I’d like to call this research….

But its also having fun with a kite.

The kite was given to me as a Christmas present by my son (aged 23 at the time, him not me).  It’s a small kite which fits easily into a pocket and would be ideal for business people.  One can imagine herding the participants of a meeting into the car park and sending the kite aloft.  Then point upwards and exclaim “that’s were we should be”, followed by a profound silence and the sensible one saying “shall we go back inside now?”.

Despite a complete lack of electronics and telemetry, the kite gives an insight into the the nature of wind at heights between 5 and 25 metres (maybe higher, I replaced the original string with a longer one and its still climbing).  Last Saturday when the wind was blowing 3 – 4 m/s, I took the kite to two different locations.  The first was a beach where the wind was coming in off the sea and the second was a public park in an urban area a mile or so north of the seafront.  The behaviour of the kite was significantly different at each site.

On the beach, the kite effortlessly took to the air and was stable at a height of 5m and the trailing streamers had no difficulty in keeping it head up to the wind.  Once the string was fully unwound, the kite sat comfortably in the sky, maybe with the odd flutter, but I was able to hook the handle on to the bike and take the photo at the top of the page.  After half an hour, I felt guilty about bringing it back to Earth.

At the park, things were different.  I almost pointed out to the man mowing the cricket pitch who cast disapproving looks in my direction, that what he was going to do on the grass later in the day was no less ridiculous than what I was doing but life’s too short for pointless conversations.  Here the kite  struggled with turbulence up to, say, 15m and getting it airborne required many attempts, hoping that it would acquire enough upward motion to counter any downward influences.  With patience, it was possible to get the string fully extended, but the kite was never stable and was prone to twisting and each twist tied a small knot in the string.  I suggest that the number of knots in a kite string is a measure of wind turbulence.  Nor did the kite stay aloft.  Typically in urban areas, wind is not a smooth stream of air, but a series of gusts, often with significant gaps between then, it was in these gaps that the kite spiralled to the ground.  The kite suggested that conditions measured at 2m, extend upwards to at least 25m.  It was also clear that wind speed increased with height, even though the turbulence persisted.

When the next opportunity presents itself, I will take the kite into the hills to the north of the town, just because its fun.

PS – 18-Apr-2014 – I found myself on the same beach yesterday, this time the wind was coming from the NE and was blowing from the land to the sea.  The turbulence that is observable inland made it hard to get the kite airborne and once aloft, it started to drift earthwards as soon as a gust had subsided.


About SolarBucket

I trained as a mechanical engineer in the 1970's and then spent most of the following 25 years doing sums and software for Oil and Gas Exploration. Current interests are the study of wind and solar resources.
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