kloot piloot wrote:Bundy wrote:
You should know Kloot, having hang glider experience?
Highest I got in a hang glider was 16 800 ft ASL between Machadodorp and Badplaas over the Ndubazi forest. Take-off at Ndubazi was 3 720 ASL. The thermal topped out at about 18 000ft (veld fire smoke at Carolina levelled out at that height) but I chickened out. Die grond raak baie ver ! In Spain in the Pyrenees I got 14 900 ft.
A thermal is more oxygen rich than surrounding air. Once on the glide towards Barberton, and out of the thermal, I had stages where a bit of oxygen-lack plays part with your judgement, but soon you are in the 10 000 ft areas and that is OK.
But strangely, I don't like huge altitudes in the microlight ? I love the 500 ft - 1000 ft AGL (4200 - 4700 ASL) where we fly in the Brits Bushveld area. Yet on our way to Zwartkops it was fun looking at Pretoria CBD from 7500 ASL just under the TMA.
Bottom line: The height of the tailwind detemines my altitude !

Thanks Kloot, interesting!
I must admit, I have a very limited understanding of thermals so could you elaborate on the point you make re the oxygen content of the air inside the thermal? I would have thought the ozygen content would be lower due to the fact that it is warm (IE less dense) rising air? Please educate me!
I do agree with you though, I am almost always at around the same cruising level as you. As said earlier, when i climbed in the GF to 8000ft, I acctually chickened out as I was more concerned with the Carb Icing possibility on the descent!
Was lekker up there though, very smooth on that particular day but I have seen upper wind forecasts of up to 40knts

so I generally remain a lot lower... ha ha.
Where do you get your upper wind forecasts from? I refuse to pay weathersa for info that I feel should be free to pilots

I find windguru to be the most accurate in terms of the lower wind forecasts and general precipitation but I'd love to find an easy reference to the upper wind forecast?