Re: aerial re-fuelling

From: (Robert Dorsett)
Organization: Netcom Online Communications Services (408-241-9760 login: guest)
Date:         09 Jul 96 13:09:44 
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In article <airliners.1996.1134@ohare.Chicago.COM> (Dkhodges) writes:
>A question to those who know much more than I about the airline industry:
>Why is it that aerial re-fuelling, which has gained wide acceptance as a
>military technology has not gained the same acceptance in the civiian
>sector.  It seems a reasonable way to fly longer routes with less
>expensive aircraft, and perhaps a lucrative field for a "tanking" service
>as well.

A big chunk of fuel burn occurs on takeoff, where, at sea level, burn rates
can range from 10,000 lbs/hr/engine (747) to 18,000 lbs/hr/engine on some
large turbofans (such as the 777).  If the airplane is already in cruise,
which generally operates at a much lower rate (3000-4000 lbs/hr/engine on the
747, at cruise altitude), it makes more sense to extend the range of the
aircraft than put it through another cycle.

"But I said use a TANKER".  And so you did.  Instead of putting the airliner
through a cycle, you're putting the tanker through the cycle.  The end
result is the same: you're wasting a tremendous amount of fuel,
unnecessarily.  PLUS the wear and tear, acquisition, and operating costs
of the tanker.  PLUS the operating costs of the airplane already in the
air.  Plus lost time coordinating the rendezvous.  Plus the safety factors
involved in a mid-air hook-up, training requirements, etc.

Also, keep in mind that tankers are more or less just regular airliners,
with an ability to refuel other airplanes.  Unless special accomod-
ations are made, the onboard fuel capacity is the same as for their civilian
equivalent.  The other airplanes are taking fuel from the onboard capacity
of the tanker.  A tanker refuelling another big airplane of the same type is
likely to be a losing proposition, and, in military experience, it is not
unheard of for multiple tankers to be used in a refuelling mission.

Tankers make much more sense when used by the military.  A max-performance
climb out of an aircraft carrier, for example, may leave fuel significantly
exhausted, so a quick "top-off" at altitude could be just the thing to
complete the mission.  The military is also not accountable to the types of
cost-accounting which the civilian sector must balance the books with.

Robert Dorsett                         Moderator, sci.aeronautics.simulation