In part one we covered the genesis of the 737 and its troubled early years where at times it seemed as if the 737 was hanging on by its fingernails in a tough market dominated by its competition. However, Boeing persisted with the 737 and through the 1970s it slowly but surely clawed its way back from the edge and established itself as a credible contender on the short range jet airliner market.
By the end of the 1970s Boeing was once again very busy with developing the new 757 and 767. These were to be Boeing’s new flagship designs taking the company into the 1980s at the forefront of the market. They were to feature new high bypass ratio turbofan engines, new flight deck technology, advanced aerodynamics, lighter structures and reduced operating costs.
Meanwhile In California
The competition however, were not idle either. Over in Long Beach, California Douglas (by now known as McDonnell Douglas) had launched a major update of their DC-9. The DC-9 had been the 737’s arch-nemesis through the late 1960s and into the 1970s and dominated the short range airliner market, particularly in North America. MDD had come up with what was initially called the DC-9-80, later known as the DC-9 Super 80 and finally the MD-80. They took the largest variant of the DC-9 (the DC-9-50) and stretched it even further, put larger wings on it and the latest model of the JT8D engine, the JT8D-200 which was more powerful, quieter and burned less fuel than the earlier versions of this engine still in use on the 737. The MD-80 launched in 1977 with an order from Swissair, an existing DC-9 operator. It wasn’t long before existing DC-9 operators were queueing up to buy the MD-80.
Boeing realised it needed to respond and would have to modernise the 737 to keep it competitive into the 1980s. Design work began in 1979 and the initial specifications were released at the 1980 Farnborough Airshow. The 737-300 as it was designated was to be a major upgrade to the 737-200. The fuselage was stretched to accommodate a maximum of 149 passengers (versus a maximum of 130 in the 737-200). The wings received some aerodynamic refinements, the flight deck was updated with an EFIS (Electronic Flight Information System) suite and the passenger cabin was updated with features taken from the new 757. Most importantly of all the JT8D engines were replaced with new CFM56 high bypass ratio turbofans.
If It Doesn’t Fit…. Squash It
The CFM56 was a new engine developed by the CFM International consortium which was a 50:50 venture between the US General Electric and French SNECMA engine manufacturers. The CFM56 itself was based on the core of the General Electric F101 which powers the US Air Force’s B-1 Lancer strategic bomber. The CFM56-3 variant used on the 737-300 produced 22,000lbf thrust. By comparison the JT8D variants which powered the 737-200ADV produced between 15,500lbf-16,400lbf. Not only did the CFM56 deliver significantly more thrust, it burned 25% less fuel.
But wait! There’s more! The CFM56 was also far quieter than the gloriously loud JT8D – a very important consideration for forward thinking airlines in the face of pending noise regulations at major airports.
Does this sound too good to be true? Well it was. There was a problem. If you remember in part one we talked about how the 737 was deliberately designed with a low ground clearance to facilitate easy servicing. The low bypass ratio JT8D was long and slender and suited the low ground clearance very well. The new CFM56 was a high bypass ratio turbofan, much shorter and with a greater diameter than the JT8D. It didn’t fit under the wing of the 737.
Some head scratching took place. Extending the landing gear wouldn’t be practical and would require an extensive redesign of the aircraft. Eventually a solution was found. Boeing didn’t put the CFM56 under the 737’s wing. They put it in front of the wing. That wasn’t quite enough, so CFM relocated the engine accessory drive gearbox from the bottom of the engine to the side. This gave the necessary ground clearance and resulted in the 737 Classic’s distinct “squashed” engine profile.
In 1981 Boeing received launch orders from Southwest Airlines and US Air. Both customers ordered 10 aircraft with an option for a further 20 each. The “options” are where a customer can reserve slots on the production line which will be held for them until a given date. If the options aren’t taken up by that date the slots are made available to other customers.
First flight of the 737-300 was on 24th February 1984 and the first revenue flight was on 28th November that year with US Air. The 737-300 could carry a maximum of 149 passengers and had a maximum range of 2,200 nautical miles.
Boeing had a winner.
In 1985 Boeing launched the 737-400. The fuselage was stretched a further 10ft to accommodate a maximum of 188 passengers, the engine thrust was increased to 23,500lbf and the wing spar was strengthened. This new model was intended to compete directly with the MD-80 and the new Airbus A320 then under development. The launch customer for this model was Piedmont Airlines with an order for 25 aircraft.
First flight took place on 19th February 1988 and first revenue flight with Piedmont Airlines was on 15th September 1988. The 747-400 was good for a maximum of 188 passengers and a maximum range of 2,000 nautical miles.
Following customer demand in 1987 Boeing launched the third and final model of the Classic family, the 737-500. This was a shortened version of the 737-300 and was only 1ft 7in longer than a 737-200. It had a maximum passenger capacity of 132. The 500 was intended for airlines looking for a direct replacement for their existing 737-200 fleet or for airlines looking to fly long and thin routes which would be uneconomical for a 737-300. The launch customer for this variant was Southwest Airlines with an order for 20 aircraft.
First flight of the 737-500 was on 30th June 1989 and first aircraft delivery to Southwest was on February 28th 1990. This smallest member of the Classic family could carry 132 passengers and had a maximum range of 2,375 nautical miles.
The final Classic to be delivered was a 737-400 to CSA Czech Airlines on 25th February 2000. The final tally for the Classic broken down by type:
- 737-300: 1,113
- 737-400: 486
- 737-500: 389
So that’s 1,988 aircraft over a 16 year production run. To put that in perspective the earlier 737 Original family had a 20 year production run which delivered 1,144 aircraft.
Cue Ominous Music
However, it’ wasn’t all unicorns with rainbows coming out of their bums. In 1988 the Airbus A320 entered service. A clean sheet design with state of the art features it was superior to the 737 Classic in many important metrics. It was a new aircraft on the market from a smaller manufacturer than either Boeing or McDonnell Douglas and as such it had a relatively slow start. Then in 1992 the unthinkable happened. Hitherto huge and loyal Boeing customer, United Airlines, announced its intention to lease 50 A320 from Airbus with an option for another 50.
There was a new kid in town.
In part three we’ll take a look at Boeing’s response to the A320 gate crashing the 737’s party and what kind of 737 Mr Boeing can deliver for you today.
© Æthelberht 2018