20.4k views
5 votes
A two-stage rocket has the following parameters:

1st-stage propellant mass 115,000 kg,
1st-stage dry mass 9,500 kg
1st-stage specific impulse 255 s

2nd-stage propellant mass 31,000 kg
2nd-stage dry mass 3,500 kg
2nd-stage specific impulse 345 s

Determine the total Δv of the system for a payload of 8 kg and 1800 kg

User Arychj
by
7.5k points

1 Answer

2 votes

Final answer:

To calculate the total Δv of a two-stage rocket, we use the Tsiolkovsky rocket equation, separately for each stage and payload scenario, and sum the Δv values for both stages.

Step-by-step explanation:

To determine the total Δv of a two-stage rocket, we can apply the Tsiolkovsky rocket equation, which is Δv = Isp * g0 * ln(m0/mf), where Isp is the specific impulse of the rocket stage, g0 is the standard acceleration due to gravity (9.81 m/s²), m0 is the initial total mass (propellant mass + dry mass + payload mass), and mf is the final mass (dry mass + payload mass).

For the first stage, the calculations would be as follows:

  • For a 8 kg payload: Δv1 = 255 s * 9.81 m/s² * ln((115,000 kg + 9,500 kg + 8 kg)/(9,500 kg + 8 kg))
  • For a 1,800 kg payload: Δv1 = 255 s * 9.81 m/s² * ln((115,000 kg + 9,500 kg + 1,800 kg)/(9,500 kg + 1,800 kg))

For the second stage, we need to add the final mass of the first stage to the initial mass of the second stage, and then perform a similar calculation:

  • For a 8 kg payload: Δv2 = 345 s * 9.81 m/s² * ln((31,000 kg + 3,500 kg + 8 kg + the final mass of the first stage)/(3,500 kg + 8 kg + the final mass of the first stage))
  • For a 1,800 kg payload: Δv2 = 345 s * 9.81 m/s² * ln((31,000 kg + 3,500 kg + 1,800 kg + the final mass of the first stage)/(3,500 kg + 1,800 kg + the final mass of the first stage))

Finally, to get the total Δv for the entire system, simply add Δv1 and Δv2 for each payload scenario.

User T C
by
7.8k points