How far we have come from the Montgolfier balloon flights of 18th century France to today. How much farther will we go in the 21st century? In Part 7 of our look at transportation we will look at the evolution of flight technologies not including space.
When we started talking about transportation we briefly introduced how humans made the initial breakthrough to conquer the air in the 20th century using heavier-than-air technology. The 21st century will feature a wide range of technologies for air passenger travel and transport. These technologies will include alternatives to the airplane to address energy conservation and the need to reduce carbon emissions. One of these technologies, the airship, is the subject of this blog.
Airships: What Are They and Where Are They Today?
In North America at every major sporting event we see a descendant of airships hovering over the venue giving us a bird’s eye view of the playing field. These lighter-than-air blimps, as they are called, are powered balloons. They are not airships in the true sense because they contain none of the rigid framework that characterizes that technology. To understand the difference between blimps and airships, let’s look at the history.
For a period in the 20th century Germany and Great Britain turned to airships to cross the Atlantic Ocean. This was before passenger airplane technology had the capability to make a non-stop flight across several thousand kilometers of open ocean. What were these airships?
They were aluminum alloy frameworks covered by a weatherproof cloth with vertical and horizontal fins attached at the tail. Vertical fins acted as rudders. Horizontal fins allowed the airship to climb or descend. Internally airships contained impermeable bladders called gas cells. These were filled with lighter than air gases, either hydrogen or helium. Crew and passengers were accommodated either within the structure or in a suspended cabin attached to the bottom of the frame. Internal combustion engines turned rear-facing propellers that pushed airships at speeds of 130 kilometers (80 miles) per hour.
The name most associated with airships, Zeppelin, appeared in 1900 with the launch of a series of airships in Germany. Count Ferdinand von Zeppelin perfected the airship and during World War I manufactured a fleet of them for the German military to use in bombing raids over Great Britain. Zeppelins, as they were called, proved to be impractical weapons of war because they provided British flyers and antiaircraft batteries with enormous, slow-moving targets.
After the war the Zeppelin and other commercial manufacturers found a peaceful purpose for their airships, offering passenger service between major European and North American cities. The Graf Zeppelin, an airship built in 1928, flew around the world in 1929. In 1936, the Hindenburg, the largest airship of its time, began a regular transatlantic passenger service between Germany and New York City.
The cause of the Hindenburg disasterremains unknown but the use of hydrogen gas made fire inevitable as a consequence of whatever accident occurred at Lakehurst, New Jersey on May 6, 1937. Germany lacked helium. The United States was the world’s largest producer at the time and restricted export to what was then Nazi Germany. The combustible nature of hydrogen gas made the airship particularly vulnerable to almost any accident that could cause a spark. Whether it was a snapped cable, or static electricity, the hydrogen gas in the Hindenburg ignited and the craft crashed to the ground killing and injuring dozens of passengers and onlookers. The Hindenburg’s demise sounded the end of passenger airships although the Graf Zeppelin continued to fly until 1940 just after the outbreak of World War II.
Blimps survived the demise of airships, largely serving as flying billboards, or sky-mounted camera platforms. Unlike airships blimps lack the structured aluminium framework. Instead the engine, fins and crew cabin are attached to the blimp’s outer skin which remains rigid because of the helium gas contained within it. Goodyear is the brand most associated with blimps. But the technology that Goodyear is using today may soon be replaced by new designs that incorporate new materials and engine capability.
One of the pioneers in delivering this new type of airship is Aeros, operating out of Montebello, California. The Aeroscraft is a rigid variable buoyancy airship with vertical takeoff and landing capabilities. Unlike blimps and airships of old, Aeros technology uses dynamic buoyancy management and not water ballast to keep afloat and on an even keel. More aerodynamic in shape than traditional blimps and airships, the Aeroscraft contains helium cells that hold up to 400,000 cubic meters (14 million cubic feet) of the gas, negating 65% of the aircraft’s weight. The forward and aft fins, called canards and empennages respectively, create additional lift.
Almost 2oo meters in length and as tall as a 14-storey building, Aeroscraft has a cruising range of close to 10,000 kilometers (6,000 miles) and a top speed of 280 kilometers (174 miles) per hour. Aeroscraft can be used as a flying hotel, or as a payload carrier capable of delivering materials to remote areas inaccessible because of terrain or lack of roads. Aeroscraft requires no ballast and can handle payloads of up to 400 tons or 250 passengers in a hotel-like cruise ship setting.
Pelican is a Pentagon funded smaller airship being built by Aeros to deliver payloads of 60 tons to remote locations. Like its larger cousin, Aeroscraft, Pelican uses a rigid-aeroshell,variable-buoyancy from pressure-stored helium, an impermeable helium cell, and a load-bearing internal frame made of carbon-fiber. The Pentagon sees it as a quick deployment, strategic aircraft for delivering soldiers or equipment to staging areas with greater load capacity than helicopters and vertical-take-off and landing capability.
Future Uses of Airship Technology
Aeroscraft and its successors may find themselves being used for a variety of applications as this technology matures. Here are just a few that take us past the flying billboards of present day:
- Telecommunications - Deployed at high altitude (up to 20 kilometers or 12 miles), airships in the stratosphere can be ideal platforms for broadcast and other communication services. At this altitude an area 400 kilometers (240 miles) in diameter could easily be served. And airships would be much cheaper to service and maintain than satellite technology.
- Tourism – Today’s airships are capable of taking small groups on scenic tours, usually not much more than a dozen. The Aeroscraft floating hotel concept is designed to make it possible for up to 250 people to fly in style.
- Military Surveillance and Scientific Missions – For military surveillance an airship operating in the stratosphere would be able to provide higher resolution imagery than satellites over a large area continuously. Unlike drone or manned aircraft the airship could remain stationary. Similarly this surveillance capability would be highly useful for scientific observation as well as upper atmosphere experiments and studies.