One of the difficulties of building a rocket is constantly minimizing mass. Every design choice is evaluated to minimize the mass we have to add to the vehicle. The more mass we need to carry, the more fuel we need to lift it… but fuel also has mass… so you need fuel to lift that fuel… if this keeps going, we’ll be doing some unpleasant calculus.
Out rocket features three composite overwrap pressure vessels (COPVs) in two different flavors. Type 3 COPVs have an aluminum liner for extra strength and corrosion resistance. Type 5 COPVs are made of only carbon composite. The tanks that hold our helium and liquid oxygen are type 5, and the tank that holds our fuel, RP-1, is type 3.
Suffice it to say, it would be awesome if there were some sort of material with the strength of steel but the weight of fiberglass. That’s where composite tanks come in. Specifically, COPVs. These tanks are crazy light and sometimes many times stronger than comparable stainless steel or aluminum tanks.