Small satellites live or die by mass. Every gram of structure is a gram that cannot be payload or propellant — which is why the composite overwrapped pressure vessel (COPV) has become the standard satellite propellant tank and spacecraft pressurant tank for CubeSats and smallsat missions. This article explains how COPVs work, what they store on a satellite, and how to talk to a manufacturer about custom specifications.
What is a COPV?
A composite overwrapped pressure vessel pairs a thin metallic liner — usually aluminum or titanium — with a structural overwrap of carbon fiber wound in precise patterns. The liner seals the gas or liquid; the carbon fiber carries the pressure load. The result is a pressure vessel dramatically lighter than an all-metal tank at the same pressure, with excellent fatigue life. It is the same fundamental construction used in high-end terrestrial cylinders: a seamless aluminum liner overwrapped in carbon fiber, rated to working pressures up to 4500 psi (310 bar).
What COPVs store on small satellites
On a small satellite, COPVs typically do two jobs:
- Chemical thrusters need propellant tanks for fuel and oxidizer; electric propulsion systems — such as the Hall-effect and ion thrusters popular on CubeSats — need xenon or krypton stored at high pressure. A cubesat propulsion tank must hold that propellant for years without measurable leakage.
- Helium or nitrogen COPVs push propellant out of low-pressure tanks and into the thruster — the classic pressure-fed architecture. These spacecraft pressurant tank vessels run at very high pressure to minimize their size and mass.
Why carbon fiber wins in orbit
Launch cost is priced by the kilogram, so the mass savings of carbon fiber over titanium or steel go straight to mission capability: more propellant means more delta-v, longer station-keeping, or a heavier payload. Carbon fiber also handles the pressure cycles of repeated thruster firings well, and modern liner and boss-seal designs keep leak rates extremely low over multi-year missions.
Sizing the tank: pressure versus volume
Storing more gas means either a bigger tank or a higher pressure. Small satellites are volume-constrained — a single CubeSat unit is just 10 cm on a side — so designers push pressures up to shrink the vessel. That is exactly where COPVs shine: carbon fiber’s strength lets a small, high-pressure sphere or cylinder hold as much usable propellant as a much larger low-pressure metal tank. The trade is thicker walls and heavier end bosses, so the optimum is always a system-level decision between tank mass, envelope, and thruster inlet pressure.
For teams evaluating suppliers, ask for burst test data, liner compatibility with your propellant, and documented experience building high-pressure carbon fiber vessels. A manufacturer that already produces DOT and CE certified cylinders to 4500 psi understands pressure containment — the conversation then focuses on your mission’s specific qualification path, from prototype testing through flight acceptance.
An important note on qualification
Flight hardware is not just a strong tank. A carbon fiber tank for satellite flight must be qualified for its specific mission: vibration and shock during launch, thermal cycling in orbit, radiation exposure, outgassing limits, and fracture-control requirements — plus acceptance testing of every flight unit. Off-the-shelf DOT or CE cylinders are certified for terrestrial transport and use; they are not space-qualified as sold. Any satellite program should work directly with the manufacturer on mission-specific design, analysis, and test.
Talk to us about custom COPV specifications
Acecare designs and manufactures carbon fiber cylinders with aluminum liners — the same fundamental COPV construction used in aerospace — in volumes from 0.36L to 12L and working pressures up to 4500 psi (310 bar), produced on DOT and CE certified lines. If your team needs a satellite propellant tank, cubesat propulsion tank, or spacecraft pressurant tank with custom dimensions, boss interfaces, liners, or acceptance testing, contact our engineering team to discuss OEM specifications. We will tell you honestly what we can build, what needs development work, and what should go to a dedicated space-qualified supplier.