The document summarizes the final design review of a university hybrid rocket team. It discusses the team's objectives of learning rocket design principles and safe testing practices. It also summarizes the hybrid rocket engine design which uses nitrous oxide and a fuel made of HTPB and paraffin wax. The rocket body uses a carbon fiber fuselage and balsa nose cone with clipped delta fins. For recovery, it will use drogue and main parachutes deployed via CO2 ejection and altimeters. Electronics include a valve, altimeters, GPS and e-match for ignition. The team designed multiple injector plates and tested configurations but more work is needed on recovery and electronics integration.

1. Final Design Review
End of Semester Summation
Kisa Brostrom, Danny Cha, Andrew Clements, Casey Evans, Kent Evans, Sam Heyd
Joe McKenna, Conor Moloney, Chris Ryan, Johnny Wang, Matthew Weydert 1

2. Team Objective
Washington State University Hybrid Rocket Team
● Learn how to design, build and test rocket
systems
● Increased understanding and ability to
apply the rocket equation
● Increased understanding of component
design
● Increased understanding of safe practices
in regards to system testing
https://hydrogen.wsu.edu/wp-content/uploads/sites/44/2014/10/ME-483-Rocket-Design-syllabus-sp2015-v21.pdf
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3. Approach
● To address the team objectives we began by reading from
Rocket Propulsion Elements, by George Sutton, to learn
important theories and equations pertaining to the design
of a rocket
● The next step in our process was doing research about the
history of rocket design
○ Both successful AND failed attempts studied
● Finally, we progressed towards a finished concept by
working together as a team, using engineering principles to
make design decisions
Washington State University Hybrid Rocket Team 3

4. Advantages of Hybrid Rockets
● Enhanced safety from explosion or detonation during
fabrication, storage, and operation
● Start-stop-restart capabilities
● The ability to smoothly change thrust over wide
range on demand
● Higher specific impulse than solid rocket motors and
higher density-specific impulse than liquid
bipropellant engines
● Relative simplicity which may translate into low
overall system cost compared to liquids
Washington State University Hybrid Rocket Team 4

5. Disadvantages of Hybrid
Rockets● Mixture ratio and hence specific impulse may vary
during steady-state operation
● relatively complicated fuel geometries with significant
unavoidable fuel residues at end of burn, which
somewhat reduces the mass fraction and can vary if
there is random throttling
● Prone to large-amplitude, low-frequency pressure
fluctuation
● relatively complicated internal motor ballistics
resulting in incomplete description, both of
regression rates of the fuel and of motor-scaling
effects, affecting the design of the large hybrid
system.
Washington State University Hybrid Rocket Team 5

6. The Hybrid Engine
6

7. Non-Homogeneous Solids
● Problems with
○ Solid HTPB
○ Low Regression Rate
○ Solid Paraffin
○ Prone to Breakage
○ Low Density
7
● Solution: Non-
homogeneous Fuel
○Increases Regression
Rate compared to
HTPB
○Increases Stability
Compared to Paraffin
○Turbulent Surface
increases regression
Non-homogeneous Hybrid Rocket Fuel for Enhanced
Regression Rates Utilizing Partial Entrainement by Kenny
Boronowsky
Different Compositions Produce Different Results
Washington State University Hybrid Rocket Team

8. Oxidizers
Washington State University Hybrid Rocket Team 8
Red: Toxic or Sensitive
Blue: Low Performance
Black: Best Options
https://aa.stanford.edu/events/50thAnniversary/media/Karabeyoglu.pdf (Slide 21)

9. Properties of Nitrous Oxide
Washington State University Hybrid Rocket Team 9
● Nitrous Oxide (N2O)
○Density: 1.22 g/mL
○Melting Point: -90.8 C
○Boiling Point: -88.5 C
○ Advantages
■ Most Common Oxidizer in Hybrid
Rockets
■ Self Pressurizing
■ Readily Available

10. Motor Review
●Self Pressurizing Oxidizer, N2O
● HTPB/Paraffin Mixture
●Solid Injector Plate for Oxidizer Atomization
●30° Conical Nozzle
Washington State University Hybrid Rocket Team
Picture of Motor Design Here
10

11. Hybrid Motor Performance
●Important Parameters
○Regression Rate
■Higher Mass Flux -> Faster Regression -> More Thrust
○ Chamber Pressure and Temperature
■Dictates maximum thrust from the choked nozzle equations
○ Throat Diameter
■Smaller -> Higher Pressure Build Up and Lower Mass Flow
■Larger -> Lower Pressure Build Up and Higher Mass Flow
Washington State University Hybrid Rocket Team 11

12. Engine Performance Modeling
● EES Modeling
○ Changing Mass
○ Drag Force
○ Velocity
○ Thrust
○ Trajectory
● RPA Modeling
○ Gas Constant
○ Isentropic Exponent
○ Optimized Area Ratio
○ Optimized Fuel Mixture Ratio
○ Used to get Accurate EES Models
Washington State University Hybrid Rocket Team 12

13. Filling The Oxidizer Tank
13Washington State University Hybrid Rocket Team
○ Vent Feed
■ With an open vent in run tank,
there is a pressure difference
between run tank and fill tank
■ Oxidizer flows from high
pressure fill tank to the
atmospheric pressurized run
tank.
■ Vapor is vented through hole
■ When liquid reaches vent,
escaping vapor thickens and
whitens visibly.
■ Vent is closed, fill is stopped,
and run tank is allowed to
pressurize
■ Rocket is launched once
pressure is reached.
http://www.bu.edu/rocket/files/2010/02/The-physics-of-nitrous-oxide.pdf

14. The Injector Plate
14

15. Injector Design
● Our “Injector” is actually just a pattern of holes to
distribute oxidizer flow
● Balancing act
○ Mass Flow
○ Atomization of Oxidizer (Better Burn)
● Created multiple designs to see the effect of hole
size and pattern on fuel regression rate
Washington State University Hybrid Rocket Team 15

16. Injectors
● Testing Five Geometries
○ Single Port = 13/16” hole in center
○ Shower Head = 13 – 1/16” holes in double
circle pattern
○ Single Circle = 8 – 3/32” holes and 1 –
1/16” hole in center
○ Angled = Same as single circle with holes
at 15° angle
○ Cross = holes in a cross pattern with
diameters of 1/16”
● Made from 6061-T6 Aluminum
● Each Plate is 4” wide and .25” thick
Washington State University Hybrid Rocket Team 16

17. Test Set-Up
17Washington State University Hybrid Rocket Team

18. Test Set-Up
18Washington State University Hybrid Rocket Team

19. Video of Injector Testing
Washington State University Hybrid Rocket Team 19

20. Injector Testing
Washington State University Hybrid Rocket Team 20

21. Nozzle
● Material: Graphite
● Manufacturing Method: CNC Mill/Lathe
from Rod Stock
● Cost: Approx. $25/Nozzle
● Conical shape for design/machining
simplicity
● Losses from Conical shape not
significant for our purposes
● Throat Diameter 1”
● Tenting the CNC machine
● Respirators will be required
Washington State University Hybrid Rocket Team 21

22. The Rocket Body
22

23. Nose Cone Design
● Hollow nose cone allows for extra storage space
● Shorter length → less surface area → less drag
● The tip is slightly rounded/rough which is good
for subsonic speeds.
● Balsa wood (density ~7-12 lb / cu. ft)
● FR-4300 series foam (density ~5-15 lb / cu.ft)
Washington State University Hybrid Rocket Team
http://en.wikipedia.org/wiki/Nose_cone_design
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24. Nose Cone Design
Washington State University Hybrid Rocket Team 24
● Sears-Haack
○ Specific geometry based on
the base diameter and length
of the nose cone.
○ The equation for minimal drag
(Mach 2-12).
○ Approved by NASA
○ Would allow a lower center of
pressure than a conical nose
at subsonic speeds
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670030792.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670001472.pdf

25. Fuselage
● Initial Design
○ Phenolic tubing with fiberglass wrap
■ Downside
● Heavy
● Brittle
■ Upside
● Quick
● Easy to build
● Heat resistant
● Attaching
○ Cut and place coupler inside of tube
○ Cut fiberglass to correct perimeter and length
○ Wet fiberglass and set around tubes
Washington State University Hybrid Rocket Team 25
Fiberglasssupply.com

26. Fuselage
● Final Design
○ Carbon Fiber Shell
■ Downside
● Complicated to fabricate
■ Upside
● Extremely light
● Durable
● Heat Resistant
Washington State University Hybrid Rocket Team 26
carbonfibergear.com

27. Clipped Delta
Source: G. Harry Stine. Handbook of Model Rocketry, The (6th Edition). © 1994, Published by John Wiley and Sons, Inc
Washington State University Hybrid Rocket Team 27
Clipped Delta
● Good aerodynamic fin
● Low drag
● High performance rocket
Dimensions
● Span = 2x diameter
● Root length = 2x diameter
● Tip length = diameter
● Root width = 0.1x root length
● Tip width = 0.1x tip length

28. Clipped Delta Design
Washington State University Hybrid Rocket Team 28
Clipped Delta Dimension
D = 4.5 inches
● Span length = 9 inches
● Root length = 9 inches
● Tip length = 4.5 inches
● Root width = .9 inches
● Tip width = .45 inches
Manufacturing
● 3D Printing
● Aluminum
● Outsource
Number of fins: 3 (low drag) or 4 (stability)

29. Clipped Delta
http://www.nakka-rocketry.net/fins.html
Washington State University Hybrid Rocket Team
Attaching Fins
● Fairing
● Compression Fit
● Slots
● Fin Can
29

30. 30

31. The Electronics System
31

32. 32
Launch Box
Valve
Altimeter
First
Altimeter
and GPS
Electronics
Bay

33. Electronics Systems
Washington State University Hybrid Rocket Team 33
● PNP Transistor
○ engage oxidizer valve
● Oxidizer valve
○ Hazardous Location High Pressure
■ 2-Way Normally Closed Valve

34. Electronics Systems
Washington State University Hybrid Rocket Team 34
● Secondary Altimeter
○ backup tracking
● GPS
○ AIM XTRA GPS flight computer
○ Altimeter included
○ disengage valve
○ Deploy Chutes

35. Electronics Systems
Washington State University Hybrid Rocket Team 35
E-Match
● Material: Wire and Pyrogen
● 2 or more the Post Combustion Chamber

36. The Recovery System
36

37. Recovery Systems
● Ejection System
○ Deployment method
■ CO2 Cartridge Charge
● Reusable, no open flame
○ Simple nose cone ejection
○ Tender Descender
Washington State University Hybrid Rocket Team 37

38. Recovery Systems
●Drogue chute
○24 inch elliptical
○83 fps descent
●Main Chute
○96 inch elliptical
○21 fps descent
Washington State University Hybrid Rocket Team 38

39. Oxidizer Tank/Combustion Chamber
Coupling
●Initial design was flange/bolt pattern with silver solder
○Cannot silver solder aluminum
○Extremely heavy
○Large Factor of Safety
●Redesigned to use threads instead of large bulky bolt
pieces
○Cut the Factor of Safety from 3 to 2
○Cut the weight significantly
○Cut drag significantly
Washington State University Hybrid Rocket Team 39

40. Parts Ordered
Washington State University Hybrid Rocket Team 40

41. Future Estimations
Washington State University Hybrid Rocket Team 41
Estimated Total = $2742.94

42. WHAT HAVE WE
DONE!?!?!?
● Manufacturing the motor
○ Combustion chamber
○ injector plates (5)
○ Coupler
● Testing
○ Low pressure water tests
○ Leak test
● Difficulties
○ Testing required more preparation than initially
considered
○ Neglected Recovery & Electronics in an effort to get
motor finalized
Washington State University Hybrid Rocket Team 42

43. Summary
● Hybrid Engine
○ Regular Configuration (fluid
oxidizer solid fuel)
■ Fuel: 70% HTPB 30%
Paraffin Wax
■ Oxidizer: Gaseous
Nitrous Oxide
○ Single Circle injector plate
○ Conical Nozzle
● Rocket body
○ Carbon Fiber fuselage
○ Haack Series Balsa Wood
Nose Cone
○ OD 4”, ID 3.75”
○ Total length ~8’
○ 4 clipped delta fins
Washington State University Hybrid Rocket Team 43
● Recovery
○ Single deployment
■ CO2 Ejection Device
■ Tinder Desenser
○ Drogue chute
■ 24 “elliptical
○ Main Chute
■ 96 “elliptical
● Electronic Equipment
○ Hazardous Location High
Pressure 2-Way Normally
Closed Valve
○ PNP Transistor
○ AIM XTRA GPS & Altimeter
○ AltimeterTwo
○ E-Match

44. Thank you!
Washington State University Hybrid Rocket Team 44