ARO 1021L Final

What does the exponential atmosphere model describe?

Atmospheric density decreases exponentially with altitude; useful for modeling drag and heating during reentry.

What is the ballistic parameter and why is it important?

The ratio of mass to drag coefficient and reference area (m/CDS); determines how deeply a vehicle penetrates the atmosphere before deceleration.

What are the dangers of steep atmospheric entry?

High deceleration and intense heating, which can threaten vehicle integrity and crew safety.

How does a lifting entry differ from ballistic entry?

Lifting entry uses aerodynamic lift to control descent, reducing deceleration and improving maneuverability—used by the Space Shuttle.

What causes extreme heating during reentry?

Compression of air into a shock wave in front of the vehicle causes temperatures to exceed 11,000 K; heat transfers via convection and radiation.

What is the role of blunt body designs in reentry?

They create a detached shock wave that reduces heat transfer to the vehicle by pushing hot gases away.

What did Kepler contribute to spaceflight physics?

He formulated the three laws of planetary motion, laying the groundwork for orbital mechanics.

How did Newton build upon Kepler's work?

He formulated the law of universal gravitation, explaining the force behind planetary motion and enabling precise spaceflight calculations.

What is specific fuel consumption (SFC/TSFC)?

It measures engine efficiency—how much fuel is used per unit of thrust.

Why are turbofans considered efficient for modern aircraft?

They balance thrust and efficiency by diverting air around the core, reducing fuel use and noise.

What is Newton's Third Law and how does it apply to propulsion?

For every action, there is an equal and opposite reaction; propulsion systems expel mass to generate thrust.

What are the main types of propulsion systems?

Propellers, jet engines (turbojets, turbofans), ramjets, scramjets, and rocket engines.

How do rocket engines differ from jet engines?

Rocket engines carry their own oxidizer, enabling operation in space.

What are the three types of rocket engines?

Liquid-fuel, solid-fuel, and hybrid rockets.

What is the rocket equation and who developed it?

Developed by Tsiolkovsky, it relates rocket velocity change to exhaust velocity and mass ratio.

What does staging in rockets accomplish?

It reduces weight mid-flight by dropping used sections, improving efficiency and range.

What is specific impulse (Isp)?

A measure of rocket efficiency—how much thrust is produced per unit of fuel over time.

Why are solid propellants used in military and boosters?

They're simple, reliable, and can be stored for long periods, though they lack control once ignited.

Who were key inventors of the jet engine?

Frank Whittle (UK) and Hans von Ohain (Germany) in the 1930s.

What was the significance of Robert Goddard's work?

He launched the first successful liquid-fueled rocket in 1926, proving controlled propulsion was possible.

Why is a high ballistic parameter significant?

It results in a deeper trajectory with delayed deceleration, increasing structural and thermal stress.

What is the lift parameter (m/CLS) used for?

It determines how deeply a lifting entry vehicle descends before significant deceleration occurs.

How did the Space Shuttle manage heating during reentry?

It used a high angle of attack and lifting entry to control descent and heating, along with thermal tiles.

What are the advantages of hybrid rockets?

They combine solid fuel with liquid oxidizer, offering controllability with simpler design.

Why is the staging method crucial for space missions?

It drops unnecessary mass, improving thrust-to-weight ratio and mission range.

What propellants did the Saturn V use?

Liquid hydrogen and liquid oxygen, for high energy and efficient burn.

What does the variable 'Ve' stand for in propulsion equations?

Exhaust velocity of gases expelled from the rocket engine.

What historical mission used solid boosters for liftoff?

The Space Shuttle used solid rocket boosters for initial thrust.

How do ramjets and scramjets differ from other engines?

They have no moving parts and rely on high-speed airflow for combustion—used at supersonic/hypersonic speeds.