ROUTE PLANNING WHEN TAKING VALLEY WINDS INTO ACCOUNT

The direct route to the bowl (red arrow) is good if we have plenty of altitude. However if our altitude is low enough that we're likely to pass over the flatter section marked A at low altitude, it is better to take a detour (yellow arrow) to avoid the lee rotor from the valley wind (blue arrow).

SEARCHING FOR FLATLAND THERMALS WHEN LOW

1. Where's the wind coming from? Flatland flying means less leeside worries, but even a small hill may cause serious rotor.
2. Is there anywhere where the landscape is oriented better against the sun?
3. Where is the best soil for heating?
4. Where will the thermal be triggered?
This brief checklist can be summarised into an even briefer sentence: First look for easily heated soil, then try to visualise where the thermal will release!

Photo: Jerome Maupoint, Gin Gliders

THE VENTURI EFFECT

"Whenever a flow is forced through a constriction we can observe venturi effects. The flow speed in the constriction increases and the pressure drops. In the photo above we see the narrow gorge just west of the launch at Bassano, Italy. Time and again this gorge eats pilots who underestimate the venturi effect and blunder too far in, only to find that they cannot get back out against the wind. There are some small landing options but they are far from ideal."

INVERTED VALLEY BREEZES

"Free flyers should always acquire updated weather forecasts before going to launch. These will tell if adjacent regions have substantially different weather patterns that may influence valley winds locally. Thus, unusual situations are less surprising."

Photo: The flying arena around Landeck, Inn Valley, Austria. If the western Alps are covered in cloud, the centre of the heat low will be displaced towards the east and the valley winds here may be inverted.

TUCK YOUR GLOVES IN

"The key to keeping your hands warm is keeping the air off of your wrists as the blood supply is very close to the surface. For the best insulation wear long gloves and tuck your gloves inside your jacket arms. Many people tuck their jacket arms into their gloves which is what you probably do walking or skiing. But, when you are flying the apparent air is going up your arm towards your hands, so having the glove on the outside would deflect this cold air onto your wrist. Try it, it can make a huge difference."

ARRIVING AT BASE

"The nearer you get to cloud base the further out towards the edge of the cloud you should fly, preferably on the upwind side if there are no obstacles around. In the mountains on days where cloud base is beneath the peaks, you should aim for the valley side of the cloud, where a brief visit inside has less consequences."

SPEED BAR SET UP

"I have my speed bar set up so that my legs are always resting on the first step of the ladder. This way all I need to do is stretch my legs to accelerate. Having to fiddle around to find it first is ineffecient."

FINDING THE BEST LIFT

Climb rate decreasing > turn tighter
Climb rate increasing > open up the turn
Climb rate remains constant > circle radius should also remain constant
Tip:
When I encounter lift while flying straight I always keep flying straight until the lift begins to decrease again, then I turn into the wind for my first circle.

"WHEN YOU FALL OUT

When flying XC you need to have a good understanding of the maximum available altitude on the day, regardless of it being a blue or cloudy one. This knowledge will help you decide if it pays to spend time searching for that thermal you just lost, or if you should rather be heading along. If you loose it close to the max. altitude and you're not just about to go on a big transition, by all means just continue instead of wasting any more time searching."

Photo: Martin Scheel

"SOARING IN CLOSE

Soaring uncomfortably close is normally not beneficial. Besides, keeping a bit more distance will be good for the nerves."

Foto: Cross Country Magazine

"DRESS APPROPRIATELY

Don't blow that 100km day by being forced to land early because of the cold. Make sure you are dressed for the cold air at altitude. Layer up making sure there are no gaps where the cold can penetrate. Use wicking layers close to your body rather than cotton T-shirts that hold moisture. Don't be tempted to put your warm gear on too early, the warmth of the sun on launch may lull you into thinking it is warmer than it really is, if you shed clothes now you will probably regret it later, or you may start to sweat which will quickly chill you once you're at base."

Foto © Fredrik Gustafsson

THERMAL LIFESPAN

"Observe the surroundings continuously whilst flying. Only by doing so can you build a picture of which of the cu's around you are building and which are decaying. Track their lifetime to get an idea of the life span of the thermals, and which ones have already been active so long that flying to them doesn't make sense."

Fig: Six images showing the lifespan of a cumulus cloud. In the first frame the cloud is just beginning to form, from frame four it is decaying again. It only pays to head for developing cu's as decaying clouds indicate nothing but increased sink. The sequence was taken over a period of approximately ten minutes.

LET YOUR GLIDER DO THE FLYING

"If you are in a turn and you hit some lift your nose naturally rises up if you are not holding on hard to the base tube. The high performance gliders are for the most part tuned to wrap in when you push out or increase your angle of attack. The glider will automatically turn more in the direction that you are turning already (wrap up) as its nose is pushed up by rising air. It turns when it encounters lift. Oleg Bondarchuk once told Kevin Carter, 'just let the glider find the core.'"

WING TIP VORTICES

"Wingtip vortices can cause your wing to shudder when you fly through the wake behind another glider. The closer you get the more dramtic the shuddering becomes. Tandem gliders are carrying more weight and trail stronger vortices"

CORING

"As a basic rule of thumb whenever you enter lift, wait 4 seconds and then turn, because that's the time it takes you to do a full 360 and stay in the lift section, (8-10 seconds 360). Thermalling isn't just about doing 360's. You often have to fly straight for a while or do 180-degree turns just to stay in the best section of lift.
It's important to fly away from the areas of less lift as much as its important to fly into the areas of most lift. So when you're doing a 360 in a thermal, if there's a section of the 360 that the vario's beeping drops, then just turn 90 degrees away from that edge and fly straight for a few seconds then turn again, and that way you'll always tighten up on the best part of the lift and avoid the sink."

SPEED TO FLY

"Once you have taken off, use the first thermal to plot where the strongest and weakest climbs in the thermal are. Where possible try to stick to the speed to fly rule, climbing in the strongest lift and gliding from base to the bottom of the strongest lift again. By avoiding the slow climbs and inversions, you fly faster time and therefore cover more distance as a days flight is a race against time."

TO 360 OR NOT

"In weak soaring conditions I may opt to do full circles in the embedded thermals even low down. If the thermal is just 70m across or more I find that I can climb better by doing 360s than by flying figure-8s. Hang gliders will need somewhat more than that.
If the wind is strong I just soar normally - strong wind and steep slopes means good climb rates anyway."

THERMAL GENERATION

"Thermals may come from any surface that is readily heated by the sun. For your mental picture try to imagine walking over the ground where you are flying. Wherever you feel the air getting warmer you can expect thermals to originate. But, cool, shady and wet areas always hinder thermal development. The rocky SE slopes in the picture are perfect for generating early thermals, knowing this the Atos pilot flies straight to them."

COLLAPSING THE GLIDER IN STRONG WINDS

"There are many different techniques used to kill the wing and avoid being dragged. One of my favoured methods, especially useful for higher performance gliders, is to provoke a large collapse while still facing forward by pulling one A riser down and across aggressively and at the same time taking a big, fast step backwards to unload the wing. With only 20% of the wing left flying you just need a smooth pull with the rear riser as you turn and duck under the risers to face the wing. It flops gently onto the ground in front of you! Well that's of course if you get it right!...."

WING UPSIDE DOWN? DON'T PANIC!

"It's easy to rectify, first align yourself with the wind and build an 'upside down' wall, make sure you are standing at the correct angle to the wing so that the wind is flowing cleanly to the side you want to flip over. Bad airflow in this area will cause the tip to loose pressure and collapse. When all is looking good, smoothly pull on the brake to flip it over. Don't use too much brake, if the side stalls (you will see the top surface of the canopy) you are using too much brake. Use just enough to tease it over, and then build your normal wall as quickly as possible using one 'A' riser and its corresponding brake."

ALWAYS CHECK FOR OBSTACLES

"Practising your ground-handling skills should be done in places where there are no obstacles around. Failing to stick to this most basic rule may quickly put you in dire straits. And when the above happens just remember to keep smiling"

FINDING THE CORE

"Finding the core is very important. The core of a thermal is the place where the thermal is lifting the strongest. If there is wind then most often the core is to be found up-wind. This is because weaker thermals drift more with the wind than stronger ones. So if you are already in a weak thermal then as part of your 360 you should straighten out as you turn into wind and start to search upwind to try to check if there is stronger lift. Try to continue to search upwind until you find that the lift decreases, then just go back to the strongest lift you found and use that."

THERMAL DRIFT OVER CRESTS

"The same slope may produce both weak and strong thermals. To avoid the risk of getting blown back into the lee it is best to only concentrate on the stronger ones. When thermalling in strong winds it is important to always remain near the windward edge, as dropping out here only causes us to sink back into the thermal, whereas dropping out on the lee side could mean sliding down the backside unable to re-penetrate due to lack of groundspeed. In the diagram the pilot on the right is thermalling near the windward side of the thermal whereas the pilot on the left tried to push back to the high relief too early and now has to cope with a landing in turbulent conditions."

SMOKE AS A THERMAL MARKER

"Two smoke trails drifting towards each other. Where they meet - red area - there's a good chance that a thermal is releasing. The hang glider has noticed it and is aiming right for the thermal. Low down the lateral drift is stronger. This means that two pilots thermalling at different altitudes in the same thermal column will experience differentiated drift, with the lower pilot drifting more!"