1. Optimisation of the SPARTAN’S Scramjet Combustor
David Voller
“Astronomy compels the soul to look upward,
and leads us from this world to another.”
- Plato, The Republic, 342 BCE
[1]

2. Rocket Propulsion
•Current launch systems are dominated by rocket
propulsion
•Current rocket technology is operated close to
theoretical limits [4]
•~65% oxidiser and ~25% fuel mass fractions [3]
•The Saturn V weighed 2.72 million kg
•Liquid Oxygen: 1.81 million kg (~65%)
•Payload: 115000 kg (~4%) [3]
[2]

3. Scramjets For Access To Space
•Proposed use of airbreathing propulsion
•Takes advantage of increased specific impulse
•The idea of using scramjets for access to space systems
has been around since the mid 20th century [3]
•UQ’s Centre for Hypersonics has been developing the
SPARTAN which will take advantage of the rocket-
scramjet-rocket access to space system [6]
[5]

4. Scramjets: How do they work?
•Kinetic energy converts to internal energy
through oblique shocks
•Increases pressure, density, and temperature
of flow
•Compressed flow is mixed with injected fuel,
generally hydrogen
•Combustion, spontaneous or ignitors used
•Expansion to accelerate supersonic flow [3]
[7]

5. SPARTAN
•A feasibility study which investigated a rocket-
scramjet-rocket system was conducted in 2009 [8]
•Concluded that approximately 100kg could be
delivered to a 200km equatorial orbit with a mass
payload fraction of approximately 1.5% [8]
•Further design iterations suggest a payload mass
fraction of 1.26% for a launch taking 260kg to sun
synchronous orbit [9]
•SPARTAN 11.4% fuel mass, conventional rocket
systems ~90% fuel mass [9]
[6]

6. SPARTAN Scramjet Designs
•Re-usable second stage which is based on winged cone vehicle
(WCV) developed by the US National Aerospace Plane Program [9]
•Initial design uses RESTM12 Engine: start up Mach number of 6 [8]
•Further design iterations see the development of an inlet
optimised for the WCV (C-REST), the trajectory, and first and third
stages
•Further optimisation of the second stage scramjet engine will
mature the SPARTAN [8]
[10]

7. Lowering Start-up Mach Number
•Lowering the start-up Mach number allows the engine
to take advantage of higher air densities
•Constant dynamic pressure can be achieved lower in
the atmosphere. Results in higher thrust per unit
frontal area [5]
•Evaluate proposed engine design for operation at
Mach 5
•Optimisation through changing area distribution of
the combustor
[8]Current Combustor Schematic

8. Modelling
• Develop a script to model the scramjet combustor. Use for
validation against DMCycle
•Distribution of flow properties assists in understanding the
effects of area distributions throughout the duct
•Creating a script develops understanding of scramjet
modelling techniques. Allows for results to be understood and
realistic suggestions to be made
•DMCycle takes into account changing chemistry (e.g.
molecular weight, specific heat ratio)
•Utilize DMCycle script to calculate uninstalled thrust, and
scramjet performance
Attached Flow through Isolator and
Combustor (Smart, 2007) [5]

9. Scramjet Analysis
•Quasi-one dimensional analysis
•Numerically solve differential equation which describes the Mach
number distribution through the duct
•ODE developed using physical equations describing the
differential element provided to the right
•Integral relations are utilised to determine required flow
properties (Temperature and Pressure)
Assumptions:
•One dimensional, steady flow through the scramjet combustor
•Changes in stream properties are continuous
•Constant chemistry (Molecular weight, specific heat ratio)
Differential Element of Duct Flow[5]

10. Solution Method
•Shapiro’s differential equation simplified using previous assumptions [11]:
𝑑𝑀2
𝑀2
= −
2 1 +
𝛾 − 1
2
𝑀2
1 − 𝑀2
𝑑𝐴
𝐴
+
(1 + 𝛾𝑀2) 1 +
𝛾 − 1
2
𝑀2
1 − 𝑀2
𝑑𝑇𝑜
𝑇𝑜
+
4𝑓𝛾𝑀2 1 +
𝛾 − 1
2
𝑀2
1 − 𝑀2
𝑑𝑥
𝐷
•The Mach number and the specific heat ratio (𝑀, 𝛾) are known the differential equation can be
expressed in terms of constants B, C, and D to help visualise the problem:
𝑑𝑀2
𝑀2
= −𝐵
𝑑𝐴
𝐴
+ 𝐶
𝑑𝑇𝑜
𝑇𝑜
+ 𝐷
𝑓𝑑𝑥
𝐷
•Evidently, each term is dependent on a different effect. Area change, friction, and heat addition

11. Creating Script and Validation
•Validate Fanno Flow, Rayleigh Flow, and Isentropic area
change cases, using compressible flow tables [11]
•Implement each solution into one script which solves for flow
in a duct with competing friction, heat addition, and area
change
•Use script to produce a model of a scramjet which has
already been conducted using DMCycle for validation of the
complex script
Fanno Flow Validation Plots

12. Conclusions
•Implement burner solution with all effects
•Validation against DMCycle
•Modelling proposed combustor design at Mach 5
and evaluating performance
•Optimising the design using differing area
distributions
•Provide suggestions for optimal combustor designs
for operation at Mach 5
•Contribute to the future of access to space
systems!
NASA & Boeing’s X-51 Waverider [12]

13. Reference List
[1] https://wallpaperscraft.com/download/space_planet_ship_art_star_73877/1920x1080
[2] http://www.wallpapervortex.com/wallpaper-18574_rocket_launch_space_shuttle_launch.html#.V9ssgCh96M9
[3] William H Heiser and David T. Pratt. Hypersonic airbreathing propulsion. 1994.
[4] Thomas Jazra, Dawid Preller, and Michael Smart. Design of an airbreathing second
stage for a rocket-scramjet-rocket launch vehicle. 2013.
[5] Michael Smart. Scramjets. 2007.
[6] Launching Australia into Space”. 2015. https://www.uq.edu.au/news/article/2015/08/launching-australia-space
[7] https://upload.wikimedia.org/wikipedia/commons/b/b8/ScramjetDiagram.gif
[8] Michael K. Smart and Matthew R. Tetlow. Orbital delivery of small payloads using
hypersonic airbreathing propulsion. 2009.
[9] Dawid Preller and Michael K. Smart. Scramjets for reusable launch of small satellites. 2015.
[10] https://hapb-www.larc.nasa.gov/Public/Engines/Rest/98L02289r.jpg
[11] Ascher H. Shapiro. The dynamics and thermodynamics of compressible fluid flow. V1,1953.
[12] “X-51 Waverider ‘SCRAMJET’ Test Flight Fails”, 2015, http://www.universetoday.com/96829/x-51-waverider-scramjet-test-flight-fails/