Which helicopters have two rotors?
Two big rotors, one at each end and no tail rotor, is a CH-47 Chinook. Two rotors on the wingtips that tilt forward is a V-22 Osprey, which is a tiltrotor rather than a helicopter. Rotors that mesh side by side (the K-MAX) or stack on one mast (Kamov) are rare in US, UK and Australian skies.
Why most helicopters have one rotor
A spinning rotor tries to twist the helicopter’s body the other way. Most helicopters fix that with a small tail rotor pushing sideways. Helicopters with two main rotors don’t need one: the rotors turn in opposite directions and cancel each other out. So the first thing to check is the tail. No tail rotor usually means two main rotors.
Front and back: the Chinook and the Sea Knight
The CH-47 Chinook is the twin-rotor helicopter you’re most likely to see by far. It has one big rotor on top of the cockpit and another on a tall tower at the back, over a long, boxy body. It’s a heavy-lift helicopter, flown by the US Army, the RAF, the Australian Army and many others, and civilian Chinooks fight fires and haul logs. You often feel its deep, rhythmic thump before you can see it, and Chinooks often fly in pairs. Why military helicopters fly over houses.
The CH-46 Sea Knight is the Chinook’s smaller cousin, with the same front-and-back layout. The US Marine Corps retired its last ones in 2015, replacing them with the Osprey. A few civilian versions, called the Vertol 107, still work as firefighting and heavy-lift helicopters. If a twin-rotor helicopter looks noticeably small, that may be what you’re seeing.
On the wingtips: the Osprey
The V-22 Osprey has two huge rotors, one on each wingtip, mounted on engine pods that tilt. It takes off and lands like a helicopter, then tilts the rotors forward and flies like a turboprop plane, much faster than any helicopter. That makes it a tiltrotor, not a helicopter. The US Marines, Air Force and Navy all fly it. From below, a plane with oversized propellers that seem far too big for it is an Osprey.
Side by side: the K-MAX
The Kaman K-MAX has two rotors on masts set close together and tilted outward, so the blades mesh like an egg beater as they turn. It’s a narrow, single-seat flying crane built for one job, lifting heavy loads on a cable: logging, firefighting and stringing power lines. You’ll see one over a forest or a fire, not over a city.
Stacked: Kamov
Kamov helicopters stack two rotors on one mast, one above the other, turning in opposite directions. The body is short and compact, with no tail rotor. They’re mostly Russian, though some civilian Ka-32s fight fires and lift loads in other countries. In US, UK and Australian skies they are very rare.
Two engines is not two rotors
Plenty of helicopters have two engines driving a single rotor. The Black Hawk and the Apache both do, and both have an ordinary tail rotor. The H135, a common air ambulance and police helicopter, hides its tail rotor inside a round shroud in the tail. None of these count as twin-rotor.
At a glance
- Rotor at each end, long body: Chinook (or, smaller, a Vertol 107).
- Rotor on each wingtip, wings and a tail: Osprey.
- Two rotors crossing side by side, skinny body: K-MAX.
- Two rotors on one mast, stubby body: Kamov.
- One rotor and a tail rotor: everything else. Here’s how to tell those apart.
