Monday, September 27, 2010

Wave Season Has Started

Actually it started a couple of weeks ago. I have been watching the weather using Kevin’s article as a guideline. It seems to work pretty well. When the skew-T predicts wave there is usually signs of it in the clouds. Up until this weekend I wasn’t able to fly on promising wave days. On Saturday the skew-T looked good. Here is the skew-T for Saturday (historical info is available at this NASA site).

There were cloud streets and wave like clouds at 5-6K just like you would expect from the skew-T. Andy took the towplane up for a warm up and reported moderate turbulence (rotor). Bill (3J) and Tom (TH) went up first to scout things out and found usable lift to 5.5K under the clouds. Since they were sticking I took the next tow.

Off tow I was able to fly around at 5.5-6K with Tom and Bill in rough thermal/rotor lift. If I got to cloud base I would try to slide out into the clear air next to the clouds but could not contact any wave lift (in hindsight I was probably looking on the wrong side of the clouds).

After flying around Post Mills for about an hour and unsuccessfully trying to find wave lift I headed out on a cloud street going southwest. The street was working great and for the most part I could fly without circling. But if there was a clearing in the clouds I would circle up and look for wave lift. Nothing really felt like wave. The clouds seem to be honest. The darkest clouds had strong lift.

As you approach Killington Peak the terrain goes up and the fields disappear. The clouds still looked good and there was this clearing ahead so I felt pretty confident as I headed toward the peak.

This clearing turns out to be (I looked it up the next day) Plymouth VT and the Calvin Coolidge Homestead. As I approach the Green Mountains the clouds don’t seem to be working anymore. I can’t find any lift. I feel like I am kind of stuck because this is the only clearing for 5-10 miles so I don’t dare leave to go back to lower ground. As I sink lower I move closer to the clearing. Finally I fly over a steep ridge ½ mile west of the clearing and find some lift. It is strong lift but it is turbulent. I am now down to 3200’ msl which is only 1000’ over the ridge and 1500’ over the clearing. I try circling but get blown to the west and out of the lift. After struggling for what seems like a long time I figure out that if I “ridge soar” the little ridge by doing figure eight’s I can get a pretty steady climb. I stay in that same spot and finally get some altitude. As I get up to about 4,200’ I notice I am in the sunlight and there is a pretty well defined wave window right above me. The lift is consistent and getting stronger. I stay in that same spot and climb up through the window and after an hour I top at 14K (I am glad I put the oxygen tank in last week). The wave window is small and there is solid overcast west to NY, but there are larger windows to the east and I know I can get to them if my window closes.

The glide computer says I will arrive back at Post Mills at 9,600’ agl so I head for home. I can hop over the bands of clouds to stay over the wave windows but I don’t seem to be picking up much lift. I arrive at Post Mills still at 11K so I guess there must have been some. Its time to burn up some altitude and get below the clouds so I push up the speed and head towards Black Mountain. Going downwind the data logger trace shows a ground speed of 338 km/hr (210 mph!).

Sonny, Andy, Alexander and Kevin help me put the glider away when I land. Thanks!

The flight log is available here (thanks Rick):

And thank you Cal Coolidge for clearing that spot.


P.S. All day I couldn’t figure out exactly which way the wind was blowing. I should have realized that wave clouds and wave windows line up parallel to the mountain that produce them and not necessarily perpendicular to the wind. If the wind hits the mountain at a 30-degree angle the clouds will be at a 30-degree angle to the wind.

1 comment:

Anonymous said...

Tim, Awesome ride! When does the movie come out ? My brain can only absord so much of this without video ! Last I heard before I left you were at 4,200 at Killington ~ and we weren't sure how much lift you would need to get you back- even w/ the awesome tailwind. We were guessing around 40 miles - my quick check puts it at 35m - great ride- thanks for the details - I had a great time getting reaquanted w/ flying a Citabria 8GCBC taildragger- in Maine on Sunday - great fun - but nothing like your ride. Christopher