Boeing’s ecoDemonstrator is back – but this time the company is using a 787 for the role rather than the polished aluminum 737-800 which it leased from American Airlines for the first ecoDem mission in 2012. The first task for the aircraft, Boeing’s fourth 787 development unit ZA004, was an evaluation of an engine nozzle made from Oxide-Oxide ceramic matrix composite (CMC).
ZA004 flew with the CMC nozzle (No.2 engine – furthest from camera) over a period of 12 days as part of the FAA’s Continuous Lower Energy, Emissions and Noise (Cleen) program. (Joe Walker)
Fitted to one of the 787’s two Rolls-Royce Trent 1000s, the nozzle was developed under a joint effort between Boeing, Rolls, ATK affiliate COI Ceramics and Albany Engineered Composites. Boeing is still reviewing data, but preliminary results show the advanced material was not only more heat resistant, but considerably lighter with the potential for fuel savings on future designs. Boeing believes tests of the acoustically treated oxide CMC nozzle, the largest single part ever made from this material, could prove a breakthrough in improving propulsion system efficiency and open up a possible gateway to more closely integrated airframe-engine designs.
Although engine makers like General Electric have made strides to develop CMCs for use in static hot parts of engines, such as the mixer on the Passport business aircraft engine, Boeing wants to explore the wider potential of the material for everything from propulsion systems to thermal protection on hypersonic and space reentry vehicles. “CMCs are being studied for engine core applications, but as temperatures go up naturally there is impingement on the exhaust washed areas of the structure,” says Mitch Petervary, Boeing principle investigator for the FAA’s Cleen oxide nozzle. “Boeing integrates propulsion into the airframe and, as the exhaust nozzle is part of that package, that’s one of the reasons we selected it for the ecoDemonstrator,” he adds. For more on the tests see the Sept 1 edition of Aviation Week & Space Technology.
GE’s Passport engine is the first non-military engine to incorporate CMCs. The material is used for core cowls, centerbody and exhaust mixer as shown here. (GE)
The ecoDemonstrator is currently in lay-up at Boeing Field, Seattle, where it is being fitted with a new suite of technologies for test in areas covering connectivity, materials, flight deck, flight sciences and flight test efficiency. Flight tests are expected to resume in October. The 787 program will be followed in 2015 by a third ecoDemonstrator, a 757-200 leased from U.K.-based partner airline TUI.
The 757 is currently stored at Boeing Field in Seattle, but will soon undergo radical surgery to install a new active flow control (AFC) vertical tail and numerous other changes. Flight tests will be broken into three major phases and conducted through the bulk of next year. (Boeing)
Modifications to the tail will be based on results from evaluations of a full-scale 757 tail, equipped with AFC, which demonstrated increased rudder effectiveness in wind-tunnel tests run late last year by Boeing and NASA. The tests used AFC to increase rudder sideforce on demand by delaying airflow separation over the deflected control surface. Using data from the tests Boeing will position airflow actuators and instrumentation at specific points upstream of the rudder hinge. The ultimate goal is to reduce tail size and therefore drag. (NASA)