WIND SPEED AND DIRECTION

 

Ever since childhood I have been mad on aeroplanes and flying in them. I even still have an early 1930s book I bought on how to fly an aeroplane, written by W.E. Johns (who wrote the Biggles books).  It is called The Pictorial Flying Course.

The principles of flight since then have hardly changed. The aerodynamics still encompass lift, weight, thrust and drag.

In those far off days aeroplanes were biplanes and airports were grass fields (like London’s main airport, Croydon Aerodrome). 

To enable an aeroplane to fly then as now, it needs a wing (or wings) with the curved shape of an aerofoil section to provide lift. And despite immensely powerful jet engines they still use nature’s wind speed for taking off and landing (as do birds).

So, since those Biggles days, pilots have needed to know the wind direction enabling them to take off into the air quickly (into wind) and land slowly and safely (also into wind). So then, as now, a weathervane of some sort is needed.

In those olden grass field days, before landing, a pilot in the air needed to know the wind direction. So someone on the ground looked at a weathervane and rotated a large letter T and pointed the cross-piece toward the breeze. Then the pilot could look down and land into wind. Radio communication now covers the visual side of things, but a weathervane is still needed.

I once had a job as a prop-swinger, starting up the engines of Tigermoth biplanes for trainee pilots.  A weathervane or T indicator mounted just above ground level told us the wind direction for takeoffs and, from the air the T for the pilots to land. With cross winds we might have to run along beside the biplane holding on to the wing-tip to prevent the aircraft from tipping over.

There was no weather forecasting in those wartime days, so to prevent the disaster of  pupils killing themselves, an experienced pilot would refer to a weathervane and fly upwind for a period of time to ensure that good, cloud-free weather would arrive. He would then fly back over the field and stick his arm out into the strong slipstream with his thumb up. Then off would go the students until each could fly solo. (I went through it all later when learning to fly.)

Having bought a house on a hill north of Andover, in Hampshire, and when writing, running a house, garden and children, I decided to design (for myself) some weathervanes using different designs and methods of rotation. 

It was not the first time for me, since soon after the war I designed and helped to built a studio house, and decided to top it off with a weathervane in the shape of a rose (a family flower.) Made of copper, lead and iron rod, it turned out to be too large for the house and was discarded. (Years later it was recovered from a hedge and exists now as a wall decoration in someone’s house.)

My new experimental weathervanes were mainly based on sheet copper, copper tube and reinforcing rod, the most successful being a rather nasty-looking cottage garden or seaside type of a four bladed propeller with a simple vane. It not only worked splendidly but also indicated wind speed, and did both right in my garden for all to see on a fruit cage corner post. 

However, the most interesting and fun one was made from a swivelling plastic drainpipe with a vane at one end and at the other a large plastic funnel, stuck in with glue. It was to attract animal and bird life to the garden and food. To do this an ultrasonic dog whistle was fixed to the funnel’s spout end. Thus, always turning into wind, the air would be scooped in through the funnel’s wide opening to blow the whistle.

The idea was fun but was impossible to discover if it ever worked, as our ears are not tuned into the frequency of noise that wild creatures are able to hear.

But it was successful for one creature - a spider, who strung its web over the funnel’s opening to catch its prey from the incoming wind. But it also made its home in the funnel’s tube, blokking it. This object had succeeded in indicating wind direction and gave a spider an excellent home with its meals blown into its web on the wind. So, in one way, it may have been successful and not in another. 

My weathervanes were as nothing compared with one used by the Admiralty in Whitehall, London. It is a roof weathervane with a spindle stretching downward to the grand ceiling of a room with an internal weathervane on the ceiling directly beneath it. Here, Admirals could see if favourable winds would aid our navy to set sail and beat up the French, Dutch and Spanish Gallions.

I did much the same in my dockland home and added to the ceiling a painted map of the Thames to make wind direction more clearly related to the landscape.

There was, with mine, the added pleasure of attaching Christmas decorations to the internal pointer, swinging silver balls around as the wind outside eddied and changed direction.

Weathervanes are sometimes necessary and their design often imaginative and usually fun.