This document discusses the application of a multi-objective genetic algorithm for the conceptual design of single-stage rockets utilizing hybrid propulsion systems. It highlights the benefits and characteristics of hybrid rocket engines, compares them with solid and liquid rockets, and presents design optimization problems. The results indicate that while multi-combustion does not significantly enhance altitude or duration, it effectively minimizes maximum acceleration.

1. Masahiro Kanazaki
Tokyo Metropolitan University
Atthaphon Ariyarit
Tokyo Metropolitan University
Kazuhisa Chiba
Hokkaido Institute of Technology
Koki Kitagawa
Japan Aerospace Exploration Agency
Toru Shimada
Japan Aerospace Exploration Agency
Multi-objective Genetic Algorithm Applied to
Conceptual Design of Single-stage Rocket
Using Hybrid Propulsion System
The Eighth China-Japan-Korea Joint Symposium on Optimization of Structural and Mechanical Systems
○
May 25-29, 2014, Gyeongju, Korea

2. Background1 What is hybrid rocket engine?
2
Beneficial feature of HRE
・Low cost due to simple stricture
・Stop and restart of combustion⇒
Control・Safety
Hybrid Rocket Engine(HRE) ：
rocket which stores fuel and oxidizer by different phases.
Solid fuel + Liquid oxidizer :

3. 3
Background2 Difference compared with existent rocket
 Solid rocket
 Liquid rocket
 HRE：Fuel and oxidizer are mixed after the ignition is initiated.
→ Fuel and oxidizer are preliminary mixd.
 Several parameter should be optimized for suitable
combustion → Design using heuristic approach
 Multi-combustion by the control of the oxidizer supplement
Solid fuel rocket
Liquid fuel rocket

4. Backgourng3 multi-combustion
 Stop/restart of combustion during total combustion time
Maximize down range by coasting
Minimization of maximum acceleration
Maximization of duration time over the target
altitude
4
Off
On On

5. 5
Contents
 Background
 What is hybrid rocket engine?
 Multi-combustion
 Objectives
 Design methods
 HRE design using evolutionary algorithm
 Formulation
 Maximization of altitude and minimization of gross weight(problem1)
 Minimization of maximum acceleration and minimization of gross
weight (problem2)
 Maximization of duration time over target altitude and minimization of
gross weight(problem3)
 Results and discussions
 Conclusions

6. Objective
Design exploration of launch vehicle
(LV) using HRE which can carried out
multi-combustion
Discussion of beneficial feature via several
design problem
Non-dominated solution by genetic algorithm (GA)
Comparison between HRE w/ multi-combustion
and w/o multi-combustion
6

7. Design method1/2
Overview of evaluation process of HRE
7
 tGatr n
oxiport )(
K., Kosugi, A. Oyama, K. Fujii, and M. Kanazaki.,
"Multidisciplinary and Multi-objective Design
Exploration Methodology for Conceptual Design of
a Hybrid Rocket," Infotech@aerospace2011, (2011)
AIAA 2011-1634

8. Design method2/2
Optimizer and visualization
 Non-dominated Sorting Genetic Algorithm-II
(NSGA-II)
20populations and 200generation
Parallel coordinate plot : PCP
8
Evaluation of LV

9. Formulation1/3
Problem1
Maximization of maximum altitude (Altmax)/
minimization of gross weight(Mtot)
9
Design variables for LV
Design variables for multi-combustion
L/D：Aspect
ratio of vehicle

10. Formulation2/3
Problem2
Minimization of maximum acceleration(accmax)/
minimization of gross weight(Mtot)
10
MT-135
（JAXA’s rocket for weather observation（Altmax=60 km））
Alttarget：target altitude
Design variables for LV
Design variables for multi-combustion

11. Formulation3/3
Problem3
Maximization of duration time over Alttarget(Tduration)/
minimization of gross weight(Mtot)
11
Design variables for LV
Design variables for multi-combustion

12. Result1/8 12
Non-dominated soluitions（Problem1）
Maximization of Altmax minimization Mtot
Similar result
Difference for high
altitude
50generations100generations150generations200generations

13. Result2/8
Design Space(problem1)
Similar trend in design space
Interval time of combustion dv8(tinter) is almost
zero. →Multi-combustion has not been required.
w/o multi-combustion w/ multi-combustion

14. Result3/8
Problem1
Multi-combustion is not effective
for maximization of Altmax
→ Altmax is only reduced by
the temporal stop of combustion.
14

15. Result4/8
Non-dominated solutions（Problem2）
Minimization accmax and minimization Mtot
15
accmax is reduced by
multi-combustion
50generations100generations150generations200generations

16. Result5/8
Design space(problem2)
Trend of dv4(tburn) is different between two cases.
Sorting by accmax，difference of dv5(Pc) could be
observed.
Due to multi-combustion，accmax could be reduced.
w/o multi-combustion w/ multi-combustion

17. Result6/8
Design space(problem2)
Colored by dv7(tstop) (w/ multi-combustion)
)
Correlation between
dv4(tburn)，dv8(tinter)

18. Result7/8
Problem2
Acceleration is stopped, when
the combustion is stopped.
Convergence of MOGA is not
good because it is difficult to
satisfy of the constraint
regarding the altitude.
18

19. Result8/8
Non-dominated solutions（Problem４）
Maximization Tduration and minimization Mtot
19
Difference is little.
200generations

20. Conclusions
Design exploration for the LV using HRE
which can carried out multi-combustion
Evaluation for HRE which can carried out multi-
combustion has been developed
Design problem evaluation by solving several
deign problems
Multi-combustion is not effective to maximize
the altitude/ the duration time.
Better solution could be obtained by the multi-
combustion in the minimization of maximum
acceleration.
20