This rocket is part of a line of rockets that we have been developing in order to promote our rocket fuel pump technology. Our eventual goal is to reach an altitude of 100 miles with an amateur rocket. This rocket will be the first amateur liquid fueled rocket with attitude control. The technology developed in this rocket will be applied to a follow on rocket that will include our rocket fuel pump technology to achieve a high mass ratio. The mass ratio (fueled weight/empty weight) is the key to high performance. By using a fuel pump instead of heavy pressurized tanks, a liquid fueled rocket can achieve the high mass ratios needed to achieve orbit.

This rocket will use an engine gimbaling system that we have already tested. An aircraft artificial horizon gyro will be used for attitude reference.

This latest rocket is based on the previous rocket that flew well but had no control. This one uses an electric airplane gyro with autopilot outputs. The Humphrey Gyro requires 115V AC 400Hz, so we made a car stereo power booster into an inverter. A small oscillator is used to drive the low level inputs on the power booster. The output of the power booster (13V AC 400 HZ) is used to drive a couple of 400 Hz 26V to 115V transformers in series. The gyro has synchro outputs that are rectified and filtered to to provide a signal to the control circuit (1-volt DC for each 10 deg of pitch or roll). This signal is used to drive a comparator which controls a number of solenoid valves which in turn move hydraulic cylinders to move the engine. Position feedback is used to monitor the engine angle.

^ Figure 1: The 400 Hz Inverter and the gyro for the rocket

The control system is designed so that most single point failures will result in the engine returning to the straight position. Even so, for safety the gimbaling system will not be activate until after the first few seconds of the flight, and it will be launched from a rail. Once we gain more experience and confidence in the system, we will increase the mass ratio of the rocket with additional fuel and install one of our rocket fuel pumps see www.rocketfuelpump.com.

^ Figure 2: The gimbaling system

Figure 2 shows the gimbaling system. For this first flight of the gimbaled engine, we will leave the fins on to provide an added margin of stability during flight.

^ Figure 3: Working on the details of the rocket assembly

This rocket has a great deal of tubing on it to control the engine gimbaling. A hydraulic schematic (pdf 20K) is available. The valves are placed near the top to keep the rocket stable for the portion of the flight when the gimbaling is not yet activated. The recovery system is based on the proven Kimbo design. The retractable launch lugs and fire extinguisher fuel tanks are based on those used on Tom Mueller's Condor rocket. The air cylinder activated Helium Quick disconnect was Dave Crissalli's idea.

We are going to launch on September 21, 2002, provided there are no weather or mechanical problems. Contact Steve Harrington at Flometrics for more info or if you want to attend the launch.

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