Boundary Layer Ingestion: Environmentally Friendly Aviation?

Developed as a way to improve the fuel efficiency of passenger aircraft, could Boundary Layer Ingestion herald a more environmentally friendly air travel industry?

By: Ringo Bones

During the past few years, various aerospace research labs around the world, like NASA’s Glenn Research Center and the University of Cambridge’s Whittle Laboratory, are working on propulsion technology to increase the fuel efficiency of future aircraft and reducing the overall operating cost to consumers and also reducing the overall impact on the environment. Boundary Layer Ingestion (BLI) is a way of improving aircraft efficiency by reducing drag on the aircraft using the aircraft’s own engines. Analytical studies done since 2017 shows that this new technology has the potential to reduce aircraft fuel burn by as much as 8.5-percent compared to aircraft currently flown today. Boundary Layer Ingestion (BLI) could reduce aircraft fuel burn by up to 15-percent but it requires robust fan systems that can operate efficiently with high levels of inlet distortion or turbulence.

With the jet aircraft we are currently using, the engines are typically located away from the aircraft’s fuselage to avoid ingesting the layer of slower flowing air that develops along the aircraft’s surfaces called the boundary layer. The new propulsion system design – i.e. the inlet and the fan – is embedded in the aircraft’s body at the back of the fuselage in order to ingest the slower boundary layer airflow, using it to generate thrust needed to propel the aircraft. Using the slower boundary layer air means the engines do not have to work as hard, so their fuel consumption goes down. At the same time, the drag on the aircraft is reduced, since the engines are now “ingesting” part of that drag, so the overall aircraft fuel efficiency is improved and less thrust is needed by the aircraft to fly at the same speed. This means that the overall aircraft efficiency is higher and less fuel is needed to complete the flight.

According to NASA and the other teams involved in developing this newfangled propulsion concept, the design change is not as simple as it seems, but is actually quite challenging. Boundary layer airflow is highly distorted – as in turbulent – and that turbulence affects the way the fan performs and operates. These new designs require a stronger fan than the ones currently being manufactured by leading plane-makers. The new fan-blade assembly designs require a specialized inlet to help straighten out the turbulent airflow before it gets to the fan and a stronger, more durable fan to resist the constant pounding being applied by the turbulent airflow. As current problems will eventually be overcome, Boundary Layer Ingestion could herald a more environmentally friendly era of aviation before the end of the 2020s.                                   

Qantas’ Flight To Nowhere: Not Environmentally Friendly?

After just earning the reputation as the fastest selling flight in history, is Qantas’ “Flight To Nowhere” quite unfriendly to our embattled environment?

By: Ringo Bones

According to the Australian flag carrier’s spokesperson, the recently offered Flight To Nowhere by Qantas has just earned the reputation of one of the airline company’s fastest selling flight in history after all the tickets on offer have been snapped up in just 10 minutes. There were 134 seats up for grabs on the Boeing 787 Dreamliner priced between $575 (£445) and $2,765 (£2,145) depending on the class of ticket. The 7-hour flight is scheduled for October 10, 2020 and takes off from Sydney and returns to Sydney after overflying scenic routes that includes the Great Barrier Reef and Uluru – formerly known as Ayer’s Rock. There are also 13-hour flights that will take-off from Melbourne to Antarctica and back again for £636. Singapore Airlines already has plans for such a similar scheme scheduled for next month.

The popularity of such trips and the reason why the cheaper 7-hour “Flight To Nowhere” got snapped up in just 10 minutes is in part due to the fact that Australia’s borders are currently closed to all inbound travelers bar Australian citizens, residents and immediate family members due to the COVID-19 pandemic. Outbound travel is also prohibited unless citizens are granted an exemption. Qantas has previously states it does not expect to be flying any international routes before the second half of 2021, except possibly to New Zealand. The airline’s revelation about their upcoming international services suggests that Australia will not open to visitors for the rest of this year nor the first half of 2021.

Sadly, such moves are criticized by environmental groups because it is such a carbon-intensive way for Australia to keep its domestic tourism industry up and running and given the size of the windows in a typical Boeing 787 Dreamliner means that these planes are not purposely built as airborne sight-seeing planes. I think the only few positive benefits of such flights is that pilots lacking a few hours of flight experience could gain full professional status by serving in such flights and given that jet engines need a minimum of once every two weeks of firing to maintain their air-worthy status might only be achieved via Qantas’ Flight To Nowhere program amidst the global COVID-19 Travel Restrictions.

Did COVID 19 Kill The Boeing 747 Jumbo Jet?

Even though British Airways had slated to retired their entire fleet by 2024, did the COVID 19 pandemic hasten the demise of the Boeing 747 Jumbo Jet?

By: Ringo Bones

When the civil aviation celebrated the 50^th Anniversary of the maiden flight of the “Queen of the Skies” back in February 2019, the Boeing 747 was notably remembered for democratizing global air travel during the 1970s. First thought of as a stop-gap measure by Boeing’s design team at Seattle during the late 1960s before the global airline industry would start using the supersonic capable Concorde and competing designs as their primary fleet, who knew that value-for-money subsonic speed air travel would define the airline industry for the rest of the 20^th Century. Before the Concorde was retired, the Boeing 747 Jumbo Jet was the second fastest operational civilian commercial plane with a top speed of just over 650 miles per hour. And it also achieved a record first back in 1989 when it flew nonstop from London to Sydney.

A number of airline companies already retired their fleet of 747s during the second half of 2019 and in the United States the venerable Jumbo Jet was relegated as an air freight carrier. British Airways had planned on retiring their planes in 2024 but has brought it forward four years sooner because of the air travel downturn due to the COVID 19 pandemic. Last year, British Airways is the world’s largest operator of the Jumbo Jets with 31 planes in the airline’s fleet. For all intents and purposes, it could be said that that COVID 19 pandemic actually killed the Boeing 747 Jumbo Jet as a civilian passenger aircraft, or at least hastened its retirement.

As a four-engine subsonic aircraft, the Boeing 747 Jumbo Jet is far less efficient than modern twin-engine models that are made almost entirely of high-strength composites – such as the Airbus A350, Boeing’s own 787 Dreamliner or even the older Boeing 777 – all of which are cheaper to run in terms of fuel consumption. And by retiring their fleet of Boeing 747 Jumbo Jets, British Airways might just achieve their goal of achieving net-zero carbon emissions by 2050.

Did A 13 Year Old Girl Help Design The Spitfire’s Weapons System?

It would also have been much of a dream job for boys within her age but did a 13 year old girl helped design the weapons system of the iconic Supermarine Spitfire?

By: Ringo Bones

Now, 80 years after the start of the Battle of Britain on July 10, 1940, the RAF has finally recognized the role of an unseemly inventor and mathematical genius. In 1934, Hazel Hill, a teenage girl from north London, carried out the calculations that proved the new generation of fighter planes – i.e. Spitfires and Hurricanes – should carry eight fifty caliber machine guns, instead of just four. In a documentary researched by her granddaughter, Felicity Baker, a journalist, Hazel Hill’s contribution that allowed the Spitfire to dominate the Battle of Britain and denied the Nazi’s their British conquest finally got the recognition it deserve. Yet – until now – the compelling story of the schoolgirl who helped to win a war has been sadly untold. Hazel Hill’s only recognition was in a memoir written by her father’s superior officer in the UK Air Ministry.

Fortunately for Hazel Hill and her dad, the historic mathematical collaboration happened way before Number 10 declared that the Supermarine Spitfire’s design details were part of the UK’s Official Secrets Act or she could certainly have been denied access to it. In the summer of 1934, Hazel Hill, a 13 year old girl from north London, was approached by her father, Captain Fred Hill, a scientific officer in the UK Air Ministry who was trying to make the case for the new generation of fighter planes. Despite her youth, Captain Hill drew upon his daughter’s mathematical intellect and discussed plans with her as to how it could be possible to arm Spitfires with eight 50 caliber machine guns, as opposed to the four which had been originally suggested. Along with her father, she worked through the night on complex calculations that would shape the future of fighter planes like the Spitfire and the Hurricane. The work was done by lamplight over a kitchen table in north London. Night after night throughout the early months of 1934, Captain Fred Hill and his 13 year old daughter burned the midnight oil plotting graphs and laboring over complex algorithms.

When they got access to the new “calculating machines” of the time – which to our eyes today, resemble very rudimentary vacuum tube based computers – father and daughter worked long into the night analyzing the data that was previously obtained at their kitchen table. Their complicated calculations showed conclusively that each Spitfire needed to be capable of firing 1,000 rounds a minute – per gun. They also calculated the exact distance the Spitfire – whose top speed was about 360 mph – had to be from the enemy to hit them, just 755 feet.  The biggest thing was the huge increase in speed of the new fighters, which was way beyond anything people had experienced before – says mathematician Niall MacKay, the current head of the Department of Mathematics at the University of New York.

  It was tiring, unrewarding work but they both sensed how vital it would prove to be. And their instincts would before long be ratified by history because their intricate calculations would go on to help the RAF secure victory in the Battle of Britain – a triumph that many historians now believe changed the course of World War II. Bent together over their graphs, father and daughter concluded that the new generation of aircraft being built by the UK government to prepare for future war should be armed not with four powerful machine guns but eight – an idea was seen as deeply radical, even improbable at the time. Yet only then, the Hills had come to believe, would a new generation of Spitfires and Hurricanes have sufficient firepower to bring down enemy aircraft. A scientific officer in the UK Air Ministry, Captain Hill managed to convince his superior officers of the importance of his and Hazel’s findings – and six years later, in 1940, their calculations were put to the test in the skies above Britain as the RAF fought Adolf Hitler’s much feared Luftwaffe in a four month battle that has been described as the most important military campaign ever fought. The Battle of Britain is often referred to as the first major military battle which was fought entirely by air forces. Who knew that Reginald Joseph Mitchell’s iconic design could still be improved by a 13 year old girl from north London?

Kort Nozzle Propellers: Unsuitable For Aviation Use?

Even though some vertical takeoff and landing aircraft and dirigibles use them, are Kort Nozzle propellers largely unsuitable for general aviation use?

By: Ringo Bones

This sort of propulsion system is more well-known n the maritime, rather than the aeronautical engineering field, although there are experimental vertical takeoff and landing  / VTOL aircraft designs from the 1960s, and my first fascination into one is from an early 1960s aviation magazine published in India that I first saw in our public library back in the 1970s. Mostly featured in futuristic looking VTOL aircraft designs from the early 1960s - like the tilting ducted fans of the X-22 - and in more contemporary dirigible designs, it seems that the Kort Nozzle propeller is largely unknown in the field of general aviation.

Originally developed for maritime propulsion, the Kort Nozzle propeller is an assembly of a conventional screw propeller and a short nozzle named after the device’s inventor, L. Kort, a German engineer. The nozzle is rigidly attached to, or forms part of, the structure of the ship, and the propeller of the ship revolves inside the nozzle.  

The basic principle of a screw propeller working inside of a cylindrical tube or a tunnel was proposed soon after the development of practical screw propellers. Robert Griffith patented a ship stern in 1845 that provided for a screw propeller working in a short tunnel. Other variations of such hull construction were patented by C.A. Parsons in 1877, J.I. Thornycroft in 1879 and by many others. Kort revived the idea around 1925 but generally improved it by making the tube into a short nozzle, wider at the mouth than at the exit and with airfoil-shaped cross sections. By practical tests, Kort demonstrated that by this arrangement, a generally increased thrust was obtained for the same power input, as compared with the conventional screw propeller.

Even though highly efficient propellers – in terms of converting engine power output to forward thrust – were already invented and used in maritime applications from the 1850s onwards – early aviation pioneers more often than not ignored the science and engineering behind this designs and thus failed to achieve true heavier than air powered flight in the 19^th Century.  Many historians cite the Wright Brothers developing their own working propeller – albeit independently from existing maritime propeller design advancements made since the mid 19^th Century – that was largely responsible for the success of their epoch making December 17, 1903 first flight.

From a maritime propulsion engineering perspective, the practical gain of the Kort Nozzle propeller over the conventional open propeller for equal propeller diameters is well substantiated. The gain is greatest when the ship speed is low and the propeller is heavily loaded, than is, when the slip velocity is large. For this reason, Kort Nozzle propellers are used principally on towboats, fishing trawlers, and similar vessels which pull heavy loads at low speeds. For such vessels, the addition of a Kort Nozzle may increase the towrope pull per shaft horsepower by as much as 30 to 40-percent. On the other hand, for fast sea-going ships, the Kort Nozzle offers no advantages because the small gain in efficiency obtained by it is usually offset by increased appendage resistance of the hull. For the same reason, Kort Nozzles, or similar devices, have not been found advantageous for use in aircraft and most general aviation applications.

Novel Coronavirus Now Threatens The Global Airline Industry?

Given it already caused a global stock market sell-off, will the novel coronavirus soon threaten the global airline industry?

By: Ringo Bones

The World health Organization has just declared as of March 9, 2020 that the novel coronavirus as a Public Health Emergency of International Concern. About a month ago, a global stock market sell-off now threatens to plunge the global economy into a recession that could be worse than that of 2008. Could the global airline industry suffer the same fate?

Around the time of the 2020 Year of the Rat Lunar New Year festivities, when the Beijing Government declared a public health emergency citing the rapid novel coronavirus spread that started in Wuhan, it didn’t take long when almost a quarter of a million scheduled flights to China were cancelled in order to limit the spread of the coronavirus. Even before the end of February 2020, there were 238,939 flights to China that were cancelled. Easyjet stocks fell by 18-percent and the IATA states that the novel coronavirus could cost the global airline industry by as much as 29.3 billion US dollars. It is not only the airline industry, travel firms are experiencing their biggest fall since the 2008 Global Credit Crunch.

Shares in many American, Asian and European airlines tumble. Carriers have been forced to cut flights due to the coronavirus. Australia’s Qantas says that the novel coronavirus outbreak could cost it by up to 99-million US dollars. If the outbreak doesn’t abate by the middle of 2020, more than half of the world’s airline companies could face bankruptcy due to cancelled flights.

Will There Be A Global Pilot Shortage?

With air travel demand expected to more than double during the next 20 years, are the powers-that-be of the global civil aviation industry doing their part to avert this looming problem?

By: Ringo Bones

During the 2019 Paris Air Show, Boeing CEO Dennis Muilenberg stated that a growing shortage of pilots represented “one of the biggest challenges” facing the airline industry. In February 10, 2020 the BBC ran a news story on the ever increasing demand for air travel is growing so rapidly that by the year 2038 that 804,000 new pilots are expected to be needed. The biggest need will be in the Asia-Pacific region where a projected “improving economy” of Mainland China will result in more people booking flights compared to recent years. More people in the United States will be expected to fly during the next two decades, but unfortunately, the U.S. will be experiencing a pilot shortage in 2020 as experienced pilots are reaching the mandatory retirement age of 65. But how do we solve the problem of pilot shortage during the next 20 years?

In the Philippines, college-age students have opted to pursue medical courses – mostly as nurses to work in the United States – because they can earn money to pay their college debt much sooner if they’d pursue a career on civil aviation. Maybe Boeing and Airbus should offer scholarships to worthy but financially impoverished potential pilots here in the Asia-Pacific region?