A380 PUSHING TECHNICAL BOUNDARIES

Airbus has always been at the forefront of pushing technical boundaries in aviation and excelling in aircraft design and technology. Airbus says efforts to lower the weight of the world's largest airliner lay behind recent A380 wing cracks and pledged to learn from mistakes that lay dormant for a decade, as repair costs looked set to climb towards 500 million euros ($A642 million).

DOWNWARD FACING WINGLETS

Aircraft designers have traditionally used winglets as a means to reduce induced drag and save on consequent fuel burn aka operating costs. Over the years several designs have emerged and the classic end plates and winglets are common in Boeing and airbus models. General aviation aircraft on the other hand have more innovative designs of winglets to enhance operational cost benefits.

While an equivalent increase in wingspan would be more effective than a winglet of the same length, the bending force becomes a greater factor.  Typically, a three-foot winglet has the same bending force as a one-foot increase in span, yet gives the same performance gain as a two-foot wing span increase.  For this reason, most designers have concentrated their efforts in winglets designs to reduce drag.

MITSUBISHI FLIGHT TEST

Mitsubishi Aircraft Corporation has completed the first flight test on Pratt & Whitney’s PurePower  PW1200G engine for the MRJ, just a week after it announced a delay to the programme

The PW1217G for the 90-seat MRJ90 flew on a specially designed stub wing aboard Pratt & Whitney’s Boeing 747SP flying test bed from Pratt &Whitney’s Mirabel Aerospace Centre in Canada.

Tests to validate the engine's fuel efficiency, durability and other performance metrics, will be conducted over roughly one year so they will be completed in time for the MRJ's maiden flight. In-flight testing will be done with the engine installed in an ultralarge aircraft.


The PW1217G engine uses geared turbofan technology, which the company says can reduce noise and fuel consumption by having the large fan rotate slower. This is expected to improve the MRJ's fuel efficiency by around 20% over rival jets in this class, which seat up to 100 passengers.

Mitsubishi Aircraft has announced a new schedule for the MRJ, delaying its launch by more than a year. Behind the pushed-back schedule were inadequate inspections of aircraft parts by parent Mitsubishi Heavy Industries Ltd. (7011).

The company will step up its sales campaign in such markets as the U.S. and Southeast Asia now that engine tests have begun.(adapted from Nikkei and Mitsubishi)

NEW GENERATION PURE POWER ENGINES: GEARED TURBOFAN

Today, the turbofan engine has found a home on practically all jet-propelled aircraft. However, the ambitious emission goals of ACARE 2020 cannot be fully met with the current turbofan concepts and industry majors need to look elsewhere to find a viable solution.

A high bypass engine is the key to reducing both fuel consumption and noise and developments are underfoot aimed to raise the bypass ratio above ten and optimize individual components for better aerodynamic efficiency.

BOEING WINGLET DESIGN FOR 737 MAX

B737 MAX

In continuation of our coverage on WINGLETS and FUEL SAVING A320 SHARKLETS, we bring the news about Boeing announcement and breakthrough on new winglet design concept for the 737 MAX. The new Advanced Technology winglet will provide MAX customers with up to an additional 1.5 percent fuel-burn improvement, depending on range, on top of the 10-12 percent improvement already offered on the new-engine variant.

FLIGHT AT EXTREMELY LOW SPEEDS

S tall speed is defined as the lowest airspeed at which 1 'G' level flight can be achieved. However it is also possible to fly the airplane at speeds below the defined stall speed. This regime is outside the certified flight envelope. There are several important factors that a pilot must know when the airplane is at extremely low speeds.

NEXT GENERATION ENGINE

PW1000G- Pure Power

PurePower PW1000G engine with Geared Turbofan™ technology is a state of the art gear system that separates the engine fan from the low pressure compressor and turbine, allowing each of the modules to operate at their optimum speeds. This enables the fan to rotate slower and while the low pressure compressor and turbine operate at a high speed, increasing engine efficiency and delivering significantly lower fuel consumption, emissions and noise. This increased efficiency also translates to fewer engine stages and parts for lower weight and reduced maintenance costs.

The PurePower PW1000G engine’s fan-drive gear system is just one component of this next-generation engine. The PurePower PW1000G engine also incorporates advances in aerodynamics, lightweight materials and other major technology improvements in the high-pressure spool, low-pressure turbine, combustor, controls, engine health monitoring and more.

KUCHEMANN'S CARROTS

A

s we do the pre-flight walk around , and inspect  the wing underside we rarely give a second glance at the canoe shaped flap track fairings under the wings. Some are slender but many appear somewhat oversized to accommodate just  the flap fairings. Or do they serve some other function?

The physics of airflow alteres violently as it expands from subsonic to supersonic speeds. As the aircraft passes through the transonic speed range, local airflow approaches sonic speeds over the wing and body of the aircraft and leads to the formation of shock waves and consequent large increase in drag.

At transonic speeds, it was found, that the time-honoured principle that the drag of the individual elements of an airplane could be added in a linear manner to give the approximate drag of the entire configuration could no longer be relied upon.

Researches by Dietrich Kuchemann in the UK and Richard Whitcomb of NASA , in early 1950s, established that this wave drag can be minimised by a fuselage wing configuration synthesis, where the cross sectional area changed smoothly along the length of the aircraft. Known as the Area Rule, its basic tenet postulates that the wave drag of a simple equivalent body of revolution would be the same as a more complex wing body arrangements.

Initial  application of area rule designs can be seen in the   “Coke Bottle” or “Marylin Monroe” indented fuselage body shapes to reduce the effect of the presence of wings as in F-102 and F-106 aircraft. This, however had practical limitations and alternate efforts to address the local discrepancies in cross sectional areas led to the concept of attaching conical and pod shaped bodies along the wing , nacelle and fuselage. First successful application of this principle to combat wave drag effects was in Convair- 990. Following applications of the local area rule, several pylon, nacelle, and wing fairings were embodied, to smooth out the area distribution and facilitated in raising the cruise speed from 0.8M for the basic aircraft to 0.89 M for the modified airframe.

 These anti shock bodies  christened as ‘Whitcomb After-bodies’ or ‘Kuchemann’s Carrots’ are widespread in today’s designs.

Anti shock bodies were also apparently developed by the Soviet Designers during the same time , as seen in their installations in TU-16 and through subsequent designs such as the TU 154.

On most modern designs, the mechanism for deploying the wing flaps are encased in canoe shaped pods , which serve as anti-shock bodies and can be seen in A300/310, A 380 and Boeing 757 to name a few. Known to most as flap track fairings, garnering little attention, these pods nevertheless have an important role in transonic drag reduction and fuel economy.