Buoyant aircraft (BA) are distinct types using both atmospheric flotation and aerodynamic
principles to fly. They include airships or dirigibles and free or tethered (captured) balloons or
aerostats. Airships are steerable types designed to ply courses, loiter and hold position, as
needed. Simpler balloons or aerostats were the first aircraft and have been an integral part of
the aviation industry since 1783, when both manned hot-air and gas filled types took to the
air. Manned airships began 1852 with a unidirectional (UD) form (increasing complexity). From
proven ability 1901 to fly a figure eight course they then were proclaimed to be dirigible.
BA (manned or unmanned) subsequently found many applications in various sectors,
including: defence, surveillance, telecommunications, transport, tourism, advertising,
research and so on. Balloons/Aerostats witnessed steady growth and hold promise for
continued expansion. However, UD airships have had a checkered history leading to extensive
abandonment. This review provides an overview of the current status, highlighting challenges,
applications, new ways and growth prospects.
Airships are free flying BA with power, propulsion and control systems that use an aerostat as
a buoyancy aid to negate self-weight in the atmosphere, which non-BA types (aeroplanes,
rotorcraft & missiles) don’t. In the late 20th Century, largely inspired in the UK by Airship
Industries, a resurgence of interest began leading to several new types with then better
materials and reliable systems to adopt but based on previous non-rigid UD types.
Several new types were built and certified, also by other competing companies, some still in
operational service. These developments enabled the lost technology to be re-established.
However, at the turn of the century, versatile small drones flooded the market taking interest
away from airships resulting in several business closures. The huge ill-fated CargoLifter
transport airship venture also was closed 2002 when people realised the huge costs to
develop rather large types before the industry sector for them was sufficiently established.
However, now well into this 21st Century with climate warming causing havoc, airships with
naturally sustainable qualities from low power needs and large surfaces to mount solar
voltaic panels offer new ways to minimise aircraft environmental harm using electric airships.
Indeed, a conference 25-26 September 2025 in Nürnberg, Germany, provides information
about these developments and some of the possibilities underway.
The main benefit of aerostats is enduring low powered flight. They also are aerodynes able to
fly with excess weight (heaviness) so may be classified as semi-buoyant lifting bodies. When
tethered, they also can use kiting methods. However, lifting bodies such as the space shuttle,
designed to get dynamic lift from their form, were not designed with atmospheric flotation in
mind. Actually, there’s no reason why airships designed to reach the upper atmosphere could
not then continue into space. Private research activities are underway for this.
Aerostats are vessels that function in similar ways to submarine hulls but designed instead
with extreme lightweight as displacement bodies to expel and keep air out against
atmospheric pressure. This normally is done using a lighter-than-air (LTA) gas to inflate and
internally pressurise them, similar to the way party balloons filled with helium (He) work. The
hull then may be made as a thin gastight flexible envelope, where the LTA-gas acts as an
internal lightweight structural member with low super-pressure to cause pre-tension that
stiffens and stabilises it (countering atmospheric pressure). Buoyancy (applied externally)
results from reduction of atmospheric pressure with height from its lower to upper surface
until near space altitudes.
Aerostats thus can float and ascend with excess buoyancy in air, reliably supporting all up
weight (AUW) including airship systems & payloads. That’s because the atmosphere buoys
them (not LTA-gas) enabling flight without power. Even so, like submarines, airships need
power to ply courses against currents, where drag must be minimised for adequate headway.
While it’s possible to add airship systems to bulbous balloons (making them dirigible) this
depends on applications intended. They would be a good choice for localised purposes (such
as forestry) where tethered types have been used before. However, for purposes needing
regular long distant flight, streamlining becomes important.
The fish or cigar form was adopted for airships from the outset but introduced numerous
consequences to the extent that such types fell from grace and hardly feature now – only a
few in operational service, still with issues to solve. Those attempting their revival now also
face stiff non-BA competition and exacting aviation authority regulations as well as lack of
existing ground infrastructure to succeed. Without government support (not evident yet)
repeating history in a bullish manner as CargoLifter did with large types is rather risky! To
overcome this easier ways are needed to rebuild the airship industry from the ground up.
As it happens a number of small airship developments and now new omni-directional (OD)
types are emerging that operate in better ways. OD types with rotund planforms also enable
simpler ground arrangements, obviating moored weathervane issues and masts, from ability
to ground fix them. They first may be developed as tethered aerostats (not easy for UD types)
enabling early revenue earning duties that later may be further developed as airships using
the same ground infrastructure. Also, after gaining flight data and ground handling knowhow.
This can be with much greater payload ability than UD types for point-to-point duties like
rotorcraft but with much longer range and endurance for serious heavy-lift services anywhere.
A precursor to airships thus is aerostats. Tethered to the ground with strong cables, they fly
over long periods, providing stable platforms for various systems and payloads. They also are
scalable to carry seriously heavy outsized payloads – more than aeroplanes. Interest in their
technology is driven by versatility and cost-effectiveness to meet diverse operational needs.
This now may be realised with simpler, relocatable, essentially lower cost OD types.
In the defence sector, aerostat systems play crucial roles in surveillance and reconnaissance
missions. Equipped with advanced sensors and cameras, these platforms offer persistent,
high-altitude surveillance capabilities, enabling operators to monitor vast areas for extended
periods. Aerostats are particularly useful in border security, coastal surveillance, and
counterterrorism operations, as they also would be when upgraded as airships.
Defence forces (in particular) recognise the value of tethered aerostat systems for enhanced
situational awareness and intelligence gathering. By deploying them over remote or
challenging terrains, they gain a valuable edge from monitoring adversary movements and
detecting potential threats. These abilities also offer civil society ways to monitor many other
issues such as forest fires; traffic flow along roads, rails, rivers, canals; coastal watch;
policing awareness and other duties anywhere, such as at events or for urban overwatch.
Additionally, tethered aerostat systems serve as effective communication relays in remote or
disaster-stricken areas. By carrying communication payloads, these platforms provide
temporary connectivity solutions for emergency response teams and humanitarian missions,
facilitating coordination and information exchange.
In recent years, the tethered aerostat systems market has seen contributions from both
domestic companies and international players. Countries with strong research and
development capabilities have led to the creation of advanced aerostat technologies that
cater to specific defence and civilian needs. Collaboration between international firms and
foreign entities also have facilitated technology transfer and knowledge exchange, driving
innovation and market growth.
However, challenges in the tethered aerostat systems market (primarily UD types) has been
diverse and multifaceted. A major obstacle is their weather dependence. Wind conditions and inclement weather can limit the deployment and operation of these platforms, affecting their
availability and reliability. Advanced weather prediction systems and robust ground
infrastructure can help mitigate these challenges to some extent. OD types with streamlined
forms and simple fixation against the ground would help to mitigate these challenges.
Security concerns are another critical issue. As tethered aerostat systems may be used for
surveillance and intelligence gathering, the risk of unauthorised access or data breaches
must be addressed. Implementing encryption, secure communication protocols, and
physical security measures is essential to protect sensitive information.
These matters are addressed by new OD types, which operate from smaller sites with rapid
set-up/dis-assembly ability for operation and re-deployment. They also can be moved while
aloft in operation and, while grounded, use protective secure fencing, camouflage netting and
automated ground surveillance systems relaying data to mobile command centres.
Furthermore, the high initial costs of UD aerostats and their ground facilities can deter
potential buyers. However, OD aerostats offer somewhat lower cost solutions (both ground
and air) that, with ability to remain airborne for extended periods without constant re-fuelling
needs, the investment is more worthwhile. Governments and private operators thus need to
carefully assess the benefits of each type to justify the initial expenses.
Regulatory challenges also play a role in the tethered aerostat systems market. Operation of
unmanned aerial vehicles (UAVs) is subject to various regulations, including airspace
restrictions, licensing rules and safety standards. Aligning aerostat operations with existing
regulations while ensuring continued innovation and operational flexibility is a delicate issue,
needing separate treatment from non-BA types that recognises their differences.
Despite these challenges, the future prospects of the aerostat systems market remain
promising. The global trend of increased defence spending and the growing demand for
border security and surveillance solutions create a conducive environment for market growth.
Advancements in materials science, aerodynamics, sensor technologies and new ways likely
will drive the development of more efficient and capable aerostat and airship systems.
As new OD types are adopted and the technology matures, costs also are expected to
decrease, making aerostat systems more accessible to a broader range of users, including
smaller defence agencies and private enterprises. The ability of tethered aerostats to serve as
cost-effective, long-endurance surveillance platforms makes them attractive alternatives to
non-BA types for various duties.
International collaborations likely will continue to play a vital role in shaping the aerostat
systems’ market. Joint development programmes and technology transfer initiatives with
allied nations contribute to a more comprehensive and competitive aerostat ecosystem.
In conclusion, the tethered aerostat systems market holds promise for sustained growth,
driven by the technology’s versatility and cost-effectiveness. It also is an enabler for new
airships, helping to establish the industry and ground infrastructure for them. Defence and
surveillance applications, as well as disaster response and communications, offer significant
opportunities for aerostat and airship deployment. Indeed, small airship developments with
reduced complexity (both ground and air) are an enabling way for their return. Overcoming
challenges related to weather dependence, security, cost, and regulations will be critical for
unlocking the full potential they have, positioning leaders in this innovative aviation sector.
Note: This review is a revised version of a report by A&D for UK aerostats needing technical
correction, better explanations and new developments’ material not considered before but
offering ways to enable the industry sector meet the challenges it faces. These are important
matters affecting future developments, needing new ways to thrive.
Charles Luffman
