Back to the Future
Is the Concorde’s return a reminder that the time has come for it to have an offspring?
Air Line Pilot, September/October 2002, p.24
By Capt. Tom Duke (Ret.)
The arrival of Air France and British Airways Concordes at John F. Kennedy International Airport on Nov. 7, 2001, not only re-inaugurated supersonic transatlantic flight but heralded almost 26 years of superior worldwide niche air travel service. Through almost superhuman management and political effort, the Anglo-French consortium has kept the dream of high-speed air transportation alive and very well. But will any current ALPA members ever fly a next-generation SST?
Through Internet searches, a book called Concorde and the Americans, a visit to a British Airways hangar with Safety Services, and some help from some good folks at NASA, we managed to assemble enough information to try to answer the question. Manned powered flight is less than 100 years old, but seems to have hit the speed-of-sound barrier and to have lost some of its pioneering ambition. Some new ways of looking at things may be required.
The early days
In the late 1950s, supersonic military bombers were an urgent requirement and sparked great interest in passenger service that used similar technology. At that time, supersonic speed was the best perceived way to outrun fighter-interceptors and deal with enemy radar. By the early 1960s, the Air Force had B-58 Hustler wings operationally ready, winning bomb competitions, and making lots of noise setting world speed records, such as flying from Los Angeles to New York and back in 4 hours 41 minutes. The jet airliner age was already shrinking the world with peaceful competition in the cold war era. Fuel was cheap and the sky was the limit. In civilian aviation, Mach numbers approaching the speed of sound were tempting, but attaining them was tricky and expensive.
By 1969, the overland sonic-booming Hustler was obsolete, replaced by missiles and the swing-wing, terrain-hugging FB-111.
Any effort to fly passengers faster than the speed of sound would obviously need to be an international effort between competitive industries and governments. In the West, the British, French, and Americans almost negotiated the program to death, forming alliances, breaking them, and trying over again.
In 1961, a U.S. government/aviation-industry program began to build a prototype American SST, which the program said would be "superior to that being built in any other country in the world." Boeing won the competition with a swing-wing proposal that would carry 300 passengers at Mach 2.7. Delays and disagreements marred the program. Technical problems with the swing wing forced a change to a delta-wing design, further delaying the program. Boeing’s heart was in the subsonic mass-market B-747. By 1971, public sentiment toward the SST went from lukewarm to opposed, and federal funding for the project was cancelled.
In the 1970s, the Concorde team tried to entice the Americans into a consortium without success. The final result was an Anglo-French effort as NASA concentrated its considerable engineering talent on space, and American airplane manufacturers concentrated on the lucrative subsonic market. A Boeing SST mock-up lies in a field near Cape Canaveral.
The Russians are coming
The Soviet design bureaus directed their efforts to competing with the West with the Tu-144. It first flew in June 1969 and exceeded Mach 2 in May 1970. It was shown at the Paris Air Show in 1971, and one crashed on a demonstration flyby there in 1973, not far from where the Concorde went down in July 2000.
By 1977, both the Concorde and the Tu-144 were tested and ready for airline passenger operation. They were very similar in appearance until you got close. Both had droop noses, double-delta thin wings, and no horizontal stabilizer. Each had four engines, mounted in pairs under each wing. The Concorde would carry 100 passengers, four seats per row in a 9-foot–6-inch wide cabin similar to the DC-4 while the Tu-144 reportedly could carry 140–150 in a slightly larger fuselage. The Tu-144 flew at Mach 2.4 with afterburners while the Concorde flies at Mach 2.0 with afterburners off and more efficient electromechanical/hydraulic controlled intake ramps providing high-speed augmentation. The Concorde’s range was about 3,700 nautical miles; the Tu-144’s, 1,936 nm.
Aeroflot ceased passenger operations to Siberia in June 1978 after less than a year of scheduled operations because of high operating costs. Although manufacturers had hopes of huge production runs, only 20 Concordes (including prototypes and pre-production airplanes) and 18 Tu-144s were built. NASA and Boeing used one Tu-144LL, a specially modified D model with improved engines, in the late 1990s as a test platform for future high-speed transport research. The rest—minus the two that crashed —are parked or in museums.
At one time, an apparent market existed for 74 Concordes. Potential customers included American, Braniff, Continental, Eastern, Pan American, TWA, and United. Foreign carriers placing orders included Air Canada, Air India, Japan Airlines, Middle East Airlines, Qantas, and Sabena. When the time came to confirm, Pan Am balked, and the house of cards tumbled, leaving only Air France and BOAC as buyers. Overcoming the public objection to supersonic flight over inhabited territory was impossible.
Air France and British Airways launched commercial service simultaneously on Jan. 21, 1976, with flights from Paris to Rio de Janeiro via Dakar and from London to Bahrain. Inaugurating Concorde service to the United States was considerably delayed mainly because the Port Authority of New York and New Jersey objected to the Concorde’s noise and because of overland supersonic flight restrictions.
Because the FAA owned and operated Washington-Dulles International Airport in those days, early flights came into that countryside airport on May 24, 1976. Finally, service to John F. Kennedy International Airport (JFK) began on Nov. 22, 1977. When the FAA finally issued the U.S. type certificate for the Concorde in January 1979, Braniff operated flights between Dulles and Dallas/Fort Worth as extensions of Air France and British Airways flights in the restricted subsonic mode. Finding it unprofitable, Braniff ceased service in June 1980.
For 24 years, Air France and British Airways operated the Concordes with no major accidents. Valuable lessons were learned and problems fixed along the way. An early warning of things to come happened on June 14, 1979, when a tire failed on takeoff at Dulles and a passenger reported a hole in the upper portion of the wing to the steward. When the flight engineer came back to review the hole, his comment was, "Mon Dieu!" He returned to the cockpit first to recommend dropping in at JFK and then dumping fuel and landing at Dulles. The only immediate indication of a problem was that a tire had failed. The plan had been to land in Paris. The investigation revealed that rubber and metal shrapnel from a flailing tire had penetrated the fuel tank in the left wing but no fire had resulted. The engineering departments of both operators designed deflecting and protecting fixes and challenged tire makers to build better tires. With only a few incidents, tire failures remained a high but not a grave concern until July 25, 2000.
With only dual tandem wheels to spread the loaded 408,000-pound takeoff weight (about the same as the B-767-300ER) at liftoff speeds of more than 200 knots and max tire speed of 217 knots, the required tire pressure on the Concordes sometimes approaches its limit of 232 pounds per square inch. Any large tire fragment from an explosive blowout could be extremely destructive. High-speed landings and braking caused fast wear and tear and frequent tire changes. The fleets were extremely well maintained. As with any leading-edge technology, the SST had no room for a fly-fail-fix concept. The early Tu-144s had triple bogey six-tire main landing gears to solve the problem partially. Later models had eight wheels per main landing gear and have handled takeoff gross weights as heavy as 440,000 pounds.
The Concordes now have new blowout-friendly tires, in accordance with accident report recommendations. The new tires are designed to never explode; if a tire is cut and fails, the tread will burst into many small pieces. The airplanes also have Kevlar-lined fuel tanks, wiring, and landing gear mods, and the airline has stricter runway FOD checks.
Besides several other tire failures, Concorde’s 24-year history includes three honeycomb rudder delaminations in flight. As reported in the British Airways Air Safety Reporting system, in one event, the crew felt a thump and heard a buzz in supersonic flight over the Atlantic and another ripple when decelerating from supersonic flight on descent. The flight crew had no out-of-the-ordinary problems flying or controlling the airplane. The tower reported that the rudder looked damaged as the airplane landed. The crew took on a look of astonishment ("Blimey!") on a post-flight walkaround, now learning that the thump and buzz were caused by the loss of 40 percent of the lower rudder.
Concorde’s unique characteristics
According to British Airways, the aluminum alloy fuselage skin of the Concorde heats up to varying extremes in flight. A temperature probe on the nose is redlined at 260.6 degrees F. This factor sometimes limits Mne. A gap aft of the engineer’s panel large enough to stow the captain’s hat in cruise would flatten it during landing and make it unavailable. The fuselage lengthens in flight and the cabin panels float free. The airplane is made with advanced state-of-the-art aluminum alloy metallurgy and, with the high-heat, moisture-free flight regime, has proved to be almost corrosion-proof. The high temperatures also provides a self-annealing effect sometimes called aeronautical serendipity.
The windows, which are very small compared with those of other airliners, are designed so that three windows would have to fail before an emergency descent to a safe altitude would take too long. Decompression is slow. The cabin pressurization maintains a comfortable 6,000 feet in cruise up to 60,000 feet.
With the ogival wing plan-form, the Concorde has no need for spoilers, leading-edge devices, swing wings, canards, or flaps. The four trailing edge devices droop slightly at takeoff and landing to lower the pitch a few degrees. The elevons provide roll and pitch control with fly-by-wire technology that was ahead of its time. The airplane is a real gas-guzzler at low altitudes and subsonic speeds. Until it flies above 300 knots indicated (400 knots at max takeoff weight), it is flying behind the power curve and a noticeable rumble is audible in the cockpit. High-altitude, high-speed flying is a range necessity.
The normal checkout for the Concorde takes about 6 months. British Airways crews receive 19 four-hour simulator rides, 2 normal and 17 loaded with abnormals. Pilots get a minimum of 14 landings (usually at Shannon) and then fly the line for 2 months with a check airman before receiving a line check. Class sessions, which are one-on-one with instructors, use blackboard and chalk and no computer-driven training aids. Four months after checkout, pilots go back for recurrent training. British Airways has 25 captains, 15 first officers, and 17 flight engineers checked out in the Concorde.
Concorde takeoffs are timed to around 45 seconds with max-gross-weight takeoff V1 at 165 knots, VR 195 KIAS, and V2 about 220 KIAS. Fuel flow with "reheat" (afterburners) is about 220,000 pounds/hour and fuel capacity is 209,946 pounds! The initial pitch target at rotation is about 13.5 degrees. After the Concorde pilots retract the landing gear and accelerate to 250 knots, they must follow a noise-abatement procedure that requires them to shut down the afterburners and reduce power. The rate of climb slowly increases from about 1,500 feet per minute to 3,000 fpm until speed is increased to attain the Concorde’s heavy-weight best lift-over-drag ratio at 300 knots plus. The cockpit is very noisy until the drooping nose is streamlined (by a pilot pressing a button near the landing gear handle) and speed exceeds 300 knots.
During flight, the engineer is constantly shifting fuel to improve fuel burn efficiency and stability as the airplane changes speed. At takeoff, the MAC is 51–52 percent and in cruise at Mach 2.0, 58 percent. This keeps the elevons relatively flush. When decelerating, the center of gravity must again move forward. This makes for a very busy cockpit during a missed approach or on training flights.
As fuel shifts aft, the rate of climb improves along with speed and fuel efficiency. Best climb is maintained by flying Vmo and following a barber pole gauge. Maintaining the best speed is easy when hand flying, but "George" provides fewer warning horns. Reheat is needed to accelerate from Mach 0.90 to Mach 1.7. When accelerating past Mach 1.0, the only unusual indication in the cockpit is a slight jump on the vertical speed and altimeter at around FL300.
At Mach 1.3, computer-controlled inlet-guide ramps lower to slow down the intake air. At Mach 1.7, the afterburners are turned off, and the Olympus non-bypass engines are able to increase speed to Mach 2.04 (1,150 knots) with about half the fuel flow. At cruise speed, the air entering the engines is reduced by intake ramps to 500 knots. This drop in intake airspeed now provides 45 percent of the thrust, the engines 50 percent, and the convergent/divergent effect of the nozzle and stowed thrust reversers, 5 percent. Fuel flow at Mach 2.04 cruise is approximately 45,200 pounds per hour—a reasonable rate—at altitudes up to 60,000 feet.
The aircraft is designed to fly like a bat out of hell in cruise, and all other flight regimes are amazingly successful compromises.
The flight from Heathrow to Kennedy is scheduled for 3 hours 50 minutes. With the time zone changes, arrival time is earlier than departure. The record eastbound Kennedy–Heathrow flight time was 2 hours 46 minutes 59 seconds. Passengers pay about $1,500 per seat per hour and are pampered by six flight attendants. The flight crew has triple INS for navigation and has the latest TCAS and GPWS. Such short flights mean little need for modernizing with GPS, and the airline has no plans to upgrade the cockpit to "glass" displays.
The top-of-descent point is critical for minimum-time descents into the high-fuel-burn airspace. The flight plan also must consider where the airplane will be when it goes subsonic so as not to produce a boom for the citizens on land. With low power settings, the aft cabin is difficult to cool. A perfect approach where the least power is used is highly desirable. Holding or making delaying turns forces constant recalculations and fuel transfers. A missed approach or go-around sometimes results in the crew notifying ATC that they need special handling and expedited landing. Missed approaches or aborted landings often cause the Port Authority’s phones to ring off the hook with noise complaints.
The nose is drooped even lower for a better landing view. When lowering the gear, the flight crew looks for four lights—two mains, a nose, and a tail bumper because of the high angle of attack required with no flaps available. The airplane is certified for Cat 3 approaches. Vref is 162 KIAS at 275,000 pounds. Autothrottles and reference to instruments and angle of attack are strongly recommended to 500 feet HAT. Touchdown is very nose high, the nose gear must be carefully flown down, and the thrust reversers are quite effective.
Young for its age
The Concorde fleet is relatively young considering its age. The airplane’s design life is 6,700 cycles, recently extended to 8,500 cycles with a planned flight program to 2010 or longer. The high-time airplanes so far have flown 18,000 to 20,000 hours. The daily utilization rate is about 2.3 hours, about one-third the normal rate of subsonic jet airliners. Yet, with fully amortized aircraft, first-class–plus ticket prices, and honest bookkeeping, the fleets operate profitably. At one time, the Concorde was responsible for 20 percent of British Airways’ profits for the year. Concorde parts are hard to come by, and maintenance is top-of-the-line pricey.
Justifying an economic demand for mass transit in SSTs in the present context is difficult to perceive. With new weight-saving interiors, the refurbished and updated systems and structures, however, the Concordes will continue to serve an increasing demand for fast transatlantic business and vacation travel well past 2015. However, that still begs the question, "Should we be preparing to build a bigger and faster SST, or will we risk increasing available transoceanic flight times in 10–15 years?"
If we build them, will they come?
To date, a follow-on supersonic transport is still in the dream-about-it stage, despite the relative maturity of the current operational airliners and military supersonic airplanes. In the early 1990s, NASA and interested U.S. companies entered an agreement with the Tupolev design bureau to convert one of the newest Tu-144s, an airplane that had never seen commercial service, into a flying test bed to evaluate new technologies imagined for the follow-on SST.
European airframe and engine companies did not participate in the project but came up with concepts and improvements for a future SST on their own. They look for a 250-seat multi-class cabin with a 5,500-nm range at Mach 2.0. They specify an efficient subsonic fuel burn and seem to be hesitating before investing great sums in the project. Their picture of the airplane resembles the Concorde and earlier McDonnell-Douglas proposals.
From 1990 to 1995, the NASA High Speed Research (HSR) Program studied environmental problems such as engines-emission effects on the atmosphere, airport noise, and sonic booms. The dream was that any new SST would have to be bigger, faster, longer-ranged, lighter, more fuel efficient, more automated, more resistant to radiation, more environmentally friendly to the ozone layer, and a lot quieter. Market experts saw a demand for some 500 aircraft worth $200 billion and 40,000 jobs by 2010. The baseline for goals included a speed of Mach 2.4 (1,408 knots) and a range of more than 7,000 nautical miles with 300 passengers at a price about 20 percent higher than comparable subsonic costs. The hope was for profitable transpacific turnarounds with one airplane in 1 day at non-curfew passenger-friendly arrival times.
In 1994, the studies began to focus on economic viabilities dealing with weight, performance, acquisition and operating costs, materials and structures, aerodynamics, propulsion, efficiency improvements, and critical engine components. Other research involved ground and flight simulations for advanced control systems and flightdeck instrumentation and displays in NASA facilities and aircraft.
The Tu-144 tests
By 1996, the NASA/industry/academic team was ready for airborne tests with the Tu-144 in the real world with a planned 32-flight test program. Tupolev upgraded its test craft with more powerful Tu-160 Blackjack bomber engines and removed the passenger seats to make room for six data- collection systems. One experiment was to test the feasibility of eliminating the forward-looking window and replacing it with a synthetic-vision system to eliminate the need to droop the nose for takeoff and landing. This would save 10,000 pounds and allow pilots to fly in low-visibility conditions and provide an even more sweeping view from the cockpit.
In 1998, two pilots from NASA Langley were privileged to fly three of eight remaining experimental flights in the Tu-144LL (flying laboratory) in Russia. One was Rob Rivers, an ALPA member when he flew for Eastern Airlines, who has also flown the Concorde. Rivers’s flight was to test handling qualities and evaluate, among other things, whether landing with the nose cone blocking the windscreen was feasible by looking out the side windows (à la Lindbergh in Paris). He reports that the Tu-144LL handled very well with speeds on takeoff and landing a little higher than those of the Concorde for the weight.
The NASA/aviation-industry program results revealed that the high speed civil transport (HSCT) envisioned would need to be very long (300 feet for 300 passengers). It would require mufflers the size of a Greyhound bus that were very heavy for efficiency and range, and very big for low-impact sonic boom. Over-land restrictions would apply. It would also be quite a polluter, using existing fuels, and would require engine technology not yet available. The synthetic-vision experiments in NASA subsonic aircraft (see "Aviation Safety Research is Alive at NASA," November/December 2001) show promise for other airplanes with a backup forward-looking windshield. The synthetic-vision system uses multiple sources including radar, moving map, ADS-B, infrared, and low light, and selects the best at the moment for display. This is helpful for both improved enroute and ground operations, making all flight almost as good as or even better than in VMC.
The gut feeling of the risk takers was that they should stay subsonic with large profitable commercial transports. Hence, the Mach 0.95 sonic cruiser is on the Boeing drawing board, and Airbus has begun cutting metal for the Mach 0.89 A380.
How about a mini-Concorde?
Many of us forget that modern air transportation has room for counterbalancing, competing models—small jets with high frequency or niche, or huge jets with high capacity, lower frequency, and ultra-long range. Both Russia’s Sukhoi and U.S. Gulfstream have been exploring follow-on bizjet versions of supersonic transports that would carry from 8 to 14 passengers. Smaller twin-engine airplanes with 1.8–1.95 Mach speeds and ranges as great as 4,850 nm are possible with derivatives of current technology. Sukhoi, which is seeking investment and technical partners and has the interest of Boeing, has spun its airplane off its very agile fighter technology.
Japan has a government/aviation-industry effort under way to build a Mach 2 supersonic airplane that will undergo flight testing—as a rocket- boosted 1/10th scale model—in Australia in 2002.
Gulfstream announced a proposal to build an airplane called the quiet supersonic jet (QSJ). It would have two tail-mounted jet engines, a T-tail, and highly swept (70 degrees inboard, 60 outboard) wings with a range of more than 4,000 nautical miles and room for 8 luxury or 14 business-class passengers. The QSJ needs only a 6,500-foot runway and would cost up to $100,000,000.
Gulfstream anticipates competing with current New York–London B-777 first-class and Concorde seat prices, charging about $9,000 for the round-trip in the 14-seater. The cabin has one seat on each side of the aisle at a 40-inch pitch.
The New York–London flight time is 3.5 hours with a crew of three. Transcontinental U.S. flight time would be 2.6 hours. In a 12-hour work day, a New Yorker could go to Moscow, Rio, or Honolulu, and back with a minimum of 2 hours on location.
Gulfstream management notes that some airlines are altering their business models and considering operating more smaller jets. It foresees sufficient sales for profitability and many other missions for variations and derivatives of the QSJ, including airliners with as many as 60 seats in scheduled service by 2015. Gulfstream recognizes that overcoming the technical and regulatory barriers will take a focused effort in the coming years. Whether the Concorde will remain the only supersonic bizjet/mass transport around in the future will be interesting to see.
The sky is still the limit
So, are any current airline pilots destined to fly a supersonic transport? Scott Crossfield, the banquet speaker at ALPA’s 2001 Air Safety Forum and an early sound-barrier test pilot in the 1940s and 1950s, believes that if all the money had not been pulled from the SST years ago to concentrate on space exploration, we would be flying an Orient Express from the United States to China in 2 hours at 105,000 feet at Mach 5 by now. The craft would use methanol-derivative fuel, fly above the ozone layer, and likely create a sonic boom at acceptable over-land noise levels. He still has great faith in this generation to work its way through the problems and pull it off like the aviation pioneers and dreamers of generations past.
Think about it as you lumber along at Mach 0.80 on a 17-hour flight some day.
Capt. Tom Duke has logged more than 11,400 hours in military and Part 121 four-engine transports. The former Director of Safety of the U.S. Air Force Reserve, he has been a researcher for the NTSB. His most recent article was "Runway Incursion Update," May 2001.