At one time in my career at Autonetics, I was assigned the task of designing, building, and testing a miniature version of the G6 gyro, used even today as part of the Minuteman missile . I was tasked to design the gyro to include as many performance enhancing features as I could find space for. The yet to be designed gyro was designated as the G22 gyro. It was a dream assignment for me for sure.
Over the years, I had developed an informal ‘list of improvements’ I would try to incorporate into any free rotor gyro design projects I was associated with. These ‘improvements’ were the result of my belief that our free rotor gyro designs should be based on the principles of simplicity, symmetry, smoothness, purposeful cancellation of error sources, and balance between energy centers. Except for the mandate that the gyro was to be a small free rotor gyro with a spherical gas bearing, ie, a miniature G6 gyro, I had a clean sheet of mylar to lay my gyro design on. My dream assignment had a darker flip side but I did not pay much heed to the details of that part of the task as there was nothing I could do to mitigate these conditions. The drawings would be made by my long time associate, Antonio ‘Tony’ Carrenza, and I would have access to experts with many years of experience in designing motors, torquers, electronics, gas bearings, test equipment, and tools. Tony and I literally started with a blank Mylar sheet. He laid out the gas bearing and we designed our little gyro around it using the principles listed above. I sometimes wonder what became of this drawing.
It had been my experience that the machining tolerances of the component parts of our gyros were too restrictive and did not adequately take into account surface finish. I also had questions about the statistical assumptions that were made as part of the tolerence setting process. I remember trying to set tolerances that were loose enough to not require otherwise unnecessary smooth surfaces and at the same time protected the interchangeability of mating parts. The contour of the interior and exterior surfaces were of concern as they were often the determining factor in the selection of the machining process. It was my goal to keep the machining of the gyro parts as simple as possible.
I remember spending a lot of design time on the motor and torquer interface of the gyro to maximize the symmetry between the motor and torquer halves in keeping with my belief in energy balance. I believed that a successful design requires that symmetry with respect to the center of the gyro be maximized and I believed that deleterious effects often cancelled each other out and it was to facilitate this that symmetry across the center line of the gyro was sought.
The fill gas rotated at speeds in excess of 100 mph and the ‘smoothness’ of the interior space of the gyro presumably had a lot to do with the turbulence of the gas and the random drift of the gyro. The proximity of the interior surfaces to the rotor was balanced between closer for laminar gas flow and further away to minimize drag on the rotor. I remember consulting with our gas bearing expert on how much drag we would have for a given interior space configuration.
In keeping with my goal of symmetry across the gyro centerline, I had Tony design the motor and torquer halves to be as similar as possible. The most obvious difference between this and previous designs was the addition of a speed control pickoff to the torquer half. This was done to balance the spring rate effects of the case-to-rotor angle pickoff in the motor half of the gyro. The G6 gyro had a low spring rate due to to fortuitous spring rate cancellation effects and it was planned the G22 would benefit from this as well.
After six months of work, the technicians in the cleanroom were close to final assembly of the first gyro when I had a visitor. He held the title of Chief Scientist and a Phd. degree. I knew him as a fairmined person and I respected him. He was there to hear from me about the work we were doing in bring the design of the G22 to a successful conclusion. I told him the complete story of the work, warts and all. When I finished, he knew in detail what I knew. He then explained that he was reviewing all IR&D projects with the objective of eliminating those deemed not in line with current IR&D needs. My G22 project was on the block because the G22 was an ‘orphan’ gyro, ie, it did not have a designated system use at Autonetics. That was the dark side of the project that I referred to earlier. Shortly after, I was told that my task was ended and I was to stop all work except that necessary to bring about an orderly end to the project. Since the Government owned everything, everything pertaining to the G22 project was boxed up and shipped to ‘who knows where’.
That is why you never heard of the G22 gyro and why I will never know if we would have been successful in meeting our design goals. It is like an itch you cannot reach to scratch – frustrating!