THIS IS A TEST


I present this image as a test of your modeling sensibilities. I assert that you lack the ‘right stuff’ to become a true modeler of railroad rolling stock if you heart does not  skip a beat when you see this image. It has it all! The flatcars can be easily modelled from readily available cars and the ‘big watchmacallit’ on the cars is simple to model. Have fun! 

MY MOTHER AND HER DAD


MY MOTHER AND HER DAD

I believe this photograph was made when my mother was three years old. I further believe  it was taken on the occasion of her adoption by the Powell family. Her mother had died and her father could not care for her. I do not believe she ever saw him again. He died the year I was born, in 1932. My mother was born in the town of Olds. This town is located in Alberta Province, Canada. I consider myself as half Canadian and half US citizen. I think I can see something of my brother Don in my grandfather’s visage. I can see my sisters in mom’s face. We have a large number of cousins we have never met who live in British Columbia, Canada.

WHY YOU NEVER HEARD OF THE AUTONETICS G22 GYRO


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! 

 

 

THE HOME FRONT IN 1943


Here is proof that Norwalk was ready for anything during WW II. We had just returned from a mission when this photograph was taken. 

THE SPELLING TEST


Before there was an N73 system there was an N57 system, Like the N73, it was a strapdown system. In the simplest of terms, a strapdown system is one without gimbals. Too simple! In an ordinary Inertial Navigation System (INS), the stable platform, or instrument cluster, is kept at local level by torquing the gyros to keep the sensitive axis of one of the accelerometers pointing towards the center of the Earth. Since it is impossible to keep the  vehicle carrying the INS level at all times, a means of allowing the INS to stay level and at the same time allow the vehicle to maneuver is required. The motion of the vehicle is decoupled from the INS stable platform by a set of gimbals. A strapdown INS is one in which the entire INS is fixed to the vehicle and rotates with it. Now you know. The decoupling is done mathematically in the computer. This was the new world I was to work in until I retired. The input/output device for the N57 computer was an IBM selectronic typewriter. I never learned to type and I am very slow. That, plus the fact that instructions to the computer must Be 100 % correct every time. Bad things tend to happen otherwise. I had barely started in my new job when I was asked to input a set of instructions to a computer in order to initiate a test sequence. The instructions were typed out on a sheet of paper and I slowly and methodically typed them into the IBM typewriter. I pressed “enter” to start the process. It was the end of the workday and we left. It was expected the test would run that night and be completed when we came the following day.

I came in the next morning and found out the test had not even started. It was my fault, I was told, because I had  misspelled a word in the instruction sequence. Not good! I went and made my apology to the engineer who ordered the test and who had given me the typed instructions. He was a little miffed because he had lost a day of testing because of my mistake. I went back to my other work knowing I had not made a friend of the engineer. Later that day , I was approached by the engineer whose test I had screwed up and he began to apologize to me for incorrectly accusing me of screwing up his test. I was confused by the turn of events until he got the part where he admitted that he had misspelled the instructions he had given me for entry into the computer. I felt sorry for him as he turned himself inside out playing a part that was clearly unfamiliar to him. It was a long time before our relationship became normal. I do not know what was worse for my feelings, being the goat or the vindicated goat. Both ways, I felt bad.

 

GETTING CLOSER TO THE PICKEL BARREL


There was a period of time when I was assigned to work with the Group that had design responsibility for the G6 gyro. Ray Noar, the Manger of  the group, was an expert on the subject of the G6 gyro having been the Responsible Engineer for the gyro prior to his becoming a Manager. The G6 gyro was used on the Minuteman I, II,and III missile. I believe it is still in use on the MM III missile. We were to consider ways to improve the G6 gyro’s performance. I have a vague recollection of a larger effort to improve the accuracy of the Minuteman III missiles and we were part of that. We used the Minuteman INS error budget as a guide to rank possible improvements in gyro performance and consequently we were looking at ways to reduce gyro ‘random drift’ and ‘gas bearing model’ errors. The ‘random drift’ of the G6 gyro ensemble was well known because the random drift rate of each gyro produced was measured during the acceptance testing of the gyro, but we realized a reduction of the INS error due to gyro random drift would require a much better understanding of the mechanism of random drift within the gyro beyond a suspicion it was somehow related to gas flow inside the gyro.

The speed of the gas flowing inside the gyro was in excess of 100 mph due to the friction between the gas and the spinning rotor. Ray believed that if we could learn how this gas flow was related to the random drift rate, we could find a way to reduce the random drift rate of the gyro. The big question before him was how to the visualize and measure the turbulent effects of a gas moving ever 100 mph. Ray’s approach was simple; he slowed the process down by substituting a fluid for the gas. This fluid would have a viscosity such that when rotated at a much slower speed than 100 mph, the Reynold’s number would be the same as that of the gyro fill gas. The turbulence of the fluid was made visible by mixing powdered aluminum with the fluid. This was all done inside a clear plexiglass full scale mockup of the gyro that permitted high speed photography as the means to record the fluid flow dynamics. Using this apparatus, Ray was able to “see” the formation and subsequent history of vortices in the fluid. By studying the patterns of turbulence in the fluid, he came to the belief that controlling these vortices was the key to reducing the random drift rate. His idea for vortex control was to place channels adjacent to the locations where the vortices started forming and thus contain them. He was instrumental in the design of the channel inserts that became part of the improved gyro. I believe the addition of these channels reduced the random drift rate of the gyro, but I do not recall by how much. It was amazing to watch a vortex form, detach and dissipate adjacent to the rotor surface. As I recall, he also devised a better way to calculate random drift from the raw test data.

The drift rate of the gyro changed as the acceleration of missile launch loaded the gas bearing of the gyro. A mathematical model, based on an earlier analysis by Stan Cogan, was used to predict the acceleration dependant drift rate changes and inflight real time corrections were made to the computed flight path of the missile being launched. The G6 gyro ensemble averages of the gyro’s sensitivities to acceleration and acceleration squared were the basis for the calculation of the corrections to the flight path. It was thought that if a practical method could be found to additionally measure the individual gyro’s sensitivity to acceleration to the fourth power, and if this and the individual, not the ensemble average, gyro’s measured sensitivities were used, that improvements in missile accuracy would be realized.

The gyro acceleration and acceleration squared sensitivities were already being measured during acceptance testing of each gyro. No comparable tests for higher order gyro sensitivities was available. I was working in the test laboratory developing new G6 gyro test methods that used a “linear vibrator” machine. This was a machine that imparted horizontal motion to the test gyro without rotation input. For these tests the gyro was mounted on the machine with the gyro spin axis in the horizontal plane. The angle between the test motion input axis and the rotor spin axis could be set at a predetermined  fixed angle. Gyro drift rates over a range of acceleration inputs were then measured for each of several fixture angles. These data were then used to calculate the gyro model coefficients. I had barely started to acquire test data when I was offered a position with the Group developing a new strapdown system that was based on the Autonetics Electromagnetically Suspended Gyro (ESG). I quickly accepted the offer and I turned over my G6 gyro work to others to complete. The development of test methods to measure the higher order model coefficients continued and an improved version of the G6 gyro became part of the Minuteman III INS. I was in effect starting a new career as a test engineer for strapdown systems.

 

 

 

 

 

CRUD! IF IT IS ONLY AN ACRONYM, WHY WON”T MY BEARING START?


I was introduced to crud a short while after I was introduced to the spherical gas bearing. (This bearing was the engineering tour de force at the literal and metaphorical center of the Autonetics G6 and G9 gyros.) I do not recall the exact circumstances of my first experience with a gas bearing, but it is very likely one which  involved a bearing which had failed to start rotating after power had been applied to the motor. What better way to inform a newly minted engineer about “black crud”. The term “Black crud” was the generic name given to the contaminating material often observed in failed gas bearings after disassembly. The term “black crud” had thus been inserted into my engineering lexicon where it has remained until this day. After I had decided to write of my experiences with “black crud”, I realized I did not know much about the words “black crud”. When I am faced with questions of that sort, I seek answers by entering the appropriate words into the Google search engine. After I entered the word “crud”, the search engine returned the usual avalanche of possibilities. The word “crud” is apparently completely generic in that it can range in meaning the noxious substances found in sewers to a more modern computer acronym. The word “black” has more specific meanings ranging in context from physics to psychology. I used the term “black crud” sans a definition for many years, but everyone seemed to know what I meant nonetheless. Thanks to the Google search engine, today I would say that “black crud” was the unknown substance found in failed gas bearings. It is the presumptive immediate cause for the failure of the bearing. The primary source of the “black crud” is usually not revealed by inspection of the in situ “black crud”. All bearing “crud” appears black due to the minute quantity of “crud” allowed by the very small dimensions of the gas bearing gaps. In my experience, staring at deposits of “black crud” will not reveal what it is, but trying to understand how it got there may yield clues as to origin. Even the use of marvelous machines of modern science such as the infrared spectrophotometer may not yield a satisfactory answer to the questions of origin being asked. Lifting a deposit of “black crud” and removing it without contamination is an art form mastered by only a few technicians. The first name of one such person was, very appropriately we thought, Merlin.

I was assigned the task of disassembling all G6 gyros that failed for any reason during acceptance test, determining the reason for the failure, and appearing monthly in person before the Air Force Minuteman Project Officer to present my findings for each failure. Going to Norton AFB every month was a big deal for us. Despite the serious nature of the assignment, I found it to be a lot of fun. Some of what I presented concerned gas bearing “no start” failures. I remember the times I presented Merlin’s infrared spectrophotometer charts, with their many bumps and dips, of samples of “black crud” taken from  failed bearings. I usually went through the litany of the various hydrocarbons that each bump represented and then delivered the punchline. I once showed them a chart made using a sample of hand cream. It was obvious the “black crud ” lifted from the failed bearing was hand cream. I was glad the Air Force did not have a policy of shooting the messenger or I would not be telling the story as they were not happy. However, most of the “black crud” was found to be the filler material added to epoxy resin in order to lower the thermal coefficient of expansion to a value closer to that of steel. This epoxy resin mixture was used several places inside the gyro and these could become sources of contamination.

The gyro is filled with a mixture of Hydrogen and Helium gases. This gas is caused to rotate at a speed exceeding 100 mph by frictional contact with the rotor. I always thought this high speed gas would be very effective in dislodging potential contaminants from their hiding places. The self-pressurizing property of the gas bearing required a constant flow of gas into the bearing thru small holes that led from the outer surfaces of the rotor into gas feed grooves that were located at the edge of the thrust pockets of the bearing. This arrangement of holes and grooves acted like a miniature vacuum cleaner. We sometimes observed a green powder deposited in the groove. The green color was from a dye mixed in with the calcium carbonate filler material.

I had exclusive use of a Farr bench inside the dust free instrument assembly area. This is where I did my gyro diagnostic disassembly work on failed gyros. The bench was located in an area of the room that had a direct line of sight to the managers desk on the other side of a large window in the wall between us. A failed gyro was a not a common event, but when it happened I would do my thing at my Farr bench. The Manager was well known to us as somewhat of a comedian, he was fun to be around and he had the knack of keeping tense situations from becoming worse. When I was at the bench, we would communicate using hand gestures. Like I said, he was fun to be around. His name was Gerry Sammons. The usual business of diagnostic teardown was routine and aften boring and a little horseplay at the higher levels of management helps.

The G6 gyro is sealed inside a welded, gas tight, magnetic shield can. Helium gas is added to the gyro gas mixture to permit the performance of a final mass spectrometer leak check of the gyro. I believe that Helium gas has the greatest diffusion rate of all the gases and it is notorious for being difficult to seal. The welded can was the absolute fix.  If a gyro is to be disassembled, the can must be opened by first milling the weld bead from the can. When the technician sat down a the bench, there was a gyro before him with the can weld bead removed. One time we removed the gyro from the can and I found a smashed red plastic protective cover of a fairly large round connector. I was taken aback by this turn of events and I replaced the gyro back into the can. I signaled Gerry he should put on his protective smock and come inside. After Gerry arrived at the bench and saw what I had found, he immediately suspected I was playing a practical joke on him. I finally convinced him I was not. We never did find out how that red protective cover came to be inside the welded can. If it was a case of attempted sabotage, it was a most clumsy one.

We had the use of a McCrone particle Atlas to aid us in the identification of anything we found in a gyro. With the aid of the Atlas we identified a hair from an Angora rabbit. But my all time favorite find was finding a Turkey Feather. That’s right, a whole Turkey Feather. These were duly reported to the Air Force Project Officer. I survived the ordeal without undue loss of blood as I recall.

I had moved on to other tasks when I became aware of a project to investigate the characteristic events that transpired as a coasting gas bearing contacted the stationary surface and stopped rotating. It was hoped that a “good” gas bearing could be identified and accepted and a “about to be bad” bearing would be set aside for disposition. It was an attempt,no less, to invent a “crud” finder machine. A noble endeavor indeed. I stayed in touch with Mike Albertson, the Supertech doing the work, as I was interested in the outcome.

The Instrument Test Laboratory had been for many years performing gyro drift tests using an apparatus which utilized a servo circuit to cause a single degree of freedom rotating table to constantly maintain one of the two gyro pickoffs at null. A servo circuit kept the other gyro pickoff at its null by constantly torquing the rotor. As the rotor drifted over time, the drift test table moved with it, thus the table angle was identical to the rotor drift angle. With suitable modifications, the drift table could be made to keep the drift table pickoff at null, ie, it was servoed to its own pickoff. The current flowing in table torquer was proportional to the force necessary to keep its pickoff at null.

The principle that was being exploited was simple. A gyro is mounted on a drift table such that the gyro spin axis is coaxial with the table axis. The drift test table is servoed to its self. If the gyro spin motor power is turned off and the rotor is allowed to coast, the drift table torquer current will be a measure of the drag torque acting on the rotor. If the coasting rotor contacts “crud” in the bearing as the rotor slowly looses lift, the event will leave a characteristic change in the table torquer current recording. It should be possible to reliably detect “soon to be bad” rotors! I do not remember if the machine was ever incorporated into the formal gyro acceptance tests, but I do remember it being used to diagnose rotor bearing problems for a long time thereafter. I remember being impressed by the sensitivity of the machine.

 

 

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