8. Cross-Country Flying
Gliders can fly long distances using thermal lift to stay aloft. Much is involved in efficient cross-country flying, with the fundamental skill being the ability to find lift and effectively climb in it. Several factors influence decisions made by the skilled cross-country soaring pilot, and most every decision is based somewhat on predictions of weather and thermal conditions ahead on course.
One decision made by the cross-country soaring pilot is launch time. Too early a launch can leave a pilot landing back at launch for another flight or landing out after a short flight only to watch conditions improve. Waiting too late to launch, however, could limit the flight in the case of deteriorating conditions or simply because of limited daylight. The desired task for the day greatly influences the optimum launch time. If you want to fly as far as possible, then you'd launch as soon as conditions would support prolonged soaring flight. With a shorter, predetermined task, you might estimate the time required to achieve goal and launch at a time that would place the flight during the peak soaring period of the day. Often during competition, however, the choice of launch time is somewhat determined by the competition organizer/director, so the successful pilot should be skilled at working lift in even the weakest conditions.
Another important decision made by the cross-country soaring pilot is when to leave lift. It's not always in a pilot's best interest to stay in lift. Time can be wasted trying to climb in weak or small thermals if there are stronger, larger thermals around. At low altitudes one might choose to stay in poor lift until he spots definite better lift that's within his glide range, while at higher altitudes he might choose to leave poor lift and continue on course expecting to find better lift ahead. At any point in the flight (except for the final glide, which is discussed below), lift should only be left when better lift can reasonably be expected within your current glide range or when the top of the thermal is reached.
A similar decision is made when climbing in the thermal that's lifted you to an altitude from which you can glide to goal. This last glide of the flight is commonly known as the "final glide". Leaving at lower altitudes often results in lower average speeds on final glide, which can mean lower overall course speeds. Leaving with too much altitude, however, can result in such long climb times in this last thermal that, even though the final glide speeds are higher, the overall average course speeds are lower. In general, in a weaker thermal, leave lower, and in a stronger thermal, leave higher in order to achieve the best average course speed.
When you've decided on a task, press "CTRL-t", and instructions for selecting a task will appear on screen. For a list of possible waypoints or goals and more instructions, press "SHIFT-L". Next, press the "SHIFT-<key>" combination corresponding to your preferred task (see 9. Command Summary). If you'd like a task with a turnpoint in it, you must select two waypoints - one for the turnpoint and one for the goal. First, press "CTRL-t" and enter the turnpoint waypoint. Then press "CTRL-t" again and enter the waypoint for the goal. After selecting the goal of a two-leg, or "dogleg", flight task, the program calculates the total task distance and computes the FAI turnpoint sector (see Rules of Competition below) about the turnpoint. This may take a minute or two, so wait until you see the course length displayed on the screen. After setting a task, whether a straight-line or dogleg course, the length of that task will be calculated and displayed on the screen.
In-Flight Navigation and Analysis
At any time, whether or not a task has been selected, there are functions available to display the distance, bearing, and glide ratio to all available waypoints and to the plane's starting position. These "CTRL-<key>" functions are listed in 9. Command Summary. Also available at any time are the "CTRL-v" function, which displays the local magnetic variation, and the "CTRL-a" function, which displays the current indicated airspeed, sink rate, and glide ratio through the air (not necessarily the glide ratio across the ground - unless the wind is calm). This "CTRL-a" function is a valuable tool for generating flight performance data for aircraft.
If you've selected a task for the flight, then other functions are available in addition to the ones above. Pres "CTRL-f" to display flight computer data, including elapsed time, course distance achieved, average course speed since selecting a task, current course speed, and estimated time to arrival at goal. Also, if a goal has been chosen for a flight, the adventure will monitor that goal and will congratulate you upon crossing it. Upon achieving goal, you will also be told the task length, your flight time, and your average speed for the task. If you land without achieving your selected goal, then you're told how far short of goal you landed, your flight time, and your average course speed for the flight. Of course, in competition, speed is generally not considered for a pilot not making it to goal, but it's nice to know your speed, anyway.
Cross-country soaring competition is an excellent arena for practicing maximum-efficiency and maximum-speed cross-country flying and for testing one's skills against some of the best pilots. The general format of a cross-country soaring competition is to have several pilots fly the same pre-determined course with the winner being the pilot to complete the course in the fastest time. If no pilot completes the course, then the winner is the pilot who comes nearest to completing the course. Most courses consist of at least one turnpoint, which allows the launch and landing sites to be the same if desired. Also, some competitions have an open-distance format, wherein pilots can launch whenever they choose and fly in whatever direction they want, with the winner being the pilot to fly the farthest straight-line distance.
While not all competitions are conducted using the exact same rules, there are some common aspects of competition rules, such as those related to flying a predetermined course. Of primary importance are the proper verification of flight task turnpoints and the proper crossing of goal. Crossing goal properly is fairly straightforward. One simply needs to cross within 500 feet (horizontally) of the exact goal point at an altitude less than or equal to 1000 feet above ground level (AGL). In Cross-Country Soaring 98, the exact goal point is the center of the runway or the intersection point of two runways at the goal airport, but the best way to ensure flying directly over the exact goal point is to use the "CTRL-<key>" navigation function for the goal airport and fly straight towards it.
Verification of turnpoint achievement is more difficult, though.
A photograph is required to prove turnpoint achievement. If the pilot
fails to take a valid turnpoint photo, then he isn't credited with making
the turnpoint. In this case, the pilot should land as near the turnpoint
as possible in order to be credited with as much distance as possible.
The photo must be taken from a point that proves that the pilot actually
passed by the turnpoint on the proper side. Here's how this standard
FAI turnpoint sector is defined (see the figure below). Draw a bisector
to the angle made by the two adjacent course legs that meet at the turnpoint.
On the outside of the turnpoint, construct an arc centered at the turnpoint,
one kilometer (0.62 miles) in radius, and swept 45 degrees to either side
of the bisector. This quarter-circle is the standard FAI turnpoint
sector, and the photo must be taken from within this sector for the photo
to be deemed valid. It's a good idea to sketch the flight course
and the turnpoint sector on the map before the flight to get a better idea
of where the sector is. Press "CTRL-p" to snap a photo, and you'll
be given an on-screen message telling you whether or not your photo was
valid. Try to take a good photo the first time, though, because your
camera only has three exposures of film, and you don't want to waste time
trying to simply get a valid turnpoint photo, anyway.
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