marcsbigfoot20b27 wrote:
Truck came with the USAF Altimeter and air speed indicator (from a Cessna or something) in a crude wooden center console. I scrapped it and made an aluminum one and painted it. Needed something to hold the air bag controls and gauge, so I added the other two and a pitot tube in the grill (can tell when Im drafting, or headwind). Also added a 4 port high power usb charger on the side.
Cool!
The Submarine need is as follows. We know that an altimeter simply measures pressure/vacume.
Think of a huge closed cylinder with a 100+ men... oops, people, living in. We make Oxygen from pure water, make pure water from sea water, remove CO2 and CO from the cylinder and exhaust it from the cylinder, we store air in massive tanks to allow us to surface and to operate valves, etc. We change the volume of the cylinder by adding and removing fluids from tanks, etc, etc.
We have an altimeter just like yours mounted in the submerged ship control area. Upon submerging, we re-set the altimeter to Zero. As time goes on, sometimes weeks or even months at a time, the internal pressure of the cylinder can vary quite a bit. The altimeter allows us to keep track of what that pressure is. (I've seen more that 4000 feet of elevation on occasions.) We read the altimeter in inches of mercury rather than feet of air.
Now think of getting ready to come to the surface and open the hatch(es) to the outside. If their is a large vacuum in the boat, you'll never get the hatch open. (It swings outward.) If there is a large pressure in the boat, the hatch could fly open and seriously injure or kill the man - oops, person - opening the hatch.
In fact the last report the Surfacing Officer receives is like, "Sir, the boat is prepared to surface, 2 inch pressure in the boat." The officer would take the appropriate steps to equalize that pressure before directing that the hatch be "cracked" and opened.
PS The gender neutrality is due to the Navy's new policy allowing women to serve on Submarines.
