Delta-Phoenix Rocket Project: On Saturday, May 21, 2005, the San Diego State University student rocket project launched the Delta-Phoenix, a 1000 lbf. thrust liquid bi-propellant rocket, in the Mojave desert. The launch proved to be spectacular and dramatic. Some preliminary videos and pictures are posted on the SDSU Rocket Project website. The SDSU rocket project website is in the process of being updated so periodically check back.

The rocket is based on the LR-101 motor used on the Atlas rocket for attitude control. It is a regenerative cooled engine, which means the fuel is circulated around the motor casing to cool it. The LR-101 burns liquid oxygen (LOX) as its oxidizer and aviation kerosene (Jet-A) as its fuel. High pressure helium is used to pressurize the two propellants. The propellants are stored in two stainless steel tanks. These tanks are custom made from surplus fire extinguishers. They are hydro-tested several times to over 600 psi. The LOX tank has a 9 gallon capacity and the Jet-A has a 6 gallon capacity. The high pressure helium is stored in a composite cylinder rated at 4500 psi. The helium is regulated from the cylinder through a pair of high-flow pressure regulators. The LOX helium supply is regulated to 525 psi and the Jet-A helium supply is regulated to 485 psi. Each tank has a pressure relief and pneumatically actuated vent valve. Both tanks supply propellant to a pair of pneumatically actuated ball valves. The LOX ball valve initiates a sequence valve which initiates the actuation of the Jet-A valve; this assures the proper sequence of propellants entering the combustion chamber.

The rocket's airframe is composed of four 1-inch square aluminum extruded stringers joined to 11 wood bulkheads. The entire airframe is covered with 0.025 inch aluminum skin which is pop-riveted to the stringers. Aluminum hatches were installed near critical or serviceable components. The fins were made from epoxy/carbon-fiber covered balsa wood. The nosecone was purchased commercially. The recovery system consisted of a 60" X-style drogue and a 18' diameter main parachute. The nosecone had it's own 48" diameter parachute. The activation of the recovery system was done with two G-Wiz fight computers.

The rocket was transported to the RRS-Mojave Test Area the day before the launch. It under went final assembly, integration and checkout Friday evening. On Saturday morning the parachutes and recovery systems were installed and armed. All pre-launch activities went very smoothly. The Delta-Phoenix rocket would be second that day to launch after the CSULB P6 rocket .

Sometime in the early afternoon the Delta-Phoenix was carried to the 50' tall mobile launch rail. Jet-A fuel was loaded first and then LOX was loaded. In the final minutes a regulator failed that was used to actuate the GSE (ground support equipment). CSULB was kind enough to lend us a regulated cylinder of air and we were back on schedule. High pressure helium was then remotely loaded onto the rocket. The remote disconnect of the helium fill line failed to actuate and had to be manually disconnected. Road and air checks were made and a 10 second count down began. At T-5 second the pyro-lance igniter was lit.

Winds were light (0 to 5 mph), temperatures were around 100 F and skies were clear. Perfect weather for a launch. At T-0, the rocket motor roared to life perfectly, however, as the rocket started to move up the launch rail the exhaust plume immediately diminished to about 1 or 2 feet long. When the rocket was just about to leave the launch rail, the exhaust plume suddenly grew to over 20' long. After leaving the nearly vertical rail, the rocket arched over and began to fly a rather flat and level ballistic trajectory. The motor burned for ~15 seconds and the rocket impacted the ground 18.1 seconds into the flight at a shallow angle. There was no indication that the recovery systems were initiated. A small brush fire started and was quickly put out. The point of impact was 0.98 miles due south-southeast of the launch site. The debris field covered about a quarter of an acre. All debris except the helium tank was recovered and hauled away. The peak altitude determined from the telemetry data was ~800 feet.

Post video and data analysis and inspection of the motor (recovered intact) showed that the motor experienced an anomaly. At ignition, it is believed that rust was liberated from the internal fuel passages in the motor and partially blocked the fuel manifold ports on the injector plate (a screen filter prevented the fuel injector holes from being clogged directly). Post inspection of the motor found small rust fragments in the fuel manifold just prior to entering the injector plate. At this point 25 GPM of LOX and only a small amount of fuel are flowing into the combustion chamber. Since the motor depends on significant fuel flow through it's internal passages for cooling, the throat section of the nozzle experienced a burn through. This can be seen on the flight videos when the rocket is just about to leave the rail and the exhaust plume instantly grows to about 20'. It seems that the burn-through in the motor nozzle caused significant thrust asymmetry which was most likely the reason the rocket arced over when it left the launch rail. Also, from the acceleration data obtained by the telemetry the motor never developed the full thrust except for the brief moment after ignition (~15-20 msec). Using the average mass of the rocket through out the flight the average thrust of the rocket was estimated to be about 350 to 450 lbf, far below the nominal 1000 lbf. The motor was donated to the project by the San Diego Aerospace Museum. It's history was unknown and there is speculation that it was from the Atlas that used to stand in front of the Convair building in San Diego for 30+ years.

Special Thanks:
Thanks to Dave Crisalli and the Reaction Research Society (RRS), Kevin Baxter and Friends of Amateur Rocketry (FAR), Paul Breed and NetBurner, the San Diego Aerospace Museum, 3Dyn, F&B Performance Engineering, John Garvey, Mike Novratil, B&M Machining and Welding, Shadow Aero, the entire staff at Flometrics, the SDSU Aerospace Department, Stig Johannson, Dr. Joe Katz.

Also, Joey Brown will be stepping down as the SDSU Rocket Project leader. Joey graduated in May and has taken a job at JPL. We wish him the best of luck there. Victor Sanchez will be taking over as the new Rocket Project leader and is already demonstrating his ability to excel. Look for exciting things to come!

If you have any questions or would like to support the project please contact one of the following:
Victor Sanchez, rocketsanchez@gmail.com
Steve Harrington, sharring@flometrics.com
Carl Tedesco, ctedesco@flometrics.com

--- Carl Tedesco