Airplanes have undergone huge transformations since the invention of air transport. In various ways, planes have been modified to cater for the rising needs of users and to address challenges experienced in the use of past models. As technological advancement is realized, greater lift to drag ratios, load ratios and velocities are expected to be characteristics of commercial airplanes. Moreover, passengers using commercial airplanes are also more likely to go for the faster planes to be sure that longer distances would be covered in relatively short durations. The overall range of planes also contributes a lot to attractiveness in the commercial industry. For instance, it is more likely for a plane characterized by all the amenities to attract more passengers than a normal, load and passenger only plane.
Through the years, airplane manufacturing companies have carried out a lot of research on the different designs that optimize utilization and also provide the best characteristics for the airplanes in the air transport industry. The aerodynamic design of the planes impacts many of the major characteristics of airplane performance during flight. Although many changes have been realized in the aerodynamic design of airplanes, the structure of the wings is one of the factors that are persistently pursued to enhance effectiveness. Through transformation from the medium sized wings to more open and large wings, plane manufacturers realized the unutilized potential in the plane design process. The modification of the wing shape is one of the major changes that have been made and retained in the commercial sector. Presently, most of the commercial and military planes use a swept wing design, whose main advantage is that it reduces the draft and also prevents shock formation during delays.
Martinez-val et al, (1-3) assert that the swept wing design which is presently used for commercial and military airplanes with minimum modifications is based on the medium sized flight wings technology, which is considered technically and operationally feasible and efficient. Such wing designs enhance the operational field of the planes while also improving the cruise performance. Large passenger planes such as the many Boeing models which are utilized in the contemporary times rely on the swept wing model. This model, contrary to the conventional perpendicular wing structure that was previously in use for both commercial and inside use planes, enhances aerodynamic performance through reduction of induced drag and delay of drag rise (Kulfan 3). The swept wing structure provides various advantages when compared to the past design used in the wings. However, it also has one major disadvantage with regards to performance sustainability.
Advantages of the Swept Wing Design
From its inception in the 1950s, the swept wing design has remained in use not only for commercial airplanes but also for the military planes which undergo constant development, especially in terms of velocity advancement and comfort availability. The resilience of the swept wing design amidst constant technological advancements is an accurate indication of the advantages of such design. The major rationale for the development of this wing design was that it helped in delaying or avoiding shock formation during flight progress. This is particularly based on the fact that the design helped to curb the impacts of excessive drag that was experienced with the perpendicular wing design (Anderson 423).
According to Anderson (423-424), the swept wing design helped to move the wing span of commercial airplanes and others into more convenient positions with regards to interactions with the air during flight. The angle of sweep for the swept wing aircrafts ranges from 0 to 45 degrees depending on the actual body design of the aircraft. Initially, production of a swept wing aircraft would involve segregated production of different parts of the plane and eventual assembly into the whole. The swept wing can angle either backwards or forwards depending on the intended speed and the desired ratio aircraft speed to the speed of sound (Kulfan 4). Most of the commercial airplanes that are based on the swept wing design have allocated mach numbers of between 0.7 and 0.88. This implies that they fly at near sonic speed and thus have the capacity to go through longer ranges within short durations.
The swept wing design reduces the impact of drag through delaying air compressibility at near the sonic speeds. Air compressibility is a common phenomenon in airplanes operating on straight wing designs, whereby the increased pressure of air on the wings at high altitudes and high velocities results in greater drag on the airplane wings (Anderson 424). The swept wing design controls this through exposure of limited area to the oncoming air pressure during flight. The wind direction in the swept wing design is categorized as a parallel vector and a perpendicular vector (Kaulfan 6). The parallel vector is considered to be of zero magnitude in terms of the resultant drag. On the other hand, the perpendicular vector’s magnitude is also limited due to the angling property of the airplane wings.
While the aerodynamic design of the plane enables it to reduce the effects of drag on the flight progress, the key challenge faced in such design is on the aspect of lift. The lift to drag ratio in any plane should be as high as possible to enable the plane build momentum and thereafter achieve high altitudes as required during the flight. With the swept wing design however, the produced lift has to be directly proportional to the speed of the wind that passes above the wings hence making it difficult for the ratio to rise further than a certain maximum value. With such kind of challenges, it is clear that accomplishing the optimum speed during landing and take-off can be a key difficulty for the swept wing airplane designs (Anderson 424).
As in the other plane designs, the swept wing design can undergo on-flight upsets caused by different factors. The vulnerability to upset is however low based on the expectations from the same. Carbough and others (par. 5-6) provide an overview of potential causes and outcomes of upsets during various flight modes. According to Carbough and others (par. 4), an airplane operating based on the swept wing design could be upset due to high pitch altitudes, particularly when the nose dip is greater than 10 degrees or the angle of banking is greater than 45 degrees. In each case, such flight modes indicate lack of consideration of the aerodynamic characteristics and capabilities of the plane. Moreover, the planes may be upset during flight conducted at speeds other than the recommended at specific altitudes.
Based on the range of possibilities associated with upsets in the swept wing airplane design, various strategies are provided by authors such as Carbough and others (par. 6- 7) for the recovery of plane control during and prior to an impending upset. Such strategies are linked to the aerodynamic fundamentals of the plane, and lack of knowledge thereof can result in disastrous effects on the plane. The findings of Carbough and others (par. 8) indicate that pilots intending to undertake the flight of commercial airplanes, all of which currently have the swept wing design, must be trained on strategies for handling particular upsets including stalls. This may however be challenging as it is difficult to note an impending stall or on-going stall. As such, experience and practice is required for any pilot to be capable of managing flight operations successfully whether the plane design is a swept wing or not.
The swept wing airplane design is the most robust wing design that has been used over the years in the maintenance of aircraft security and control of speed. Through the design, it became possible for aircrafts to control the drag experienced through limiting air compressibility at velocities close to the sonic speed. With the capacity to delay shock formation while at the same time taking advantage of the large wing spans associated with the typically large airplanes used for commercial purposes, the swept wing design has remained one of the major technological advancements that cannot be reversed in terms of aircraft development. Presently, most of the commercial airplanes rely on swept wing designs for optimum performance in terms of velocity and loading. The key disadvantage of this design however, is that it has the potential of reducing efficiency during landing and takeoff operations due to the limitation of lift at such flight conditions. As such, it is expected that airplanes with this design would rise at slower velocities compared to the straight winged designs.
Anderson, John D. Jr. A History of Aerodynamics. New York: McGraw Hill, 1997, pp.423–424
Carbaugh, Dave, et al. “Aerodynamic Principles of Large Airplane Upsets.” The Boeing Company, 2003. www.boeing.com/commercial/aeromagazine/aero_03/textonly/fo01txt.html. Accessed 15 May 2017.
Kulfan, Brenda M. “Aerodynamic of Sonic Flight.” n.d. www.brendakulfan.com/docs/tas3.pdf. Accessed 15 May 2017.
Martinez-val, Rodrigo, et al. “Flying Wings and Emerging Technologies: An Efficient Matching.” 24th International Congress of the Aeronautical Sciences, ICAS 2004.