This document is presented to compare the two commercially successful and super-efficient airplanes, the Boeing 707-320B and Boeing 787-9. This document will identify the key innovations in airframe and propulsion technology, and also further discuss on why the basic design and appearance of aircraft remain unchanged over 50years.
| |Boeing 707-320B |Boeing 787-9 | |Wingspan |44.42 m |60 m | |Length |46.6 m |63 m | |Gross Weight |152400 kg |251900 kg | |Cruising Speed |977 km/h |1041 km/h | |Range |9913 km |14800 – 15750 km | |Service Ceiling |10973 m |13100 m | |Power |4 x JT3D Turbofans (Pratt & Whitney) |2 x Trent 1000 (Rolls Royce)/ General Electric | | |Each producing 80kN thrust |Each producing 330 kN thrust | |Passenger Cabin |Mixed class :141 |Mixed class: 250 | | |Economy class : 189 |Economy class:290 |
Innovations in Airframe
Throughout the years since aircraft was created, engineers are constantly improving the efficiencies, durability and speed of its Airframe. From the beginning of 1920s, the all aluminium structures to the high-strength alloys and high-speed airfoils in the beginning of the 1940s. However as flying becomes more commercialised, people were not satisfied with just travelling at higher speed; they want to travel a longer distance with lesser fuel burnt! Hence, by the beginning of 1960s and 1980s, long-range design air frames and light weight composite researches were developed respectively.
The materials used to construct airframe ideally require light, durable characteristics and at the possible lowest cost. The Boeing 707-320b airframe is constructed mainly using aluminium. The properties of having high tensile strength, light in weight, easily alloyed with other various metals, make aluminium very favourable in meeting the requirements of the aircraft construction.
Many suggested that they would much rather fly a metal plane then a plastic one. However, as for Boeing 787-9, it is made up as much as 50% of composite material, approximately 32000 kg of carbon fiber reinforced plastic made from 23 tons for carbon fibre. These composites used to construct the B787 is not like any common plastic, it is stronger, lighter and offers greater strength to weight ratio than anything else. The boldly introduced airframe construction weighs 20% lighter than the conventional aluminium designs. This approach allows the airplane to carry more payloads and fly a further distance. In addition to the overall weight saving, moving to a composite primary structure also promises to increase resistant to fatigue and corrosion, reducing both the scheduled and non-routine maintenance burden on airlines.