Airships, also called dirigibles, served as an alternative to transoceanic travel by boat in the early 1900s. However, the future of dirigibles as transportation vehicles ended when the Hindenburg, a giant hydrogen-filled dirigible, burst into flames over Lakehurst, N.J., in 1937. Once airplanes were recognized as safe for passenger travel, few saw a need for commercial airships.
Most airships you see today are used as flying billboards, like the Goodyear or Fuji blimps you see hovering above major sporting events. But airships may soon provide more than advertising. One German company is bringing back the mammoth dirigibles of the early 20th century to fill a niche in the transportation industry. CargoLifter AG is investing in the idea that dirigibles have an advantage over other forms of transportation. The company says that its giant CL 160 airship can reach areas that are too difficult to reach by train, truck or current cargo ships. And they can haul more cargo than even the biggest heavy-cargo-transport military airplanes.
In this edition of How Stuff Will Work, you will learn how these new airships differ from their predecessors, how they will work and just why we will need these giant transport vehicles.
The CL 160 Structure
It seems only appropriate that a company located just a few miles south of Berlin would be responsible for breathing new life into the airship. After all, it was German Count Ferdinand von Zeppelin who first flew a dirigible in 1900, which is how airships came to be called "zeppelins." CargoLifter's CL 160 airship design harkens back to the time of those early zeppelins; but the company has incorporated some exciting new technology.
The overall size of the CL 160 is overwhelming. Nearly three football fields in length, it can easily swallow four of Goodyear's largest blimps. The airship is 853 feet (260 meters) long and has a maximum diameter of 213 feet (65 m). While the Hindenburg was filled with hydrogen, which is flammable, the CL 160 will hold more than 19 million cubic feet (550,000 cubic meters) of non-inflammable helium gas. Here are the basic components of the CL 160:
- Envelope - The envelope, which is the skin of the airship, holds the helium gas. Waterproofed cotton or jute, a strong fiber used to make burlap, was used for the envelopes of early 20th century airships. The material was pulled taut over an aluminum frame. The CL 160's frameless, semi-rigid envelope is made of a proprietary airtight, multi-layered film that resembles a rubberized fabric. The material is about one-sixteenth of an inch thick. This advanced material will reduce the amount of helium lost during flight to almost zero. Photo courtesy CargoLifter AG Nose cone
- Nose Cone - The nose cone is fitted to the front end of the envelope to provide a better aerodynamic shape. It has a diameter of 85 feet (26 m) and is attached to the envelope by nose slats. The nose cone is a complex subsystem on the airship. It provides a connection for the landing mast when the airship is on the ground. Thrusters integrated on the nose cone will allow for side-to-side movement. It also contains rope winches, a monitoring camera, control gears and a communication system for ship-to-ground communication.
- Keel - The keel, made of aluminum, runs the entire underside of the ship. Its function is to transfer, absorb and distribute the payload and all of the installations that are responsible for lifting cargo. Many of the airship's other components are connected to the keel, including the nose cone, two engine wings, the lower side tail unit, loading crane equipment, crew space, four main engines, 12 maneuvering engines and the electrical and mechanical systems. The keel is about 820 feet (250 m) long, 49 feet (15 m) wide and 33 feet (10 m) high.
- Tail Unit - The tail unit's function is to maintain stability and maneuverability, making sure the ship stays on course. It is comprised of four steering fins, each of which contain a rudder. The tail unit is 243 feet (74 m) wide, and each fin is 138 feet (42 m) long and 72 feet (22 m) high.
- Engines - The CL 160 will be propelled by 16 turbine engines. The CL 160 will be able to travel at an average cruising speed of 56 mph (90 km/h), and can cross about 6,200 miles (10,000 km) before refueling its engines.
CargoLifter hopes to have its first airship finished by 2002, with a multi-ship fleet circling the globe two years later. The company plans to build about four airships per year beginning in 2004. The ships will be manufactured in Brand, Germany. In October, the company announced that it will build a second plant in New Bern, N.C., which will be completed by 2005.
In November 2000, CargoLifter completed the hangar that will house the CL 160 airship. As you can imagine, the hangar has to be enormous to house such an airship. The hangar in Brand, Germany, is one of the largest self-supporting hangars in the world. It is about 1,200 feet (360 m) long, 700 feet (210 m) wide and 350 feet (107 m) tall.
Here are some interesting facts about the hangar:
- Nearly 1.4 million cubic feet (40,000 cubic meters) of concrete were used to secure the foundations for the over-arching steel girders that make up the hangar's frame.
- 14,000 tons of steel were used for the arch construction.
- A three-layer polyester-fiber membrane is stretched between each of the five steel arches.
- Each side has a shell-shaped door that can open up to 660 feet (200 m) wide.
- The hangar holds 194 million cubic feet (5.5 million cubic meters) of space.
- It is large enough to completely enclose the Louisiana Superdome, one of the largest indoor stadiums in the United States.
CargoLifter says the CL 160 isn't designed to take the place of other cargo transport vehicles, such as trucks, trains or airplanes. Instead, the airship will supplement those conventional means when it is necessary to get large cargo to hard-to-reach locations. The airship is equipped with a loading frame that can carry up to 160 tons (352,000 pounds / 160,000 kg).
The airship's loading frame is attached to the keel. During the loading phase, the airship hovers about 328 feet (100 m) in the air while the loading frame is lowered to the ground using winches installed in the keel. To keep the airship stable during loading, four guide cables are lowered to the ground and anchored to pylons.
Unloading is a little trickier. The airship is carrying a very heavy load, so if it lowers the cargo to the ground and the cargo is simply removed from the loading platform, the airship would soar into the sky due to the sudden decrease in weight. To maintain stability, the airship is equipped with a system that will pump in water to compensate for the weight of the unloaded cargo. Also, the payload is not lowered all the way to the ground. It is lowered by the winches to about 130 feet (40 m) above the ground. Cables attached to the loading platform are lowered to the ground and anchored to stabilize the loading platform. The cargo is then lowered the remaining 130 feet by cable. The entire unloading process will take about two hours.
For more information on airships, check out the links at the end of this article.