I2S - Lecture 9-10

Question 1

Name the propulsion concepts

Answer 1

• Chemical
• electrical
• nuclear
• other (solar sail, cold gas, beamed energy,…)

Question 2

How is thrust obtained?

Answer 2

Either with a high mass flow or a high exhaust velocity

Question 3

Compare the efficiency of different propulsion concepts

Answer 3

Electrostatic Propulsion has the highest specific impulse while having relative low thrust, on the other hand chemical have high thrust but low Isp

Question 4

What are manoeuvres that are suitable for electric propulsions?

Answer 4

• Transfer via spiraling
• Station keeping of satellites

Question 5

What is the thrust profile for solid propulsion?

Answer 5

Thrust profile is a function of the propellant surface geometry and the resulting regression/progression/neutral rate of thrust

Question 6

What are factors for the propellant choice?

Answer 6

• Burn rate
• Operational temperature range
• aging
• toxicity
• production cost

Question 7

Why electrolysis propulsion?

Answer 7

H20 goes through a electrolyser and 02 and H2 gets seperated to be fed into Electric thruster, hot-gas thruster (H2) or Cold-gas thruster and both mentioned before (O2)

Question 8

What are typical for liquid propulsion?

Answer 8

• Liquid Hydrogen (LH2) + Liquid Oxygen (LOX) / high efficiency/ thrust
• Refined Kerosene (RP-1) and LOX / high efficiency/ thrust
• Hydrazine N2H4 / for reliability and simplicity

Question 9

Name some favorable qualities of propellants

Answer 9

• High energy content
• high density and low vapour pressure
• low viscosity
• low toxicity
• good availability and low cost