I’ve been thinking about how fast the Scottish pilots manage to go in wave and whether they used ballast. I know nowt about actually flying in wave so e-mailed John Williams (who then also put me in touch with Santiago Cervantes). I expect you/others may already know this but I found it very interesting.

John explained that when he used to fly a LS8-18 he did use water in it. He put about 30% antifreeze into the tail tank, but left the wing tanks plain water. I imagine the thermal mass was large enough that not much froze (or there’s room for expansion). John achieved 150.1 kph around a 500 with the LS8 on 15m tips using 100 kg of water. He did mention that the dump system often froze, so typically landed with the ballast on board, but this was “not normally a problem with the wind strength needed for wave”. Kevin Hook flies a DG400 so is always carrying the fairly heavy engine, but mainly flies in 15m mode to increase the wing loading further.

John and Sant (who flies a dry Libelle) also had the same tips for maximum speed: don’t stop to climb, and fly in lift as much as possible, not least as the wind speed is usually lower there. Sant says his Libelle is happy in up to 50 knots! Towards 70 knots things get tricky, especially crossing bars.

Sant mentions that the hardest part of wave flying is simply getting into it, and this is where turbo and self-launch gliders have the advantage. Once in though so much is possible: a 500 has been done in an Astir too, and one pilot has even done a 300 km OR in a K6e from Aboyne!

I would like to add a few comments. You say: “Sunday didn’t look, or at least I thought it didn’t look, so promising for wave.” My thoughts on Saturday evening were exactly the same and for roughly the same reasons. If I had known how good it was going to be I might have made more effort to take an early launch (the tuggy Sean tells me he was at Shobdon by 8:30 and could have come earlier if I wanted). Also I would have benefited from water ballast, and what’s more there wouldn’t have been any danger of freezing because the lowest outside air temperature I saw was +6C.

So a few learning points for me there! I shall no longer dismiss a day simply because the upper winds are very light. I should have known that anyway from an experience many years ago of climbing over the Black Mountains in a strong easterly and finding that above FL200 I could continue climbing slowly to FL230 while circling in very light winds. A met man with access to a tephigram for that day told me later that above FL230 the winds were westerly!

It’s interesting than weather Jack’s 5th rule of thumb for wave that the temperature at 500mb should be no lower than -24C applies to all these days.