Ubiquity and Omnipresence
Boeing’s legendary 737 airliner series is so common worldwide that most of us barely take notice when one flies overhead, the truth is that we really should take more notice of it and respect its unique place in aviation.
The 737 is, after all, the world’s most produced and used airliner of any category. By some estimates there are more than 1,000 of the type airborne at any given time and the 737 series represents roughly 25% of all airliners currently in operation.
The 737 has been in production for nearly 50 years and has been built in three distinct generations with a fourth generation set to enter production in 2017. Chances are that if you’ve traveled on shorter airline routes then you’ve likely traveled on a 737.
Let’s start our look at the “Baby Boeing” with a few key events in it’s life to this point in time:
Boeing 737 Milestones
1964: Initial design work on 737 begins.
1965: Lufthansa announced as launch customer.
1967: First flight of 737-100 version.
1967: First flight of 737-200 version.
1967: First 737-100 delivered to Lufthansa.
1968: United Airlines becomes first user of the 737-200.
1973: First T-43, military version of 737-200, delivered to USAF.
1984: First flight of 737-300, the first major revision to the 737.
1988: First flight of 737-400 version.
1988: Last 737-200 delivered.
1989: First flight of 737-500 variant.
1993: Second major revision, the “Next Generation” series, announced.
1997: First flight of 737-700 model.
1997: 737-800 makes its first flight.
1998: First flight of 737-600 version.
1998: Boeing Business Jet, BBJ, version makes maiden flight.
2000: 737 becomes first airliner in history to achieve 100 million flight hours.
2001: C-40 Clipper, military version of 737-700, enters service.
2004: 737 “Wedgetail” Airborne Early Warning version first flown.
2006: 5,000th 737 built and delivered.
2009: Maiden flight of 737-800 based maritime patrol aircraft, P-8 Poseidon.
2011: Third major revision, 737 MAX series, announced.
2013: P-8 Poseidon enters service with US and Indian navies.
2016: First flight of 737 MAX.
Boeing Plays Catch Up
It’s perhaps difficult to believe that with as prolific and successful as the 737 has been in its life, Boeing really was a bit late to the party with it.
The market for short haul, narrow body airliners was becoming increasingly lucrative in the early to mid 1960s and by the time Boeing began planning the 737 in 1964 the aircraft’s initial rivals for the market; the British Aircraft Corporation 1-11 and the Douglas DC-9 were well underway. The BAC 1-11 had its maiden flight prior to 1964 and the DC-9 flew for the first time in 1965.
To make up lost time, Boeing used the same fuselage for the 737 as they had for the 707 and 727 before it. As this common fuselage cross section was somewhat wider than those of its counterparts, the 737 could carry more passengers than either the BAC 1-11 or DC-9. Boeing further increased the aircraft’s passenger capacity by placing the engines under the wings rather than on either side of the rear fuselage as was done with the BAC and Douglas designs.
The Originals: 737-100 and 200 series
Distinctive in appearance by their stubby fuselage and long, narrow engine pods; the initial series of the 737 family very quickly established the aircraft’s reputation for ease of service, versatility, self-sufficiency and ability to operate from remote locations with rudimentary facilities.
When fitted with a system known as a gravel kit, the 737 could operate from semi prepared runways in Canada’s north as well as other spartan regions around the world. The gravel kit consisted primarily of a deflector device fitted around the nose landing gear and a metal pipe attached to the lower lip of each engine intake, air was blown downwards towards the runway through these pipes and prevented debris from being ingested by the engines while the aircraft was taxiing and taking off. This adaptation allowed the 737 to operate in areas that its competitors often could not.
While the -100 saw only modest production, the -200 was the first major variant of the family with over 1,000 built in total. While production of the -200 is long since finished, modifications to the remaining airworthy examples are still being produced and made available. Many of these modifications concern noise reduction and fuel efficiency issues.
The Classics: 737-300, -400 and -500
Before the 1970s were out, Boeing was already examining ways to improve upon the great success of the 737-200 and keep demand high for the 737 family of aircraft.
The driving forces which led to the new generation of the aircraft were increased fuel efficiency, passenger carrying capacity and engine noise reduction. In the face of addressing these issues, Boeing also aimed for a significant degree of parts commonality between the 737-200 and the new generation variants.
To tackle the matters of fuel efficiency and noise reduction, a new engine was required. The General Electric CFM-56 turbofan was selected as the new engine, though incorporating it into the 737 required an adjustment in the position of the engines’ accessory devices to compensate for the 737’s low ground clearance.
The re-positioning of the engine accessory packages from directly under the engines to a spot on the side of them gave the required clearance between the engines and the ground; however, it also created distinctively shaped engine pods which were wider at the bottom and gave raise to the term “Hamster pouch” as a nickname for them when viewed directly from the front.
Fuel efficiency and general flight performance were also improved by refinements in the aerodynamics at various locations around the fuselage, wings and tail. Some aircraft of this generation were retrofitted with winglets on their wingtips to further increase fuel efficiency by reducing drag.
The Next Generation: 737-600, -700, -800 and -900
The same forces which inspired the creation of the “Classic” series of the 737 family through the 1980s were again at play to inspire the development of the “Next Generation” or 737NG series in the 1990s.
An additional catalyst for the new developments was the Airbus A319 and A320 series of airliners from Europe. The A319 and A320 brought a great deal of new technology to the short haul sector which the 737 had become the dominant force in and Boeing would need to modernize it in order to stay competitive.
The 737NG received redesigned engine pods which further increased fuel efficiency and reduced noise. Several drag reducing refinements were also applied to the wings for fuel savings and performance increases.
With the 737-800, a significant increase in size was instituted in order for the aircraft to not only compete more directly with the A320 in passenger capacity, but also to replace Boeing’s own 727 narrow body liner in many airline fleets.
Outside of commercial interests, the 737NG has found users in the corporate and military sectors as well.
Based on a combination of the -700’s fuselage and the -800’s wings; the Boeing Business Jet, or BBJ, has found clients in the military as well as the corporate sector it was initially aimed at. In US military service, the BBJ is known as the C-40 Clipper.
The 737-700 serves as the basis for the E-7 Wedgetail airborne early warning aircraft which entered service in 2009 with the Royal Australian Air Force and has since been taken on charge by the Turkish and South Korean air forces as well.
Developed from the 737-800, the P-8 Poseidon maritime patrol aircraft entered service with the US and Indian navies in late 2013.
The 737’s Future and Useful Links
As it stands, the 737 family would certainly seem to have another 50 years of practical service guaranteed to it across commercial, corporate and military sectors.
In 2011, Boeing announced the 737 MAX series as the forthcoming new generation to the aircraft family. The MAX series is planned not only to compete with the upcoming Airbus A320neo variant, but also supplement Boeing’s own 787 Dreamliner long haul liner.
As of December 2013, Boeing had nearly 2,000 firm orders for 737 MAX aircraft and the first of them are expected to enter production in 2017. The MAX version flew for the first time in January of 2016.
This is a link to the History page of a quite thorough site about the 737, History on all the variants plus much, much more can be found here: