Number 4 please.

3. Consider a design of a hydrazine (N2H4) thruster for a satellite. The thruster produce 350 mN of thrust (at steady state) with a total impulse of 410 kN/s. The thruster is intended to operate with a hydrazine storage tank regulated to 25 atm and held at a constant storage temperature of 290 K using a high pressure (maximum of 65 atm nitrogen) tank and regulator used to maintain the hydrazine tank at the prescribed operating pressure. The products leaving the catalyst bed consist only of NH3, N2, H2, with NH3 making up 30% of the mixture (by mole). For this preliminary design exercise, assume the thruster will use a nozzle having an area ratio of 40 of a conical nozzle with 15 degree half-angle. Assume a constant for all of these.

4. Your goal is to redesign the thruster described in Problem 3 for operation as a resistojet. Assume same thrust and total impulse with the same hydrazine feed system, catalyst bed and nozzle shape with the same expansion ratio and the propellant composition entering the nozzle as in problem 3. (a) Assuming that the maximum temperature that can be achieved is 1900 K determine the specific impulse of the resistojet. (b) How will the nozzle diameter and length change with this modification? (c) What can you conclude from this exercise compared to Problem 3.