ChrisAtUpw@....... wrote: > Dear Mr.Harris, > > Thank you for a very interesting letter. > > > First, as some may know, inertial navigation depends on the use of very > > precise gyros to stabilise a platform about all three axes. > Were they using all air bearings and quartz controlled synchronous > motors, please? You would not believe what the gyros looked like! Each one was a cylinder about 5 inches in diameter and 8 inches long. The rotor was floated in a can in a dense fluid. The pivots were small jewel bearings. > > Was the angle sensing LVDT, LCDT, optical fringe or what? > The acceleration sensing and precession torquing was done with an item called a microsyn. It is a small rotary magnetic assembly similar to the linear ones in principal. > > > Mounted on the platform are two very precise calibrated accelerometers > > which measure the two components of the horizontal acceleration. > What principle was used for measuring accelerations and were they low > range absolute units, rather than 'AC' / piezo etc. types, please? > > > The outputs of these accelerometers is doubly > > integrated, and used to correct the vertical orientation of the platform by > > precessing the gyros. Back in the 50's, such a platform could be > stabilised > > to something like a minute per hour or less. > It sounds impressive. Do you know if there are any inertial platforms > going cheap on the used equipment market? Getting one might be a good start > to developing a gradiometer! > It is my understanding that the airlines use inertial sensors now. It should be a good place to start. I wrote the first major military proposal for an inertial system for GM, and I believe that they made the systems for commercial use later. > > Regards, > > Chris Chapman > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>