Historically, airships have endured awe-inspiring success due to their sheer size, but also spectacular failure such as with the infamous Hindenburg crash. Throughout history, there have been dramatic and disruptive airplane innovations, which have altered the course of events. We are in the midst of the next major revolution with the advent of the drones. In recent years, interest in airships has slowly seen a comeback with modern uses in tourism, surveillance, freight, and military operations.
Transformational Airplane Designs
The desire to fly has enthralled humankind for centuries. As far back as 1700 BC, legend indicates that Daedalus prepared two pairs of wings and along with his son, Icarus, launched over the sea. While Icarus crashed to his death from having flown too close to the sun, Daedalus did survive. Although there were myriads of attempts at flight, it was not until the 18th century that saw considerable progress in flight. Advances in aerial navigation, basic aerodynamics, and aeronautical principles led to the development of the glider and the first manned flight. The 18th century also saw development of the ballonet: an elliptical vehicle capable of flight against the wind.
Lighter than air (LTA) vehicles, also known as airships or dirigibles were derived from balloons and evolved by trial and error. There are gas filled, tethered, untethered, and novel vehicles that advanced in development as new materials and technologies became available. The first dirigible was flown by Henri Giffard in 1852 from Paris to Trappe. The dirigible was steam engine powered and achieved speeds of 6.7mph. This was followed by a gas engine powered dirigible in 1872, metal dirigible powered by a Daimler engine in 1897 and the first zeppelin flew in 1900, achieving speeds of 18mph.
By 1909, pleasure flights were offered in the Zeppelin followed by commercial flights the following year. By 1914, almost 34,000 passengers were carried. With the advent of war, Zeppelins were used for air raids provoking a wave of international outrage at his act of German barbarism. The success of the Zeppelin led to the building of a fleet of airships. Hydrogen was used in these lighter than airships (LTA). The two lifting gases typically used were Hydrogen and Helium. Hydrogen was lighter, provide more lift and was cheaper, but was highly flammable. Helium was a commodity during the war, since US had monopoly on helium supply in the world and were the sole users of helium in airships.
In 1930, the fatal crash of LZ-128 due to a hydrogen fire resulted in the death of all passengers and pilot. The consequence of this event, led to the development of LZ-129 also known as the Hindenberg. Regular transatlantic service began in 1936. The Hindenberg crashed at Lakehurst, New Jersey killing all aboard on its first North American flight in 1937. Pan American Airways started scheduled flights across the Pacific. The Hindenberg was obsolete even before it flew, marking the end of the airship era.
After the first successful powered flight by the Wright Brothers in 1903, rapid progress occurred in aircraft design spurred especially by the two World Wars where dominance in air afforded the most success. Before the end of the 20th century, man had flown higher than the birds that he so eyed wistfully before flight had become a reality. The first men had landed on the moon, walked in space and unmanned exploration of the galaxy and beyond advanced quickly leading to improved technologies to support these efforts that also benefited other uses that were more firmly rooted on Earth.
The first pilotless, steam powered aerodromes designed by Samuel Langley flew in 1986 along the Potomac River and were used for aerial reconnaissance in the Spanish-American wars. During the World Wars, they were used extensively for reconnaissance. The first unmanned aerial vehicle (UAV) flew a merely decade after the first successful Wright Brothers flight.
In 1917, Elmer Sperry and Peter Hewitt, constructed a radio controlled automatic airplane called the “Hewitt-Sperry Automatic Airplane” that could fly 50 miles and carry a 300lb bomb. The success of the “flying bomb”, led to the rail launched Kettering Aerial Torpedo “Bug”. Through the 1920s and 1930s, progress continued in the remotely controlled ships. The “Pilotless Aircraft Branch” of the US Air Force was established in 1946 and three types of drones were developed with air launched Q-2, the most important one that became the “father” target drones. Following the success of pilotless and remotely piloted technologies, the US Air Force began experiments in the 1950s for high altitude reconnaissance.
The remotely piloted or unmanned aircraft systems (RPAS/UAS) can have varying levels of automation and autonomy. The many applications that these vehicles can be used for include security, monitoring, emergency response, surveillance and recreation. The evolution and revolution of new technologies and advancement in automation have transformed the drone into a domesticated item that now is used recreationally by millions of people and the list of commercial uses continues to grow.
The Rebirth of the Dirigible
Interest in airships has rejuvenated as transportation needs to remote and distance areas arose in recent years. Previously these remote areas that are not easily accessible by roads such as in Canada and the Artic were serviced by airfreight, sea shipments, and ice roads. The impact of global warming has the continued use of these ice roads unreliable. Lockheed Martin has been under a contract to build heavier than air airships that can carry up to 20 tons of cargo to serve these areas. There is also a growing interest to using airships in congested overly populated areas to relieve rush hour traffic nightmares.
There is mixed opinion on the economic practicality of these especially concerning with passenger and freight operations; however, advances in technology and innovation supports viability in the modern use of the dirigibles. They have excellent range performance and low cost. In recent years, research continues on the modern application of LTA designs for tourism, surveillance, border patrol, freight and lifting operations, and special military operations.
Dirigibles can be classified by hull such as rigid, semi-rigid and non-rigid; by payload capability such as heavy-lift or medium lift; and by vertical force such as heavier than air or lighter than air and hybrid. In addition, there are several unconventional airships:
- Spherical airships that achieve trade-off between maximum lift and minimum air resistance and prove excellent for mooring as shown in Figure 4. Prototypes of Spherical airships have been built by 21st Century Airships Inc., a Canadian company.
- Lenticular airships that are shaped like wings and helpful for maneuver control and make it possible to compensate for accidental overloading. Prototypes of this type of airships were created by French LTA Corporation
- Double-hull and multiple hull designs used for hybrid vehicles and achieve a reduction in in length for a given volume of gas providing increased lift and load capability. Advanced Technologies Group Ltd., a British company has built the double hull design
- Winged airship designs derived from airplane design, and exploits the aerodynamic lift generation capability and provides natural stability. The whale shaped airship, Manned Cloud, is shown in Figure 7. Proposed by French designer, its purpose is to serve as a luxury fitness, spa and restaurant.
Through application of new materials, technologies and techniques, modern airships can be designed that are safe, stable and reliable and humankind’s fascination with airship design continues to grow and evolve. There are also innumerable drone designs based on their mission and purpose from small quadrotors to the large Global Hawk and Predator drones.
From Dirigibles to Drones: A marriage made in heaven
In 2013 Jeff Bezos, Amazon’s CEO, announced that they would start testing drones for utilization in package deliver. More recently, Amazon has filed a patent with the US Patent Office for a giant flying warehouses or Airborne Fulfillment Centers, which would house merchandise, warehouse workers and drone launching platforms that would be used to launch drones to make deliveries. The airship will hover over the intended delivery area at an altitude of 45,000 ft. Winged drones with little or no power would glide down to the delivery site to deliver the package. After delivery, they would be collected at the collection zone and shuttled back to the airborne fulfillment center.
Two centuries later, humankind continues to remain fascinated with the dirigible. In recent years, drones have revolutionized and captured our attention to the same if not higher level. In addition, I suspect they will continue to excite and fascinate us in the future. In combining these two revolutionary and transformational technologies, it seems Bezos has proposed a marriage made in heaven at 45,000 ft.