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Re: was Arcjet, now solid boosters






>From: sco@sco-inc.com
>To: Mahlon Haunschild <mahlonhaunschild@home.com>
>CC: amsat-bb@AMSAT.Org
>Subject: Re: [amsat-bb] was Arcjet, now solid boosters
>Date: Mon, 04 Jun 2001 21:34:41 -0400
>
>At 07:39 PM 6/4/2001 , you wrote:
>>Especially maintenance.  The airlines have long known that the per-unit
>>cost of jet engine maintenance is the same whether the engine is 20000,
>>50000, or 90000 pounds thrust.  Labor cost is the driving factor here,
>>not parts cost. This is the overriding reason why the Boeing 777 has
>>only two engines (or so a GE employee told me a few years ago).
>
>Over the USA if you lose one of those engines you can make an emergency
>landing ... hopefully.
>But over water to Hawaii and you will go swimming, there is no backup or
>place to land. You can only ditch at sea. If it at night (like coming back
>from Hawaii usually is) then you go into the water in the dark, not a very
>pleasant thing to consider.
>
>W4SCO
>

Well...lets sort out Apples from oranges...first lets talk about two engine 
airplanes (turbojets).  Two engine jet airplanes operating over water must 
meet ETOPS requirements and be within certian distances from land AT ALL 
times.  These numbers have gotten larger as the reliability and record 
keeping on large turbofans has gotten larger.

But in terms of an engine failure the remaining jet (and the pilot) doesnt 
really care wheather or not they are over water or over the Rocky Mountains 
(indeed under certian circumstances I would rather be pushing the mighty 
twin (the triple seven) across the mighty water (the Pacific) then say the 
little twin (the B-737) over the Rockies...

Put it another way if you have to shut down an engine at the PNR (the point 
of no return) from KLAX to KHOU in a 777 or 767 or 757 or 737 the passengers 
would only know it because a prudent captain would put the vest on etc...it 
wouldnt be any more or less exciting then losing one from KLGA to KLAX....it 
just would take you a little longer to land (landings over land must be made 
within one hour if you have an engine failure in a twin) whereas it might 
take a little longer over the water...but statistically you would still be 
as safe...ie the chances of losing the other one as remote and the airplane 
would fly quite nicely (indeed you wouldnt have to get over those nasty 
mountains).

In short twin engine ops over water is NBD (no big deal)...Ditching in an 
airplane with wing mounted turbofans is quite unlikely to occur successfully 
either day or night.

Four engines are a little different (ie the range rates are based on 1 out) 
and three engines are based on 1 out.  Its a myth that you could lose three 
in a B-747 and continue to Honorroo.

BTW my better half is right this instant pushing a B-767 across the mighty 
waters to Honorroo...for a major US airline.  She is a training captain 
there.

Robert Oler WB5MZO

ATP (thats airline transport pilot) with ratings B-777, B767/757, B-737, 
B-727, B-707, B-747 (100,200,300, 400). and I am a designated examiner in a 
couple of them. CFII/MEI I have over 17,000 hours flight time.  My other 
airplane is an F-14D Tomcat (and I am a Naval Fleet Instructor).


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