טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSchreiber Ilanit
SubjectExperimental Investigation of a Hybrid Motor with Nitrous
Oxide Oxidizer
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Emeritus Alon Gany
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

Hybrid motors demonstrate major advantages compared with other types of rocket motors (high energetic performance, increase safety, system simplicity, lower cost, non-toxic and “environment friendly” products).

Hybrid motors have been around for more than 80 years, but until recently did not play a major role in significant projects. The interest in hybrid propulsion rejuvenated after the space shuttle Challenger disaster in 1986, particularly due to their higher safety.  It has become a more significant player in the rocket propulsion arena, especially for the future space tourism vehicles. Recently hybrid rocket motors employing the oxidizer nitrous oxide (N2O) have been drawing more and more attention as they are being implemented in some of the latest space vehicles, such as “SpaceShipOne”, its successor “SpaceShipTwo” (space plane designed for space tourism), and the latest “Dream Chaser” (safe, reliable commercially-operated transportation service for crew and cargo to the International Space Station and back to Earth). All the propulsion systems for these projects were developed by Sierra Nevada Corporation and use N2O/HTPB propellants.

Although there is an increased use of nitrous oxide as an oxidizer in the industrial private sector, it seems that not enough work has been published with regards to the engine’s performance.

The objective of the present research was to perform an experimental investigation on the energetic performance, combustion efficiency, and fuel regression rate in hybrid motors employing nitrous oxide oxidizer and PMMA polymeric fuel.

Around 100 static firing tests in a laboratory system were carried out during the research, conducting 14 test series, where each series included 4 to 6 firings.  Each firing test lasted about 5-8 seconds. Chamber pressure, oxidizer flow rate, thrust, and fuel mass loss were measured.  The measured parameters allowed to calculate and to present the motor energetic performance, combustion efficiency, and fuel regression rate with a comparison to theoretical calculation and/or known experimental data from the literature.

Comparing the experimental data with theoretical performance it was found that almost 60% of all the firing tests demonstrated over 90% efficiency for both Isp and C*.