Re: Aircraft range (was Re: Why "IGW" instead of "ER", and otherquestion about 777's...)

Date:         09 May 97 03:28:58 
From:         "Darren Rhodes" <D.P.Rhodes@lboro.ac.uk>
Organization: Loughborough University
References:   1 2 3 4 5
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Alvin W. Law <alaw@us.oracle.com> wrote in article
> Pardon my ignorance here but I have a question regarding aircraft ranges
> as published by airframe manufacturers for promotional purposes.  As many
> of the so-called ultra-long haul routes are trans-Pacific which are heavily
> affected by the strong westerly wind, what kind of guidelines are the
> airframe manufacturers using to calculate the maximum range?

With regard to headwinds, Boeing publishes a report called Winds on World
Air Routes, Doc. No. D6-56162, and it lists the winds for different seasons
at different altitude for the world's major air routes. It however doesn't
list ORD-HKG or HKG-JFK. As a indicator though, for HKG-LAX (6283nm) it
gives a peak headwind of 51kts for October and mimimum of 25kts in July.
Because of this seasonal variation, most aerospace manufacturers use the
annual equivalent 85th percentile wind in performance calculations. This is
quoted as 24kts headwind at 39,000ft. For the return leg,
the 85th percentile is -63kts or a 63kt tailwind at 39,000ft.

--
Mr. Darren P. Rhodes, BEng. (Hons) | Department of Aeronautical &
Tel:   +44 (0)1509 223454          | Automotive Engineering &
Fax:   +44 (0)1509 223946          | Transport Studies,
Email: D.P.Rhodes@lboro.ac.uk      | Loughborough University,
Web:   158.125.1.201/~ttdpr/       | Leics. LE11 3TU, UK