Rocket Propulsion

• Rocket propulsion

• Newton's Third Law:

• ~11.2 km/s

• Delta V Budget:

• better fuel efficiency.

• Propellant choice

• Rocket Propulsion Fundamentals
  - ___________ is essential for launch, orbital
  maneuvers, and deep-space travel.
  - _____________ "For every action, there is an
  equal and opposite reaction."

• Why propulsion is critical in spacecraft mission design:
  - Escape velocity (________): Required to leave Earth's gravity.
  - ____________ Determines fuel requirements for a mission.
  - Thrust-to-weight ratio (T/W): Affects payload capacity and efficiency.
  - Specific impulse (Isp): Higher Isp = ___________
  - ____________: Impacts storage, combustion efficiency, and engine design.

• Thrust

• Pa=0

• Ambient pressure

Thrust Equation

• __________ is the force that propels a rocket forward

  • where:

    • m = mass flow rate (kg/s)

    • Ve= Exhaust velocity (m/s)

    • Pe = Pressure at nozzle exit (Pa)

    • Pa = Ambient Pressure (Pa)

    • Ae = Nozzle Exit Area (m²)

• Seal Level vs. Thrust Vacuum Thrust

  • In Vacuum _______, so thrust is maximized

  • At sea level, ____________ reduces thrust efficiency

Thrust to Weight Ratio (T/W)

• Faster acceleration → Higher Payload Capacity

• 2.76

• Merlin 1D, 7600 kN, 13.8

• SLS Block 1

  • RS-25

________________

• It detemine acceleration capability

• Higher T/W → ___________ → ____________

Comparison of Launch Vehicles:

Saturn V

• Engine: F-1

• Thrust (kN): 7,740

• Mass (kg): 2,800,000

• T/W Ratio: _______

Falcon 9

• Engine: ______

• Thrust (kN): _______

• Mass (kg): 549.000

• T/W Ratio: ______

__________

• Engine: _______

• Thrust (kN): 8, 160

• Mass (kg): 2,600,000

• T/W Ratio: 3.1

Specific Impulse (Isp)

• Less fuel needed for a given

• Delta V

• Composite

• Liquid (RP-1/LOX)

• Liquid (LH2/LOX)

  • Hydrogen

• Xenon, 1500+

____________ and Mission Efficiency

• It Measures fuel effciency

• Higher Isp → ____________

• ________ → More Payload

Comparison of Propulsion Types

Solid Rockets

• Fuel: ________

• Isp: 250-300

__________

• Fuel: Kerosene

• Isp: 350

__________

• Fuel: ___________

• Isp: 450

Electric/Ion

• Fuel: ___________

• Isp: ______

• Exhaust Velocity

• Chamber Temperature (Tc)

• Molecular Weight (M) of exhaust gases

• Higher Tc → More energy to exhaust

• Lower Molecular Weight (M)

Calculation of Specific Impulse

Specific Impulse is:

• Derived from _________

• Directly dependent on

  • ____________

  • ____________

• To Increase Isp:

  • ________ → _________ → Higher Ve

  • Lower ________ (e.g hydrogen over kerosene) → Higher Ve

• High-pressure combustion

  • Sea level engines

  • Vacuum Engines

  • Underexpanded

  • Overexpanded

    • Flow Separation

  • Optimally Expanded

    • Maximum Thrust Efficiency

Nozzle Expansion and Performance

• Nozzle converts ____________ gases into high speed exhaust

• Optimized Nozzle Design

  • ___________; Shorter nozzles to match ambient pressure

  • ____________: Large bell nozzles for efficient expansion

• Key Considerations in Nozzle Expansion:

  • __________; Pe > Pa (Exit Pressure is Higher than the Ambient Pressure) → Wasted Efficiency

  • ___________: Pe < Pa (Ambient Pressure is higher than the exit pressure) → __________, Potential Instability

  • _____________: Pe = Pa → _________

• Conical Nozzle

• Bell Nozzle

• Aerospike Nozzle

Nozzle Contour and Design

• ___________: Simple, but slightly inefficient (~98% efficiency)

• ____________: More Efficient, commonly used in modern rockets

• ____________: Self adjusting expansion for different altitudes

3000K

• Regenerative Cooling

• Ablative Cooling

• Film Cooling

Engine Cooling

Extreme Temperatures (~_______) required advanced cooling methods:

• _____________: Fuel circulates around the chamber walls

• ______________: Heat-resistant materials vaporize to protect the engine

• _____________: Injecting unburned propellant along the walls

1. Gas Generator Cycle (Open Cycle) - with Flight Start Tanks

Combustion Cycles

______________________

Advantages: Simple design, reliable, well-tested.

Disadvantages: Waste of some propellant, lower efficiency compared to staged combustion.

Examples: The F-1 engine (Saturn V first stage) and Merlin engines (Falcon 9 first stage).

2. Gas Generator Cycle - with Ground Start Tanks

Combustion Cycles

____________________

Advantages: Reduces on-board weight, improves first-stage efficiency Disadvantages: Requires ground- based pressurization systems, limiting launch flexibility

Examples: RD-107/108 engines (Soyuz first stage), older Soviet-era launch vehicles

3. Gas Generator Cycle - with Tank Head Start

Combustion Cycles

____________________

Advantages: Eliminates the need for additional starter systems.

Disadvantages: Requires precise fuel pressure regulation to avoid combustion instability.

Examples: Vulcain engine (Ariane 5 first stage).

4. Gas Generator Cycle - with Solid Propellant Start Cartridge

Combustion Cycles

______________________

Advantages: Requires no external ignition system, highly reliable.

Disadvantages: Non-reusable, limited throttle control.

Examples: RD-107/108 engines (Soyuz rocket first stage).

5. Preburner Cycle (Staged Combustion Cycle)

Combustion Cycles

_________________

Advantages: Higher efficiency, allows for higher chamber pressures, leading to higher specific impulse (Isp).

Disadvantages: More complex, requires high-temperature-resistant materials.

Examples: RS-25 (Space Shuttle Main Engine, SLS core stage), RD-180 (Atlas V first stage), Raptor (SpaceX Starship).

6. Expander Cycle( Cryogenic Engine Operation)

Combustion Cycles

______________________

Advantages: Extremely high efficiency, multiple restarts

Disadvantages: Limited to cryogenic fuels, lower thrust capability Examples: RL-10 (Centaur upper stage), Vinci (Ariane 6 upper stage), BE-3U (Blue Origin New Glenn upper stage)

• Higher thrust

• Higher specific impulse (Isp)

• Compact engine design

• More mechanical stress

• complex turbopump systems

• cooling demands

Combustion Chamber Pressure

Higher chamber pressures generally result in:

✓ __________ - More forceful ejection of exhaust gases.

✓ Greater efficiency -_______________.

✓ ______________ - Smaller chamber size for the same power.

* Higher pressures come with challenges:

X ___________ on engine components.

X More ____________required.

X Greater _________ due to higher temperatures.

Ascent Flight Mechanics

• launch to orbit

• gravity

• drag and heating.

• High dynamic pressure (qmax)

• Trajectory optimization

• LEO, steep climbs

• GTO and interplanetary

• fuel efficiency.

• Nuclear thermal propulsion

• Hypersonic air-breathing boosters

_________________

The goal of this is to efficiently transition from _____ to _______ while minimizing fuel consumption, aerodynamic stress, and structural loads. It is also crucial for mission success.

Challenges of the ascent phase:

• Overcoming ______ - Most fuel is spent in this phase.

• Aerodynamic forces - Rockets must avoid excessive ____ and ___

• Structural loads - _____________ occurs early in flight.

• __________ - Ensures efficient orbital insertion.

Ascent trajectory is mission-dependent:

• _____ launches prioritize _______ to reduce drag losses.

• ______ and _________ launches need precision staging and burns.

Key advancements in launch vehicle design: *

• Reusable rockets (Falcon 9, Starship) reduce launch costs.

• Computational optimization of trajectories improves _________

• New materials (carbon composites, stainless steel) improve weight-to-strength

Next-gen technologies:

• ___________ for Mars missions.

• ________________ for lower- cost access to space

• single-stage rocket (SSTO)

• Staging

• Serial Staging:

• Parallel Staging

Rocket Performance and Staging

• A___________ is inefficient due to excessive fuel weight.

• ______ improves efficiency by discarding empty tanks and engines.

Staging Strategies:

1. ___________ Each stage ignites after the previous one is discarded. (e.g., Saturn V)

2. __________: Boosters ignite with the main stage, then detach. (e.g., Space Shuttle SRBs, Falcon Heavy side boosters)

• Example: Saturn V Rocket
  

• Provide maximum thrust

• Lighter, more efficient engines

• High- efficiency orbital insertion

• payload fraction.

• structural weight.

• AV efficiency.

Staging Mass Optimization

Optimal staging ratios for mass efficiency:

• First stage (~60% of total mass): _________

• Second stage (~25% of total mass): __________.

• Third stage (~15% of total mass): __________

Key.benefits of staging:

• Improves ___________

• Reduces __________

• Maximizes __________

Launch Trajectory Phases

• Vertical Climb

• Gravity Turn

• Max-Q (Maximum Dynamic Pressure)

• Staging Events

• Orbit Injection

Gravity Turn Maneuver

Falcon 9

• 2.5, seperation

• 6-8, orbit

Ascent Trajectories (__________)

• A rocket's ascent is divided into key phases:

1. _________: Clears the dense atmosphere.

2. __________: Gradual tilt to gain horizontal velocity.

3. ____________: Peak aerodynamic stress.

4. ___________: Boosters/jettisoned tanks improve efficiency.

5. ___________: Final velocity achieved.

________________:

• Reduces gravity losses.

• Saves fuel for later orbital maneuvers.

-
Example: ______ Launch Profile

• First stage burn: ~__ minutes, then ____.

• Second stage burn:____ minutes, achieves ____

• Strength

• Weight:

• Thermal resistance

Rocket Vehicle Structures (Materials & Design)

Structural design must balance:

• ________: Withstand thrust and aerodynamic forces.

• _____ Minimize unnecessary mass.

• _________ Protect against re-entry and atmospheric friction.
  

• Axial Loads

• Lateral Loads

• Thermal Loads

• Monocoque design

• Stringers and frames

• Thick aluminum walls

• pressurization

Load Considerations in Rocket Structures

Some Structural Loads During Ascent:

• ______: Compression from thrust.

• _______: Bending due to aerodynamic forces.

• _________ Heat from friction and rocket exhaust.

Structural Optimization Techniques:

• ___________: Load-bearing shell.

• ____________: Internal support structures.

Example: Saturn V vs. Falcon 9

• Saturn V: _______ for extreme loads.

• Falcon 9: Relies on_________ for structural rigidity.
  

Launch Vehicle Selection

• Payload capacity

• Target orbit or trajectory

• Propellant type

• Expendable vs. Reusable

• Upper stage capability

_______________

1. is critical for mission success.

Key considerations:

• ________ - Can the rocket carry the spacecraft?

• ____ or _____ - LEO, GTO, interplanetary, etc.

• _______ - Solid, liquid, or hybrid.

• ____ vs. _____- Cost and availability.

• ___________ - Critical for reaching final orbit.

2. Determines launch windows and trajectory options.

3. Affects payload integration and structural requirements.

4. Influences mission cost and feasibility.

• high thrust- to-weight ratio

• Not throttleable,

• 250 - 300

• good for liftoff

• Higher efficiency,

• Complex plumbing

• 350-450 s

• good for precise maneuvers

• boosters

• main stages

• SRBs

• SSMEs

Solid vs. Liquid Propellant - Fundamentals

Launch vehicles use different propellant types, each with advantages and disadvantages.

Solid Propellant

Advantages: Simple, reliable, _________

Disadvantages: ___________ once ignited it cannot be shut down

Isp =_______ s

Thrust Profile: provide high thrust instantly ( good for ______).

Liquid Propellant

Advantages: ________ can be throttled and restarted

Disadvantages: __________, requires cryogenic storage

Isp = _______

Thrust Profile: allow throttling (good for _______).

Common Use Cases:

• Solid rockets: Used in ____ (e.g., Space Shuttle SRBs, Vega).

• Liquid rockets: Used in ______ (e.g., Falcon 9, Saturn V).

Example: Space Shuttle Launch System

• _____ (solid): Provided 71% of liftoff thrust.

* _________ (liquid): Provided sustained thrust with high efficiency.

• Small launchers

• Medium-class rockets

• Heavy launchers

• Super-heavy launchers

• Upper stages

Launch Vehicles and Upper Stages

• Launch vehicles are categorized by mission class:

1. _________ (e.g., Rocket Lab Electron, Pegasus XL).

2. __________ (e.g., Falcon 9, Soyuz).

3. __________e.g., Delta IV Heavy, Falcon Heavy).

4. __________ (e.g., Saturn V, SLS, Starship).

• __________ play a critical role in final orbit insertion.

• Space Shuttle

• 18.3 m by 4.6 m

• (Canadarm)

• Reusable Orbiter

• Crew compartment

• Hubble Space Telescope Deployment (1990).

Space Shuttle Payload Accommodations

The ________ had a unique cargo bay instead of a traditional payload fairing.

Payload bay dimensions:

• _____long x _____ wide

• Allowed for modular payload racks.

Key design features:

• Robotic arm (_________): Enabled in-orbit payload deployment.

• ___________: Allowed multiple flights per vehicle.

• ___________: Allowed astronauts to manually operate payloads.

Example Missions:

• ____________________ ISS module deliveries (1998-2011)

• Expendable rockets

• Atlas V

• Delta IV Heavy

• Ariane 5

• Soyuz

Expendable Launch Vehicles (ELVs)

___________ are used for one mission only.

Key ELVs and their capabilities:

___________

• Payload to LEO: ~18,850 kg

• Notable Uses: Military & NASA payloads

____________

• Payload to LEO:~28,790 kg

• Notable Uses: National security payloads

_____________

• Payload to LEO: ~21,000 kg

• Notable Uses: ESA, Galileo, Webb Telescope

______________

• Payload to LEO: ~8,000 kg

• Notable Uses: ISS cargo, crew transport

Advantages of ELVs:

✓ Simpler than reusable vehicles.

✓ Can be optimized for specific payloads.

Disadvantages of ELVs:

X High cost per launch.

X No hardware recovery→ More expensive than reusables.

• Payload size & mass.

• Target orbit or trajectory.

• Cost constraints

• Starship (SpaceX)

• New Glenn (Blue Origin)

• SLS (NASA):

Key Considerations for Launch Vehicle Selection:

✓_____________ and _______

✓ __________ or _______

✓ ____________ (expendable vs. reusable).

✓ Mission timeline & launch availability.

✓ Availability of upper stage configurations.

The Future of Launch Vehicles:

• __________: Fully reusable super-heavy launcher.

• ____________________: Reusable heavy launcher for commercial payloads.

• _______ Super-heavy expendable for deep- space missions.