Seattle Central Community College, Seattle, Washington

Science and Math Department2008-2009

Members: Colin Webb, Cooper Clausen, Luan Duong, Brian Injugu

Team organizationTeam lead: Colin Webb

Electronic system: Cooper Clausen

Recovery system: Luan Duong

Logistics: Bryan Injugu

Project’s GoalsTo participate in 4th Intercollegiate Rocket Engineering

Competition in Utah June 24th-27th, 2009.The project is student led and researched.The rocket must be constructed with a minimum amount of

cost.The rocket must clear the launch rail and reach an

estimated altitude of 10,000 ft.The avionics must record data multiple times during flight

and be retrieved easily after flights.The single state recovery system is controlled by avionics

onboard the rocket continuously.The recovery system must land the rocket on the ground

safely and in a reusable condition.Flight data including the peak altitude must be provided

within 2 hours after recovery.

Propulsion SystemHomemade hybrid rocket engine using

Hydroxyl Terminated Polybutadiene (HTPB) as the solid fuel and N2O as the oxidizer.

Why hybrid? It’s a simple and easy to make engine minimizing the overall cost of the rocket.

Weight: 20 lbs N2O + 23 lbs HTPB

IgnitersHomemade igniters

using black powder and magnesium filings

Nichrome wire heats up, ignites black powder/magnesium filing mixture

Nozzle17-hole showerhead injecting nozzle allows

proper vaporization to the igniters.Graphite thrust nozzle cast directly to the

solid fuel grain

Oxidizer Tank and Plumbing systemReconditioned aluminum storage tank pressurized

to 750 psiRadio controlled fuel plumbing system and fuel

hose ejectionFuel ball valve connected to a radio controlled

actuatorContains 20 lbs of N2OEstimated thrust is about 600 lb, provided the

rocket an initial acceleration of 3.7 G’s.

Recovery SystemSingle stage deploymentElectronically controlled by G-Wiz HCX flight computer system.Auto-detected apogee chute release.Barometric and acceleration sensors provide

accurate apogee detection and precise chute release control.

30 ft diameter military surplus parachute Spring loaded pilot chute deploys the main chute.Search radius is about 2 miles from the launch

rail

Electronics Launch SystemControlled by radio signals.Radio transmitter and receiver modules are

TLP434A and RLP434. Digital signal are encoded by an HT12E chip.3-event digital signals including: to open or close

valve gas, and to eject the fuel hose.A circuits which detects the orientation of the

valve will fire the igniters automatically.4 power supplies to minimize supply decoupling

issues during design and testing phases.

StructureA simple structure of 3 aluminum U channels and

9-inch diameter plywood bulkheads. Reinforced by more U channels, L brackets and

riveted together.Solid fuel grain is attached by an aluminum

casing and reducer framing.The body was reinforced by concrete form tubes.Due to the lack of composite materials, lowing

down the weight is impossible.As a result, we opted to forego having a payload

and attempt to launch the rocket as is.

Nose ConeSelf-constructed nose cone was made from

marine type fiberglass laid around a mold and rounded at the tip.

Conical design chosen over ogive in the interest of easy fabrication

Construction road cone used as the mold

FinsCalculated dimension of the fins was

obtained using the Barrowman’s equations and a spreadsheet calculator provided online

3 fins spaced 120 degreesConstructed from Attached directly to engine housing

Launching ProcessStep 1: Fill the oxidizer tank with N2OStep 2: Move rocket to vertical launch

positionStep 3: Eject fuel lineStep 4: Initiate fuel delivery / ignitionStep 5: Main chute deployment just after

apogeeStep 6: Locate / Recover rocket on ground

and retrive altitude information

Possible Failure PointsWill plumbing hold 750 psi?Will igniters create enough energy to ignite

nitrous oxide?Will injection nozzle vaporize fuel?Will thrust be sufficient to lift rocket off?Will thrust be sufficient to achieve altitude

and stability?Will G Wiz detect apogee?Will parachute deploy properly?