Another factor is speed. Those cable cutters require a bit of force to
successfully sever the wire. Oh, and a major transmission line can
have dual or even quad-wires of a greater diameter or strength than
the average bear. Those cutters are almost worthless in that
circumstance.
Another factor is that even though the cutter can be successful in
severing the wire, the impact and sudden decelleration usually does
substantial damage to the chopper itself. It doesn't turn the event
into a safe passage, but what it does is give the occupants of the
chopper a fighting chance of surviving under SOME impacts.
The cutters also become greatly less effective when the cable strike
is at an angle. Obviously, when the aircraft is accellerating or
climbing, the plane of rotation of the main rotor blades is tilted
downward quite a bit and the blades will impact the wire first. But
that's only part of the story, If the lines are running north-south,
for example, the most effective protection is gained when the aircraft
if going east-west. But when the aircraft is going, say, north-east,
the cutter may never actually get to the cable as the cable will
typically impact the cabin itself or get caught in the landing gear.
There was a recent crash where the cable came through the windscreen
and actually killed the pilot. The fall to earth killed the rest of
the occupants.
BTW, most cropdusters have cable deflection/cutting equipment
installed too. However, those aircraft have additional protection
designs built-in too. Like placing the pilot far enough back and
behind the tanks, steel cage structures which provide crushability to
the front, but protection to the pilot (like a race car) and wing
designs that have a massive progressive stall characteristic that
prevents abrupt attitude changes. A cable strike in ANY aircraft under
even the best of conditions is potentially a career or even
life-altering event.
This past year, the big evil telco I work for, had several cable
strikes by cropdusters. In only one case did the pilot fly back to the
airport--the rest they did an immediate field landing. All pilots and
planes survived, but much damage done to the planes. In one case, the
plane took out a 400-pair cable. Those are extremely heavy cables. The
cutter sliced the cable, but the airplane sustained major damage from
the impact of the broken cable against the airframe itself.
Now if we can just keep people from stealing our lines for the copper.
The idiots are climbing the polls to cut the lines right off of them.
One night, somebody stole a half-mile of aerial. We replaced it and
two nights later it all disappeared again.
AG
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|