Deputy Secretary of Transportation John Porcari and Federal Aviation Administration (FAA) Acting Administrator Michael Huerta saw firsthand progress in making air travel more environmentally and energy efficient. This September, the Boeing Aircraft Company flew its first “ecoDemonstrator*,” a modified American Airlines 737 aircraft, to Washington Reagan National Airport to show Porcari, Huerta and other aviation stakeholders new aircraft technologies that offer the promise of cleaner and quieter flying.
Here's one of the new things they're working on:
One of the promising technologies fitted on the wings of the ecoDemonstrator is the CLEEN Adaptive Trailing-Edges to improve fuel-saving aerodynamic efficiency and also decrease aircraft noise during approach.
Roseflyer From United States of America, joined Feb 2004, 9194 posts, RR: 52 Reply 4, posted (1 year 3 months 1 day 20 hours ago) and read 11169 times:
Boeing regularly works with a select group of airlines on new technology. Boeing is working with American Airlines to borrow one of their brand new 737s prior to delivery and instrument it up to test various new technologies. A couple years ago Boeing was using a Continental 737 to test various other improvements. Southwest has offered new airplanes as well for testing. Many of the new technologies that are being developed need to be tested on an actual airplane. Boeing will borrow airplanes from airlines to conduct flight tests and then return them to their normal configuration prior to delivery. This saves the cost of having to maintain an airplane for flight test purposes and airlines benefit because Boeing pays them for their airplane and also they get improved products.
If you have never designed an airplane part before, let the real designers do the work!
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 11, posted (1 year 3 months 1 day 1 hour ago) and read 5664 times:
Quoting 777222LR (Reply 6): Does anyone have a link to diagrams of the trailing edge devices and variable engine nozzles?
The test nozzle is fixed on a per-flight basis (they can change the nozzle profile between flights). It all goes to the trade between weight/complexity and fuel savings of being able to vary the nozzle in flight.
Quoting DocLightning (Reply 7): Seconded. Can someone explain how "CLEEN" is supposed to improve efficiency?
Adaptive trailing edge is designed to tweak the wing camber for lower induced drag in cruise.
Variable nozzle is designed to tweak engine exhaust velocity for improved propulsive efficiency (higher TSFC).
Quoting horstroad (Reply 8): aren´t these new trailing edge devices just smaller flaps?
Basically, yes. The art is in exactly where to put them for various flight configurations.
DocLightning From United States of America, joined Nov 2005, 18031 posts, RR: 57 Reply 12, posted (1 year 3 months 23 hours ago) and read 3801 times:
Quoting tdscanuck (Reply 11): Adaptive trailing edge is designed to tweak the wing camber for lower induced drag in cruise.
Can you give me a hand-waving explanation on how that works? So far back on the wing, the flow would be pretty separated, right? So how would a little flap thingie sticking down from the underside alter the aerodynamics to improve efficiency?
You only get best L/D for a wing at a particular C_L...but, since airlines fly by dynamic pressure (aka IAS), the actual C_L will vary with weight. As a result, there's only one weight/speed combination where the wing is performing at its best and it slowly drops off as you go to either side. The drop off isn't dramatic, which is why this wasn't much of a focus until the last decade or so, but it is there.
Since the drop off isn't dramatic, the changes required to tweak the wing back to its optimum point are also small, hence you can do it with a tiny flap.
Quoting DocLightning (Reply 12): So far back on the wing, the flow would be pretty separated, right?
There is very very little flow separation on the wing at cruise. There's really just the wake and that's not much thicker than the trailing edge itself. It doesn't take much. This idea, as far as I can tell, is basically a souped up version of a Gurney flap (http://en.wikipedia.org/wiki/Gurney_flap) and they're only 1-2% of chord.
Quoting DocLightning (Reply 12): So how would a little flap thingie sticking down from the underside alter the aerodynamics to improve efficiency?
By making very small adjustments to the wing C_l to push it towards the optimum point.
The concept is already validated on the 787 as Variable Camber Trailing Edge, and soon to be seen on the A350, but they integrated it right into the flap drive on those aircraft. The 737 already has a flap drive system that they don't want to play with very much, so this is basically a retrofit cruise flap system.