时间:2011-04-05 11:37来源:蓝天飞行翻译 作者:航空 点击:次
To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. You can dampen oscillation by reducing your airspeed to at least 10% below this critical one, going slower if necessary while increasing power. Turning could provide enough centrifugal force to stop it as well, which is also the usual remedy when the load starts to swing, but this will increase its effective weight, possibly to more than your lifting capabilities (a good reason for not being too tight on payload), so applying centrifugal force in these cases could make things worse. Load swing is proportional to speed and the length of the sling – the faster you go, the more it occurs because of the load’s own lift and drag. Put simply, the load will always move further in a swing than the aircraft does – if you move 4 feet to the right, the load will travel eight, after a short pause, as it moves four feet to the other side of you. As it takes as long to swing through 15° as it does through 45, like any pendulum, if you move the opposite way, as is natural, you just make the load swing faster. Going with the swing, that is, load to the left, helicopter to the left, will stop it quickest (do it on your side so you can see what’s going on, but it works both ways). This has the effect of moving the fulcrum point from under the helicopter to over the load, which removes the directional vector. If you want it to in a particular direction, wait till it is going that way before correcting it, then you will be almost pushing it into place. Put simply, don’t pull the load the way you don’t want it to go. Setting Down |