In the 1970’s, I was the”Test Director” of an inertial guidance system test laboratory. The laboratory’s mission was the development, testing, and evaluation of an unconventional Inertial Navigation System (INS) designed for use in aircraft. The system utilized the Electrostatic Gyroscope (ESG), which was invented and developed by our Company for use in submarine guidance systems. The Lab was part of our company’s “Instrument Group”. This group was a direct descendant of the “Aerospace Lab” of North American Aviation, Inc. (NAA), which was located in Downey, California. The INS was designated as the “N73”. In addition to extensive tests in our laboratory, the INS evaluation tests involved aircraft. These tests were done using various types of aircraft – from USAF fighter-planes to a wrecked and Earth-bound Northrup F-5 fighter-plane. One of the test airplanes was a Beech “Queen-Air” equipped with cargo doors. We used this aircraft to demonstrate the suitability of the N73 INS for the nascent “Tomahawk” cruise missile. The tests were conducted at low altitudes, some as low as 50 feet. It was an exciting period in my life and these stories are from my experiences as test director.
We flew to Lambert Field, located in St. Louis, to finalize the planing for the upcoming test program. Upon arrival we were escorted to a large hanger, which was used for the final assembly of the F-15 fighter plane, where the initial planning meeting took place. We had anticipated a formal presentation of the test plan for the flights and we were prepared to suffer through a long meeting. Instead, we were led to the test aircraft and we were introduced to the McDonnell-Douglas team, consisting of a test engineer and a pilot. The details of their plan were presented to us and they were very sparse indeed. They wanted to subject the N73 system to low level flights with straight line paths and durations up to the flight capabilities of the test aircraft. We could fly to any destination within the lower forty-eight states we chose. We then explained to them our INS was a non-conventional strap-down system, which simply means the INS moves with the aircraft, as there are no gimbals in the system. As soon as he heard the words “strap-down”, Joe, the pilot, began to laugh and he told us he had test flown other strap-down systems and they all failed to perform when he subjected them to his “special” test maneuvers. He made it plain he did not think highly of strap-down systems. We bit our tongues and changed the subject to our flight destinations. We were coming to no conclusions until I told Joe my Son was stationed at Bergstrom AFB in Austin, Texas. He said Austin was OK with him and we would also go to Pensacola and visit his son. He went on to say the seafood on the Alabama coast would be a treat for us. Someone mentioned Los Angeles and the was it for the itinerary discussion.
We were anxious to look at the airplane’s interior and gauge any problems we might face in the installation of our system. We said as much to Joe and he again burst out laughing. He said he has never had an INS installed in his airplane that did not need a week of preparation and debugging. We climbed aboard and Joe went somewhere else. We knew we were being challenged and we knew what we had to do. So, we sat in the airplane and completely designed the installation in every aspect including sketches for our shops to work from. This effort took several hours to finish but we left the hanger with a confident feeling that our proud NAA heritage would be upheld by our work. We left for home to start the work of bringing the installation hardware to a state of readiness.
As the installation hardware fabrication work approached completion, our team assembled the “tool-kit” that would be needed for the INS installation. Our goal was to have the right tool for each installation task identified during the planning trip and thus ask for nothing from our hosts. We had a reputation to protect, ours and that of our Shamans and Wizards who designed and built the N73 INS. We were happy campers and our confidence grew as the amount of mid-night oil being burned grew larger.
Our usual method of transporting the INS to test sites away from Anaheim was to assign one of the project engineers as a courier to hand carry the INS using commercial transportation. The INS carrier box was too large to fit into a standard airline seat, so two first class tickets were booked. But seemed to us we needed a classier transportation method for this trip as we wanted to add to the proud NAA Heritage and we did want that. We decided to have the INS carried to St. Louis in our mobile INS test laboratory and the “NAV VAN”, as it was named, would serve as our base of operations for the duration of the test program. The remainder of the team would fly to St. Louis. The team would also return to Anaheim in the “NAV VAN” and gather navigation data during the trip home. I will save that story for another time. I have a few tales to tell you that you may be interested in, especially the one where I took the NAV VAN on a side trip to visit my Mom and Dad in the desert, using a rough dirt road to find them and taking INS data all the way.
The “NAV-VAN” was already parked next to the hanger when we arrived at Lambert Field and we started the installation of the N73 into the Queen-air shortly thereafter. The installation of the test equipment and check-out of the N73 went quickly and smoothly. We turned the N73 on and went into the align mode. Eight minutes later, the system was placed into the navigation mode. We announced to the McDonnell-Douglas team that the N73 was ready to fly. It had taken us forty five minutes to install and checkout the system. We asked for an immediate test flight. Our request was hurriedly granted. The engines of the Queen-air were started and power to the N73 test equipment was transferred from ground power to aircraft power. We were soon airborne and on our way to an area where we could maneuver the airplane safely. Joe, our pilot, tried his best to “upset” the N73 and we were treated to a rather exciting “E-ticket” ride in the process. Joe finally gave up and conceded our strapdown system was a “keeper”. We returned to the airport and taxied to the initial point in the hanger. The aircraft position as reported by the N73 was within 0.1 NM of the position reported when we left the initial point. We were pleased and ready for the next test phase.
(to be continued)