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What you're asking here is how to take into account waste variables such as gravity loss, aero-forces, and ISP loss at sea level. These all depend on your rocket's specific flight profile. For example, rockets with high thrust to weight ratios will experience less loss due to gravity, but much greater loss due to air resistance. Your thrust to weight ratio ...

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The highest possible specific impulse could be achieved by using a 100% efficient e = mc^2 mass to energy converter. Specific impulse is defined as the number of seconds that an engine can provide 9.8 newtons of force given one kilogram of propellant. Here's a bit of math to find this value: c ~ 300,000,000 m/s c^2 ~ 9 * 10^16 m^2/s^2 Plugging in one ...

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...Or is the first thrust gain mentioned above due to the increase in specific impulse with altitude, so that if you account for the change in specific impulse, then you've automatically accounted for the change in thrust? That's correct. The thrust change is because of the rising specific impulse. Thrust is essentially propellant mass flow rate times ...

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The rocket equation is meant to work with constant specific impulse. If you want to stay with the Rocket Equation, you can 'split' any stage into more 'virtual' stages (where the initial mass of the next stage is equal arbitrarily chosen dry mass of the previous one), find what delta-V you need to reach roughly 10km altitude and generate a 'virtual' stage ...

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I don't believe any orbital rockets use nitrous oxide as an oxidizer. Zubrin claims it can be used with an ethelyne-ethane fuel blend to produce 320s specific impulse but that seems optimistic. Wikipedia says it can be used in a catalyzed monopropellant thruster for around 180s. N2O/ethanol has experimentally demonstrated 250s-260s. SpaceShipOne/SpaceShipTwo ...

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