Structure cost is the cost of the structure, this includes the interface, static engine parts, propellant and reactant tanks. This is generally the largest expense after the cost of the pump. In the case of a graphite structure, this is the largest expense. Because structure cost increases quickly with tensile energy, high tensile materials are usually only worth using on reuasable rockets.
Given exhaust velocity, empty mass, structure exhaust scale, structure mass scale, structure tensile scale, tensile energy and ten ton structure price, structure cost is calculated which is in turn used to calculate total rocket cost.
structure cost = pow( ( empty mass / 10,000 ), structure mass scale ) * pow( ( tensile energy / 205,000 ), structure tensile scale ) * pow( ( exhaust velocity / 3,330 ), structure exhaust scale ) * ten ton structure price
total rocket cost = initial labor + pump cost + structure cost
This is used in rocket cost.
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