On June 26, 2014, the Society for Advanced Rocket Propulsion
(SARP) rocket team launched its high-power rocket
at the 9th Annual Intercollegiate Rocket Engineering Competition (IREC)
hosted by Experimental
Sounding Rocket Association (ESRA). The high power HTPB/N2O hybrid
rocket reached an altitude of 7000 feet at a velocity of 1100 ft/sec
and was on track to reach the desired 25,000 foot elevation before the
thrust chamber burned through and structurally failed. All components
of the rocket were recovered. The team received the Jim
Furfaro Award for Technical Excellence.
Propellant
I had a number of duties over the course of the year as we designed our
rocket. One of the first tasks that the Propulsion team needed to
finish was to determine the propellant composition. We decided on
a HTPB/Paraffin Wax/Aluminum Powder fuel with Nitrous Oxide (N2O)
oxidizer. To determine the best ratio of HTPB to Paraffin, numerous
small-scale fuel grains were made with different amount of each, and
then tested in a subscale motor.
To create the fuel grains, the fuel mixture was mixed and then poured
into a phenolic liner and placed on a lathe to cool/harden.
Carbon powder was added to the mixture to reduce thermal transport
during the burn and minimize the risk of sloughing.
Instrumentation
Two sensors were utilized for the hydrostatic testing: a pressure
transducer and a force sensor. I
assisted in choosing an NI DAQ to use and helped set up the LabView VI
for data
collection.
Testing
We started the testing process using a subscale thrust stand.
The goal was to determine the thrust and pressure produced by each fuel
composition, and also determine the regression rate of each fuel so
that the
performance of the full-scale motor could be predicted. The subscale
motor
produced around 100 lbf of thrust.
Once a fuel composition was decided upon, testing
progressed
to full-scale burns. The full scale motor produced roughly 1000 lbf of
thrust
during testing, as predicted.
Lessons Learned
I learned a lot about using instrumentation and
sensors, how hybrid rockets work, and that I really enjoy running
hardware tests. In addition, I gained more experience with working with
a team, and how to enjoy an experience even in the midst of failure.