Re: B747 technical questions

Date:         11 Jul 97 02:09:25 
From: (Simon Craig)
Organization: OzEmail Ltd - Australia
References:   1
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In article <airliners.1997.1385@ohare.Chicago.COM>, wrote:

>Some questions:-
>1) For the 5th engine which can be installed on the pod under the wings,
>can it be used as part of the aircraft's engine thereby making the
>aircraft run on five engines?

No, it's for carriage only.  A number of components are removed and most of
it is blanked off to prevent it turning (windmilling) in flight.

>2) What is the best EPR number to be attained?  Is it the smaller the
>number the better or the greater the better?  Since EPR=turbine
>discharge pressure: compressor inlet pressure.  And why?

On a Pratt & Whitney or Rolls Royce engine, the higher the ratio, the more
thrust is produced, ie 1.72 is take off power (58,000 lbs) on a RR RB211
524G that my company operates but at idle that would be a lot lower.  The
General Electric engine does not use EPR to calculate thrust.  It uses the
fan speed (called N1) instead.

>3) What is in the inside of an aircraft tyre?  I mean is it
>filled/pumped up with air like that of car tyres or is it built as a
>solid whole piece??

It is a tubeless tyre inflated with nitrogen - as it is an inert gas that
is less likely to support combustion (from brake heat, etc).


Simon Craig

--- I complained because I had no PowerMac; then I met a man who used
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