Post flight analysis - was it me, or was it the weather?

In my last post, I ended with how much I was looking forward to the Inter-club league this year, especially since I'd organised it and it was being hosted at my home airfield. Sadly, it lived up to it's nickname - the 'inter scrub league' and we managed collectively to amass zero kilometres - even despite a mass relocation to a different airfield when we thought local weather conditions might give us something (it didn't). I'm however pleased that the turnout from local clubs was great and showed that there is enthusiasm and willingness to cooperate to put on an event. We'll try again in August.

The weather still hasn't settled fully, either that or I'm paying much closer attention to it than in previous years when my goals were first to fly, then to be able soar locally - where of course now all I want to do is go places.

So far this year I've done a few short flights; a 100km at the end of March, and then a couple in the 130km range more recently. These are my longest (in distance) solo flights to date, and have been good for confidence building given that none resulted in a landout - but to be honest, I don't feel at all fazed about going further if we get the day for it, neither of the two longer flights occured on very 'straightforward' days - but we have to learn to use what we get, especially in the north of the UK where scratching around looking for a weak thermal to stay up is quite often what we have to deal with!

I wanted to talk about these flights for a different reason. I'm really getting into my post-flight analysis - just like with any sport, it's important to measure how you performed and highlight areas for improvement. With gliding it's about speed; because going faster allows for going further when flying for fun; in competitions - it's how you win.

To that end, I wanted to share what I'm doing in case it's useful to you, but I want also to hear from you about what you look for when and if you analyse your own traces. I'll include links to the IGC files with each, so you can have a look at my traces yourself if you wish - and tell me where you think I've missed something. The sofware I'm using to look at the traces is SeeYou.

I'm mainly going to be looking at three areas.

Routing - you only get scored for speed on point A to point B; so it's most efficient to fly straight there and cover only the distance you need to cover. Not always possible because sometimes you have to stop and find lift and it's not always where you'd like it to be. You also get blown by the wind, and of course, make other decisions that might affect where and how far you go.

Climbing - where speed is lost; essentially, since most thermal climbing involves stopping to circle, the longer you need to spend doing it, the slower your average. Not circling (wave, convergences, cloud streets in the right direction) are the best ways to climb if you can do it, but when you have to circle - it's about stopping in the best lift, staying with it as efficiently as possible, and leaving it before it goes weak. On windy days, thermal climbs can also take you off track, or push you along.

Speed - by which I mean inter-thermal speed; the faster you go, the more ground you cover; but also the faster you lose altitude depending on your aircraft. To go fast, you need to be good at climbing, and judging what's right for the day - or the at least the time/place you presently find yourself.


12th May (View IGC)

Weather: Light NE'ly (2-5kt), a little hazy with cloudbases 3,000-4,000ft
Declared: Sutton Bank, Beverley, Catterick, Pontefract, Sutton Bank for 302.6 km
Achieved: Sutton Bank, Beverley, just under half way to Catterick, and home - 141.1 km at 50kph 😓

The day looked good, and I would argue that it looked better than it was and caught out a few people. There were a few declarations of 300km with only one completion - and that was in a 25.5m Nimbus, not a 15m club class like my own!

At the time, I thought I'd made a huge meal of it - particularly the outbound leg. I felt like I was low a lot of the time, that I was struggling in weak lift for a lot of the time, and that progress had been painfully slow. So what does the data say?

Routing:
I'm already 3.5km off track by the end of my first thermal on task, having turned about 70-80 degrees to find the lift. In fact, this seems to be a trend for the whole Sutton Bank-Beverley leg of the trip. I should have started upwind so that I could drift back onto track, rather than away from it. At Malton, where I had no real business being - I'm around 10km off track over high ground - which would have contributed to my altitude anxiety.

I flew 84.1km to Beverley; despite it only being 64.4km away. so thats around 27% more distance covered than was needed. If that had been direct; it would have been 27% more speed - and that would have been a more respectable 54 kph, rather than the sluggish 42 kph that it was.

By contrast, I flew my route back to Sutton Bank covering 68.1km for a straight line distance of 62.7 (measured just short, as I hadn't intended to stop and finish at that point). The speed back was 55kph, having only deviated in total by around 8.5% - notably, on the way back I was upwind of track, so thermals would blow me closer to the correct course, rather than away.

Next time; I'll look to make a start well upwind of track if possible and not deviate so much - making routing decisions earlier will result in being able to sample the same clouds without such huge course deviations.

Climbing:
Looking back, I'm quite happy with my climbing although I wasn't at the time. I averaged 1.5kts in the weaker conditions heading south, and 2kts coming back. I had four goes (totalling just under 3 minutes) at thermals that didn't work on the way out to Beverley, and also improved that significantly on the way back with only just over one minute of failed thermalling.

I can see that my turns were all done within a 100-150m diameter on the way down, but the thermals below 3,000ft were difficult to centre. I was questioning my piloting skills during the flight, but later on, others would report that anything below 3,000ft had been difficult for them to centre also. The learning point here is perhaps that once this had been realised - trying not to drop below the critical height would have done wonders for my speed and stress levels!

The thermals were also considerably stronger higher up; and so my speed had been hurt by having to accept poor lift (quite a few below 1kt) due to being stuck at around 2,000' over ground that was 500' above sea level; this had also resulted in limited options. I should have clocked this early and made it my mission to get high and stay there.

Speed:
I was reasonably happy with my speed; pretty much in the order of 50-60kts indicated for the whole task; which is a good operating band for an LS-1f and seems reasonable considering the problems I had been having gaining height.

The decision to abandon:
You won't get this from the trace; but you will see that things seemed to be going much better heading back North. I climbed up to around 5,000ft near Sutton Bank and pushed on toward Catterick, but the climb was to cross a large area of blue sky with a couple of clouds near Northallerton.

Of course - the clouds didn't work by the time I reached them, I don't remember what the sky ahead of that looked like - perhaps more blue. While I had the height to press on, I decided to head back home at that point. Maybe it's just because home was close by?

The sky looked much better over the ridges to the northeast; considerably off track but perhaps this would have been the time when accepting a large course deviation to fly in better sky would have resulted in a longer achieved distance?

Returning from my furthest point was not straightforward either; it was a marginal glide, I headed back for the ridge line anticipating that the gentle breeze might at least reduce the sink, and the sun might kick off a thermal - both of these things happened and it was enough to climb the extra couple of hundred feet needed to get home.


16th May (View IGC)

Weather: Strong E'ly (15-20kt), excellent visibility with bases rising (eventually) to around 5,000ft
Declared: Sutton Bank, Ripon, Burn, Sutton Bank for 129.6km
Achieved: Sutton Bank, Ripon, Burn, Sutton Bank - 129.6km at 55.4kph 😎

This felt like a better day, with stronger lift about - but the problem was always going to be the wind. Last time we had had a strong easterly, we had tried to go east into it - but encroaching sea air had lowered the cloudbases too much to be able to continue. This time, I was going to do a downwind leg in the weak conditions, and hope to be able to come back into it when the day was a little better. The assumption had been that whilst the south was looking better; there could be problems where crap air was being blown in from the Humber Estuary - and so there was.

My gut feel about the task was that it had gone reasonably well; but the long southerly and slightly back-into-wind leg had taken longer than it needed to.

I think the data agrees with that sentiment - let's take a look.

Routing:
The first leg was from Sutton Bank to Ripon - a distance of 22.8km and I flew 22.9km to get there. You can't really argue with that! It was a straight run downwind, with a couple of decent thermals on the way and my speed was a very pleasing 81 kph!

The second leg was the longest, and it also had an into wind component - I covered 81.2km for a scoring distance of 52.2km and that blew my speed - only 38kph. Having covered around 55% more distance than I needed to - could I have done 59kph? Not in this flight. You can see that the track south is quite deliberate, rather than a meander around and this was because any further east was blue sky - that Humber influence. I also had to clear the Leeds East/Sherburn ATZ areas, which only extend to a couple of thousand feet, but the wind was such that when I set off to do so, I wasn't confident that I could make the other side without sinking too low - so I ended up going the longer way around, where there were also visible clouds to work.

I might have been able to save 10 km if I'd been able to jump the airspace or get cleared through it, but it would still have meant crossing a blue patch. Speaking of which....

Burn to Sutton Bank - the third leg. 54.6km as the glider flies, and 56.6km covered. I compensated for the wind by keeping York in my sights, knowing I'd be pushed left of it. Humber influence had cut off the way I'd come down; and the sky was completely featureless until York - I had thought I wouldn't make it back at all, so set off on glide for Rufforth with the intention of making the retrieve a little easier. Routing in the blue is easy enough; you pick where you want to go and then you just go.

A blue thermal south of York was indicated by a spike to 10kt on the vario as I flew directly through the core (luck rather than judgement); and then a pair of circling birds of prey to help keep me in it meant that I could climb away, get to where the sky was still visibly working, and push on to get home. Maybe I prayed, if I did, they were answered.

Climbing:
A task average of 2.8 knots is nothing to be ashamed of'; this is where I could have done with a second trace from an accompanying glider with which to compare - but Toby in his Std. Cirrus had other ideas and visited a farmers field near Ripon on the way back from Leyburn.

3.5 knots on the way to Ripon, 2.5 knots on the way to Burn, and 3.5 knots on the way back to Sutton suggested that the second leg was not only off track, but the climbs weren't working so well - or I wasn't working them well. On closer inspection, thermals down the leg looked like this:

  • 3.9kt for 1,024ft
  • 1.7kt for 164ft 
  • 3.1kt for 699ft
  • 4.3kt for 446ft
  • 2.6kt for 1,388ft
  • 1.4kt for 308ft
  • 2.4kt for 1,539ft
  • 1.7kt for 1,476ft
  • 2.4kt for 1,004ft
  • 2.9kt for 1,407ft

Good climbs looked to be achievable all the way down my chosen track then; I correctly abandoned the first weak climb quickly, and tried to stay high. Again, below 2 knots I abandoned another weak one, but ended up sticking with a 1.7kt climb for almost 1,500ft - why did I do that? I had 3,000ft at the start, so this appears to have been poor judgement on my part because not only did I spend 8 minutes in that climb, I also got blown 4km back away from the turning point. It almost certainly would have been better to reject the climb, continue south, and look for something stronger.

Speed:
81 kph on the first leg, and even faster (over 82kph) on the return leg from Burn, so it was definately heading South that killed any speed for the task.

I think the learning from this one is that into-wind legs are the ones where you have to be extra sure about the quality of the thermal you're taking, too weak and you actually don't get anywhere - because by the time you get back to where you started to climb, you may have lost the height you gained anyway.

I stick with a climb that was too weak on the way down and I think that cost me dearly, but overall I'm pleased with how the rest of the task was handled.



So tell me, do you analyse your own flights like this? What do you look for in the data that tells you how well you flew? Leave a comment or get in touch.

Comments

  1. Wow. Very thorough analysis. I only eyeballed my trace. I knew I took to many weak climbs, but the conditions weren't great and I wanted to make sure I could do an out and return, so I stayed fairly conservative. Next time I'll only take good climbs high and refuse or maybe go to half cloud base in weaker climbs. All depending on the conditions. My next aim is to get my speed and confidence up.

    (Nora)

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