Author: Harry Medlicott

 (All rights reserved by the author! This material has been published with the consent of the author. Every unauthorized copy is subject to copyright)

Part One

These notes contain suggestions which may help those pilots who wish to develop their cross-country flying ability.

Put a reasonably competent pilot who does little more than local flying in the same thermal as a good competitive cross-country pilot and he will usually climb just as well. Inter-thermal techniques are not a magic art and the good cross-country pilots are not supermen
endowed with extraordinary qualities. The ability to fly cross country in a safe and efficient manner is within all of us.

Practicing can be done in conjunction with local flying. When I, as an inexperienced coastal pilot, first flew at Lake Keepit, panic took over whenever the altimeter registered below 3,000ft and I behaved as though an outlanding was inevitable and almost immediate…
not a good mental state to find lift!

To overcome this natural caution and disquiet at leaving the airfield I used to fly backwards and forwards between Manilla and Gunnedah record my times at each turnpoint. On some days I managed the trip six times and got too bored to be concerned about height. There were airfields within easy gliding range all the timeneven when under 2,000ft and this security enabled faster flying and being selective as to lift.

The most important decisions we make are: The direction we will point the glider and the speed we will fly upon leaving the thermal. It is a waste of time to arrive at the top of the thermal and
then waffle around for a few turns making up our mind and making hurried decisions. It is also far easier to see the clouds for the next 20 or 30 kilometres when you are well below cloud base.

Ingo Renner looks along track as he is thermalling and identifies which cloud is growing best and thus being fed by a good thermal.

When it is time to leave and that is before the lift has weakened, his decisions are made and there is no wasted time. We can all practice the skill and study clouds, thermal sources and identify climbing gliders whilst thermalling. Our lookout will also be enhanced.

The speed to fly between thermals is always a point of discussion. Do we fly a MacCready setting and regularly alter speed or do we fly “block” speeds? i.e. setting a speed and only altering it when conditions change, such as encountering the edge of a thermal or
failing to find lift and reducing our expectations.

Our best pilots almost use “block” speeds. Variometer delay means slowing down in most lift and speeding up in sinking air is inefficient and distracts pilots from the all-important task of looking ahead for clues. Speeding up in sink often means that we blastnthrough the lift which is on the other side of the pre-thermal sink.The factor which is the major determinant in cross country speeds is the achieved average rate of climb not the speed at which we fly.

When we reach the top of the thermal we should have made a simple decision… to either fly for speed or range. If lift ahead is uncertain, our climb was not as good or as high as we expected or we are about to cross a cloudless area (a blue hole) then we should fly for range… irrespective of how good our last climb was. The speed for range in most modern gliders such as our LS6, LS7 or a Discus is about 70kts.

At this speed the sink rate is still modest but we can still average close to 100kph cross-country if we can keep out time spent thermalling to less than 25%, but if we drop to 60kts the best we can achieve is about 80kph. 60kts is reserved for when the search for lift has become critical.

The speed range when flying for speed depends on the glider, its wing loading and general condition but generally is between 70 and 90kts. Flying at 100kts is seldom justified as most gliders are well past their efficient speed range, the rate of sink is very high and we have greatly reduced our search range. For best results on reasonable days gliders such as our LS6, LS7 or the Discus should be flown at about 80kts dry and not more than 90kts when water ballast is carried.

When lift of 4kts or more is available water ballast will help increase average cross-country speeds. My own experience is that gliders will carry a certain amount of water quite easily but beyond that it requires extremely good and regular lift to justify very high wing loadings.

The LS6, LS7 and Discus handle up to about 100 litres extremely well with an average weight pilot. At this wing loading either fly 12½% faster for the same sink rate or fly 25% further at the same speed for the same loss of height and thus extend our search range. Conditions ahead will decide how to best use the extra performance. If flying at 70kts or less or if thermals are rough and difficult to work we are better off without water.

On days when we are using 6kt thermals it is most unlikely that there are many 8 knotters around but it is often possible to reduce our inter-thermal sink rate by ½kt which has the same effect as 2 extra knots in a thermal. We can often plan our track to the next obviously good cloud to intercept wisps or haze domes which may be the top of a new thermal.

We can deviate 20deg off track and fly very little extra distance. I will go for a series of wispy clouds leading the better conditions rather than one reasonable cloud with a blue hole beyond.
If the reasonable cloud doesn’t produce a thermal then we are left to fly through the blue hole

…end of part 1