Tassie has some kind of wave activity going on somewhere more often than not. I live at Mount Nelson near Hobart (on the far right-centre of the picture above) and often walk just up the road to the signal station where there is a good view of Hobart, Mt Wellington and surrounding hills. Except when it is calm or nearly calm, there nearly always appears to be some kind of wave action visible in one direction or another. Sometimes this can be quite spectacular with the classic large lenticular clouds indicating wave to 25000 feet plus.

These can be observed in the North East, South East and sometimes the South West depending on the wind direction. However much of the time, the wave is not of the highly spectacular variety, but shows lines of clouds which look more like cloud streets which are lying across the wind. These are sometimes as low as about 4000 feet, though often higher maybe around 5000 to 7000 (judging from the height of Mt Wellington). Associated roll clouds are often visible underneath at levels well below the height of the mountain.

A weather pattern that will generally provide wave in front of the front in northerlies, and then again after the front in westerlies.

The lee of Mt Wellington can be very rough in a strong wind attested to by many power pilots who have ventured into the area in windy conditions. However, at the same time there will be good lift just above the height of the mountain.and the associated wave can be very strong indeed. I have been in this area in my Maule M5 going up at 1500 feet a minute with the engine at idle.

The Dimona in Wave over Mount Wellington

9,200 ft, climbing 9 m/s

Other areas can show similar very strong wave action.

Many years ago, I had a half share in a Cessna 180. On one day when wave was apparent, my partner in the 180 (Ian Jarvis) and I took off from Bothwell and climbed out to the wave which was over the Derwent Valley. We established ourselves in the wave at about 7000 feet and were climbing so well that we decided to switch the engine off and see how it went.

This we did (it took quite a bit of doing to get the prop stopped, but we managed it by flying right on the stall in a nose high attitude for about a minute until the prop finally came to rest). We proceeded to fly up and down the wave at about 50 knots with one notch of flap set, just a knot or two above stall. On the straight we slowly climbed, averaging around 100 ft per minute. On the turns to come back we would lose a bit and then start climbing slowly again as we moved along the wave front. We did this for an hour and 17 minutes (we timed it) and gained about 1300 feet before the lift weakened to where we could only maintain height.

We could have gone on longer but decided to call it a day. Now a C180 with 2 up and about 2/3 fuel weighs over 2000 lbs and has a lot less wing area and a lot more drag than say a Blanik. That gives you an idea of how strong the wave can be! As a matter of interest, we decide to do an air start of the engine. It took over 3500 feet of height and quite a high speed to get the prop turning again (don't worry, we had our landing position all picked out, and a finger hovering over the starter button).

There are many other stories that have been told. When I first came to Tassie, one of the old timer pilots told me a story of someone in a Chipmunk going up to 24000 feet in the lee of Ben Lomond. He switched the engine off and still couldn't get down for quite some time. Associated with these strong updraughts are often very strong downdraughts.

Dave Cooper from the ACST had a small Grumman and tells the tale of being caught in a down draught in the Coal River valley and dropping from 3000 feet or so to within 200 feet or so above the ground within a time frame of what seemed to be only a few seconds. The aircraft suffered some structural damage and the incident frightened the living daylights out of him. What goes up must come down!

Most of these tales are from power pilots. Why?

Very few glider pilots have put the time and resources into trying to explore these wave systems. It takes time, good equipment, quite a few dollars and a bit of nerve to have a go. For myself, I think I would prefer a motor glider before I go charging out too far from civilisation under strenuous conditions and over some of the most inhospitable and unlandable terrain in Australia.

Mac Forster (mentioned previously, Sandfly ) was one who explored the wave in the Southern Tasmania region and had many long and interesting flights in his Pik20B. He basically devoted several years of his life to this and had quite a few tales of his own to tell. Another time!

Well, we now have a Dimona H36 motor glider based at Cambridge and we have now had a lot of  wave flights around Hobart, Mount Wellington, the Derwent & Huon Valleys, and also around Bothwell.

We've had some great flights!  If you are down this way and the weather is right, give us a call!