All teams are provided with a “kit” – set of (mostly cardboard) templates to assist with rocket assembly

Our kit will be a “North Star” design seen on the right◦ 2 stages – K-sized engines (approx 2100 N-s impulse,

200 lbf thrust) choice of different engines of varying thrust and burn times available

AIAA Competition Goals:◦ Model rocket flight path as accurately as possible,

results are compared to actual launch results◦ Flight stability and reliably is most important aspect of

competition◦ Secondary goal is to reach as a high an altitude as

possible◦ Must deliver a payload to apogee, jettison it to take

flight data, and return all rocket parts safely to ground Primary payload is provided by a local high school, who

will be working with the team to integrate their project into our rocket design

High school team tasked to design and build payload for the rocket, which will be flown to apogee (max altitude ~ 10k ft) to record and store flight or atmospheric data

Quality and accuracy of data most important competition output

Payload structural/electrical durability and ease of integration most important part of rocket team’s needs

To provide Young Professionals the opportunity to apply their engineering and project management skills to develop a hands-on, fast paced project, which will allow team members to prepare their product and see it in action as part of a competition on a yearly basis.

Most participants have never have the opportunity at work to design and build a system of this magnitude from scratch, then watch it in action.◦ Also provides team members with an opportunity to practice skills or learn

new related skills which do not get tested on a regular basis at work

Also provides an opportunity for professional networking among coworkers, the ability to work and network with project mentors

Thrust(depends on engine)

Gravity

Drag(varies with velocity)

Wind (Drag Component)

X

Y

F = ma

Through flight, rocket will get lighter (fuel burned), and faster (more drag) – forces always changing

Cg, Cp positions and symmetry for every stage of flight determine stability

Cp – “Center of Pressure”

Cg – “Center ofGravity” (also center of mass for our purposes)

Stabilizing torque

1. How do we raise the center of mass?

2. How do we lower the center of pressure?

Center of mass raised:- by adding more mass to front (payload) or - by moving same mass higher in rocket

Moving mass higher preferred -- heavier rocket will not accelerate as quickly (waste of fuel)

Center of pressure lowered:- by making fins larger

Larger fins cause more drag, so rocket will not fly as high at fast speeds

What if the Cg and Cp are too close together? Rocket is “understable” – small changes in force means rocket may fly

erratically

Rocket is “overstable” – will fly towards wind, which lowers max altitude and makes rocket land miles away (also inefficient)

What if the Cg and Cp are too far apart?

Rocket is “unstable” – will fly erratically or not at all

What if Cg is behind Cp?

Engine burn (Ascent)0–6k feet

Burnout, coast6-10k feet

Chute Ejection, recovery10k-0 ft

Semi-parabolic trajectory (free-fall)

Exponential trajectory (arcing)

Linear trajectory (terminal velocity)

Wind

X

Y

Ascent

Coast

Recovery

Time

Velocity

Max G

Burnout

Apogee

Terminal Velocity

Max Q

Burnout

Chute Ejection

Engines are classified into a lettering system based on their total impulse (N*s).

Smallest is “A” at 2.5 N*s, for every following letter the total impulse is effectively doubled.

Model rockets use up to the letter “F” (highest letter legally purchasable in CA without a permit)

Most smaller engines use black powder as the propellant.

ALL engines use common nomenclature to estimate its properties:

C6-5Classification

Average thrust (Newtons)

Ejection charge delay (sec)

HPR engines range from “G” through “M” and all require NAR (National Association of Rocketry) Certification to launch individually

“M” requires special Level 3 Certification

These engines are not pre-built, they require loading grains into a reloadable mount.

Typically fuel is Ammonium Perchlorate, the same propellant as found in space shuttle SRBs.

Must collect and store data during launch Must be build to correctly fit payload bay (5.5”

diameter) Must adhere to weight maximums and minimums

◦ Cg of payload must be centered radially◦ Cg should be as high as possible axially

Must be able to tolerate expected forces during launch and landing◦ 8 G’s sustained during launch, possible “shock” during

landing after 20 ft/sec descent◦ Rocket will vibrate – payload may need to internally

dampen◦ Parts should not shift during launch

Should be self-powered◦ Internal battery should last from time when payload is

mounted into rocket, through landing

Examples of data that can be recorded◦ Altitude (pressure)◦ Temperature◦ Acceleration in all axes◦ Velocity◦ Stress/Strain◦ GPS

Design considerations◦ You don’t want to record data while rocket is sitting

on launch pad – need to “trigger” data collection◦ How will you get data off payload once landed?

You may NOT use off-the-shelf data recording hardware◦ This is a competition rule

Entire payload should be able to easily integrate into rocket day of competition◦ Should be self-contained◦ External sensors if needed will need to be hard-

mounted to the rocket ahead of time

If transmitting data live, must not interfere with rocket’s telemetry frequencies◦ Rocket uses 900 Mhz and 2.4 Ghz for comm