Re: [Phys-l] operating room physics

[Hugh Haskell <haskellh@verizon.net>]

At 08:29 -0600 03/04/2010, Brian Whatcott wrote:
> When trucks refuel aircraft, the first step is clipping on the grounding
> strap connecting bowser and airframe.
It's not just refueling. On combat aircraft, stray discharges can set 
off explosives or even launch missiles. This is a big problem on 
aircraft carriers, where the static charge on an aircraft just 
recovered can be considerable, and is typically insulated from the 
deck by the aircraft's wheels. The arresting cable should take care 
of most of the problem, but the electrical connection between the 
tail hook and the rest of the plane cannot be guaranteed, so, once 
the plane is parked one of the first things done is to connect a 
ground wire between the plane and the deck. When the plane is moved, 
the ground wire is switched from the deck to the tractor.

I've seen the results of an accidental launch of a missile from a 
parked aircraft. It's really scary. Fortunately, the explosive 
doesn't usually go off because the missile will hit something before 
it has time to arm itself. But seeing the tail end of a missile 
sticking out of the fuselage of a plane is a powerful reminder to be 
really careful about keeping an aircraft grounded (and not tying off 
the interlock switch that disables the firing circuit when the 
landing gear is carrying any weight).

Hugh
--
Hugh Haskell
mailto:hugh@ieer.org
mailto:haskellh@verizon.net

So-called "global warming" is just a secret ploy by wacko 
tree-huggers to make America energy independent, clean our air and 
water, improve the fuel efficiency of our vehicles, kick-start 
21st-century industries, and make our cities safer. Don't let them 
get away with it!!

					Chip Giller, Founder, Grist.org