Monday, December 3, 2012

Trough Soaring

I took PM to Springfield last Thursday for a little trough soaring.  Trough soaring is like wave soaring.  Both use mountain waves.  In wave soaring you ride the crest of the wave to high altitudes.  In trough soaring you ride around in the trough of the wave hoping to get up to the crest.

It was a nice 3 hour flight (the data logger was not working for the first half).  A lot of it was hanging around between 5,000' and 6,000' waiting for stronger lift.

Thank you Walter for towing and Sonny for wing running.

PM is currently in Walter's hangar and ready to fly (I have the data logger and battery).



JS said...

Nice, Tim, very nice.

What were the parameters on the skew-T that forecast this condition for you?

I've always thought of the wave trough as the next step to the rotor.

Isn't this true?

If you can find the wave trough, isn't the wave up somewhere close by?

Tim said...


It was a pretty good looking forecast (we haven't had many since Gorham). Winds were forecasted to 30 kts @ 270 degrees @ 5K' and steadily increase to 60 kts @ 10K'. Stable air above about 4K'. The only problem I saw in the forecast was a wind shift of about 15 degrees (to 285 degrees) at 5K'.

There was unmistakeable signs of wave lift between 5K' and 6K' - smooth lift perpendicular to the wind, above cloud base and in front of clouds. But at that altitude there was also turbulence, broken up cumulus, and areas of heavy sink. So yes the bottom of the wave and rotor existed at the same altitude (you know that from the time spent behind the Horn).

My disappointment in the day was either the wave stopped at 6K' or I could not find strong enough lift to get me into the stronger part of the wave.

Okemo is over 10 miles away so the wave has to make 3-4 wiggles before it gets to VSF, and there are a lot of smaller mountains and valleys in between. This means that the wave is broken up into smaller segments and changes quickly over time (at least at lower altitudes). Maybe I should have taken a tow to Okemo?