The four-engined 707 was Boeing’s lengthy haul masterpiece and entered service in 1958. With the marketplace for jet transports linking main cities of the world sewn up, Boeing shifted its consideration to the subsequent market phase, brief and medium haul flights between smaller cities. By shrinking the 707, they added a brand new sort to their product line – the 720. It was the first jet to serve lots of the ports it served, and for seven of the sixteen clients that purchased 720s new, it was their first turbine powered plane.
The Boeing 707-120 Stratoliner first flew December 20, 1957 and entered service with Pan Am on October 26, 1958. The stretched Boeing 707-320 Intercontinental first flew January 11, 1959 and entered service with Pan Am on August 26, 1959.
In the meantime as early as 1956, research started to deal with the subsequent market phase, brief and medium haul between second tier cities. Beneath the designation of the 707-Zero20, ten configurations have been thought-about, principally with 4 engines, and a few twin-jets. Probably the most promising twin was the 707-Zero20-6, which was 6 ft (1.83 metres) shorter than the future 737-200 however with almost twice the wing space and a big tail.
In July 1957 Boeing selected a 4 engined configuration meant to hold as much as 130 passengers on routes as much as 1,700 miles lengthy, utilizing an airframe with the actual exterior dimensions of the 707-120 Stratoliner, however with vital structural modifications which lowered the gross weight by 62,000lbs (28,122kg) from 247,000lbs (112,037kg) to 185,000lbs (83,915kg), though no orders have been but positioned. In addition to the Pratt & Whitney JT3 turbojet, further engine choices have been GE’s J79 and Rolls-Royce’s Avon 26.
Lastly the design was frozen on a configuration that shrank the 707-100 by Eight ft, however retaining the 707’s 130 foot wingspan. A fiberglass “glove” was fitted to the vanguard between the fuselage and the inside engine pylon, which elevated cruising velocity barely and assisted in subject efficiency. Vanguard flaps have been fitted to the full span of the wing, decreasing touchdown and takeoff speeds by 10 mph, and on strategy, the plane flew with a extra nose-up angle. Different modifications, principally involving decreasing airframe weight, included thinner fuselage pores and skin and smaller wheels on the undercarriage. The engine choice was standardised on the Pratt & Whitney JT3-C.
TWA and Delta had each ordered Convair’s CV-880 jet for his or her brief and medium haul routes, and with United about to put an order for 30 CV-880s, Boeing couldn’t stand to see one other huge order slip away, in order that they formally launched the 707-Zero20. Nevertheless, United’s president William A. Paterson didn’t need to be seen to be backtracking on his dedication to the DC-Eight, and requested a reputation change – the Boeing 720 was born.
N7201U rolled out of the hangar on October 30, 1959 and took to the air on November 23, 1959, commanded by Tex Johnston with Lew Wallick in the co-pilot’s seat. The second 720, N7202U, acquired airborne on January Eight, 1960. Exams included most gross weight takeoffs and landings, stalls at each weight and configuration, and flutter checks. Speeds of as much as Mach Zero.95 have been flown. The certification course of with the FAA started on January 18, 1960. The third 720 to fly, N7203U, joined the programme in March.
At Boeing Area in a short-field touchdown check, N7201U, weighing 135,000lbs (61,235kgs) and with a 6mph tailwind, cleared a simulated impediment of 50 ft off a steep strategy and got here to a full cease inside 2,200 ft (670 metres). As a result of the intention was to deliver jet service to smaller fields for the first time, the 720 was meant to routinely function out and in of runways of 5,500 ft (1,676 metres).
Certainly one of the 720s went to Edwards Air Pressure Base in the California desert for aborted takeoff check runs, together with fourteen “accelerate-stop” checks the place the plane was accelerated to 165mph (266kph) earlier than the throttles have been slammed shut and braking started. Two checks have been carried out at an all-up weight of 230,000lbs (104,326kg), 13,000lbs (5,900kgs) above max gross weight. No tires burst in any of the checks.
N7201U was launched to United Airways for crew coaching on April 28, 1960, in anticipation of entry into service in early summer time. After a 5 month check programme with the three 720s flying a complete of 442 hours together with 148 hours particularly for certification with FAA inspectors current, the sort was licensed for public transport service on June 30, 1960.
United operated the world’s first income service by a 720 on July 5, 1960, when N7201U, configured with 44 first class and 53 coach seats, flew from Los Angeles to Chicago by way of Denver. Three days later Los Angeles to Seattle by way of Portland was opened, adopted by service to San Diego and Las Vegas.
American Airways adopted on July 31, 1960 with “Jet Gateway” service out of Cleveland to Los Angeles by way of St Louis. New York to Chicago noticed its first 720 on August 14, extending from Chicago to Phoenix and on to San Diego on August 27. By the finish of summer time 1960, New York – Chicago was operating 5 occasions a day in each instructions. American have been proud of their 707s so their 720s have been branded the “707-023 Astrojet” (23 was AA’s Boeing buyer code).
Engine know-how was advancing at a quick price and Pratt & Whitney advanced their already profitable JT3C turbojet into the JT3D turbofan, which was quieter, extra environment friendly and extra highly effective, particularly at low speeds.
Boeing provided the new engine choice for plane on order, in addition to conversions for present JT3C powered machines. Turbofan outfitted 707s and 720s have been suffixed with a “B”, creating the 707-120B and 720B. Pilot suggestions stated the new powerplants was like including a fifth engine.
American Airways was an early adopter of turbofan engines, and introduced they might convert all fifty of their Boeing jets – in service and on order – to B normal. Their N7537A was the first 720B to roll off the line at Renton and was used to certify the new variant, first flying on October 6, 1960. It logged 60 hours of check flying with Boeing earlier than starting the FAA certification course of in December at Edwards which concerned extra “accelerate-stop” workouts, typically at weights in extra of the most licensed weight. In early February 1961, American’s third 720B carried out 103 route-proving flights round the USA together with excessive altitude work at Colorado Springs up in the Rocky Mountains, snow and ice encounters in New York, Kansas Metropolis and Omaha, and the warmth and humidity of Miami. The final check was carried out for the FAA on February 23 1961 and the 720B was licensed the following month.
Of the sixteen airways to purchase 720s new, Irish flag service Aer Lingus was considered one of the seven for whom the sort was their first turbine gear. Aer Lingus’ transatlantic routes have been shorter than most, heading out from Shannon to Boston and New York with flying occasions typically as brief as 4 hours, making the medium-hauler a more sensible choice than the bigger, costlier 707. Their first plane was handed over to the airline on October 14, 1960 and went to Tucson Arizona the place it spent the subsequent eighteen days flying spherical the clock to coach Eire’s first fourteen jet pilots. EI-ALA entered service on the Dublin-Shannon-New York service on December 14, 1960, with Dublin to London beginning in early 1961.
Braniff Worldwide ordered solely 5 720s to reinforce their 707 fleet, and entered service on February 20, 1961 flying Chicago – Dallas – San Antonio. Their second plane entered service April 30, and opened up service on the multistop Minneapolis – Kansas Metropolis – Dallas – San Antonio – Mexico Metropolis run.
The FAA took supply of their very own 720, N113, constructed to Braniff specs, on Might 5, 1961, principally to coach security inspectors, who wanted, in the FAA’s personal phrases, “Skill in aircraft equal to that of the airline pilots whose operation they monitor.” This was the solely 720 to by no means carry passengers.
Western Airways had been immune to pure jets – “Would you buy the Queen Mary to sail across Lake Tahoe?” requested CEO Terry Drinkwater, however the prospect of Hawaiian service modified his thoughts, and Western started 720 service on Might 15, 1961 from Los Angeles to Mexico Metropolis; on June 1, they started three every day flights from Los Angeles to Seattle (one nonstop, one by way of San Francisco, one by way of Portland).
The first non-US service to start 720B service was West Germany’s Lufthansa, who kicked off on Might 20, 1961 with an unique run to South America, routing Frankfurt to Santiago de Chile by way of Paris, Dakar, Rio, Sao Paolo, and Buenos Aires. July 1 noticed the begin of 720 service to Tehran with stops in Vienna, Rome, Beirut, Cairo and Baghdad.
Northwest started 720 service from Minneapolis to New York on July 1, 1961 and shortly expanded service together with intra-Asia flights out of their Tokyo hub.
Japanese Air Strains launched the first of fifteen plane with service from New York to Miami by way of Jacksonville on September 24, 1961, and to Fort Lauderdale on October 1, with their “Golden Falcon” service.
Excessive altitude airports in the 32,000-mile route community of Colombian flag service Avianca reminiscent of Quito (9,220 ft) and residential base Bogota (Eight,260 ft) made the scorching rod 720B a pure option to be the airline’s first turbine-powered hardware, first showing on the route from New York – Montego Bay – Kingston – Bogota on November 24, 1961.
Whereas ready for the first 720 supply, Continental’s present fleet of 707s was labored so exhausting that N70773 was the first Boeing jetliner to clock up 10,000 hours. The first 720 supply happened on April 30, 1962; nevertheless the interval turned out to be a tragic one for the airline as on Might 22 a 707 was blown up in midair by a suicide bomber for insurance coverage (the tragedy was the foundation of the plot of the bestselling novel and field workplace blockbuster Airport) so the 720s have been rushed into service on routes from California to Texas and Chicago, then Dallas – Midland/Odessa – Albuquerque – Denver, adopted by Amarillo, Phoenix, El Paso and Tucson as extra frames got here into service and the capability squeeze on the rapidly-expanding service started to ease.
El Al operated two 720Bs beginning in April 1962 from Tel Aviv to European ports in addition to an extended haul path to Johannesburg by way of Tehran, avoiding airspace of unfriendly nations, which meant a sixteen hour journey with two full crews on board and twenty-five course modifications alongside the means.
Ethiopia’s excessive altitude capital Addis Ababa 7,500 ft above sea degree made the sporty 720B an ideal introduction to jet service for Ethiopian Airways. Their first two machines have been flown collectively from Seattle by way of New York, Madrid, Athens to Addis and arrived on December three, 1962. Inaugural service passed off on January 15, 1963, Addis – Asmara (Eritrea) – Nairobi; the subsequent day the return flight continued northwest out of Ethiopia to Athens and Madrid.
One other unique service for whom the 720 was their first turbine gear was Pakistan Worldwide Airways (PIA), who started jet service on February 12, 1962 twice weekly from Karachi to London by way of Tehran, Geneva and Frankfurt; and twice weekly by way of Tehran, Beirut and Rome. Twice weekly service quickly adopted to Dhaka (then the provincial capital of East Pakistan which might later separate to type Bangladesh). In April 1962 London service prolonged to New York, and Moscow was added.
After intensive crew coaching by TWA at Kansas Metropolis, Saudia started jet service with a 720 flight on the busy route from Jeddah to Beirut on March 15, 1962. Riyadh, Dhahran, Cairo and Bombay quickly adopted.
The final service to put new 720s into service was plucky little Pacific Northern Airways based mostly up in Anchorage, who put the first of their two machines into service on the run right down to Seattle on April 27, 1962, adopted by service to Ketchikan and Juneau.
As 720s continued rolling off the line at Renton, the preliminary operators expanded service. By 1962 United served twenty-five cities with their 720s, together with 9 flights a day in the busy San Francisco-Los Angeles market. The final non-fan 720 at American was transformed and returned to service as a B mannequin on February 1, 1962 and the fleet grew to 25 machines. Western stored including new planes in small batches till the fleet grew to twenty-seven, together with the 154th and final 720B constructed, delivered to Western on Eight September 1967. At one level their whole fleet was standardised on Electras and 720s.
TWA leased 4 Northwest 720s to start service with N792TW from New York to Kansas Metropolis on July 22, 1962. Nevertheless the lease was short-lived and TWA standardised on the 707 and returned the 4 720s to Northwest by the finish of October.
Lufthansa used six of the sort on its brief haul European community, and so as to add capability to New York in summer time 1962 with a cease in Shannon. October three, 1962 marked the introduction of a brand new stopping service throughout Asia, routing Frankfurt – Munich – Rome – Cairo – Dhahran – Karachi – Calcutta – Bangkok – Hong Kong. In April 1965 Lufthansa inaugurated Sydney by way of Athens, Karachi, Bangkok, Singapore and Darwin. European locations included Vienna, Madrid, Barcelona and Las Palmas. They have been bought in pairs to Pan Am; the final one departed in February 1966.
Pan Am, who ordered over 100 707s, by no means purchased 720s from Boeing however purchased three ex-American machines in addition to the six Lufthansa to function shorter worldwide providers to the Caribbean and Central America till the early 1970s.
PIA made historical past on April 29, 1964 by turning into the first non-communist airline to function to China, routing Dhaka (then a part of Pakistan) – Guangzhou (then Canton) – Shanghai utilizing 720s. They added six secondhand 720s as the decade wore on, 5 from Western and one from Alia / Royal Jordanian. They flew their 720s proper as much as the finish of the 1980s.
A notable incident in Western Airways service started on June 2, 1972, when a Vietnam vet and his girlfriend hijacked a 720 and after letting off half the passengers in San Francisco, and stopping in New York to select up gasoline and a navigator, flew throughout the Atlantic to Algeria the place they have been granted political asylum. This stays the longest-distance hijacking in American historical past.
The 1970s noticed most of the preliminary clients start to promote their fleets. United and Japanese by no means transformed their 720s to B fashions, and commenced to retire them round the flip of the decade. A number of went to journey golf equipment and constitution operators resembling Trans Polar and AeroAmerica, who grew their turbojet fleet of 720s to eleven plane for a mixture of constitution operations together with vacation flights in Europe out of a hub at West Berlin, and scheduled flights akin to Seattle to Spokane, till they shut down in 1982. Alaska Airways purchased the three Pacific Western 720s and one from United for some interim capability, parking the fleet in 1975.
Six of the turbojet United fleet went to a Miami-based start-up, Air Belize; three have been all-economy 132-seaters and three freighters. The operation led to 1980 and one, N64696, turned a Miami fixture, parked in the entrance yard of the George T. Baker Aviation Faculty for scholar mechanics to tinker with till it was scrapped in 2000.
One other second residence for turbojet 720s was the Dominican Republic – Aeromar flew two on passenger providers, as did Aerovias Quisqueyana till 1977 and Hispaniola Airways flew from Puerto Plata to Miami and New York till 1984.
Some turbojet 720s discovered work with European carriers, akin to Calair in Germany, and Conair of Scandinavia who took 5 every from Japanese.
The 720Bs with turbofans discovered second careers at better-known airways – Greek flag service Olympic Airways took seven from Northwest for its European community from 1972 till 1980, Somali Airways took three from Lufthansa for its base in Mogadishu, and Air Malta leased and later purchased two PIA 720Bs, including six from Western, flying proper as much as October 1989. Ariana Afghan operated one ex-Pan Am plane from April 1972 till 1980 out of Kabul on multi-stop providers to Europe.
British constitution service Monarch Airways operated seven 720Bs between 1974 and 1983 – 5 ex-Northwest and a pair from American. Danish vacation airline Maersk additionally flew 5 ex-Northwest 720Bs till 1981 once they migrated to Conair to switch their much less environment friendly fleet of 5 ex-Japanese 720 turbojets.
The most important operator of second-hand 720s was Center East Airways of Lebanon, who operated twenty-one 720Bs over thirty years; eleven (greater than half) have been destroyed by warfare. Their odyssey started with the short-term lease of three Ethiopian Airways 720s in 1966. American bought 9 -Zero23Bs to the Beirut-based service in 1969, adopted by 4 extra, the final arriving in Might 1973. Three -047Bs from Western have been purchased in 1974, bringing the fleet to sixteen. As soon as the Lebanese civil warfare began in 1975, the quantity began to drop, starting with the tragic bombing of OD-AFT on New Yr’s Day 1976 over Saudi Arabia en path to Dubai, then OD-AGE was wrecked when it was hit by a shell on June 27 whereas parked. The 2 misplaced plane have been changed by a pair of -047Bs from Western Airways and an uneasy peace settled on the capital for the remainder of the 1970s, till OD-AFR was destroyed by a dynamite bomb shortly after touchdown again at Beirut from Tripoli (Libya) in 1980.
Israeli fighter jets destroyed 4 720Bs (and a pair of 707s) on the floor in June 1982, and another in August. In August 1985 two 720Bs have been destroyed by shelling of MEA’s parking space. Hostilities round the capital of Beirut turned so dangerous in the late 1980s that air travellers from the east aspect of the metropolis have been unable to succeed in the airport by floor transport, so MEA opened up a twice a day rotation to Kleyate, sixty-one miles away, utilizing their 720s, to feed visitors to their worldwide community that might usually have arrived by personal automotive and taxi.
The Lebanese civil struggle led to 1991 and common 720 operations got here to an finish round the similar time, though the sort was lively for crew coaching and advert hoc gear substitutions. Two plane, OD-AGB and –AFM, have been returned to service in June 1994 as post-war visitors ranges elevated dramatically (-AGB, inbuilt 1960, was at the time was the oldest flying jetliner in the world). These two courageous troopers lastly left Lebanon in December 1995 for brand spanking new lives at Pratt & Whitney Canada as flying check beds.
On a happier notice, 720s have been utilized by many rock bands in the 1970s. Greatest recognized was Starship I, ex-United -022 turbojet N7201U that had $1 million spent on its forty-seat VIP inside in 1973 earlier than flying the likes of Led Zeppelin and Elton John round the US on live performance excursions. Led Zep later chartered Ceasars Chariot N7224U, one other pimped-out 720 with an analogous provenance which noticed service with the Bee Gees the following yr.
5 720s handed by means of the palms of McCulloch Company, who used the plane to fly potential consumers to see land websites on the market in Arkansas, Colorado, Nevada and Arizona all through the 70s. For additional income they did the event constitution for NASA, sports activities groups and rock bands.
Saudi Prince Nawab Bin Abdul Aziz acquired an Western -047B in 1978 for his personal personal transport; in 1980 it was obtained by Sheik Kamal Adham. In 1988 it was bought to JAR Plane Service and flew VIP charters out of Beirut till the early 2000s and stays parked in Malta to today.
Taiwan, aka the Republic of China, used ex-Northwest Orient -051B as a head of state transport, with its serial quantity 18351 turning into its army registration, from December 1971 till February 1996.
A number of 720s have been used as flying testbeds. Allied Sign, later Honeywell, flew an ex-Northwest -051B out of Phoenix Sky Harbor from 1987 till July 2008 and was used for testing and certification of a number of engine tasks. Boeing repurchased two 720s – one turbojet -Zero25 from Trans Polar in 1972 to develop anti-submarine warfare know-how which was parked in 1979, and an -051B from Conair in 1987 to path missile warning methods, excessive accuracy navigation techniques, and digital warfare techniques, till it was parked in 1992.
Hughes Plane purchased a 720 from Ethiopian Airways in 1989 and transformed it to a flying laboratory for acoustic emissions exams generally known as the Superior Infrared Measurement System, earlier than being handed over the US army to hitch the Protection Superior Analysis Tasks Company (DARPA) from 1993 till retirement in 1998.
Probably the most spectacular experimental use of a 720 was the sacrifice of the FAA’s personal N113 in a remote-controlled crash in the California desert on December 1, 1984. The intention of the undertaking, referred to as the Managed Influence Demonstration, was to review the effectiveness of a gasoline additive which it was hoped would inhibit ignition in a crash, and in addition to research the crashworthiness of plane seats and construction.
Throughout the ultimate strategy, the plane obtained low and sluggish, and commenced a diverging rolling movement. Since the knowledge acquisition techniques had been activated, the flight was dedicated to influence, which was extra violent than meant. Quantity three engine exploded and the cabin was ruptured by posts cemented to the runway to simulate obstacles encountered in an off-airport crash state of affairs. The huge ensuing hearth represented a big setback for the experimental gasoline however the knowledge collected on crash survivability was deemed a hit and simply as necessary.
Pratt & Whitney Canada acquired OD-AFQ from MEA in 1986 and reregistered it C-FETB to be used as a flying check mattress for his or her plane engines, with a second machine, OD-AGB, coming from the similar supply in 1995. Two others have been acquired to be scrapped for elements to maintain the programme, which offered air checks for a lot of Pratt engines together with the PW307A, PW308, PW545 and IAE V2500.
The 720 period, which lasted fifty-two and a half years, got here to an finish on Might 9, 2012, when Pratt & Whitney delivered C-FETB to Canada’s Nationwide Aviation Museum at CFB Trenton. Different 720s on show are the Taiwanese head of state plane at Kansghan AFB close to Koahsiung, an Avianca machine at the Childrens Museum of Bogota, and PIA have stored considered one of their fleet at their Planetarium in Lahore.
Whereas the 720 was solely ever meant as a stop-gap earlier than the creation of devoted brief and medium haul machines similar to the 727 and 737, the sort was the first jet at many airports and over half of its buyer airways, and went on to serve a whole lot of airways and tens of millions of passengers for over half a century – a exceptional achievement for the child of the 707 household.
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