After enabling traditional style airships to return in the late 20 th century, led by J Roger Munk and his friend (business partner) John E R Wood, who began in the 1970s through Airship Developments Ltd with their first AD500 Skyship design and later (in the early 1980s) continued developments through Airship Industries (AI) with an improved 2nd
version plus bigger SKS types, in the later 1990s through the Advanced Technologies Group (ATG) the pair subsequently took to the development of a semi-buoyant tri-lobed variant called Skykitten.
This new airship type appears to be based on an earlier 1970s French design called Dinosaure, of which a smaller scaled down prototype called ‘Dino 2’ was built and test flown mid-1978.
The reasons for this change in direction stemmed from facing difficult issues associated with traditional style airships, to manage them at ground level and to deal with load exchange – the process to add ballast when unloading and to remove it when loading payloads. This is necessary due to airships remaining airborne at ground level from buoyancy, to maintain equilibrium (EQ) preventing ascent or descent without using ground fixation methods. It was bothersome for operators and military customers familiar with roll-on roll-off (RORO) methods used by aeroplane operators that are quicker and simpler, where being heavier-than-air (HTA) makes sense.
However, the issue here is, “how much heavier should this be?”, where non-buoyant aircraft that don’t use an aerostat to enable buoyancy, can sit easily on the ground with their weight fully reacted at undercarriage positions.
Yet they still could be shifted and turned upside down in storms (causing damage) and hit by flying debris if not retained or sheltered, as ship deck aircraft are. Also, where semi-buoyant types with a large aerostat are inclined to behave like tumbleweed.
Aircushion limpet methods used were a way to mitigate some of the issues, if they work reliably – not proven yet. Also, while prototypes at relatively small scale have demonstrated promise (much easier to manage) scaling up introduces issues not solved yet. It’s fairly certain that UD types will need ability to align with wind directions in a way similar to traditional airships and, with wide-body types, perhaps also roll motion, where these both may be managed in automated ways using turntable facilities – then enabling fixation and RORO methods.
Other issues for these UD wide-body types carrying passengers in close-coupled gondolas beneath their aerostat is emergency escape following collapse of their aerostat over the gondola and snow clearance from their upper surface. It’s thus early days for these new types, where it would be best to investigate the arrangements further at small scale and
introduce them for services they suit at that size to build the industry for them at lower cost.
After all, if large airship developments fail to please again it may cause widespread downfall affecting all BA developers, lasting perhaps 20 years or so, which it did when CargoLifter closed in 2002.
For these reasons, some airship developers went right back to the BA industry’s roots (balloons) to find alternative ways, now being developed by some from grassroots upward. This is what 21 st Century Airships Inc in Canada did, founded
1988 by Hokan Colting.
His spherical airships naturally were OD, didn’t need tail surfaces or mooring masts, could be simply fixed with VLC methods anywhere and were much easier to develop/operate at low cost. They basically met KISS principles (keep it simply simple) that designers should heed and were able for many duties, overlook by airship originators from the outset.
If this had occurred in the 19th Century when airships began, it could have changed history for the industry to become and remain successful, which still can occur – needing people to work together for this goal. Naturally, aerodynamicists understand that spheres have a high coefficient of drag, although this often is lower at the higher Reynolds numbers for
airships, where it reduces as size increases. Even so, a further way to reduce drag without compromising OD ability too much is to adopt a discus (lenticular) form, which some new developers are pursuing and finding that it has merit.
As it happens, during the 1970s, Roger interacted with Thermo-Skyships, Isle of Man, on a lenticular Sky Ship development they were pursuing. Even so, this project didn’t go ahead from the traditional form being preferred, which Wren Skyships and the Advanced Airship Corporation took up instead but without success. However, it may be said that the real advocate for lenticular airships is Pierre Balaskovic, a French University Professor, who later enabled a manned version called Alizé that flew.
Interestingly, these lenticular airships also get good aerodynamic lift from airflow, where the aerostat acts as an aerodyne or lifting body, solving the problem for load exchange and enabling stability for simpler tethered aerostat variants.
