High On Planes

In India there is a fascination with everything that is double decked! Double decked buses are a tourist attraction in Bombay. People reminisce about days when they travelled in the upper tier of a double decked train compartment. Even a double decked sandwich is more tempting to us than a normal one. The news of a double decked aircraft therefore, at first, seemed to be a caricature on this fascination. For, what could possibly be larger than the largest jumbo jet, the Boeing 747, in 1990? The engineers at Airbus had a very jumbo answer.

They were handed over a couple of billion euros, the kind of money big companies toss around. With it they were asked to make a plane that would carry more people across more miles with lesser fuel and lesser noise than any of the planes the world had ever seen. A big gamble was underway. Several factories sprung up across the UK, Germany, Spain and France to assemble the largest, quietest, most efficient passenger airliner in the world, codenamed A3XX. It was conceived on the premise that commercial air travel would develop along the hub and spoke model. Boeing, which was Airbus’ strongest rival, had placed its bet on a completely differing point to point model by starting work on its next generation 787 Dreamliner. The jury is still out on which side made a wiser decision.

Many of the world’s leading airlines have placed orders with Airbus for the A380. Some of them to offer their passengers unheard of luxury, some of them to provide their passengers long haul non-stop epic journeys and some to achieve economies of scale and bring some succor to their balance sheets. A plane that caters to these varying, arguably opposing needs must be an engineering exhibit that beckons inquiry.

Plenty of early designs of the A380 were scrapped. They were either too big to fit on runways or they were too heavy to get off the ground or let’s just say some were not a sight for sore eyes. In 1994 however, Airbus revealed the final design to an eager audience at the Farnborough Air Show. The super jumbo would have two decks (much to the ecstacy of the Indian folks), with seats on each running the entire length of the fuselage.With those many seats, the mega plane would be able to shepherd 853 passengers through the stratosphere in a single journey!

One of the first A380 (then A3XX) designs

It dawned on the designers that the A380, with 617 tonnes of machinery and 800+ passengers, would require such enormous wings to provide the necessary lift to get airborne, that they would out-span any of the existing runways of the world. As Richard Hammond puts it – “It’s no good if you can fly, when you have got nowhere to fly to”; the A380 had to have shorter wings. Quite a few principles of modern flight have been borrowed from the books of Mother Nature and the A380 designers too found it a useful resource to come up with the design of the plane’s wings. The inspiration came from the adaptive design of the eagle. Just like the scavenger curls up its wings at the ends for additional lift, a winglet was appended to each of the wings of the A380 to provide the additional upward force without altering the wing length. The winglet has now become commonplace to improve on efficiency of all aircraft.

The winglet that avoids formation of vortices at wingtips to provide additional lift

Conventional design in the early 90′s allowed for a plane’s fuselage to be constructed with aluminium. That was fairly good technological evolution considering that the Wright brothers had started with a fragile wood structure for their invention just 100 years prior. But not good enough for the A380.  With mammoth proportions, a body designed using aluminium would be be so heavy that it would guzzle litres of fuel by the millisecond. An unfeasible recourse would be to reduce the thickness of the aluminium employed, for that would make it so soft that any member of the winged species could crash through it. The solution to the strength vs weight puzzle was found in a Dutch university’s aerospace engineering laboratory. The laboratory had engineered Glass Laminate Aluminium Reinforced Epoxy (GLARE), which was a light weight, high strength aluminium composite, something that exactly matched the needs of the A380 designers.

The caption for this one is on the fuselage

Like any other passenger liner, the A380 requires power for 2 primary purposes. First, to provide for passenger comfort. Second, for propulsion, without which the first one would be of no use. Passenger comfort  implies optimum cabin pressure and temperature, in-flight entertainment, timely warm food and chilled beer, well functioning toilets and myriad other things that go into making an experience luxurious. Just as an aside, the A380 houses one of the most sophisticated plumbing systems on the plnet to keep the passengers from running up and down and here and there every time they need to answer nature’s call. Propulsion systems on the A380 need to get the super jumbo clocking at 280 km/hr at time of take-off. All the power requirements are met by four turbofan engines supplied separately by Rolls Royce (Trent 900) and Engine Alliance (GP 7000). In this season of uncertainty and bankruptcies Airbus must have found it wise to source its important component from more than one supplier.

One of the four Roll Royce Trent 900 engines that power the A380.

Other than the wings, fuselage and engines there are other parts like the tail, landing gear and safety systems each with their own little story of problems and triumphs and then there is the story of Airbus logistics that binds them all together. Whether it was monetary rationale or pure idiocy that drove the decision to manufacture individual parts of the A380 across countries is lost on me. But the bringing together of the super-jumbo’s components from Germany, Spain and UK to a central assembly plant in Toulouse, France by land, sea and air is now a matter advanced supply chain inquiry. Special trucks were manufactured to carry sections of the fuselage, barge captains precisely monitored tidal movements to maneuver the wing sections under bridges and the Beluga, Airbus’ super transporter plane, ferried parts of the A380 over several journeys. It was from behind the doors of this factory in Toulouse that the first A380 rolled out for its premiere test flight.

At the time of writing this post Airbus had made delivery of just 57 A380s after a marathon of delays and order cancellations. Yet since its first commercial flight in 2007 the A380 has taken over 15 million passengers to their destinations and seems to be living up to its promises of unprecedented fuel efficiency and lower emissions per passenger km. Passengers of extravagant means are treated to drinks in a bar in the sky and even the economy class amenities  are far superior than that on any other plane.

Skybar on board the superjumbo.

Even though the Indian aviation authorities are yet to approve A380 operations on Indian airports, many Indian airlines have already placed orders for the superjumbo. While Airbus struggles to bring their delivery schedule on track, the approval papers for the the A380 should be able to dodge through the  bureaucracy. Till then I’m going to have to wait for my double decked fantasy to take the shape of a plane in front of my eyes.

The computer generated Air India A380

The Concorde

To find oneself travelling at a speed greater than that of sound had always been the territory of privileged fighter pilots and crazy men driving jet powered cars in the Nevada desert. Very few on this planet could count themselves as a part of that population. However, in 1969, the first successful test flight of the Concorde promised to extend the possibility of supersonic travel to a broader audience. The story of the Concorde, the plane that ferried passengers over the Atlantic in record time for 27 years, is a rather engrossing one.

In the early 1960s, engineers in France and Britain were separately working on designs of an aircraft which could trample down the sound barrier. Both groups wanted to realise their designs as prototypes but none had the money to do so alone. As a fortunate result, the French and British governments decided to come together and accomplish the development of an SST economically. And so began the work, to bend steel into the first pieces of the Concorde.

Sud Aviation and Bristol Aeroplane Company, the companies that initially began work on the designs, were merged into Aerospatiale and British Aircraft Corporation respectively, as the Concorde evolved from drawings on paper into the first test flights. The name of the plane, in Britain, was trimmed down to just Concord, an English word, and to much anguish of the British pride, back to Concorde again!

The fuselage was adorned with the Concorde’s characteristic delta shaped wings as ornaments, each holding a pair of Rolls Royce SNECMA Olympus 593 Turbojet engines in pods fitted under them. The combined output of these 4 powerhouses would take the 100 or so passengers aboard the aircraft, to twice the speed of sound at 51,000 feet. The fact that speeds of that magnitude would lead to considerable heat generation was understood by designers of the Concorde well in advance. And boy, did they handle it well? The fuel was used as a coolant, the nose was made out of a special alloy and the entire body covered with special paint to reflect most of the heat.

A pair of the engines on one of the wings with complex intake ramps

The intricate design of the air intake ramps took care of critical issues such as moderation of shock waves, drag -in case of engine failure- and generating thrust at supersonic speeds. It is a remarkable observation that at Mach 1.5+ speeds, 63% of the total thrust was provided just by the ramps. Indeed, the engineers did have success with economizing on fuel consumption.

One of the daunting problems encountered by the designers of this marvel was the separation of Centre of Gravity and Centre of Pressure as the jet approached Mach 1. The Centre of Pressure moved rearwards and played a game of catch-me-if-you-can with the Centre of Gravity which tried to keep up with the former’s movement by shifting fuel from one section of the fuel tank to the other. I reckon this solution must have been the result of a very dizzy day dream of one of the designers!

Fuel movement along tanks to shift the Centre Of Gravity

The sound generated by the Concorde was, to put it mildly, tremendous! The principal reason why many of the initially placed orders for the aircraft were cancelled was that it produced decibels that shattered windows and eardrums without a care. The uproar in the US east coast against such noise prodded the technologists and investors to take heed of the environmental angle in any endeavour. In that regard, the Concorde is accredited by many to have altered the corporate culture towards the eco system.

At its Mach 2.02 cruising speed, the nose and the front of the aircraft would get more heated than the rear, leading to an amusing experience for the passengers and the crew. They would  find themselves strolling through a temperature gradient as they walked down the aisle. Contrary to the experience in the church, this walk would lead them to feel cooler. Also, passengers at the rear of the cabin often saw the front seats see-sawing as the flexibly designed fuselage twisted and turned to accommodate shear forces when the jet banked from one side to the other at bullet speeds.

From 1976, when it was first pressed into commercial service to 2003, the year it gracefully retired,  Concorde had travelled to 6 continents. Despite a short cabin height and less than ample legroom, many businessmen chose to fly aboard this slender beauty for the sheer 50% reduction in travel time it offered. There are stories of whimsical Saudi princes chartering the plane at such short notice that the pilots did not have enough time to put on their uniforms. This, and many other anecdotes scattered across biographies of pilots and first hand accounts of  enthusiasts, make up the unusual yet captivating history of this aeronautical masterpiece  that we shall remember as the Concorde.

Concorde with the Red Arrows aerobatics team flying over London