原点降落的方法

第二：动态耗能的办法，即pump或者butterfly法，即连续拉刹车，松刹车，动作就像使用气枪打气一样；这个动作的实质是让伞在平衡状态的两侧震荡（即迎角过大，迎角过小），大阻力，小升力；这个动作在定点着陆中也有人采用，须要指出的是，这个动作是有难度的；实施这个动作需要保证既不失速，也不能过度前冲，造成很大的俯仰摆荡，导致坠地；所以一般都不建议采用这个动作；

第三：下放襟翼：

原点降落有难度的时候，通常是松了刹车就冲过了，带刹车就被动力气流托起来了；所以我们要做的是：减小速度，同时减小升力（实际应该说保持升力不变）由

重力在伞的翼弦垂直方向的分量＝升力＝1/2空气密度×速度的平方×升力系数×迎角×升力面积，

重力在伞的翼弦方向的分量＝阻力＝1/2空气密度×速度的平方×阻力系数×迎角×升力面积，

阻力公式只是需要将升力系数换成阻力系数即可； Ok，要降低速度意味着要增加阻力，增加阻力的方式有增加伞翼弯度（带刹车），增加人的阻力，从坐姿改为站姿；同时还需要减小升力系数（为什么要减小？因为一带刹车就升上去了，所以减速的同时还要减小升力系数），看升力公式，弯度增加了（拉刹车同时还导致安装角增加），会导致升力系数增加，所以我们只能减小迎角，减小迎角在此时的唯一方式是减小安装角，即蹬加速

所以实际动作就是蹬加速增加下沉率，同时带刹车降低速度，不至于冲过去了；这个动作在很多海滩飞行片里面常见，稍微注意一下就可以看到；

第四：双边或者B失速，双边就是减小升力面积，B失速就是改变伞翼翼型形状，降低升力系数；但是着两个方法都不建议采用；

http://www.expandingknowledge.com/Jerome/PG/Tip/English.htm#Top_Landing 上面给出了8种方案

Top Landing

L2 - 1998/12/1. You have the habit of making Big Ears (Execution) to top land because it should be more stable through turbulence and it produces a higher sink rate. Do you think you have enough control to brake your wing if it wants to surge forward ? Are you ready to handle a Frontal Collapse (Recovery) ? Do you think using the Accelerator (Usage) at the same time makes you less or more susceptible to a Frontal Collapse (Recovery) ? See Vide Frontal Collapse while under Big Ears.

L3 - 1996/5/18. On your approach to a top landing, you realize you are too high. Don't over-brake and be close to Stall (Full, Recovery), as it may just happen. Just overshoot, get into the lift again, get altitude and retry. Beware of making your approach from the back as you may get into rotors. Try making your approach from the side instead and turn into the wind prior to flaring. Ask the locals about the best approach for the site.

L3 - 1999/1/15. To reduce your glide ratio and improve the landing. Approach from the side (let's say the wind comes from your right), weight shift as much as you can to the right and maintain your axis with the left brake. This degrades the glide (good). Just before touching down, let go of the left brake and the wing will face the wind.

L3 - 1999/3/21. What is harder than top landing ? Deciding not to do it. If there are strong thermals in the area, or turbulence, think about it twice. This is especially hard when you see others top land before you, beware of this Group Effect.

L3 - 1999/12/5. Top Landing - Make people aware. Make people aware that you are attempting to do a top landing. They will enjoy watching you miss/succeed and you will avoid having someone inflate his wing in your flight path, or cause turbulence. See Image: Make people aware that you are trying to top land.

L4 - 2004/6/2. Top Landing - Increase Body Drag. To reduce your glide ratio (good), adopt an upright (standing) position and spread arms and legs, which increases the drag from the pilot. See also Reduced Pilot Drag.

L4 - 2000/12/14. Flapping. Some pilots flap their wing to degrade its Lift/Drag performance in order to facilitate top landing (common in Taiwan). The technique consists of pulling your brakes in small consecutive bursts (1+ per second). If we are attempting to duplicate a bird's wing flap during landing, lets remember that unlike them, we can not move our leading edge up and down, backward and forward, increasing its relative path through the air. What really matters is not to Stall (Theory). The question boils down to the following : If by flapping, the flow which was starting to reverse is re-established more quickly when we let off the brakes, than the time that it takes to reverse it while pulling the brake, then flapping could be better than a steady state equivalent braking. But this remains unanswered. Remember that flapping will not prevent your wing from a Stall (Theory). Alternative methods : Perform S-turns or Big Ears (Execution). See also : Butterfly.

L4 - 2000/12/14. Butterfly. This technique consists of repeatedly deep braking for about 2 seconds and releasing. The wing ends up doing ample pitch motions. I don't recommend it. See also : Flapping.