直升机飞行员手册直升机操作手册 The Helicopter Pilot’s Handbook

时间：2011-04-05 11:37来源：蓝天飞行翻译 作者：航空 点击：次

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Once in flight, remember that the load is the part that should be kept straight and level, not the helicopter, and keep away from anything underneath that could be damaged (well, try anyway!). Only with imminent danger to the aircraft should a load be jettisoned, usually from excessive swinging (commercially, dropping loads is regarded as a non-macho thing to do, but it's your backside the helicopter is strapped to). As a point of interest, 10 gallons of fuel from 500 feet will go straight to the basement of a 3-storey house. If you drop anything obnoxious in water, expect your company to pay for the clean-up and testing.
Unless in rough air, beeping the RPM down helps with the lift and the fuel burn.
If you get an engine failure in the mountains with a load attached, consider not jettisoning it. This may sound daft, but it may stop you from falling down a crevice or something
– just try to keep the line taut so you don’t get a nasty jerk at the end.
Load Behaviour
Every load has its own VNE, unfortunately usually only found by experiment, which is why you should always start off slowly and build up to a point where it starts to give trouble, then back off, as low as possible, so there is less height to get rid of in a hurry. Most helicopters will carry loads at quite high speeds, but the load itself might not be able to handle it—a sudden input of drag when something falls off could become quite a problem. Although customers don’t like to pay for unnecessary flying, there’s no rush. Take it easy. Also, remember your machine’s VNE with the doors off!
External loads increase the frontal area of the whole aircraft, which naturally increases drag, so you will need more power overall. A load may be easy to lift, but present enough drag to cause severe difficulties, particularly where you reach power limits too quickly to maintain forward flight, and the load overtakes you and pulls you along. A long-line needs more anticipation, so you need a high degree of co-ordination and patience. It's not the sort of thing that can be learnt in any other way than with lots of practice.
Unevenly shaped loads will tend to spin and, if they're slung without reference to their centre of gravity, could tip over. A drogue chute can stabilise them, but use a windsock type rather than a pure parachute, which will bounce around trying to spill the air out (or punch holes in it). Naturally, these must be kept well away from the tail rotor. Logs or cut timber usually fly poorly unless a tail is installed, which can be made out of a bough or piece of plywood, so it sticks out of the back.
Oscillation or excessive vibration can come from a number of places, usually a combination of the stability characteristics of the load and forward speed. Heavy or dense loads, such as bags of cement or drums of kerosene, will not usually present problems due to their mass, but large-volume loads of low density can oscillate at a certain critical speed, again usually only found by trial and error.

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