# Does a dual-rotor helicoptor like the Chinook transition from hover to forward flight differently than a single rotor helicopter?

I watched this video of an RAF Chinook taking off vertically and transitioning to forward flight.

I'm curious if the method for increasing lift to move forward, controlled by the cyclic in a single rotor if I'm not mistaken, is different when you have two rotors along the length of the aircraft. My untrained assumption is that to lift the rear of the helicopter and start moving forward, you would increase power or the collective on only the rear rotor.

• May just be pitch changes on both rotors Apr 8, 2020 at 22:08

The cyclic (dubbed control stick for the CH-47) takes care of that, not separate collectives (there's only one collective for both rotors per seat).

For forward flight, the pilot moves the control stick forward; the thrust of the aft rotary wing is increased while the thrust of the forward rotary wing is decreased, causing the helicopter to move forward. Since there is a large range of longitudinal control, high forward speed and extremes in center-of-gravity travel are inherent.

Source: CH-47 familiarization manual (see pages 55-56; PDF; 40 MB)

• Very good doc(pdf) but where is the citation(pages ?) Apr 10, 2020 at 8:08
• From pilot point of view, it is cyclic, but mechanically it is differential collective and the description clearly says so. Apr 10, 2020 at 13:44

First

-collective variation = intensity

-cyclic variation = direction

The CH-47 Chinook is a heavy maneuver and assault helicopter manufactured by Boeing. Its two tandem rotors (set of horizontal rotors mounted one in front of the other) are counter-rotating and are controlled synchronously in stationary and in translation, thus their torque effect is canceled out by their opposite direction of rotation. It is equipped with two turboshaft engines with a power of 2,850 hp to 3,750 hp,(help to moving forward) with a maximum weight of 18.5 tonnes. Photo below we see that the rear rotor is raised relative to the front rotor.

an asymmetry of the lift between the 2 rotors implies a tilting along its pitch axis and causes the device in forward flight.the tandem rotors are very bulky and not very maneuverable, which constitutes their main defect. Note also that the lengthening of the fuselage makes them more sensitive to strong wind

So it's mostly like an helicopter with one rotor( cyclic variation to move forward) but a few different.your hypothesis is not really right because the two rotor are connected and are controlled synchronously in stationary and in translation(same speed) The main MGB gearbox is interconnected with the shafts of the two turbine engines. A seven-section shaft connects the main gearbox to the front gearbox, and a two-section shaft connects the main gearbox to the rear gearbox. The oil cooling fan is driven by the rear gearbox.