Helium & COSH in flight

I don't know what cosh is, except maybe a small club, but when you compress any gas, you increase its density.

COSH (as I understand it) is the method of controlling craft altitude by releasing gas from tank into bags on airship displacing air and create lift, then pumping it back again to lose height, I'd like to understand Helium's properties in both compressed & uncompressed state

I also don't know what a "COSH" is, but I do know physics. What matters in buoyancy is volume (how much space something takes up), and Helium is very compressible.

When the helium takes up more space... the airship will be more buoyant and will climb. I am guessing that COSH is just a device for pressurizing/depressurizing Helium.

If you want to understand the physics, read about Archimedes principle.

Archimedes is so yesterday.

https://www.popularmechanics.com/flight/a9798/this-is-whats-inside-an-airship-16292688/


The Aeroscraft uses a buoyancy system called COSH, for Control of Static Heaviness, which is inspired by submarine technology. The system eliminates the need for runways and ground crews. That could make this airship ideally suited for moving heavy cargo to remote locations.

BUOYANCY
Aeros's first planned production model will have 18 helium tanks (1). To increase lift, the pilot releases helium, which is much lighter than air, from the tanks into the large envelope (2) that makes up most of the volume of the ship (cargo hold not shown). This applies pressure to the four large air bladders (3) located along the sides of the Aeroscraft.

As the bladders are squeezed, much of this air is expelled to the outside. The overall density of the Aeroscraft decreases and the ship rises. To descend, the pilot reverses the process. Three powerful compressors (not shown) force the helium from the envelope back into the storage tanks. A partial vacuum develops inside the envelope and the airbags expand, pulling in dense air from outside the ship. The Aeroscraft sinks. (The transfer of air is assisted by a system of fans and valves.) In flight, the Aeroscraft's shape helps it de-velop some additional lift, but this is not needed for takeoff and maneuvering.