1. Tropos-1 Hybrid rocket Project
Seattle Central Community College, Seattle, Washington
Science and Math Department
Members: Colin Webb, Cooper Clausen, Luan Duong, Brian Injugu

2. Team organization Team lead: Colin Webb
Electronic system: Cooper Clausen
Recovery system: Luan Duong
Logistics: Bryan Injugu

3. Project’s Goals
To 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.

4. Propulsion System
Homemade 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

5. Igniters Homemade igniters using black powder and magnesium filings
Nichrome wire heats up, ignites black powder/magnesium filing mixture

6. Nozzle
17-hole showerhead injecting nozzle allows proper vaporization to the igniters.
Graphite thrust nozzle cast directly to the solid fuel grain

7. Oxidizer Tank and Plumbing system
Reconditioned aluminum storage tank pressurized to 750 psi
Radio controlled fuel plumbing system and fuel hose ejection
Fuel ball valve connected to a radio controlled actuator
Contains 20 lbs of N2O
Estimated thrust is about 600 lb, provided the rocket an initial acceleration of 3.7 G’s.

8. Recovery System Single stage deployment
Electronically 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

9. Electronics Launch System
Controlled 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.

10. Structure
A 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.

11. Nose Cone
Self-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

12. Fins
Calculated dimension of the fins was obtained using the Barrowman’s equations and a spreadsheet calculator provided online
3 fins spaced 120 degrees
Constructed from
Attached directly to engine housing

13. Launching Process Step 1: Fill the oxidizer tank with N2O
Step 2: Move rocket to vertical launch position
Step 3: Eject fuel line
Step 4: Initiate fuel delivery / ignition
Step 5: Main chute deployment just after apogee
Step 6: Locate / Recover rocket on ground and retrive altitude information

14. Possible Failure Points
Will 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?