Mooring mast

A mooring mast, or mooring tower, is a structure designed to allow for the docking of an airship outside of an airship hangar or similar structure. More specifically, a mooring mast is a mast or tower that contains a fitting on its top that allows for the bow of the airship to attach its mooring line to the structure. When it is not necessary or convenient to put an airship into its hangar (or shed) between flights, airships can be moored on the surface of land or water, in the air to one or more wires, or to a mooring mast. After their development mooring masts became the standard approach to mooring airships as considerable manhandling was avoided.

Airship mooring masts can be broadly divided into fixed high masts and fixed or mobile low (or ‘stub’) masts. In the 1920s and 1930s masts were built in many countries. At least two were mounted on ships. Without doubt the tallest mooring mast ever designed was the spire of the Empire State Building which was originally constructed to serve as a mooring mast, although soon after converted for use as a television and radio transmitter tower due to the discovered infeasibility of mooring an airship, for any length of time, to a very tall mast in the middle of an urban area.

Another unique example may be found in Birmingham, Alabama, atop the former Thomas Jefferson Hotel. Now known as Thomas Jefferson Tower, the mast has been recently restored to its original appearance. It was originally erected in 1929 as a way for the hotel to capitalize on the futuristic public image of airships inspired by the success of Graf Zeppelin. However, the tower itself was never intended to be used and would likely not withstand the stresses involved.

The mooring mast atop the Rand Building in downtown Buffalo was similar, with the mast designed to attract what was then a popular means of air traffic. However, records from the local Courier Express and Buffalo Evening News have no reference to a zeppelin using this particular mast.

The structure known as the ‘mooring mast’ was invented over 100 years ago when a solution was needed for ground handling problems that resulted in many airships crashing, being deflated or being significantly damaged. Previously to the mooring mast, major problems with mooring emerged as on-land sheds could not handle adverse weather conditions and meant many airships were damaged when landing. In their book, González-Redondo & Camplin discuss the first attempted solution that partially overcame the ground-handling difficulties, a shed that floated on water which could turn freely and automatically align its long axis with the direction of the wind. This meant that airships could now land regardless of air currents. Airship design was then altered to allow blimps to float on water so that they could be placed into their water hangars more easily, but a lack of any method of open mooring meant that airships still suffered from engine failure, damage due to a change in weather conditions (storms) and operational difficulties involved in such anchoring systems. Multiple airships were lost under such circumstances. In an attempt to avoid the various issues with loading airships into their sheds and to prevent further accidents, engineers would often deflate their blimps, accepting the financial loss and time cost of any damage caused by dismantling it out in the open.

To find a resolution to the slew of problems faced by airship engineers to dock dirigibles, Spanish engineer and inventor Leonardo Torres Quevedo drew up designs of a ‘docking station’ and made alterations to airship designs. In 1910, Torres Quevedo proposed the idea of attaching an airship's nose to a mooring mast and allowing the airship to weathervane with changes of wind direction (see Fig.1). The use of a metal column erected on the ground, the top of which the bow or stem would be directly attached to (by a cable) would allow a dirigible to be moored at any time, in the open, regardless of wind speeds. Additionally, Torres Quevedo's design called for the improvement and accessibility of temporary landing sites, where airships were to be moored for the purpose of disembarkation of passengers. The final patent was presented in February 1911 and Leonardo stated his claims regarding the nature of his invention as such:

1)    '[The mooring mast] comprised a metal column erected on the ground to the top of which the bow or stern of the airship was directly attached by a cable

2)   [The airship] moors at the top of the metal column on a pivoted platform so that it can turn in a circle about the column and remain end-on to the wind;