Activity 4.2.1B – Model Rocket Engines

Problems:1. Once ignited, is the thrust from a model rocket engine uniform (constant over

time) or does it vary during the engines burn?

2. Once ignited, can a solid propellant rocket engine be turned off?

3. Consider this diagram which shows (with the yellow boundaries) the shape of the solid propellant’s burn surface, and thus the shape of the flame front.

A. What causes the thrust of a solid propellant engine to change over time?

B. The thrust of a rocket engine depends on two factors. What are they?

C. If you were the rocket engine designer, what characteristics of the engine could you change to vary the amount of thrust the engine produced?

Please send any comments to: Curator: Tom.Benson@grc.nasa.gov

Responsible Official: Kathy.Zona@grc.nasa.gov

4. Rocket engines can make use of liquid propellants as well as solid, consider the following liquid fueled rocket.

A. What is the primary advantage of a liquid fueled rocket?

B. What types of vehicles make use of liquid rocket engines?

5. Rocket engines rely on chemical reactions that rely on combustion.

A. What exactly is combustion?

B. In model rocket engines is the oxidizer a solid, liquid, or a gas?

C. What three things must be present for combustion to occur?

D. Combustion produces a mixture of heated materials that leaves the engine. What do we call this heated escaping material?

Please send any comments to: Curator: Tom.Benson@grc.nasa.gov

Responsible Official: Kathy.Zona@grc.nasa.gov

6. The nozzle is a critical part of a rocket engine.

A. What type of nozzle do rocket engines typically have?

B. What is the primary purpose of the convergent portion of the nozzle?

Please send any comments to: Curator: Tom.Benson@grc.nasa.gov

Responsible Official: Kathy.Zona@grc.nasa.gov