Sycamores

Strange things helicopters …

The Norfolk and Suffolk Aviation Museum has four helicopters on display, unusually in our collection they are both pairs. Two Whirlwinds and two Sycamores.

This article is primarily interested in the Sycamores. The first is an ex RAF example ( BRISTOL SYCAMORE HR.14 – XG518 ) and is displayed as an Air Sea Rescue version. Sycamores were based at Norwich Airport when it was an RAF Station known as RAF Horsham St Faiths.

The second airframe is ex-Army ( BRISTOL SYCAMORE HR.14 – XG523 ). It was involved in a heavy landing which damaged it beyond economical repair to flying condition. It was converted to a rig used for training engineers. The control runs to the main rotor are still in place and still work. This is not always a blessing as will be seen later.

We did fit an electric motor to the gearbox to rotate the blades and demonstrate the complex way in which helicopters fly. Unfortunately, we currently have an oil leak in the gearbox which makes a terrible sound if you try to turn it. Sorting that out is on our list of projects.

As can be seen from the photographs below there are three main controls in a helicopter. There is a conventional control column which does unconventional things, a set of rudder pedals, and a device known as the collective. The rudder pedals would usually control the tail rotor via a complex mechanism to increase or decrease thrust on the tail rotor, and thus twist or yaw the helicopter left or right. This helicopter doesn’t have a tail, so this mechanism doesn’t work as such.

The control column changes the pitch of the main rotor, in a helicopter the column is also known as the cyclic. The pitch is increased on the blades as they pass the direction opposite that in which the column is pushed. As each blade rotates the pitch increases and decreases. Clever eh! The helicopter will tip and move in the direction that the column is moved.

The collective raises and lowers the pitch of all the blades at once. As you pull the lever up the helicopter goes up, as you lower it the helicopter goes down. Obviously going up takes more ooomph, so at the top of the lever is a twist grip such as you would find on a motorbike. Twist it one way to increase power, the other to decrease.

As may be realised flying a helicopter is rather harder than an aeroplane, but it will do things that aeroplanes can only dream of.

We have further modified this helicopter, by means of various links the controls are connected to a computer running X-Plane flight simulator. A large screen has been installed inside the cockpit so that visitors can pit their abilities against this 1950s helicopter.

Images of the Sycamores including simulator showing gearbox and interior (Click to enlarge)

Remember that as you move the controls, you are moving not just computer links, but also the rotor blades. Thus it is quite difficult to work, in addition to being tricky to fly. I was once told by as former Sycamore pilot that this is quite realistic. We open the simulator up on various event days and some days across the school holidays. For every flight where a successful sortie is flown, at least 20 end in a crash.

If you want to try your hand at flying this beast, keep looking at our events calendar and blog. We will usually post in advance days it will be running.