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DESIGN ORIGINS:
Although the short-range, low-capacity section of the marketplace used to be saturated with twin-jet designs, inclusive of the Sad-Aviation SE.210 Caravelle, the British Aircraft Corporation BAC-111, the McDonnell-Douglas DC-9, the Boeing 737, and the Fokker F.28 Fellowship, Dassault-Breguet believed {that a} higher dual, accommodating no less than 150 passengers and working over sectors now not than 932 miles, used to be had to fill the space between those different designs and the 336-passenger Airbus A300.
Market research carried out in 1968 indicated the will for as many as 1,500 plane on this class all the way through the following 9 years. Of the present varieties, solely the Caravelle 12 and the DC-9-50 accommodated 130 single-class passengers in high-density configurations, whilst the others carried significantly fewer. The BAC-111-200, as an example, solely had a skill of 89 and the F.28, even in its final stretch because the F.28-4000, accommodated 5 fewer than this. Dassault-Breguet’s supposed airliner used to be noticed as an early airbus, economically working short-range, high-density routes, similar to the ones between France’s primary inhabitants facilities.
Unlike 4 of those 5 different twin-jets, its personal configuration, on account of a number of sizes and design answers, used to be a traditional low-wing monoplane with a fuselage vast sufficient, like that of the 737, for six-abreast trainer seating, two pylon-mounted engines, and an similarly standard tailplane. Its total look, in reality, used to be very a lot a reflect symbol of that 737, except for that its turbofans have been hung decrease and forward of the wing, versus Boeing’s underside attachment association, and its fuselage used to be longer to allow six further six-abreast seat rows to be put in.
Project go-ahead used to be contingent upon receipt of no less than 50 company orders for the ultimately named “Mercure,” or “Mercury,” however solely Air Inter, the French home provider, dedicated itself to 10 on January 29, 1972. So satisfied used to be Dassault-Breguet in regards to the integrity of its design and the sector marketplace’s want for it, that it introduced this system based totally upon the only airline order.
The French govt lent 56 % of the release prices, whilst 14 % used to be carried via Dassault-Breguet itself and the remaining via its 5 risk-sharing companions, that integrated Aeritalia of Italy, Canadair of Canada, CASA of Spain, the Eidgenosisches Flugzeugwerk of Switzerland, and SABCA of Belgium. Each used to be accountable for portions and techniques manufacture: Aeritalia, the tail unit and the tailcone; Canadair, the wing panels, the forefront, the flap tracks, and the engine pylons; CASA, the primary and 2nd fuselage sections; Eidgenossisches Flugzeugwerk, the engine air intakes and the cowling panels; and SABCA, the flaps, the spoilers, the ailerons, and the airbrakes. Final meeting would happen on the Bordeaux-Merignac manufacturing plant in Southern France.
MERCURE DESIGN FEATURES:
The Mercure 100 in its initial-and, within the tournament, only-version, featured an all-metal, five-section, semi-monocoque fuselage of round form vast sufficient for six-abreast trainer seating and stretching 112.11 toes in size, giving the plane a 114-foot, 3.5-inch total size. Of the 5 different low-capacity, short-range twin-jets, solely the Boeing 737 presented enough width for this configuration.
The airframe used to be designed for 30,000 flight cycles and 40,000 airborne hours.
The low-set wings, whose two-spar torsion containers have been made from a continual spar, 8 pores and skin panels, stiffeners, and machined ribs, have been geared up with three-section out- and downward-extending vanguard slats, (versus the 5 suited for the prototype), two-section triple-slotted trailing edge flaps, an aileron, 3 spoiler panels, and two airbrakes. All have been hydraulically operated by the use of twin actuators, which themselves have been fed via 3 impartial circuits.
The spoilers, interrupting raise upon primary wheel spin-up, operated along with the aileron in flight so as to supply lateral keep watch over.
The 100.3-foot wingspan, leading to a 1,250-square-foot house, featured a 25-degree sweepback, generating a 96.25 pounds-per-square-foot loading. Other wing floor spaces integrated the trialing edge flaps (261.6 sq. toes), the ailerons (45.2 sq. toes), the spoilers (49.5 sq. toes), and the velocity brakes (36.6 sq. toes).
Wing main edges have been deiced by the use of engine bleed air.
The standard tailplane, once more very similar to the 737’s, consisted of two-spar horizontal and three-spar vertical surfaces, leading to a 37-foot, 3.25-inch total plane peak. The former, fixed with 3 levels of dihedral and of the variable-incidence sort, had a 41.11-foot span and a 257.3-square-foot house with 86.1 sq. toes of hinged, hydraulically actuated elevators. The 166.3-square-foot fin used to be provisioned with a 64.1-square-foot, hydraulically-operated, dual-section rudder.
Power used to be supplied via two nacelle-encased, sound absorption-treated, thrust reverser-equipped, 15,500 thrust-pound Pratt and Whitney JT8D-15 low (1:1) bypass ratio turbofans pylon-mounted to the wing vanguard underside. Differing from the direct wing underside association of the 737, the configuration positioned the engine beneath and forward of the airfoil, necessitating an extended undercarriage strut. Several variations of the engine powered the Boeing 727, upper skill Caravelle variants, the DC-9, and the 737 itself.
Fuel, whose skill used to be 4,860 US gallons, used to be presented on the starboard wing’s outer vanguard, with further issues on the true floor. Oil skill used to be 11.9 US gallons.
The Mercure 100 rested on a hydraulically-operated, twin-wheeled undercarriage consisting of Kleber-Colombes tires, Messier-Hispano wheels, oleo-pneumatic surprise absorbers, Messier-Hispano brakes, and antiskid devices. The nostril equipment, whose tire measurement used to be 30 x 8.8 and whose force used to be 123 psi, used to be steerable and retracted ahead. The primary equipment, whose tire measurement used to be 46 x 16 and whose force used to be 141 psi, retracted laterally into wing and fuselage wheel smartly fairings. The undercarriage might be manually prolonged all the way through hydraulic failure stipulations.
Nose wheel guidance and observe enabled the plane to be grew to become 180 levels at the floor on a 70-foot-wide floor.
Entry used to be supplied via 71-by-33-inch ahead and aft, port aspect doorways, the primary of which standardly featured an extendible, lighted, handrail-provisioned airstair and the second one of which might be optionally so geared up. The ahead and aft, starboard-side galley servicing opposite numbers respectively measured 71-by-33- and 65-by-33-inches. Four 39.4-by 20-inch overwing emergency exits, two on each and every aspect, facilitated egress.
Although the Mercure 100 used to be standardly operated via a two-person team, two further observer seats have been supplied. Vision used to be via two ahead and 4 aspect home windows, in addition to two eyebrow panes. Incorporating generation designed for Dassault-Breguet’s well-known combatants, it used to be provisioned with a head-up show, decreasing the time between sky scanning and tool tracking for extra quick keep watch over and corrective motion, if required.
Three 3,000-psi impartial hydraulic techniques powered the main and secondary flight controls. The first two, pushed via Abex engine-driven pumps, powered the forefront slats, the trailing edge flaps, the spoilers, the tailplane, the nostril wheel guidance, the undercarriage, and the brakes. The 3rd, powered via a Vickers electrically-driven pump, supplied backup energy for ailerons, the elevators, and the rudder.
The 83.7-foot-long, 11.11-foot-wide, and 7-foot, 2.75-inch excessive cabin, with an 882-square-foot ground house and 5,717-cubic-foot quantity, used to be each wider and longer than that of any twin-jet as much as that point and thus facilitated a large number of category divisions and seat pitches and densities. This flexibility used to be additional provisioned via its oblong, closely-spaced, polarized, mild filtering passenger home windows and the 4 ahead and aft get right of entry to doorways.
Originally equipped with a large cabin glance, it featured a flat ceiling with recessed, subtle lights; particular person, upward-opening overhead garage compartments for carry-on baggage; and paneled sidewalls. Galleys, bathrooms, and garment closets might be put in in 11 places. The galleys themselves might be merely or broadly provisioned with ovens, refrigeration devices, espresso makers, garage compartments, counters, waste receptacles, and meal and beverage carts, and may just serve the rest from an aperitif to a scorching meal suitable to the time of day. Installation and the selection of devices integrated the ahead, proper aspect (two devices), the ahead, left aspect at the back of the passenger door (two devices), the aft, proper aspect forward of the servicing door (two devices), the aft, left aspect forward of the passenger door (one unit), and the aft, proper aspect at the back of the servicing door (one unit).
Lavatories, which standardly consisted of a lockable door, a chrome sink and counter, dispensers for tissues, cups, and bathroom paper, a lighted reflect, and a recirculating rest room, may just similarly be put in in quite a few places, together with at the ahead, proper aspect at the back of the servicing door; at the ahead, left aspect at the back of the passenger door; at the aft, left aspect earlier than the passenger door; at the aft, left aspect at the back of the passenger door; and at the aft, proper aspect at the back of the servicing door.
Garment garage closets is also put in in seven ahead and aft places.
Seating densities, configurations, upholstery, colour, and design, like galley, bathroom, and garment closet places, numerous in line with buyer specification, however each and every seat itself used to be provisioned with a seatbelt, an ashtray, a pull-down tray desk, and a literature pocket. Each additionally reclined.
A dual-class, 120-passenger association entailed 12 four-abreast firstclass seats at a 38-inch pitch, their pairs spanning 54 inches in width and thus allowing a 31-inch aisle, and 108 six-abreast trainer ones at a 34-inch pitch, their triples spanning 61 inches and the ensuing aisle measuring 17 inches in width.
A dual-class, 132-passenger configuration entailed 12 firstclass seats at a 38-inch pitch and 120 at a 34-inch one, however the further skill used to be completed via both relocating or casting off some galley, bathroom, and/or garment garage closet amenities.
An global, single-class association entailed 135 to 140 six-abreast seats at a 34-inch pitch, whilst its single-class home counterpart greater the skill to 150 at a 32-inch pitch. The sort’s most single-class skill used to be 162 at a 30-inch pitch, which used to be 32 greater than the related 737-200’s and 23 greater than both the Caravelle 12’s or the DC-9-50’s.
Garett air con and Hamilton Standard pressurization techniques, the use of engine bleed air, produced an 8.3-psi cabin differential.
Baggage, shipment, mail, and reside animals have been carried in 3 lower-deck holds.
The first two compartments may just respectively accommodate 5 and 4 727-type shipment boxes, whilst the 3rd solely authorized bulk or free lots. All have been heated, lighted, and pressurized, and housed oxygen and potable water provide tanks and bathroom waste receptacles. A powered loading machine might be optionally put in.
The Mercure 100 presented the next weights: an empty working weight of 70,039 kilos, a payload of 32,850 kilos, a most ramp weight of 121,250 kilos, and a most takeoff weight of 120,150 kilos.
Weights for export aircraft-that is, the ones ordered via carriers as opposed to Air Inter-differed, as follows: a most zero-fuel weight of 105,820 kilos, a most ramp weight of 125,660 kilos, and a most takeoff weight, after taxi gas intake, of 124,560 kilos.
Fulfilling its design objectives, the Mercure 100 presented the next payload, a better passenger skill, and extra shipment grasp quantity than any earlier dual.
It used to be additionally ready to move extra passengers for its weight than some other twin-jet, reaching awesome working potency.
Only the 727-200, which used to be additionally powered via the JT8D engine, may just exceed the Mercure 100’s skill with 169 passengers, however at a significantly upper reasonable weight of 145,000 kilos and with an extra powerplant.
The Mercure 100 additionally presented the bottom gas burn consistent with passenger on a standard 630-nautical mile European sector when working at its long-range cruise velocity at 33,000 toes with a 137-mile diversion allowance
These comparisons point out 4 fundamental design superiorities.
1). The very best gas mileage consistent with seat of all jetliners wearing fewer than 250 passengers.
2). The very best reasonable velocity of all short- to medium-range business plane.
3). The lowest empty weight consistent with seat.
4). The very best payload of all twin-jets weighing lower than 200,000 kilos.
Optimized for brief flight occasions, the Mercure 100 coated 500 nautical mile segments in 5 to fifteen mins lower than related twins as a result of its excessive climb, cruise, and descent charges. Combined with its fast turn-around capacity, those efficiency figures facilitated excessive day by day usage charges.
The plane required a 4,630-foot runway for touchdown based totally upon a 136-mph (118-knot) manner velocity and a 109,790-pound most touchdown weight.
Short turn-around occasions have been made conceivable via a tailcone-installed Garrett-AiResearch GTCP-85-163C auxiliary energy unit (APU) that supplied floor energy for cabin conditioning, engine beginning, and an emergency electric provide; the ahead, left (and not obligatory aft, left) Aerozur airstair; and the starboard aspect galley servicing and decrease deck luggage and load grasp get right of entry to doorways. Because sectors have been brief, the quantity of galley servicing and cabin cleansing used to be little. And, whilst the plane might be refueled in ten mins, its excessive takeoff to touchdown weight ratio enabled it to perform a number of sectors earlier than this used to be required.
Turn-around occasions thus numerous from 10 to fifteen mins at intermediate stops and from 20 to twenty-five mins at terminating issues the place extra intensive provisioning used to be wanted.
Aircraft at their most gross weight required a 6,300-foot runway for takeoff and may just climb at 3,300 fpm.
Despite those reputedly awesome design features, the sort’s number one deficiency used to be its payload-range inflexibility. On a standard Air Inter flight with 150 passengers cruising at Mach 0.78 and at 32,000 toes with a 200 nautical mile diversion allowance, as an example, the Mercure 100”s vary used to be solely 800 nautical miles. Only payload restrictions would have greater this-to 1,200 miles with a 25,000-pound payload and 1,600 miles with a 21,000-pound one-rendering it not able to milk its passenger cabin and load grasp benefit on routes that eclipsed short-range ones.
FIRST FLIGHTS:
The first Mercure 100 prototype, designated 01 and registered F-WTCC, first flew from Bordeaux on May 28, 1971 powered via two 15,000 thrust-pound Pratt and Whitney JT8D-`11 turbofans, however integrated a shorter fuselage than that supposed for manufacturing variations.
Because efficiency proved beneath design goals, it used to be retrofitted with 15,500 thrust-pound JT8D-15s and retook to the sky 4 months later, on September 7. But the extra energy did little to beef up its deficient low-speed dealing with traits, which have been, partially, remedied with the addition of horizontal stabilizer dihedral, leaving it to once more fly, now on this configuration, nonetheless two months later, on November 18.
The 2nd prototype, 02 and registered F-WTMD, joined the flight take a look at program the next yr on September 7. The upper thrust engines and the tailplane dihedral, together with full-span vanguard slats, delivered the supposed efficiency.
The first manufacturing edition Mercure 100 supposed for release buyer Air Inter, incorporating all of those changes, together with the full-length fuselage, first flew from the brand new Istres manufacturing plant on July 17, 1973 and used to be awarded its French sort certificates the next yr on February 12.
Air Inter took supply of the primary of its ten plane on May 16, integrating the sort into its shuttle-type French home direction community. It won its 2nd instance seven days later, on June 11.
Of the 10 ordered, the primary six have been delivered in 1974 and the rest 4 the next yr, alphabetically registered F-BTTA via -BTTJ.
Although its first 4 plane have been solely provisioned with Category II touchdown capacity, its last six featured the upgraded, Category III same old, enabling it to habits approaches with 500-foot runway visible levels (RVR) and 50-foot determination heights (DH). The preliminary 4 have been due to this fact introduced as much as this capacity.
Accommodating 150 passengers in single-class, six-abreast, three-three, preparations with 32-inch seat pitches, its ten Mercure 100s have been smartly won via its passengers and operated multiple-daily roundtrips between a dozen French home towns and cities on sectors that numerous between 50 and 70 mins, demonstrating its speedy turn-around capacity.
Its skill, alternatively, proved too over the top for call for. Lower than expected load components, together with escalating gas costs, paradoxically brought on Air Inter to in the end gain a fleet of Sud-Aviation Caravelle 12s, working them on lots of the identical routes, however with decrease prices. Although it in brief flirted with the speculation of promoting its Mercures, the French govt mandated their endured operation, however supplied a subsidy to take action.
Structurally, alternatively, the Dassault-Breguet airliner used to be sound and presented technological comparison to different twin-jets.
During the primary 5 years of operation, the 10 Mercure 100s carried out greater than 90,000 hours, consisting of a few 100,000 53-minute segments and reaching a mean 98.5-percent dispatch reliability. Each plane operated 8 to 10 day by day flights.
Equipped with an absolutely monitored computerized pilot and head-up tool studying shows, they carried out Category IIIA landings all the way through deficient climate stipulations, and nonetheless completed a 98- to 99-percent reliability fee.
On March 25, 1985, Air Inter took supply of the second one prototype, F-WTCC. Already having been provisioned with the longer fuselage, the upper rated engines, the forefront slats, and the tailplane dihedral, it used to be introduced as much as complete manufacturing same old, giving Air Inter an 11-strong fleet.
PROGRAM CONCLUSION:
Because no different provider or operator ordered the Mercure 100, which, to some extent, used to be designed for Air Inter’s widespread home direction machine, just a dozen, together with the 2 prototypes, have been ever constructed. Although the design used to be an aerodynamic good fortune and it used to be extraordinarily dependable in day by day operations, it used to be a monetary failure as a result of a number of causes.
1). Like the Vickers VC-10 and the Hawker Siddeley HS.121 Trident, which had respectively been designed for British Overseas Airways Corporation (BOAC) and British European Airways (BEA), it used to be aimed toward Air Inter and its distinctive high-density, multiple-frequency, short-range home routes, a machine which no different provider maintained.
2). Dassault-Breguet, in all probability with out selection, hired then-current generation for it, incorporating the present Pratt and Whitney JT8D engines that powered different twin-jets, such because the DC-9, the 737, and the later variations of the Caravelle and due to this fact electing to make use of its thrust for payload and passenger skill versus vary.
3). Because it introduced the Mercure program overdue, those and different twin-jets had already captured many of the marketplace and presented the vital payload and vary diversifications to take action. While without equal stretches of the Caravelle, the DC-9, and the 737 resulted, respectively, in most passenger capacities of 139, 139, and 130, their levels have been considerably better, providing operators extra flexibility.
4). Although marketplace research for an airbus-type of plane have been correct, their timing used to be now not. Only after the Nineteen Eighties used to be the 150-seat dual prevalent.
5). Finally, the Mercure 100’s working economics may just now not be totally exploited if its further skill used to be now not stuffed.
While all of those components ended in the sort’s death and led to its paltry manufacturing run, Dassault-Breguet formally attributed the cause of its discontinuation as, “Fabrication stopped after completion of the tenth (production) aircraft due to the extremely penalizing evolution of the US dollar exchange rate.”
Despite what used to be indubitably a failure via many measures, the Mercure 100, whose final scheduled flight came about on April 29, 1996, completed an enviable operational file. Air Inter’s 11 plane carried some 44 million passengers, logging 360,000 airborne hours all the way through 440,000 flights with a 98-percent dispatch reliability all the way through their 22 years of carrier, by no means having brought about a unmarried fatality.
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Source via Robert Waldvogel
