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.Williams, T, 2009 (Reissue), "Airship Pilot No. 28", Darcy Press, UK,
Mast types
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.
Leonardo Torres Quevedo
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 Francisco A. González Redondo. The Mooring Mast: History and Controversy, pp. 12-17, The Airship Heritage Trust: No. 69, 2013. (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;
3) The “crab” or winch receiving the end of a cable attached to the airship and the point of attachment on the airship; and
4) The cone connected to the upper end of the column, conforming to the end of the airship'
Early enhancements Mooring an airship by the nose to the top of a mast or tower of some kind might appear to be an obvious solution, but dirigibles had been flying for some years before the mooring mast made its appearance. The first airship known to have been moored to a mast was HMA (His Majesty's Airship) No.1, named the ‘Mayfly’, on 22 May 1911. The mast was mounted on a pontoon, and a windbreak of cross-yards with strips of canvas were attached to it. However, the windbreak caused the ship to yaw badly, and she became more stable when it was removed, withstanding winds gusting up to .Ventry, A. and Kolesnik, E, 1982, ‘Airship Saga’, Blandford Press, Dorset, Further experiments in mooring blimps to cable-stayed lattice masts were carried out during 1918.Jackson, R., 1971,"Airships in Peace and War", Cassel and Company Ltd, London WC1,
Impact of minor developments following Leonardo Torres Quevedo's design
Mooring mast technology following Leonardo Torres Quevedo's design became widely utilised in the 20th century as it allowed an unprecedented accessibility to dirigibles, negating the manhandling that was necessary when an airship was placed into its hangar. Due to his inventions, mooring masts were designed simply to allow airships to be docked on ships, land and even atop buildings, all while withstanding gusts and adverse weather conditions. Such versatility meant that mooring masts became the standard approach to docking dirigibles, as blimps could now operate from mobile masts for long periods of time without returning to their hangars. Developments to these mooring technologies allowed for further advancement of airspace technology in the 20th century.
After the advent of Torres Quevedo's revolutionary rotating mooring tip, the mooring mast structure was constantly improved and developed upon over the following decade. High and low masts were experimented with by French, English, American and German engineers in order to determine which technique was the most effective in terms of stability, cost, ground-handling and their ability to allow blimps to weathervane and therefore minimise outdoor-related damage. The procedures for mooring to either a low or high mast were the same, with the blimp approaching the protected side of the mast at the same height. The nose winch is then attached, and the dirigible is fixed into the rotating mast tip, free to move with the wind. Low masts required a number of ground crew members to constantly attend to the changing directions of the wind as they attempted to re-inflate and repair the airships. In order to reduce the large number of men required to bring the blimps in and out of their hangars and on and off their masts, a number of additions were made to Torres Quevedo's traditional design. Examples of these include cradles and lattices that were attached to mobile mooring structures to further limit the amount of yawing and pitching, and pyramidal towing masts known as “iron horses” that were able to extend the height of the original mast structure.
Between 1900 and 1939, ground handling methods for rigid-airships were constantly developed on. Split into three main systems; The German, The British and the American, these procedural techniques each has major advantages and disadvantages. The British system (as discussed in Gabriel Khoury's Airship Technology) is most similar to Torres Quevedo's design, which makes sense seeing as his patent was the main influence for British engineers concerned with mooring dirigibles at the time. All three major rigid airship ground handling systems are extensively discussed in his book.
British high mast operations The British mooring mast was developed more or less to its final form at RNAS Pulham and Cardington in 1919–21 to make the landing process easier and more economical of manpower
The following account of the British high mast in its fully developed state at Cardington, and its operation, is abridged from Masefield.Masefield, Sir P, 1982, "To Ride the Storm: the story of the airship R101", William Kimber & Co., London, Mooring masts were developed to act as a safe open harbour to which airships could be moored or unmoored in any weather, and at which they could receive (hydrogen or helium) gas, fuel, stores and payload.
The Cardington mast, completed in 1926, was an eight sided steel girder structure, high, tapering from diameter at ground level to at the passenger platform, from the ground. Above the passenger platform was the of the conical housing for the mooring gear. A lower platform above the ground accommodated searchlights and signalling gear in a gallery wide. The top platform, at the height of , from which passengers embarked and disembarked to and from the airships, was in diameter and encircled by a heavy parapet. The top rail of the parapet formed a track on which a gangway, let down from the airship, ran on wheels to give freedom for the airship to move around the tower as it swung with the wind. An electric passenger lift ran up the centre of the tower, encircled by a stairway to provide foot access.
The upper portion of the tower, from the passenger platform upwards, was a circular steel turret surmounted by a truncated cone with its top above the passenger platform. A three-part telescopic arm, mounted on gimbals, projected through an opening at the top, free to swing from the vertical in any direction up to 30 degrees of movement. The top of the arm consisted of a bell-shaped cup mounted to rotate on ball bearings.
A cable extended through the bell-mouth which, linked to a cable dropped from airship to be moored, enabled the nose of the airship to be drawn down until a cone on the nose locked home into the cup and so secured the airship to the tower. The telescopic arm was then centred, locked in the vertical position, and made free to rotate on a vertical axis so the airship could swing, nose to tower, in any direction of the wind.
In the machinery house at the base of the tower three steam-driven winches operated the hauling gear through drums in diameter to give cable hauling speeds of 50 feet a minute.
While an airship approached the mast slowly against the wind a mooring cable was let out from nose to the ground and linked, by a ground party, to the end of the mooring cable paid out from the mast head. The cable was then slowly wound in with the airship riding about above the mast and down wind, with one engine running astern to maintain a pull on the cable. At this point, two side wires – or ‘yaw guys’ – were also connected to cables taken from the nose of the airship to pulley blocks some hundreds of feet apart on the ground and thence to winches at the base of the mast.