Re: End of airliner evolution?

From:         falke@pweh.com ( 0 Falke_Charlie phone dist )
Date:         11 Oct 96 19:44:49 
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I Macduff wrote many intriguing questions.  At the risk of posting a
too large note, I'll interleave my answers.

> I would like to hear others views on where advances in aeronautics will
> take us and how far away is the end.  I find it curious that the basic
> design of airliners hasn't changed that much ( nothing revolutionary
> anyway) since the 707.  How efficient can you make jet engines?

OK, I guess I can't say anything "revolutionary" is added between the
707 and today, but the evolutionary changes in engine and aerodynamic
efficiency, and control technology such as active control of CG, have
resulted in range and fuel economy today that would have been regarded
as pure science fiction in the 60's.  Further improvements in
propulsive efficiency are still possible with still higher pressures,
temperatures and bypass ratios.

> Do higher speeds (supersonic) come free or will they always require
> compromise (ie fuel efficiency, safety, approach speeds)?

Fuel efficiency, yes, but the goal being worked is +10% from subsonic.
Safety, no.
Approach speeds, not necessarily.
The big technical hurdles now are noise and NOX emissions.

> Are there any revolutionary aerodynamic designs still untried in the
> wind tunnels or computer simulations?

Always.

> I believe that fifty years from now we will be flying airliners very
> similar to todays, with only minor enhancements.  They will still be
> almost entirely subsonic and have very similar overall performance.

I believe 15 or 20 years from now routes to the Pacific rim will be
dominated by 300 seat mach 2.4 to 2.6 transports with entirely composite
airframes.  Engines will have ceramic or ceramic matrix composite
turbines and burners, and geared fans.  Overall efficiency will
probably be another 40% better than it is now, at least.
   50 years ahead is scary to guess.  50 years ago, PW thought there
would be no significant commercial use of jets. But I'd think many of
the changes will be the result of dwindling supplies of fossil fuels.
The best way to get perspective about looking X years into the future
is to go back X years into the past, and see what they were calling
for the present.  My favorite is Bill Gates in 1981, saying "640K
ought to be enough for anybody."  I saw a great collection of such
quotes, i'll send it out if I can dig it up.

--
Charlie Falke                 Pratt & Whitney
System Test Team Leader       C/O Boeing Comm AP grp.