FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1991
1991 - 0527.PDF
TECHNICAL: AIR TRANSPORT NASA examines laminar-flow 757 BY GUY NORRIS IN SEATTLE Boeing is considering new flight tests of its hybrid laminar flow control (HLFC) system at the request of US research agency NASA. The company is currently analysing data from the initial trials, which were completed last August using the first pro duction 757 as a testbed. "NASA has asked us to work with them on further HLFC tests but we have not replied yet," says Boeing HLFC pro gramme manager Adelbert Nagel. "We're now considering what our next steps should be. The equipment is still on the aircraft so we are considering further tests." The early trials produced much better results than ex pected, leading to predicted sav ings of between 5% and 15% in cruise specific fuel consump tion. Tests were conducted on a 6.7m section of wing leading edge, which is treated to de velop laminar flow. Boundary- layer air is sucked through 19 million laser-drilled holes of up to 0.0125mm diameter, to re duce turbulent flow. . Nagel says that, if further tests go ahead, Boeing "...will tune up the system to provide more uniform suction and slightly improve the quality of the data"; otherwise, no changes would be made, he says. A jf Wing-mounted HLF sensors may re-appear on the 757 testbed Tests aimed at establishing how far laminar flow would remain intact downstream from the leading edge without overall suction showed that 60% of the chord was covered, compared with the predicted 40-45%. "No difficulties were ex perienced with holes blocking, and in fact the main surprise was just how few surprises there were," adds Nagel. Best results were obtained during cruise conditions at 39,000ft (11,900m) and M 0.81 — little, if any laminar flow was gener ated during climb or descent. Although tests have proved the potential benefits of HLFC, Nagel says it is less certain of the benefits in terms of eco nomics. "It could mean all kinds of bad news in terms of manufacturing," he says. The test HLFC system, de signed by Boeing engineer Jack Williams, has been test flown for 90h in some 20 flights. Nagel says that Boeing and NASA need to make a decision by mid-year because of pressure for space on the 757. The air craft is also the avionics testbed for the YF-23 Advanced Tactical Fighter and is to be fitted with the GEC Avionics fly-by-wire flight control system for the Boeing 777. - • FAA approves DC-9-10 Stage 3 hushkit The US Federal Aviation Ad ministration (FAA) has cer tificated a noise-reduction kit designed to bring the JT8D- powered DC-9-10 aircraft within Stage 3 noise limits. The programme is a joint effort between ABS Partnership and Pratt & Whitney. The noise-reduction hardware will cost $1.2 million per aircraft. ABS holds the supplemental type certificate (STC) granted by the FAA, and is responsible for airframe design changes as sociated with the noise reduc tion effort as well as for market ing the hushkits. Pratt & Whit ney provides technical direction and is responsible for engine modifications. The DC-9-10-series aircraft noise reduction kit consists of an acoustically treated inlet and tailpipe, modified thrust rev- erser and the Pratt & Whitney internal exhaust mixer. The in ternal exhaust mixer combines fan and core air in the tailpipe, reducing the velocity of the hot core exhaust air and reducing low-frequency jet noise. ABS says: "FAA certificates also are expected in the second quarter of 1991 for hushkits for DC-9-30 aircraft with JT8D-7 and -9 engines. The hushkit price for the DC-9-30 series aircraft is expected to be be tween $1.5 million and $1.9 million, depending on engine and aircraft weight." V The companies continue' to test hushkit hardware designs on DC-9 models with higher takeoff gross weights. The total certification programme should be complete in about a year. • Honeywell adds laser gyros in inertial upgrade Honeywell has introduced an upgrade package to replace the inertiai navigation systems (INS) on older-generation wi- debodies with a new INS and flight management system (FMS) incorporating laser gyros, global positioning system and satellite communications. The package, dubbed FAMIS (full aircraft management and inertial system), is aimed at operators of Boeing 747-100s, -200s and -300s, Lockheed L-lOlls, McDonnell Douglas DC-lOs, DC-8s and Airbus A300s. Flight testing will begin early next year, with certifica tion and first deliveries ex pected by the end of August 1992. The system will replace the "spinning-wheel" gyros of the older INS with a new laser- gyro inertial reference unit, which can be integrated with a global positioning system re ceiver for additional accuracy. There is also a flight data management unit, which in cludes the FMS long-range navi gation operations program and database developed for the 747- 400; a multipurpose control dis play unit; and an optional ad visory map display. Roger Keller, vice-president of marketing for Honeywell's air transport systems division, says that the full system will cost around S800,000, exclusive of installation. The advisory map display, which British Airways is install ing on its 747 fleet, will cost another $130,000. Honeywell is negotiating a "turnkey" installa tion programme with Tracor. British Airways is upgrading its entire 747 fleet to be com patible with the 747-400s, and is installing a full flight manage ment system, with both vertical and long-range navigation. Keller says that FAMIS will not include vertical navigation, as this would make the system "too expensive". The company has not yet taken any orders for FAMIS, as it only decided to proceed with development in February. D FLIGHT INTERNATIONAL 6 - 12 March, 1991 17
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
