SPARROW

stem.nasa.gov

National Aeronautics and 

Space Administration

DATE

NASA STEM

NASA Student Launch ARW 

Rocket Structures

PRESENTED BY NASA Student Launch

DATE July 24, 2023
SPARROW

stem.nasa.gov

All high-powered rockets have the same basic parts. 

From the outside of a rocket, only a few are visible

Nose cone

Airframe 

Fins

Rail Buttons

Motor Retainer 

On the inside of a rocket, there are: 

Couplers

Motor Tubes

Centering Rings

Bulk plates /Bulkhead

Hardware: Overview

Parts List:

1. Fiberglass nose cone

2. G10 nose cone bulk plate

3. Pre-slotted body tube

4. G10 centering rings

5. 38mm motor tube

6. G10 fins

7. Eyebolt, nut, washer set

13. Aero Pack 38mm Motor Retainer

2
SPARROW

stem.nasa.gov

Subassemblies:

A subassembly is an assembled unit designed to be 

incorporated with other units into a finished product

The nose cone can be considered a subassembly

A booster subassembly, sometimes called a “fin can”, is built from:

• A section of airframe 

• a motor tube

• centering rings

• bulk plates

• fins

• motor retainers 

• couplers

Hardware: Subassemblies

The nose cone subassembly has a 

removable plate on the bottom for 

access to the interior volume where a 

payload can be carried. 

The fin can subassembly is ready for 

installation into a custom-made carbon 

fiber airframe.

The motor tube subassembly is 

removable so the builder can inspect 

the fin tangs and centering rings 

between flights. 

3
SPARROW

stem.nasa.gov

Nose Cones:

Forward most section of a rocket, missile, or aircraft

Can be the payload or used to shield payload until deployment

Shape chosen for minimum aerodynamic resistance (drag)

Typical HPR nose cone shapes:

Conical, Ogive, Elliptical

Typical HPR nose cone materials:

• Composite: made of two different materials with different 

properties. The new material has better performance 

characteristics than the original materials on their own.

• Fiberglass –glass and plastic. Strong and affordable

• Carbon fiber – polymer resin and tiny carbon fibers. Very 

lightweight and strong

• Urethane plastic – not brittle, has greater elasticity and strength 

that regular plastic.

Hardware: Nose Cones

4
SPARROW

stem.nasa.gov

Airframe:

Generally smooth thin-walled cylinders with an aspect ratio (length : diameter) 

of roughly 10:1 to 20:1

Encompass the rocket’s propulsion system, recovery system, electronics, and 

payload

Nose cone fitted to the forward end

A set of fins are mounted towards the aft end.

For Minimum Diameter rockets, the airframe also serves as the motor tube

Typical HPR airframe materials:

Fiberglass

Carbon fiber

Phenolic – resin impregnated, spiral wrapped, heat cured tube; stronger than 

cardboard, helps to strengthen with fiberglass or carbon fiber.

Blue tube –"shatterproof" alternative to phenolic that has been used for military 

operations in tank ordinance

Hardware: Airframe

High powered rocket airframes are typically made of non-metallic, 

high strength to weight ratio composite materials like carbon fiber, 

fiberglass, phenolic and blue tube. (NAR rules) Paper and 

cardboard will not handle the loads of high-powered rocket motors 

unless they are sufficiently reinforced with composite materials.

Carbon fiber airframe

5
SPARROW

stem.nasa.gov

Airframes:

Generally, fin slots in airframes come one of two ways:

End slotted airframes:

• the fin slot is cut all the way to the end and the airframe 

can be slipped over a fin can subsystem.

Tang slotted airframes:

• The fin slot is stopped before the end of the airframe

• The fins must be epoxied on after the motor tube 

subassembly is installed. 

Hardware: Airframes

The rocket you can build from the workshop is tang slotted. 

A jig is any device used to 

maintain, mechanically, the 

correct position relationship 

between a piece of work and 

the tool.

6
SPARROW

stem.nasa.gov

Couplers:

Joins multiple segments of airframe

Its Outer Diameter (OD) is equal to the 

Inner Diameter (ID) of the airframe it 

connects

makes a good place to store electronics 

(avionics bay)

Typical HPR coupler materials:

• Fiberglass

• Carbon fiber

• Phenolic

• Blue tube

*Note: when joining airframes with a coupler, the coupler should 

extend at least one airframe diameter into each joined segment. 

So, if you were to join two 6-inch diameter airframes, you would 

need a coupler at least 12 inches long.

Hardware: Couplers

The avionics bay in the photo is built from a 12-inch-long 

coupler with a 4-inch collar or switch band in the center. 

The collar allows direct access to the switches that power 

on the altimeters. This coupler joins two airframe 

segments that contain the recovery system by clicking into 

place with quick connect snap buttons.

7
SPARROW

stem.nasa.gov

Motor Tubes:

Any tube inside of a rocket that is intended to fit a rocket motor

Diameters are typically called out in millimeters and refer to the maximum 

diameter motor it is design to hold

• 38mm

• 54mm

• 75mm

• 98mm

Larger HPR motor tubes may only encompass half of the tube because a fulllength motor tube can be heavy

Typical HPR motor tube materials:

• Fiberglass

• Carbon fiber

• Phenolic

• Blue tube

Hardware: Motor Tubes

38mm Motor Tube Subassembly 

before installation

8
SPARROW

stem.nasa.gov

Motor Retainers:

Any device that positively retains the rocket motor case inside of 

the rocket prohibiting it from falling out during flight

There are many commercial motor retainers available for every size 

motor

It is also very common for rocket builders to fashion their own 

motor retainer

Hardware: Motor Retainers

In this workshop, you will be provided an 

Aero Pack 38mm motor retainer. The Aero 

Pack motor retainer base epoxies to the 

bottom end of a motor tube. The threaded 

cap screws on to the base after the motor 

has been installed into the motor tube. 

9
SPARROW

stem.nasa.gov

Centering Rings:

Are used to concentrically align small tubes, like motor tubes, 

inside of an airframe

and take many shapes depending on the number of inside 

tubes that are to be aligned

Bulk Plates / Bulkheads:

Circular disks that fit inside of tubes to separate volumes

serve as the mounting structure for other components

Typical HPR CR & BP materials:

Birch Plywood

Fiberglass

Carbon Fiber 

Hardware: Centering Rings, Bulk Plates and Bulkheads

10
SPARROW

stem.nasa.gov

Fins:

Most rocket fins are designed with: 

• low aspect ratios (AR < 4) 

• taper ratio between 0.2 and 0.4 

ideal for minimum induced drag (δ)

Typical fins Materials:

• G10 fiberglass

• Carbon fiber

• Plastics

• Plywood 

More complex fins are composites of two or more of these 

materials 

Hardware: Fins

11
SPARROW

stem.nasa.gov

Fins:

Flat fixed stabilizing structures extending from the body of a rocket that give stability 

in flight

There are four common fin shapes:

Each fin has several features used to characterize its design & performance:

• Tip chord (ct)

• Root chord (cr)

• Span (b)

• Leading Edge (LE) 

• Trailing Edge (TE)

• Aspect ratio (AR)

Hardware: Fins

12
SPARROW

stem.nasa.gov

Through-The-Wall (TTW):

Widely used fin mounting technique 

The fin tang passes through a slot in the airframe and epoxies flush 

against the motor tube

Epoxy fillets are applied on every side of each joint.

Construction Technique: Fins

13
SPARROW

stem.nasa.gov

Epoxy:

Epoxies are two-part adhesive systems – 1) resin and 2) curing agent

Chemically react to cure/harden and adhere materials together 

Mixing epoxy can prove to be messy 

Time critical task that require some technique and planning to maximize use

Construction Technique: Epoxy

14
SPARROW

stem.nasa.gov

Rail Buttons:

Most HPRs use rails / not rods 

Require rail buttons

Usually, hard smooth plastics 

Slides freely inside channel of extruded aluminum

Constrains the rocket’s movement until sufficient velocity is 

achieved that the fins become effective for flight stability

Two rail buttons are required, and one is typically located:

• Near the bottom of the booster or center of pressure

• Near the center of gravity

Should be rigidly mounted to the rocket

• Large washer and nut inside airframe near a CR.

Hardware: Rail Buttons

15
SPARROW

stem.nasa.gov

Rail Button Jig:

Simple tool to accurately and quickly repeat rail button alignment 

Made from a length of angled aluminum with drill bit alignment 

guides

The angled aluminum will align itself when laid flush on the 

airframe

Tape the jig in place with some masking tape

Drill the forward and aft rail button screw holes with the desired 

size drill bit

Small rail buttons usually use a #8 size machine screw

Construction Technique: Rail Buttons 

16
SPARROW

stem.nasa.gov

Development Testing:

Developmental tests are conducted during the design 

phase of the project

Generally, only a representative test of a component of a 

subsystem 

Verify that the hardware will perform as required 

Develop a manufacturing method conceived of in the 

early design process before committing resources to the 

development of the flight hardware 

Structural Testing

Qualification Testing:

Qualification test are conducted at the end of the design 

process

These tests are generally flight components or entire 

systems

Once Qualification Tests are completed, the components or 

systems can be classified as approved for flight 

17
SPARROW

stem.nasa.gov

In flight, a rocket is subjected to four forces:

• Weight - always directed towards the center of the earth and acts through the 

center of gravity

• Thrust – Opposes Weight depends on the mass flow rate through the engine 

and the velocity and pressure at the exit of the nozzle

• Lift - act through the center of pressure

• Drag –depends on the shape, size, and velocity of the rocket and on properties 

of the atmosphere

Summation of these forces, accounting for the direction, results in a net external 

force on the rocket

The resulting motion of the rocket is described by Newton's laws of motion

• Newton’s 1st Law: Every object in a state of uniform motion tends to remain in 

that state of motion unless an external force is applied to it.

• Newton’s 2nd Law: The relationship between an object's mass m, its 

acceleration a, and the applied force F is F = ma.

• Newton’s 3rd Law: For every action there is an equal and opposite reaction.

Forces on a Rocket

18
SPARROW

stem.nasa.gov

Questions?
SPARROW

stem.nasa.gov