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KAP in low winds

Cris

I had an interesting day with my 8’ Rokkaku a while back and thought I would file a report. Of late I have been trying to take photographs of a particular area in the South Bay salt ponds and it has proved a difficult puzzle. The target is former Salt Pond E8A, which was returned to tidal flow a few months ago after 150 years of being diked. The difficulty arises from the levee breaches that restored tidal flow as they also prevent access to the normally upwind sections of the levee from which I would stage.

On Sunday the National Weather Service teased me with a forecast for light winds out of the SSE. Such a wind would allow me to fly toward Salt Pond E8A from the southern side of the 500-foot-wide Old Alameda Creek flood control channel. When I arrived on site, there was the faintest of breezes, probably less than 2 mph, and it was out of the west – drat. I fooled around for an hour or so hoping things would freshen and they eventually did. The wind built into a steady flow of 4 – 6 mph as measured on the ground by my little Kestrel anemometer, still out of the west. While this did not look good for getting a camera aloft I decided it would be fun to try anyway.

The following sequence of images was taken as I coaxed my 3.5 lb. dSLR cradle to working altitude.

The Rokkaku aloft waiting for more wind.

I started by getting my 8’ Rokkaku rigged and flying. It was happy indeed to fly in a 4 mph breeze but did not generate much lift. After flying for 10 minutes I pulled it down and adjusted the bow lines to a minimum bow and that helped a bit. Without much hope for success, I attached my Picavet to the kite line and rigged the dSLR cradle. I then stood there watching my camera fly a foot or so off the ground for a few minutes.

The camera cradle is launched. I am lifting the anchor line tied off to my trailer hitch in order to keep the camera cradle out of the dirt.

With little else to do, I tracked the wind with my anemometer. And every now and then the wind would increase by 1 mph or so from its otherwise steady 4-5 mph. When those slight increases occurred I could feed out a little more line. The camera stayed near the ground during this process but eventually more kite line was in play.

Like a rabbit the camera hops away. This is a minute into the first increase in wind.

The 8’ Rokkaku is flying well and the breeze is consistent. If I back upwind slowly – adding 1 mph or so to the apparent air velocity – I can get the camera to rise.

Altitude gained by backing upwind.

But walking back downwind to the shade of my tailgate causes the camera cradle to drop again – ending up in the same altitude of a foot or two above the ground.

It is so interesting to see the system in such a consistent balance. At 5 mph the camera’s weight can be supported but without the possibility of gaining height. At 6 mph I can slowly climb. This was a period of pretty active kite flying since I wanted to keep the camera out of the dust. When the wind lessened I would gently inhaul a bit of line. During momentary increases in the wind, I would play line out ever so slowly. After a few minutes of knee-high cradle altitudes nature did me a favor and turned the wind up to 6 mph. I could now coax the cradle upward and start taking photos.

Real altitude at 9 minutes into the effort!

While the wind cooperated I tried to let out as much line as possible and with pumping arm motions encourage the kite upward. Over five minutes or so I was able to pay a few hundred feet of line out. 

Now we are talking. 

It was my hope that I would find a slightly fresher breeze at a higher altitude but on this occasion there was no joy. At a few hundred feet up the kite quit climbing (added line weight?) so I loitered there for a while hoping the breeze would freshen again. It didn’t. In fact, the breeze slackened a fraction and the kite started a slow, inexorable descent.

The beginning of an upwind migration.

To keep the camera at altitude I abandoned the van and started walking upwind. I would vary my pace to walk only as much as was needed to maintain camera altitude. Checking on Google Earth I can see that I had a half-mile of levee available for walking upwind. I used it all and this provided about 25 minutes of flying time with the camera at altitude.

A plan view of the van as I slowly backed upwind.

All told I was able to take about 200 aerial photographs including some coverage of my principal target – the newly flooded Salt Pond E8A. By the time I reached the end of my levee trail (it stops at the Bay) the wind was much diminished. This meant the camera was most definitely coming down but I could easily control the descent by inhauling line. The large Rokkaku makes such a technique easy and this is a great advantage of framed kites.

A panorama stitched from photos taken as I backed down the levee. The twin channels of the Old Alameda Creek outlet stretch through the center of the image. Salt Pond E8A lies just to the left of the creek channels.

Footnote:

My large Maxi-Dopero would have been a preferred kite for this session but it recently has started to misbehave when the winds reach its upper range. Under those conditions, it tilts to the right (perhaps 45 degrees) and slowly sinks. I have to sort that out before using it again for the cameras. In these light winds, it would also have made sense to use my lighter NEX-5 camera cradle (1-3/4 lbs.) but I had been inattentive and its battery was discharged.

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