Working Height Band
You've just climbed to cloud base, the sky ahead looks regular & consistent, what cruise speed do you fly? A very good question, often one would say, how long is a piece of string or just, it depends! I'll try to explain though, how I race my flights.
First Climb off Tow
Your first indication or clue comes from off tow, was it a struggle to climb away, easy strong & smooth from low down, slow at first then progressively getting stronger, or did you lose the thermal at an altitude on the way up? Finally, build a picture, are the thermals 'streaming' all the way up from the ground, are they bubbling?
Is it a CU day or a blue day? I suppose this doesn't matter so much as the question remains the same, how reliably am I finding the lift? How strong is the lift & in what height band is it the optimum?
As you can see, a constantly evolving & dynamic question. I've found one reliable way though to pick your cruise speed relative to your altitude, regardless of your wingloading or glider type...
Changing Gears
The simplest for me is this, you've left cloud base, high & happy, 100kts is feeling great at 8000'. You've been passing up thermals because they don't meet your criteria, you're looking ahead at the forever changing standard sky, your thermal model is constantly updating from the information you gained in the second paragraph...
..all of a sudden, your cruise speed goes from 100kts, down to 80kts. Remember this altitude, then add 500' & do what you can to stay above it in the future. Subconsciously you've just determined that the thermals have become unreliable to your criteria. Stay higher, take the better climbs, keep your 100kt cruise speed up the whole time!
This works for every day & is constantly evolving. You might be happy to drive to 3000' on some 10,000' days, but others, you'll be concerned when you get below 6,000'!
Naturally, you need to take into consideration the terrain ahead too, so please don't drive low because the lift is reliable low, you still need some self-preservation!
Hight Band in Thirds
Other techniques involve splitting the height band into thirds, where the top third is flying at McCready speed, the middle third is at 1/2 MC speed, the lower 1/3 is in search mode where speed doesn't matter anymore, one is just avoiding an outlanding!
To me, I like to keep things simple - the moment you pull back on the stick for your unsubconcious reason, that's the height to avoid, stay above that & your cruise speed will stay high, your overall task speed, hopefully also high!
Happy cruising!!
Adam Woolley was born into the gliding world, being the 3rd generation in his family. Going solo at 15, his thirst for efficiency in soaring flight & quest for a world championship title to his name has never wavered. One big passion is sharing his experiences & joy with other glider pilots all around the world. Adam is an airline pilot in Japan on the B767 & spends his off time chasing summer around the globe. He has now won 7 national Championships & represented Australia at 5 WGC's & 1 EGC.