posted on Jun, 13 2008 @ 09:00 AM
I suppose I can run through things that I'm aware of... and anyone can feel free to add to them.
Geared turbofans - Pratt & Whitney have contracts for the Bombardier CSeries and the Mitsubishi Regional jet. Can expect to see this powering
commericial aircraft in the 2015 timeframe. Incidentally, Rolls Royce have had a good alternative to this since the 1970s with their triple spool
Ducted fans/UHBPR turbofans - A consideration for the 737RS and A320+/NSR replacements, with Boeing postponing the 737RS you can assume the technology
isn't there yet. Also increasing the nacelle size induces more drag, the scope for improvement simply might not exist.
Unducted fans/Propfans - Used on AN-70, been tested by GE and NASA previously, well understood - does come with heavy penalties in terms of noise.
Active cancellation may be needed before it can progress onto commericial aircraft. That (active noise) won't happen (commericially) before 2020
unless there is a paradigm shift.
Bleedless engines - Used on 787 and 350, offers significant improvement in fuel burn at descent stages and stacking.
Variable nozzle engines - Good for a small improvement of 2-4% thrust at take-off, will improve sfc by marginal amounts too. Won't be around for the
CSeries or Mitsubishi, may make it onto the Boeing 737RS and Airbus NSR.
Distributed propulsion/Boundary layer ingestion - decades away - far side of 2020 to get to where geared turbofans are now IMO.
Laminar flow (both wing and nacelle) - Various projects ongoing, like EFE, two major problems being preventing surface contamination and manufacturing
tolerances. With fuel becoming a larger proportion of the direct operating costs, expect to see aircraft manufacturers produce higher tolerance
components (particularly the wing) capable of improved laminar flow. There has also been loads of work on wave drag, some of this will undoubtedly be
levered onto the next generation of aircraft (737RS - A320+/NSR)
Winglets - further refinements, but no scope for anything major.
Thinner wings - lowering the wing thickness to chord ratio can lower drag dramatically, but imposes greater strain on the wing spars etc. With the
improvement in composites, this is being pushed on aircraft like the 787, 350 and CSeries.
Warping wings - more efficient than conventional flaps, slats etc and should offer new ways to reduce wave drag, but don't expect to see this stuff
Structural improvements: Composites allow for reduced aircraft weight, and hence reduced lift dependent drag, an ongoing process, but don't expect
miracles. More likely to allow improvements in other areas, like wing thickness.
Can't think of anything else off the top of my head, if I do, will update.
[edit on 13/6/08 by kilcoo316]