Founded in 2025, based in the UK, our mission is to design and build large rigid airships

Replacing helium with hot air as the lifting gas

Rigid Thermal Airships are Rigid Airships (also called zeppelins) that use hot air as the lifting gas

In this case the air is heated to between 200-300C above ambient

• Because of their buoyancy airships are capable of vertical takeoff and landing, this allows them access to places without transport infrastructure such as roads, rails and airports and allows them to hover in place. This also allows them to fly "point to point" without the need to use several transport modes
• They are capable of carrying large and heavy cargo over long distances at competitive levelised cost
• Their bouyancy means that a propulsion failure does not result in loss of lift, a safety advantage
• Their slower speed and use of propellers instead of jet engines makes them quieter than planes

Here is a table comparing attributes of several lifting gases

	Hydrogen	Helium	Steam	Hot air
Lift/volume (kg/m3)	1.1	1.0	+200C: 0.78 +300C: 0.86	+200C: 0.51 +300C: 0.63
Initial minimum cost per cubic metre ($0.20/kwh)	$0.60¹	$10	+200C: $0.07 (1.24MJ) +300C: $0.06 (1.11MJ)	+200C: $0.008 (0.14MJ) +300C: $0.01 (0.18MJ)
Initial minimum cost per Kg of lift ($0.20/kwh)	$0.55¹	$10	+200C: $0.09 +300C: $0.07	+200C: $0.02 +300C: $0.02
Not flammable	x	✓	✓	✓
Inherent lifting gas	✓	✓	x	x
No Envelope pressurisation	x	x	x	✓
Renewable inexhaustible supply	✓	x	✓	✓
Available anywhere	✓²	x	✓²	✓
Ease of envelope access	Hard	Hard	Medium	Simple
Density variation	Low	Low	Medium	High

(All at sea level and 20C ambient)

¹ Electrolysis, ² With water

Why Hot Air

Hot air is chosen as the lifting gas for several reasons

1. It is not flammable, this is important and is the biggest problem with hydrogen

2. It is available everywhere, all the time, by far the easiest lifting gas to obtain, no filling required

3. It is by far the initially cheapest lifting gas per volume and per unit of lift

4. It's lift can be varied by adjusting its temperature and does not have the big barrier of phase change energy that steam has

5. It takes much less heat energy to warm up than steam, so heats/cools faster, cheaper and much higher % heat recovery is possible

6. It does not require pressurisation. When ascend, air pressure drops and some internal air exits to equalise the pressure. This means the lift/volume is percentage of external air density instead of fixed value when pressurised. This means as ascend, lift/volume decreases more slowly than other lifting gases and proportional lift/volume to them is increased

The envelope shape is the same prolate spheroid shape common on most airships

However the length/width ratio is reduced compared to helium airships

This decreases the surface area/volume ratio, decreasing required volume for same lift and decreasing surface area for heat loss

This increases drag on the ship which requires more powerful engines. However required thrust power scales with speed³ so a small decrease in speed reduces required thrust power significantly

The envelope is made of rigid metal beams running around and across it

Metals are used for the beams which maintain their strength at high temperatures

Around the surface, thin metal panels are placed to enclose the envelope

Below the panels, insulation is placed to significantly reduce heat loss

The envelope has a hole in the bottom to allow internal air pressure to equalise with the outside

To ascend the airship the air inside is heated, decreasing its density and increasing its bouyancy

To descend, do the opposite

Vectored propellers are placed around the airship for thrust and control

To increase and maintain heat of the envelope air a fuel must be burnt

Hydrogen is used as the fuel for heat and to provide electricity for the propellers

If the airship is in regular use, it is expected that the internal temperature is maintained just below where neutral buoyancy is achieved, this makes taking off again faster

Solar heat collection can be used to cover majority of the heat maintenance requirements during daytime

One or more heat recovery methods are used when heating or cooling internal air

The payload of the airship is placed under the envelope, any cargo and passengers go here

Our airship will use hydrogen as its fuel

This allows for 3 major advantages over fossil fuels

Firstly, hydrogen has the highest energy density of any fuel, this minimises weight of the fuel and therefore maximises range and payload capacity

Secondly, hydrogen produces zero CO2 emissions when either burned or run through fuel cells, it can also be produced with little to no CO2 emissions

Thirdly, hydrogen can be produced by the customer themselves, if the customer purchases their own zero fuel cost electricity sources such as wind and solar, and hydrogen production technology using this electricity, then they are able to produce their own fuel at zero cost

We aim to meet at least these specifications

Note that costs are conservative upper estimates and that all is subject to change

Attribute	Value
Envelope Volume	> 2,000,000 m³
Payload	> 100 tons
Purchase Cost	- Airship: TBD - Fuel self production requirements: TBD
Heat cost (+200C)	Without own fuel production - Initial (no heat recovery) < $40k - Ongoing < $2k/hour With own fuel production* - Initial: $0 - Ongoing: $0/hour
Max internal temperature	> 350C
Altitude Ceiling (MSL)	10,000 ft
Air Speed	Cruise > 50 knots Max > 60 knots
Max thrust	> 50,000 hp
Endurance (cruise)	> 16 hours
Fuel	Hydrogen (Liquid or Gas TBD)
Average levelised running cost	Without own fuel production < $3/ton/mile With own fuel production* $0/ton/mile
Ongoing heat energy from solar (daytime)	> 50%
Heat recovery	> 50 %

* Excluding ongoing maintenance costs of hydrogen production facilities

Designing and Building any new aircraft is often a multi year process due to various complexities including engineering, regulatory and financial

Our goal is to deploy the first production airship no later than 2035

The airships will be designed and built in the UK, a country with a long history of aviation and airship innovation

We are currently looking for seed funding

This will allow us to...

• Obtain an office
• Continue design of the airship
• Begin discussions with potential buyers, suppliers and regulators
• Hire initial required staff

Further funding would allow us to...

• Obtain/Construct a hangar
• Build a smaller prototype
• Get customer preorders
• Build a full scale prototype
• Complete testing and obtain certification from regulators
• Build the first production airship
• Become profitable and provide a return on investment

If you want to invest in the future of airships please contact us