Many coaxial models are also fairly small and durable, which makes them very well suited to indoor flying. Some pilots use coaxial to practice their orientations.
The lack of tail rotor also makes the helicopter easier to fly because it greatly reduces the sudden changes in torque experienced by a conventional helicopter as the load on the main motor is changed.
Disadvantages
Coaxial helicopters are typically not as fast or manoeuvrable as single-rotor helicopters, which makes them more prone to being effected by winds. Top speed is about walking pace and it is often not possible to fly against winds that are so light as to be imperceptible.
They are slightly more prone to damage than a micro Fixed Pitch helicopter, because the blade speed is higher and the parts are smaller and a little more complex.
This type of helicopter would best suit:
This type of helicopter would best suit someone who wants to dabble in helicopters without making a big commitment of money or time. They are great for flying around the house where the limited top speed isn't an issue.
