This Friday was forecast to be a good ridge between two strong depressions. The soundings showed no significant inversions which promised strong lift to cloud base but had worryingly little gap between the the wet and dry adiabatic curves, so I was a bit pessimistic about the likely cloud base. This pessimism was further reinforced by the first cumulus appearing at 09:00. However, there was no initial spread out, so I rigged 123 for yet another attempt on 300 km. The 20 kt north-north-westerly breeze meant that strong thermals would be needed if they were not to be broken up by the wind. I decided to tackle the Bury St. Edmunds - Edgehill triangle with Bury St.Edmunds as the first turn point because I expected the wind to moderate and swing south-west as the day progressed.
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My task is marked in black. |
I got a decent cable launch to almost 1400 feet at around midday. There was a good-looking cloud with a useful collection of gliders under it to the south near Top Farm so I headed that way, arriving in the lift at 1000 ft. This climb got me to cloud base (3600 ft) over Wimpole Hall, so the westerly drift was pretty strong. I headed back over Gransden Lodge, making a start over the field at 12:27 and ran cloud streets over Cambridge and Newmarket on a pretty direct route to Bury St. Edmunds. I stopped to climb over the town just short of the turn point. This took me from 2800 ft to 3900 while I drifted past the turn point, ready to head round it and off to a useful cloud street off to the north-west. This street took me round to the north of Cambridge. At this point I changed streets and ended up under a non-working cloud that eventually saw me at 800 feet, field picked, directly over the canal midway between Soham and Earith. A bit of careful scratching got me away again after 5-10 minutes and eventually to 3600 ft, all the while sitting over a long boat that was heading east. I was able to measure my upward progress by the speed with which the boat got smaller and the wind by the size of her bow wave. Another change to a more southerly cloud street saw me due north of Gransden Lodge with 1/3 of the task distance travelled. Analysing the log afterwards showed that it had taken half the total flight time to get this far. However, as the following satellite pictures show, despite the stiff breeze the day was only getting better.
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12:28 satellite picture |
17:02 satellite picture |
From here I stayed to the north of track to avoid getting pushed south by the NNW breeze and having to struggle back north. Another three cloud streets saw me past Sywell and round the north side of Northampton, cruising mostly between 2500 and 4500 feet, running up the streets at 58 kts and jumping the gaps between streets at 65-70 kts. As I came up to the M1 I checked my map to see how close I was to the Daventry Control Area and, realising that I was often travelling too high to get under it, turned south for 10 km to get round its south-east corner. In the event I almost cut it too fine, and was to spend the next 20 km skirting the edge of the inner FL45 section rather than being entirely clear of it. Fortunately, I didn't break the FL55 ceiling above me, never exceeding 5000 ft in this section. As I came past Banbury, still on the north of the M40, I could see the turn point at Edgehill and turned further south to head directly to it, hopscotching along convenient clouds. I got round the turn point at 3000 ft and straight under a good cloud immediately south of the Shenstone Gliding Club: the turn point is their club house. This cloud saw me back to 4500 ft and on to a succession of clouds and short streets that gave a straight run back to the north edge of Bedford. Here an excellent climb took me to 5200 ft and a straight final glide home at 80 kts, ending with a 180 degree pass round the club house, which marked my finish point, at 120 kts and 1300 ft.
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The route flown. |
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The barograph trace. Times are GMT: all other times on this page are British Summer Time, one hour later than GMT. |
The average thermal strength for the day worked out at 4.3 kts. The strongest thermal I used gave a 6.9 kt average climb rate. I'd pre-declared the flight and so I put in two badge claims for the Gold Distance (300 km) and Diamond Goal Distance (300 km as a predeclared triangle).
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On the 10th of July my FAI badge certificate was returned confirming that I now have the distance leg of the Gold Badge and the Goal Distance leg of the Diamond Badge.