Your connection with the sky

Pilot Log – April 4, 2010

The forecast for Sunday looked much better than the day.  Arriving at the gliderport at 10AM, I was disappointed there weren't any cumulus clouds yet, an indication of rising air. The morning sounding showed an unstable airmass, and that usually means lift early in the day.

But you can never know for certain what the day will bring until you're in the air.

First step for me is to assemble the glider. This isn't nearly as hard as it sounds. In fact, it's easy. It takes about fifteen minutes to put on the wings, the horizontal stabilizer, and the winglets. Gear down, then back the aircraft out of its dolly and it's just a preflight away from launching.

I took the first tow of the day at 1130 ET. The air felt lively, but just to be sure I rode the Piper Pawnee towplane all the way to 2,000 agl before releasing. Some false starts, but within 15 minutes I found my first honest thermal and took it up to 4,000 msl. Another 10 minutes passed when I got an idea.

Lenticulars were forming above the airport, indicating wave.  But the winds were too light from the northwest to feed them. Then I noticed that the cloud shadows were moving across the ground to the northeast, 90-degrees to wind at my altitude. These lennies were marking a wind shear between two overlapping airmasses.  I flew to the west end of one of these clouds and found 5 knots of lift to 6,000 msl. Later in the day I'd find 7 knots to 7,000 msl.

After 90 minutes in the air, the radio started buzzing with questions about the task - a 132 mile, 3-turnpoint race course that sent us first to Carlisle, PA, then to Frederick, MD, then to Hanover, PA (think Pretzels) before the final leg home to Fairfield. Six pilots were confident enough with the day to start, and the racing proved to be great fun.

Of course, by the time I took my start at 1335 ET, the clouds that marked lift earlier in the day had disappeared completely. The clouds were gone, but the lift remained, and even strengthened.

When there are no clouds, the best clues for finding lift are usually on the ground. Infrastructure can mark lift: factories, towns, large shopping centers. Clear cuts on mountainsides that face the sun are also occasional producers of strong lift. But today, my strongest thermals were over bodies of water. This surprised me, as the water is still very cold. But I doubt the lift came from the water. Instead, the water may have served as a trigger for surrounding warmer air to break away from the surface.

Here's how. Surface winds were about 7mph form the northwest. The wind was just strong enough to push the cooler air over lakes into adjoining warmer air. Warm air is less dense than cold air, so the cold slid under it, forcing it up. As this happened, other pockets of cool air were disturbed and flowed in from the edges, causing more upward movement. Voila, my 7 knot, 7,000 foot thermal!

I noted in my last flight log that I had rearranged my instruments. Here's a look at my panel.  Across the top row are, from left to right, an analog electric variometer (shows a climb of nearly 10 knots), the airspeed indicator, and a mechanical (bellows) variometer, just in case I have an electrical failure. The bottom row starts with the altimeter, next is a digital display for my GPS data logger, my flight computer, my radio, and a digital display for my backup GPS logger. Below them (out of sight) is a multi-fuction display including clock, timer, g-meter, and volt-meter. Lots of information to process in a glance, but the most important information is outside the cockpit. To keep my attention outside as much as possible, my flight computer turns variometer readings into tones. When I find lift, a low warble begins to sound. As the lift strengthens, it rises in pitch. And in the very strongest lift, the tone almost disappears, my middle-aged, rock'n'roll damaged ears sensing not much more than a series of clicks...

So how was the race? Well, I don't have all the flight logs yet, but so far I'm winning with a raw speed of 54 mph. Here's a link to my flight on the online contest. See for yourself...

Oscar Charlie
Ventus 2bx

Leave a Reply

*