presented by the coils themselves, particularly if superconducting coils are used to form the throat and expansion fields. de Laval nozzle in 1 dimension The analysis of gas flow through de Laval nozzles involves a number of concepts and simplifying assumptions: The combustion gas is assumed to be an ideal gas. The gas flow is isentropic; i.e., at constant entropy, as the result of the assumption of non-viscous fluid, and adiabatic process. The gas flow rate is constant (i.e., steady) during the period of the propellant burn. The gas flow is non-turbulent and axisymmetric from gas inlet to exhaust gas exit (i.e., along the nozzle's axis of symmetry). The flow is compressible as the fluid is a gas. As the combustion gas enters the rocket nozzle, it is traveling at subsonic velocities. As the throat constricts, the gas is forced to accelerate until at the nozzle throat, where the cross-sectional area is the least, the linear velocity becomes sonic. From the throat the cross-sectional area then increases, the gas expands and the linear velocity becomes progressively more supersonic. The linear velocity of the exiting exhaust gases can be calculated using the following equation where: {| border="0" cellpadding="2" |- !style="text-align: right"| , |style="text-align: left" | absolute temperature of gas at inlet (K) |- !style="text-align: right"| |style="text-align: left" | ≈ 8314.5J/kmol·K, universal gas law constant |- !style="text-align: right"| , |style="text-align: left" | molecular mass or weight of gas (kg/kmol) |- !style="text-align: right"| |style="text-align: left" | , isentropic expansion factor |- !style="text-align: right"| , |style="text-align: left" | specific heat capacity, under constant pressure, of gas |- !style="text-align: right"| , |style="text-align: left" | specific heat capacity, under constant volume, of gas |- !style="text-align: right"| , |style="text-align: left" | velocity of gas at the nozzle exit plane (m/s) |- !style="text-align: right"| , |style="text-align: left" | absolute pressure of gas at the nozzle exit plane (Pa) |- !style="text-align: right"| , |style="text-align: left" | absolute pressure of gas at inlet (Pa) |} Some typical values of the exhaust gas velocity ve for rocket engines burning various propellants are: 1.7 to 2.9 km/s (3800 to 6500 mi/h) for liquid monopropellants 2.9 to 4.5 km/s (6500 to 10100 mi/h) for liquid bipropellants 2.1 to 3.2 km/s (4700 to 7200 mi/h) for solid propellants As a note of interest, ve is sometimes referred to as the ideal exhaust gas velocity because it based on the assumption that the exhaust gas