Update February 2014 – Amedeo’s order for 20 high density fitout A380 affirms A380 role. A330 “light”.
Update January 2014 – Airbus ‘Mega-Twin’ Concept and research into very large twin jets the size of the Boeing 747.
A380s, Storm Petrels & Super Sonic Cars
The aviation industry continues to evolve. The changing political, economic, cultural, technological and communication landscape is forcing continued consolidation of airlines, routes and aircraft types.
It’s a case of “less is more”.
The A380 is a key player in this consolidation, transporting the rapidly increasing number of passengers between congested Asian and European international hubs. (Asia is now the largest (and fastest growing) aviation transport market with 948 million passengers flown last year, followed by North America (808 million) and then Europe (781 million) (IATA – 2013))
I am confident that:
- the A380-900 (stretch version) will be produced, and
- the A380 will fly up until the 2060s, and
- that airline ticket prices will continue to reduce as the seat counts increase on newer aircraft.
Furthermore, I think:
- the A380 will be the last large four (quad) engine commercial passenger aircraft to be built, and
- the industry will eventually build jet engines capable of 150,000 pounds of thrust.
In this blog I’ll share a few of my thoughts about aircraft “sweet spots” and why airlines ultimately invest in one brand of a spread of aircraft to bracket their operational needs. Finally, I’ll discuss why a super sonic car might influence future super aircraft designs.
Every airline’s challenge is to deploy the best aircraft type for its route structure. Indeed the selection of size and weight in aviation follows the same pattern already cast by nature.
The operational environment determines insect’s and bird’s cruising speeds that in turn determines its weight. Small birds are suited for slow cruise sectors whilst international maritime flight is reserved for the fastest cruising (heaviest) birds such as the Pelican and Albatross.
Migrating birds that migrate beyond their “sweet spot” range risk perishing at sea. Migrating birds drown if their long range cruising speed is insufficient to make headway into head winds. Reports of mass bird deaths at sea show “natural selection” at work, extinguishing the birds that cannot accurately forecast maritime weather.
The Storm Petrel understands this weight-cruising speed-wind relationship. Its name was derived by early mariners who observed the bird return to take refuge ashore before storms approached, conveniently broadcasting their foul weather forecast.
Using similar logic, we suggest that the Pteranodon, the largest flying reptile (despite its low wing loading) had such high takeoff, cruising and landing speeds that flight was restricted to souring above the cliffs along the shore.
Aircraft manufacturers apply Biomimicry into their designs. So the theories for birds also applies to aircraft – that the route length and cruise speed determines the ideal aircraft weight. Everything else is a compromise; passenger count, fuselage size & type, wings and engines.
Aircraft selection also skews towards larger seat-counts for operations into congested airports (in Asia and Europe).
The consequences for Airbus and Boeing are clear. Aircraft manufacturers must understand the demography and travelling habits of travelers and provide aircraft that are tuned to the same “sweet spot” speed and range that suits the market.
The Great Flight Diagram shows a remarkable relationship between weight and cruising speed. This graph also shows outliers. The Concorde was hopelessly over-winged for cruise flight. Compared with all other flying things, the Boeing 777s and 787s appear to be under-winged (faster) and the Airbus A350s appears to be over-winged (slower). The A380 also appears to be over-winged, but for reasons outside the scope of this review.
The risk of poor aircraft selection is just as critical for the airlines as it is for bird species. Putting the wrong airframe onto a route can have dire consequences. The airline’s challenge is to apply the right aircraft for the required range. For companies that fly long and short haul routes, its imperative to limit the number of aircraft vendors and aircraft types to minimise the costs of manpower, training and maintenance.
I have gathered aircraft performance data over the past decade, This data reveals the sweet spot ranges for many aircraft types.
I calculate that the current A380 has a sweet spot (maximum efficiency) range of between 5,700 and 6,700 air nautical miles (anm):
- 5,700 anm (Example: 12 hours flight time, London – Singapore)
- 6,700 anm (Example: 14.5 hours flight time, Los Angeles – Sydney)
I calculate the A330-300′s sweet spot is currently between 3,000 and 3,800 anm (although the heavier weight versions will increase the optimum reach):
- 3,000 anm (Example: 6.1 hours flight time, London – Dubai (2,870 anm))
- 3,800 anm (Example: 9 hours flight time, Sydney – Hong Kong (3900 anm)
I’ll publish sweet spots for other aircraft in my Big Jets book.
Understanding sweet spots make it easier to understand why Cathay Pacific needs more Boeing 777s, Airbus A330s and A350s than B747s and A380s. Cathay’s Hong Kong home base is located within 5 hours flying range from half the world’s population.
Having introduced the ideal concept of the Sweet Spot, lets now look at compromises and divergences from this rule. For sometimes the the practice is sometimes different to the theory.
Clearly the A380 is currently tuned for the longer haul and efficiency drops if the heavy airframe is flown outside this sweet spot over shorter or longer routes. In these cases the passenger count and freight load must be maximised to protect profits.
Yet the world’s A380s have flown an average sector length of only eight hours over their first six years of operation.
So despite a sweet spot time of 12 to 14 hours flight time, the A380 early adopter airlines have chosen to optimise the A380 for greater seat counts on shorter routes between congested ports. This trend (preferencing higher seat count before the sweet spot range) will continue particularly in markets where more passengers travel into national hubs that have become (politically) land-locked and undersized such as London Heathrow and Hong Kong.
- Heathrow has operated close to its capacity since the start of the decade. In 2013 it processed 3.4% more passengers, mostly because the airlines squeezed 2.8 percent more seats into (the same number of but) bigger aircraft such as the A380. I think that this trend should be adopted by Hong Kong.
- I think Hong Kong’s airport is saturated now. I flew two Sydney-Hong Kong-Sydney routes in early February 2014. I experienced delays (holding), compressed traffic separation on approach, extensive push-back, taxi and takeoff delays – all indicating that the airport was task saturated at these times. There will be no relief unless larger aircraft substitute the smaller aircraft.
Aircraft manufacturers and some airlines realise that Big Jets are in greater demand for short sectors:
- Emirates operates predominantly B777 and A380 big jets out of the (saturated airports and airspace surrounding) United Arab Emirates.
- Airbus, realising that the Asian “airpark” is full, is considering a variant of the A300 airframe with a shorter “sweet spot” range. This “trimmed” A330 could have a smaller fuel tank capacity which would lighten the wing structure, wing box and airframe weight. The resulting shorter “sweet spot” range will be better suited to the short intra-asian routes.
Very Large Aircraft (VLA)
Consider the B747 and A380 VLA aircraft deployments. The top five B747 and A380 airports (respectively) for 2013 are: (anna.aero)
- London \ Dubai
- Taipei \ Singpore
- Frankfurt \ London
- Hong Kong \ Paris
- Bangkok \ Frankfurt
These lists suggest that the VLA market is primarily used to resolve major hub congestions. Notice that Australian and USA airports fail to appear in the these lists despite the A380 having a “sweet spot” that is ideal for USA-Australia routes. From my own recent observations, the long lines of A380s transiting at the congested Dubai and Heathrow airports reaffirms my conclusion that the seat count currently takes higher priority than the “sweet spot” range.
Transaero and Amedeo are two airlines extending this concept even further ….
Super Carriers: Transaero and Doric
Airbus is trying to convince airlines to adopt the 525-seat A380 configuration.
Most A380 airlines offer between 407 seats (Korean) to ~ about 540 seats (Air France, Lufthansa). Qantas’ A380s are configured for 484 passengers (14 First, 64 Business, 35 Premium Economy & 371 Economy). Emirates plan to introduce two-class A380s with 617-seats.
My data analysis shows that that an A380 filled to the brim with 853 passengers (315/538 on the upper/lower decks respectively) provides fuel efficiencies that surpass all other aircraft types, including another darling of the skies, the A330-300.
“When we put the proper seat count on the [A380] plane, the economics are unbeatable and will remain unbeatable” (Doric Chief Executive Officer Marc Lapidus)
Two Airbus customers are listening and responding to improve the A380′s efficiency.
Amedeo (formerly Doric), an aircraft leasing company is lifting the A380′s seat count to 630. Amedeo have ordered twenty A380s to most likely fill a strategic capability for airlines that wish to provide the most competitive (low cost high density) service between congested hubs.
The Russians will supercharge low cost air travel even more when Transaero takes delivery of its first of four A380s in 2015. Transaero’s A380s will seat 652 passengers in three classes (12 Imperial (first), 24 business and 616 economy) making it the first airline to fill the aircraft closer to its certified passenger limit (of 853).
“Toulouse – we have a problem!”
Transaero’s and Amedeo’s challenge is to select a lighter cabin design. They will have a limited freight capacity (with a full passenger load) if they install heavy seats in a heavy cabin.
Currently the A380′s limiting freight related weights include: (see QF32 page 345 for more info)
242t – Manufacturers Empty Weight (MEW) (approx)
300t – Dry Operating Weight (DOW) (45 tonne cabin fit-out plus crew plus catering)
369t – Maximum Zero Fuel Weight (MZFW)
Airbus designed the A380 to be as light as possible. Airbus engineers planned (and hoped) that airlines would also fit the lightest cabin layouts, ideally weighing no more than I think about 35 tonnes.
Some airlines have installed cabin designs weighing up to 45 tonnes (heavy seats, showers, bars and two lane stairs). These “obese” cabins leave just 69 tonnes for passengers and freight (369t MZFW minus the 300t DOW). If Doric installs a heavy (45 tonne) cabin, then 652 passengers and luggage would weigh about 65 tonnes leaving just four tonnes for freight. The freight capacity can be increased if:
Transaero and Doric install the next generation of lighter seats and cabin interiors (lighter than 45 tonnes), and/or
Airbus further increases the maximum Zero Fuel, Takeoff and Landing weights. (I think Airbus cannot reduce the MEW).
A380 – Future
“… the A380 is the future. And we don’t like anyone talking about it not being around.” (Tim Clark, President, Emirates, announced Nov 2013)
I forecast that the A380 will be the largest operating passenger aircraft for decades to come (or until energy costs reduce to a small fraction of operating costs).
Airbus announced (October 2013) that the A380 program should break even (financially) in 2015 (based upon 30 sales/deliveries per year)
Evolutionary changes by Airbus, airlines and the engine manufacturers will all contribute to improve the A380′s efficiency:
- Airbus is investigating fitting massive winglets for a potential 3% increase in fuel efficiency (curiously based upon the A320).
- Both Engine Alliance and Rolls Royce have announced plans to improve their engine’s Specific Fuel Consumption (SFC). Maybe there are opportunities to refit other bigger engines to the A380 …..
- Airlines will be forced to fit better engineered cabins and more condensed seating.
The A380-800 is 73 metres long.
The A380′s published sales price is US$400m. This is higher than the “back of the envelope” figure of US$1m per ton of basic weight (without fuel and freight) although deals have been negotiated at bargain prices (Doric purchased A380 (MSN 136) for US$245m)
The A380 continues to sell. A total of 309 A380s have been ordered (end November 2013), 140 by Emirates (50 at the Dubai Airshow in Nov 2013).
I hope Airbus decides to produce the next version of the A380, the A380-900. The A380-900 will be the aircraft of choice for long range intercontinental travel.
The A380-900 is an A380-800 stretched by another six metres to make it fill a “box” 80 metres long by 80 metres wide. The latest “Code F” airports are designed to cater for aircraft having up to an 80 metre wingspan and 16 metre wheel track.
I guess that the certified seat count might increase by 80 to about 933 passengers extending the aircraft further into it’s own super league.
I think the A380 was always designed to be 80 metres long. The cruising speed, wing, fuel tank capacity, and limiting weights all point to this aircraft needing to have a higher wing loading and thus, more passengers and more weight (refer back to the Sweet Spot and Great Flight Diagram).
Airbus Chief Executive Fabrice Bregier recently announced that he thought the A380-900 will be available, maybe in in 2023-2028. I hope
Last of the Four Engines
I think that the A380 marks the last four engine passenger aircraft that will grace the skies.
Four engine (quad) aircraft traditionally provided benefits over the twins:
- better engine optimisation (for the cruise)
- reduced wing bending moments (lighter wing box and wing)
- improved range, payload and high altitude performance
- freedom to work outside the Extended range Twin Operations (ETOPs) limitations
But these relative advantages of the quad have reduced with time.
Economics now favours the twin over the quad:
- Simpler and lighter structures, Twins gain weight reductions and drag benefits from lightening the structures and optimising the flows over the rest of the wing where the third and fourth engines were removed.
- The integrated aerodynamic flows, wing aero-elastics, manufacturing purchase price, running and maintenance costs
- Cheaper to buy two big engines than four small.
Aerodynamicists prefer to design simpler “semi clean” twins rather than the more complex “dirty” quads:
- An aircraft i s now designed as a compete integrated unit, merging the fuselage, wing and engines into one complex structure. Gone are the days of treating them as many separate entities.
- Quad aero-elastics is more complicated than twin aero-elastics. This is a very complex subject. However for a simple analogy, please view my later blog: “Bio-Mimicry of shaking Dogs”. Whilst viewing the video, imagine the dogs’ ears being aircraft wings. Now consider being the engineer given the responsibility to design the ears, responsible for the shape, structures, aerodynamics and aero-elastics. Now imagine designing how to mount two engines onto the ears. Now imagine mounting four engines onto the ears…
Despite these improvements that now favour twins rather than quads, many limitations remain that prevent engine manufacturers from making engines that could power a twin engine version of the A380.
“The engines canna take anymore, Cap’n!”
( Scotty (Character) - Star Trek)
No engine currently exists that could power a twin engine A380. The A380 “twin” would probably need engines capable of producing up to 150,000 pounds of thrust, well beyond that current generation of engines that top out at about 115,000 pounds of thrust. Many factors currently limit the capability to build super-engines, including:
- physical diameter of the engine (compromising the air frame by raising the fuselage higher off the ground), and
- the capability to build fan and turbine disks that are able to withstand the incredible forces without exploding (going BANG!), and
- the maximum temperature that the High Pressure Turbine blades can withstand.
The good news is that although I think the A380′s tail fin is over-sized for the A380-800, it’s probably the perfect size for the A380-900 or even the A380 twin (I’m a little cheeky).
Interestingly, Aviation Week recently revealed the Airbus ‘Mega-Twin’ Concept and research into very large twin jets the size of the Boeing 747.
Preventing things going BANG! …
Andy Green and I know a little bit about this.
First, we need to understand that jet engine turbine disks operate very close to their temperature and rpm limits.
Aviation turbine disks are certified to survive rpm over-speeds of just 20% (44% more strain) over the maximum rated rpm. To put the centripetal forces into perspective, each fan blade on the front of the Rolls-Royce XWB jet engine (powering the new Airbus A350) experiences 100 tons of force during takeoff - equivalent to a freight train hanging off each blade.
The high pressure turbine blades (I think the most technically complex components on the entire A380) operate in even more threatening environments. At high power the blades sit within (and are impacted-powered by) exhaust air that is 400 degrees Celsius hotter than the blades melting point!
In the case of QF32, the number 2 engine on my aircraft failed when the intermediate pressure turbine disk exploded under conditions of high temperature and RPM.
Andy Green (and his Super Sonic Cars (SSCs))
Wing Commander Andy Green is the Royal Air Force fighter pilot who in 1997 set the world land speed record of Mach 1.02 (1,228 kph, 763 mph) in the twin Rolls-Royce Spey 202 powered “Thrust SSC” (Super Sonic Car) jet car.
Click here to see the video of the record breaking run. The car’s bodywork was exposed to air pressures of up to 10 tonnes per square metre. Notice the shock waves churning-plowing the hard desert surface into dust. Interestingly, Thrust SSC experienced an unexpected massive increase in drag at Mach 1. The increase was attributed to the shock waves slamming against the desert floor, shattering the hard surface into an air-rock “plasma” – absorbing critical energy in the process.
After setting the land speed record, Andy’s next challenge is to build his Bloodhound SSC car that in 2015 will exceed his previous record by 31%, exceeding 1,000 mph (Mach 1.4, 1600 kmph or 447 metres per second!).
Bloodhound SSC will be powered by a single Rolls-Royce EJ2000 jet engine (from the Typhoon Eurofighter), and a rocket motor (that incorporates an oxidiser “fuel” pump powered by a 750 hp Cosworth Formula 1 engine). The jet engine and rocket will combine to produce about 133,000 thrust horsepower, the equivalent to 180 Formula 1 cars.
You might ask: “Why do we need 130,000 horsepower to travel just 16 times our road speed limit?” The answer comes courtesy of the drag and power equations. Drag is proportional to speed squared. Power is proportional to drag times speed – so power is proportional to speed CUBED! So we need 16 cubed (= 4,096) times as much horsepower to go 1,600 kmph than we do to travel just 100 kmph (although this equation does not account for losses from (shock) wave drag). You will appreciate the Bloodhound’s high finesse (smoothness) when you divide 133,000 by 4,096 to calculate the horsepower the Bloodhound needs to travel at 100 kmph.
What has Andy’s Bloodhound got to do with the Airbus A380 and larger engines? Andy told me that the Rolls-Royce and Bloodhound engineers face similar challenges:
- One of Andy’s limiting challenges for the Bloodhound SSC car is to create the fastest wheels in history that will not explode under radial loads of 50,000 G at high speed. Bloodhound’s 90cm diameter wheels will rotate at 10,200 rpm, faster than most disks in your PC’s hard drive and three percent faster than certified 120% over-speed rpm limit for the the turbine disk that exploded on flight QF32.
- Rolls Royce also need to create larger and faster turning turbine disks that can power the next generation of commercial jet engines. Their challenge is to continually extend the size and thrust limits whilst protecting reliability.
Although Andy’s wheels will be operating in cool air in the Hakskeen Pan in Northern Cape, South Africa, the research and development for Bloodhounds SSC’s wheels will probably feed back to help Rolls-Royce design bigger more powerful turbine disks that will form the bedrock inside the next generation of larger Rolls-Royce jet engines. Maybe with Andy’s help we will see super-engines capable of powering a future two engine A380!
This blog has covered some theory of flight from the Pteranodon, through the Storm Petrel, Albatross, Concorde and A330 to the A380 quad and A380 twin. It also presents some of the challenges the engine manufacturers will face when building the next generation of turbo fan engines.
I doubt that we will ever see an A380 twin, but history shows that aviators have continually invented and improvised to make the impossible, possible.
Counter to some industry reports, I think the A380 (particularly the A380-900) will fill fly for decades, and remain the best of breed for long distance (A380-900) and also for high seat density (A380-800) travel. Tim Clark (Emirates) thinks similarly, stating in November 2013, “[the A380] it’s a really good aircraft.” In December 2013 Tim reiterated “Our customers love it and it is one of the most efficient aircraft to operate in terms of fuel burn per passenger.”
I love the aviation industry! It’s the most thrilling, extraordinary and exciting profession. But never become overconfident and never forget Neil Armstrong’s mantra:
“Expect the unexpected”
I hope you enjoyed this brief tour. The complete analysis will be included in my Big Jets book.
Good luck Andy. Good luck Rolls-Royce. Good luck Airbus. Good luck Boeing.
Rolls-Royce is a key sponsor for Andy’s Bloodhound SSC project. Coincidentally, Andy Green is also a Cresta (skeleton bob sled) rider who recently mentored my son Alexander at the Cresta Run in St Moritz.
Version 3 – added Doric information
Version 4 – added Dubai Airshow information