2 vs 4 engines: R&D costs too much ?

Date:         27 Aug 99 16:25:24 
From:         JF Mezei <jfmezei.spamnot@videotron.ca>
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A recent post mentioned the R&D mega expenditures required to produce
the engine for the next 777 which is a big reason only one manufacturer
will build one.

I am starting to wonder if the extra cost of pushing  the "state of the
art" limits to get the required performance on a twin is really worth
all the effort ?

Are we not getting to a point where conventional jet engines are
reaching the top of the bell curve and any improvements will cost more
and more ?

On the other hand, by using 4 engines (or even 3), it allows you to use
much more conventional technology which is not only cheaper  for R&D but
has greater market and hence more competition.

Also, in the theroretical A3XX plane, what sort of power is expected out
of each of the 4 engines ? Would they be using 777-class engines (90k
and above) or 747 class engines (about 60k pounds, right ?) ?

Also, is there a significant difference in weight for 4 medium vs 2 huge
engines ?