Figure 8 Landing Approaches
A Figure 8 approach is the most common approach pattern for paraglider pilots. The figure 8s are done to remain in the proper zone, just downwind of the target landing area until achieving the correct height for a final approach. Flying in this pattern will keep you downwind of the planned landing area until the desired height is reached. The expression “figure 8s” depicts the gliders pattern relative to the ground. The presence or lack of wind will affect the size of the reversing loop turns and the ground speed while holding the figure 8 pattern. Groundspeed is reduced by the wind, this will affect the groundspeed both during the lateral passes as well as the groundspeed during the reversing turns.
The goal of staying downwind of the landing area means that during each pass between the turns need to angle slightly downwind from perpendicular to the spot. If a pilot does not angle slightly downwind on these passes, then they are not doing the pattern correctly and will instead be doing wide S turns and beging to get closer to the spot. This will usually result in being too close to the spot for the final approach and this is called crowding the spot. As stated above, light or no wind will require turns that are at least 180 degrees as to where the glider is pointing. In stronger winds, the turns might be as little as 90 degrees in heading. This is because of crabbing. If there is a 10 – 12 MPH wind, for example, on the cross legs, the glider would be pointed a little more than 45 degrees into the wind to have a ground path slightly downwind perpendicular to the spot (as stated above, this is necessary for figure 8s to be done correctly). So, the turns will be just more than 90 degrees to somplete each turn and go on the next leg of the approach. Instead of thinking about all of these numbers, simply adjust the pattern to have enought drift downwind to allow for the next reversing turn.
Adjustments to the 8s include the size, location and distance downwind from the spot. In light winds, the groundspeed will be higher for all sections of the pattern. In additon, in light or zero winds, there is little or no crabbing in the cross wind legs, so the turns will be more than 180 degrees. In light winds, it is better to do a slightly wider 8 pattern a bit further back from the spot. In stronger winds, crabbing will be more prevalent on the cross wind legs and the loop turns will require turn of less than 180 degrees. This can allow for narrower loops and the ability to do the 8s closer to the target spot.
Avoid Crowding an Approach
A common problem with pilots learning a figure 8 approach is the tendency to creep forward as a result of doing “S” turns instead of doing full figure 8s. It is important to remain behind the planned distance downwind of the spot. Correctly done figure 8s will keep the pilot from moving upwind while holding the pattern. You could hold a figure 8 pattern from any height, indefinitely, just downwind of the spot and wait until you reach the correct height. It is basically like staying directly above a rectangular box drawn on the ground that is downwind of the spot.
If a pilot does S turns instead of figure 8s, they will end up too high when they get close to or above the spot. This is called crowding an approach. There are not great answers for being too high for a spot when down below about 30 ft. Turning downwind at this altitude is not safe! It leaves the pilot too low to turn back downwind, but too high to glide in to the spot. Near the ground, it is also not safe to do sharp turns, so crowding will block the pilot for landing at their desired spot.
When the 8s are done correctly, the pattern is held until the desired height is achieved and then the pilot can begin heading in to the target landing spot. The desired height should include a slight amount of extra altitude for the glide in to the spot. Soft S turns or speed to fly can be used during the final to adjust out the extra height. The point here is that the pilot can adjust out extra altitude, but cannot extend a glide without the help of lift. More on this later.
Inner and Outer Circle
So, what is the target height and at what distance? I like to use a distance of a little more than 300 ft or 100 yards to do the figure 8s downwind of. I call this imaginary distance the outer circle. If you look at the wind direction and picture a 100 yard circle around the desired landing point, you can picture a line about this distance from the center of the desired landing point. You will do your figure 8s just downwind of this circle and try to cross it at the correct height. This will be somewhere between about 40 ft (for very light or no winds) and 80 ft (for winds around 10 mph). For moderate winds about 5 mph it will be about 50 ft.
Math will help you understand why these heights work. The following table will show you why these will work for entry level to intermediate gliders that get around an 8:1 best glide.
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Distance in winds in a glider that gets 8:1 glide |
|||
|
Wind Speed |
Ground Speed (where trim = 20 mph) |
Starting Height | Gliding Distance |
| 0 |
20 |
40 | 8 x 40 x 1 = 320 |
| 5 | 15 (75 % of ground-speed in 0 wind) |
55 | 8 x 55 x .75 = 330 |
| 10 | 10 (50% of ground-speed in 0 wind) |
80 | 8 x 80 x .50 = 320 |
This may look complicated, but do not worry. These heights can be thought of more in a generalized sense. Picture that you need to be higher at the outer circle in stronger winds and lower in lighter winds. When you are going to make an approach, you will look at the wind speed and make adjustments. After practicing approaches, you will learn what heights will work and be able to adjust for wind speed. In the below pictures, you can see that there are some trees at this site that the pilots can use to cross reference their height. The trees are about 60 ft high.
In moderate to stronger winds (5 – 12 mph), the figure 8 pattern is easier to do because the turns will be less than 180 degrees. In fact, the turns might be as little as 90 degrees in winds near 10 mph. This is because of the the effect of crabbing and the resultant direction in relation to the ground.
Higher Wind Example: Picture flying at about a 45 degree angle for a 12+ mph wind. In such a wind, to reverse direction at the end of a figure 8 loop, you would only need to turn 90 degrees. In addition, during the turn, there is a very low groundspeed and the loop will not take you much upwind as you execute this 90 degree reversal. This is why, with moderate to stronger winds, it is easier to execute the figure 8s closer to the target landing spot.
Light Wind Example: Picture flying in no wind. Between the loops at the end of the 8s, you will need to head slightly downwind of perpendicular to the landing spot. This means that you would have to turn a bit more than 180 degrees with each reversing loop. In addition to this, the loops will be bigger because of higher groundspeed. In addition, the ground speed between the reversing loops will be much faster than in wind. The solution to this is to do a larger figure 8 a bit further from the spot for lighter winds. This will eliminate feeling cramped and allow for the bigger turns at the end of the loops and allow you to keep your distance from the spot (avoid crowding) until you have reached the correct approach height.
The below image depicts a Figure 8 Approach for a day with about 5 mph wind at Ed Levin Park. To have success in this approach, the pilot would need to be around tree-top level as he or she turns out of the figure 8 pattern into the outer circle / final approach area. In lighter winds or 0 wind, you would need to be just below tree-top level. In winds up around 10 MPH, it would be better to be 10 to 20 ft above the top of the corner tree as you cross the outer circle.
The Figure 8s should be done directly downwind of the Target landing spot. Imagine a pie slice directly downwind of the target spot and do the figure 8s in this. Make sure that there is always enough room to complete the turns without getting closer than about 40+ feet of the trees.
A Sample Figure 8 Approach
Do the Figure 8s in a zone downwind of the spot.
At Ed Levin, you need some imagination to de-reference the corner tree for the correct height.
The most important part of the approach is making the adjustments prior to turning onto final as you cross the Outer Circle. Anticipating a bit of height loss for the final turn and glide to the outer circle is important to plan for. It is crucial that the you don’t just do S turns instead of Figure 8s. If you do, you will move into the Outer Circle too high, we call this crowding your approach. This is because you will be too close to the spot and this severely limits your safer options for the final approach.
Learn to cross the outer circle with a little extra height. You can use speed and or turns to fine tune the height on the approach in. If you are too low, there are no ways to regain the height to make the spot. All you can do is to use the best speed to fly and hope for some lift, but this does not always happen.
Once you break out of the figure 8 pattern, you then need to continuously monitor and adjust your glide. This means looking to see if you are crossing the outer circle at the correct altitude. If you turn toward the outer circle and realize after doing so that you are going to be higher than you want, add turn or two to adjust out on the way to the outer circle. After crossing the outer circle, you can then make final adjustments. All of these adjustments need to be made as high above the ground as possible. The last 25 – 30′ of altitude should have only minor turns (less than 20 – 30 degrees, sharper turns lose altitude and this is very dangerous near the ground).
In moderate to stronger winds (5 MPH or more), above 25′ or so, you can use speed to help eat up altitude. So, if it looks like you are going to be about 30 ft past the spot, you can fly slowly into the headwind to greatly reduce your glide. Once you get to 25′, do not fly any slower than brakes at shoulders. Landings require energy in the glider and coming in too slow can be dangerous. Also avoid doing any sharp turns below this height. Sharp turns have high descent rates and this should be avoided that close to the ground. Flying slightly past the spot and landing safely is much better than pounding into the ground becaus of a low sharp turn!
In very light winds, speed will not help cut down glide much. Instead, you will need to add some S turns just after crossing the outer circle. At about 40 ft above the ground you can carve sharper turns still, within reason of course. As you get close to about 25 ft above the ground, only soft turns should be done.
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