1.4 Future Trends |
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Figure 1.9. Airbus 380
have been incorporated, improving the B737’s economic performance by about 50%.
The largest commercial jet transport aircraft, the Airbus 380 (Figure 1.9) made its first flight on April 27, 2005, and is currently in service. The heretofore unchallenged and successful Boeing 747, the largest commercial transport aircraft in operation today, now has a competitor.
The gas turbine turboprop offers better fuel economy than to current turbofan engines. However, because of propeller limitations, the turboprop-powered aircraft’s cruise speed is limited to about two thirds of the high-speed subsonic turbofan-powered aircraft. For lower operational ranges (e.g., less than 1,000 nautical miles [nm], the difference in sortie time would be on the order of less than a half hour, yet there is an approximate 20% saving in fuel cost. If a long-range time delay can be tolerated (e.g., for cargo or military heavy-lift logistics), then large turboprop aircraft operating over longer ranges become meaningful. Figure 1.10 shows an Antanov A70 turboprop aircraft.
1.3.3 Current Military Aircraft Design Trends
This extended section of the book can be found on the Web at www.cambridge
.org/Kundu and gives a brief overview of today’s military aircraft design trends, covering typical cost frame, operational roles, and design challenges. Figure 1.10 shows the Antanov A70. Figure 1.11 shows (a) F117 Nighthawk, (b) F22 Raptor, and B2 Bomber.
Figure 1.10. Antanov A70
Figure 1.11. Current combat aircraft
1.4 Future Trends
One does not have to be a prophet to predict near-future trends in the next two to three decades – the same time-frame during which younger readers will begin their career and prepare for the challenges required. It is clear that the vehicle-capability boundaries will be pushed to the extent permitted by economic and defense factors and infrastructure requirements (e.g., navigation, ground handling, and support, etc.). It is no exception from past trends that speed, altitude, and payload will be expanded in both civil and military capabilities. Reference [7] provides coverage on the aircraft-design process in the next few decades. In technology, smart
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Introduction |
Figure 1.12. Supersonic transport aircraft
material (e.g., adaptive structure) will gain ground, microprocessor-based systems will advance to reduce weight and improve functionality, and manufacturing methodology will become digital. However, unless the price of fuel increases beyond affordability, investment in aerodynamic improvement will be next in priority.
Readers are advised to search various Web sites for information on this topic.
1.4.1 Civil Aircraft Design: Future Trends
The speed–altitude extension will progress initially through supersonic transport (SST) and then hypersonic transport (HST) vehicles. The SST technology is well proven by three decades of the Anglo-French–designed Concorde, which operated above Mach 2 at a 50,000-ft altitude carrying 128 passengers.
The next-generation SST will have about the same speed–altitude capability (possibly less in speed capability, around Mach 1.8), but the size will vary from as few as 10 business passengers to approximately 300 passengers to cover at least transatlantic and transcontinental operations. Transcontinental operations (Figure 1.12) would demand sonic-shock-strength reduction through aerodynamic gains rather than speed reduction; anything less than Mach 1.6 has less to offer in terms of time savings. The real challenge would be to have HST (Figure 1.13) operating at approximately Mach 6 that would require operational altitudes above 100,000 ft. Speed above Mach 6 offers diminishing returns in time saved because the longest distance necessary is only 12,000 nm (i.e., ≈3 hours of flight time). Military applications for HST vehicles are likely to precede civil applications.
Figure 1.13. Hypersonic aircraft
1.4 Future Trends |
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White Knight carrying Space Ship One |
Space Ship One |
Figure 1.14. Rocket-powered aircraft
Considerable development in power plant technology is required to make either SST or HST commercially viable. Small-scale HST has been flown recently.
A new type of speed–altitude capability will come from suborbital space flight using rocket-powered aircraft, as demonstrated by Rutan’s Space Ship One that hitchhiked with the White Knight to altitude (Figure 1.14), from where it made the ascent. Interest in this aircraft has continued to grow – the prize of $10 million offered could be compared with that of a transatlantic prize followed by commercial success. A larger Space Ship Two is currently being developed.
Any extension of payload capability will remain subsonic for the foreseeable future and will lie in the wake of gains made by higher-speed operational success. High-capacity operations will remain around the size of the Airbus 380. Further size increases will use the benefits of a blended wing body (BWB) because the wingroot thickness would be sufficient to permit merging (Figure 1.15) with the fuselage, thereby benefiting from the fuselage’s contribution to lift (see Section 3.20 for BWB configurational advantages). Another alternative would be that of the joined-wing concept (Figure 1.16). Studies of twin-fuselage, large transport aircraft also have shown potential.
Both operators and manufacturers will be alarmed if the price of fuel continues to rise to a point where the air transportation business finds it difficult to sustain operations. The industry would demand that power plants use alternative fuels such as biofuel, liquid hydrogen (LOH), and possibly nuclear power for large transport aircraft covering long ranges. Aircraft fueled by LOH have been used in experimental flying for some time, and fossil fuel mixed with biofuel is currently being flight-tested.
A new type of vehicle known as a ground-effect vehicle is a strong candidate for carrying a large payload (e.g., twice that of the Boeing 747) and flying close to the
Figure 1.15. Blended wing body aircraft (Airbus)
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Introduction |
Figure 1.16. Joined-wing aircraft (Airbus)
surface, almost exclusively over water (Figure 1.17). (A ground-effect vehicle is not really new: The Russians built a similar vehicle called the “Ekranoplan,” but it did not appear in the free market economy.)
Smaller Bizjets and regional jets will morph, and unfamiliar shapes may appear on the horizon, but small aircraft in personal ownership used for utility and pleasure flying are likely to revolutionize the concept of flying through their popularity, similar to how the automobile sector grew. The revolution will occur in short-field capabilities, as well as vertical takeoffs, and safety issues in both design and operation. Smaller aircraft used for business purposes will see more private ownership to stay independent of the more cumbersome airline operations. There is a good potential for airparks to grow. The NASA, the U.S. Department of Transportation (USDOT), FAA, industry stakeholders, and academia have joined forces to pursue a National General Aviation Roadmap leading to a Small Aircraft Transportation System (SATS). This strategic undertaking has a 25-year goal to bring the next generation of technologies to and improve travel between remote communities and transportation centers in urban areas by utilizing the nation’s 5,400 public-use general-aviation airports (United States). The density of these airfields in Europe is much higher. The major changes would be in system architecture through miniaturization, automation, and safety issues for all types of aircraft.
1.4.2 Military Aircraft Design: Future Trends
This extended section of the book can be found on the Web at www.cambridge
.org/Kundu and gives a brief overview of near-future military-aircraft design trends, covering typical, new, and emerging operational roles (e.g., UAVs and design challenges). Figures 1.18 and 1.19 are associated with the section.
Figure 1.18. JUCAS prototypes (X47B)
Figure 1.19. Future design type
Figure 1.17. Pelican (Boeing)