Full Scale Rockets

Rocket Systems - Structural System

The structural system of a rocket includes all of the parts which make up the frame of the rocket; the cylindrical body, the fairings, and any control fins. The function of the structural system is to transmit the loads from the forces generated during the flight and to provide low aerodynamic drag for flight through the atmosphere.

Performance of a Rocket

Rocket structures must be strong but light weight. The performance of the rocket depends directly on the weight of the structure. A variety of mass ratios are used to characterize the structural weight of a rocket. The distribution of the structural weight also affects the center of gravity of the rocket which, in turn, affects the stability and control of the rocket. During the flight of a rocket to orbit, some parts of the structure are discarded in a process called staging.

Example - Atlas & Saturn V

The Atlas rocket was developed in the late 1950’s as an intercontinental ballistic missile. Two sustainer rocket engines were discarded during the launch, but the entire central sustainer section went into orbit. The Saturn V was a three stage rocket that sent astronauts to the Moon in 1969. The first stage was 138 feet tall, 33 feet in diameter, and weighed 305,000 pounds empty. The stage was filled with 4.5 million pounds of propellants prior to launch.

Rocket Systems - Payload System

A rocket's payload depends on its mission. Early rockets carried fireworks, later replaced by explosives on the German V2. Post-World War II, rockets evolved into ballistic missiles and satellite launchers for communication, weather, spying, and space exploration.

Parts of a Rocket Payload

1. Payload Bay – The compartment that houses satellites, scientific instruments, cargo, or crew modules.
2. Fairing – A protective shell that shields the payload from aerodynamic forces and is jettisoned after launch.
3. Deployment Mechanism – Systems like clamps, springs, or thrusters that release the payload into its intended orbit or trajectory.
4. Avionics & Sensors – Electronic components for navigation, communication, and data collection during the mission.
5. Thermal Protection – Insulation or coatings that protect the payload from extreme temperatures in space.

Human Payloads

Human payloads refer to astronauts and life-supporting systems carried by rockets for space missions. These payloads are designed to ensure safety, comfort, and survival in extreme space environments.
1. Crew Module – A pressurized capsule where astronauts live and work during the mission.
2. Life Support System – Provides oxygen, temperature control, and waste management.
3. Seats & Restraints – Protect astronauts from high G-forces during launch and re-entry.
4. Control Panels – Allow astronauts to monitor and operate spacecraft functions.
5. Escape System – A safety mechanism for emergency aborts during launch.

Rocket Systems - Propulsion System

The propulsion system includes the engine, tanks, pumps, propellants, power head, and nozzle, generating thrust to move the rocket. Thrust, produced per Newton’s third law, results from accelerating a working fluid, creating an opposite force. The thrust equation depends on mass flow and gas exit velocity.

Rocket Engine

A rocket engine combines fuel and oxidizer in a combustion chamber, generating hot exhaust gases that accelerate through a nozzle to produce thrust. Unlike turbine engines or propellers, which rely on atmospheric air, rockets carry their own oxidizer, allowing them to function in space where no air is present.

Types of Engines - Liquid & Solid Rockets

There are two main categories of rocket engines: liquid rockets and solid rockets.
1. Solid Rocket: – Propellants are pre-mixed into a solid form and burn continuously once ignited. Simple, storable for years, but cannot be stopped once started.
2. Liquid Rocket: – Stores fuel and oxidizer separately, mixed in the combustion chamber. More complex and heavier but allows controlled ignition and shutdown.

Rocket Systems - Guidance System

The guidance system of a rocket includes very sophisticated sensors, on-board computers, radars, and communication equipment. The guidance system has two main roles during the launch of a rocket; to provide stability for the rocket, and to control the rocket during maneuvers.

Motion

The motion of any object in flight is a combination of the translation of the center of gravity and the rotation of the object about its center of gravity. Many different methods have been developed to control rockets in flight. All of the control methods produce a torque about the rocket’s center of gravity which causes the rocket to rotate in flight. Through an understanding of the forces acting on the rocket and the resulting motion, the rocket guidance system can be programmed to intercept targets, or to fly into orbit.

Stability of a Rocket

A rocket is stable if it naturally returns to its flight path after disturbance. In atmospheric flight, stability is maintained by keeping the center of pressure below the center of gravity, using fins or added weight. Above the atmosphere, guidance systems ensure stability.

Booster Staging

What is Staging?

Rockets generate thrust to overcome their weight, with most of the lift-off mass being propellants. As fuel burns, the vehicle’s weight shifts to its near-empty structure. To reduce weight and reach orbital velocity, launchers discard sections in a process called staging.

Types of Staging

Serial Staging - In serial staging, a smaller second stage is placed atop a larger first stage. The first stage ignites at launch, burning fuel until depleted, then separates, and the second stage ignites, carrying the payload into orbit. The Saturn V used this three-stage process, discarding each stage after use, with no retrieval.

Parallel Staging - In parallel staging, multiple strap-on boosters are attached to a central sustainer rocket. All engines ignite at launch, and when the boosters burn out, they are discarded while the sustainer continues to orbit. Used in the Space Shuttle, its solid rocket boosters were recovered, refueled, and reused.