Ww2 Us Army Air Force Navigator Astro Compas Mk. II B-17 B-25 Nos Nice
Used on the B-17, B-25, B-26, B-29 and other bombers! An astrocompass is a navigational tool for determining the direction of true north through the positions of various astronomical bodies. There are certain circumstances when magnetic compasses and gyrocompasses are unreliable. The most obvious is in polar regions, where the force exerted on the needle of a magnetic compass is nearly vertical and gyrocompasses become unstable due to the rotation of the Earth. Magnetic compasses are also susceptible to disruption from magnetic fields other than the Earth’s, such as those produced by the hulls of some metal vehicles or craft. Before the advent of electronic navigational aids such as GPS the most reliable way to ascertain north in such circumstances was through the use of an astrocompass. The operation was as follows. 1 Getting the local time (by means of a clock). 2 Setting the latitude. 3 Setting (in the alidade) the star’s local hour angle (LHA) for that day obtained by means of tables or a computer program. 4 Pointing the compass pinnula to the star (sun or moon). 5 Reading the true course on the limb. Made of glass, aluminum, and steel, this is an AMAZING example! Though there are some slight marks from storage, it is in near PERFECT condition, and comes complete in the original box! Also includes the original instructions, as well as a Type D-4 Flight Computer. Appears to be 100% functional! 8.5″ tall (box is 10″x 5.5″ x 6.5″), it would make a FANTASTIC addition to any collection or display! TERMS OF SALE. Most of my items are vintage, and as such are AS-IS, so you must therefore expect a degree of wear due to age and/or usage. ABOUT ME. Although my passion is the Me109, I do offer many other German Aircraft Fw190, Me262, etc. , as well as USAF and Japanese items. Occasionally I do offer many non-vintage items such as prints and art relating to the time period. Use is solely based on my authorization only. The item “WW2 US ARMY AIR FORCE NAVIGATOR ASTRO COMPAS MK. II B-17 B-25 NOS NICE” is in sale since Sunday, May 5, 2019. This item is in the category “Collectibles\Transportation\Aviation\Military Aircraft\Other Military Aircraft Items”. The seller is “messerschmitt*109″ and is located in Studio City, California. This item can be shipped worldwide.