Bruce Goldsmith <<bruce>>
writes:

In 2003 I wrote an article called Size Does Matter! It looked at
how and why paragliders of different sizes react in different ways. And why
there is such a difference in competition results between small and big pilots.
Looking at high-level competition results from that year all the winners were on
large gliders, even when most pilots (68%) actually flew medium-sized wings or
smaller.

Pilot skill is obviously important, but I wrote at the time that, "if your
glider goes a bit better because it is bigger, then that for sure helps". This
hadn't gone un-noticed, and was why pilots flew with lots of ballast - pilots
found that they performed better if they flew a bigger glider and carried
ballast, rather than flew a glider that was the correct size for them. In fact
the FAI and PWCA had brought in rules limiting the use of ballast in
competition.

At the time I was working for Airwave and we did a theoretical study of the
difference between Medium and Large competition gliders. The prediction was that
at trim speed the Large glided 1% better than the medium but at 54km/h the Large
had a 5% advantage over the medium. Quite a significant difference if you are
racing. Size is important, I wrote, because of the Reynolds Number effect (put
simply it means the flow around a wing is relatively smoother on bigger wings
compared to smaller ones); issues around scaling in the design and manufacture
of gliders; and drag - drag on a large pilot is relatively less than the drag on
a small pilot. I concluded that this was a "fact of life" with no solution. "We
have to live with it." Big gliders were simply better.

BGD Weightless

Roll forward 15 years and we have the new "weightless concept" - a concept based
on the principle that pilots should be able to compete equally in paragliding
competitions without bring unfairly penalised by weight. As laid out above, it
is a well-established principle that bigger gliders go better than smaller ones.
However, to be heavy on a big glider is also an advantage, particularly in
racing tasks. These two facts mean competition pilots fly bigger gliders and
load up with as much ballast as they can.

The FAI limited the total equipment weight to 33kg years ago, so most
competitors now fly right at this weight limit in competition. But the result is
competition equipment is heavy and cumbersome. When these same pilots fly
outside competition though, the typical equipment is more like 10kg. This has
all lead to competition paragliding equipment being ridiculously heavy and not
at all a pleasure to use in everyday flying. The BGD Weightless concept was the
first attempt to do something about this situation.

The first event took place in Slovenia from 3-9 September 2018. At registration
pilots were asked for information about their flying weight, equipment and
experience so we could analyse all the data to progress further with the
weightless concept. The competition was split into three weight classes:

Up to 80kg

81-100kg

101kg and above.

This idea worked well, except some pilots still used ballast to push to the
limit of their class and optimise performance.

When the competition was over I analysed the results and looked at the influence
of several factors on performance. Here is what I found:

Number of years flying = no major influence on competition result

Flying hours = no major influence on competition result

Number of competitions flown = strong influence on competition results.

Before analysing the effect of weight on competition performance I removed the
influence of the number of competitions flown from the statistics. After
removing this, the resulting graph showed that there is a minor but significant
effect of weight on the competition results. The analysis of the numbers showed
that, on average, every 10kg of weight you fly with leads to 2.5% more
competition points in each task. This is based on the scoring system we used at
the BGD weightless, which was GAP.

This means that next time we run the BGD Weightless we will be able to go one
step further, and instead of using three weight classes we will use a handicap
formula based on this statistical result, of 0.25% points advantage for every
1Kg. Lets see how this pans out in reality. If we consider 2 pilots, one large
pilot with take-off weight of 120kg, and one small pilot with take-off weight of
80Kg. This is a 40Kg difference in weight which will lead to a 0.25 x 40 = 10%
difference in points between the two pilots. This is the same if it's a race or
a distance task, the points advantage will be the same. So if the heavy pilot
gets 900 points and the smaller pilot 800, then the smaller pilots points will
be increased 1.1 x 800 = 880 points. So in this example the larger pilot still
wings but the lead is reduced.

This should go someway to ironing out that weight advantage that big pilots
flying large gliders have always had. Next year in the weightless we will
continue this experiment by trying out this new handicap technique. This year
pilots took ballast to be at the top of their category. Using this handicap
calculation will remove this advantage to take ballast completely.

WE are only looking at total weight. Pilots can chose their own wing loading to
achieve the best performance but cannot change gliders. One glider for the comp.