3D Shape Task

Competition Ballooning – 3D Shape Task

The rule (or information) for this task is set out in Chapter 15 of the Event Rules

This could be regarded as the simplest task and possibly the fairest when trying to judge the skill of flying, as all competitors take off from a common launch area and all are aiming for the same target. The launch period is usually about 30 minutes so the only remaining variable is any change in wind direction between first off and last off. As stated in the rule you will be given the position of the set goal/target on the task sheet at the briefing. The goal is a place defined by grid reference on the competition map, usually a road junction. The target is a prominent cross displayed in the vicinity of the goal (usually in the field adjacent) or at a specified coordinate e.g. 200metres to the north west of the goal. If you are only given the goal reference you head for that and the cross will be close to it. Often you will only be given the coordinates of the target with no associated goal and this will be found in the middle of a field. Whichever, the first thing to do is to draw a line from your take off point to the target (or goal) and find out what direction that route gives. Remember that on a large launch field your take off point may be some distance from the common launch point so you may need to adjust your route once you arrive at the launch site. Referring to the weather information sheet will then give you an idea at what height you will need to fly to take you to the target. The next thing to do is to draw a line back from the target in the direction that the ground wind is coming from; that should give you the direction that you will be finally flying in over the target to drop your marker. The next decision is whether to take off first, in the middle with everybody else or last. There is no correct answer. In Japan when faced with multiple tasks and the winds dropping out altogether after a couple of hours it is always best to take off early. Another advantage of early take off is a fairly unobstructed approach to common targets. However having a few balloons in front will tell you a lot about the wind changes near the ground as they run in to the target and if far enough in front may well allow you to correct in time if there has been any major change. As you take off it is worth noting the wind direction near the surface. You may then amend the ground wind route into

This is what is called a ‘virtual task’ as there is no target or border to aim for on the ground and you only have points in the sky to fly to defined by shapes. That is why the task data states that it is ‘with logger scoring’ only. These can still be flown using an ‘old fashioned’ paper map without a GPS but that makes it very difficult; a GPS with moving map reduces the workload considerably. The most common 3D shapes have ended up being named after food; there is the pie (or wedding cake) and the do’nut. The wedding cake is as shown in Figure 1. This is the information you will be given on your task sheet. As in a wedding cake there are three tiers with each tier smaller than the one below. The diameter of the tiers is given as shown and these are typical values. The levels of each tier are also given and again these are typical. In this example the height of the ground would not have been

 

Figure 1: The Pie (Wedding Cake).

 

higher than about 100ft AMSL (above mean sea level) so the lowest level height you start scoring in is above the highest point on the ground that you will be flying over. The idea is that you try to fly the maximum distance within the cake. This could be the diameter but can be increased by doglegging through area if you can – or even backwards should the winds allow! It is the horizontal distance that is scored and not the vertical; going up and down through any area does not add anything. If you fly within the second tier (B) you achieve twice your distance logged and in the third tier (C) three times the distance so the more you fly in these areas the better the score. (Figure 2)

Fig 2: Vertical track through a pie (wedding cake)

Your track points are scored from your logger so you don’t have to record your entry or exit into these areas. So, to score well you need to enter the higher tiers as soon as you reach them. Thus, the skill is to ‘transition’ between each level just at the point where each edge of the tier meets the other.  You do not get disqualified if you leave the pie during the flight but it is only the track points

 

 

Figure 3: Predicted winds through the pie (straight blue lines) with actual track (red line).

 

within the pie that counts. If you don’t get the transition perfect it is better to err on staying in the lower area slightly longer than climbing too early (or descending too late) and flying out of the pie. As the wind alters with height you must plan your route through the pie. This is best done by starting at the top and working downwards. So, in this example, you take the 2,500ft wind and lay the direction across the top tier with it crossing the middle.  You then take the 1,500ft wind and draw that back from where the top line hits the upwind boundary of the top tier and draw back across the second tier. Likewise, you use the 500-750’ wind for the lower tier. That should give you your entry point (Fig 3). In fact, in this example, the pilot found that there was a lot more left below 500’ so used this on the last segment to extend his track. The aim is to cross the upper tier with maximal distance and one can adjust the entry and exit points of each tier before and after if it can give you extra distance in those segments; as long as you aim to get the maximum distance in the top tier, worth 3x your track distance. When you are flying the task, you may find the winds have altered from that observed or forecasted; in these situations, you may have to sacrifice some distance by flying above parts of the lower tiers to give you a better score in the upper tiers; sometimes you miss the upper tier or tiers altogether!

The task data may define the centre of the pie or it may instruct you to declare the centre yourself (a pilot declared 3D shape) in the logger either on the ground before take-off or at some defined point in the flight. Occasionally it may instruct you to declare the centre along a certain northings or eastings line so that the task occurs at a defined point in the flight placing it after or between certain other tasks. In the pilot declared 3D shape you estimate the entry point as explained and adjust the centre accordingly.

 

Figure 4: The do’nut

 

The do’nut is not as complex. You have two concentric circles and have to fly within them as far as possible. Again, as the rule states, it is the accumulated horizontal distance between valid track points in the area that counts. The normal approach is to fly low into the area to the left of the centre, ‘kiss’ the inner boundary and then climb to move to the right around the do’nut: that is assuming you are in the northern hemisphere where it is usually ‘right with height’, the opposite occurs in the southern hemisphere. Part of the skill is climbing at a rate that keeps you within the do,nut and does not expel you too early. There are usually no height boundaries so you can fly as high and as low as the general rules allow. To predict the entry point, draw the lower level wind such that it just ‘kisses’ the inner circle and the line back predicts your entry. You can fly the do’nut the other way around by flying the high leg first and then the low leg; this may depend on the terrain or what may obstruct your predicted track such as sensitive areas. I flew it once this way around in Poland where the upper half of the do’nut was over wood and lower down such the ground level winds had more left and flying the high-level part initially was an advantage.  There are other shapes that can be described. The next most used is the ‘Islands’ where you are confronted with a number of circles or squares one behind another, usually diminishing in size and increasing in the multiplier applied to your track length and not necessarily in a direct line behind one another. I am sure others will be thought off.

 

The Pie – World Championships 2012, Battle Creek USA.

 

Written by David Bareford