Their main operation areas being over water, the US Navy was more into the development of pneumatic life preservers then their Army Air Corps counterparts. As early as the late 1920s much research and development was put into this topic. Anyway, one early design adopted by the US navy was an H style life vest with two bladders which were still inflated orally. It seems that the AAC used derivates from this vest, designated Types B-1 and B-2. Any information of our visitors about the H style vest, the B-1 and B-2, would be welcome.
Mr. Peter Markus (1885-1973), a merchant in Minnesota who loved to boat and fish, was responsible for most, if not all, of the life preservers for the US Navy until 1945. He noticed that many people had drowned because they refused to don the cumbersome kapok-filled vests in use at that time. In 1931 they adopted another of his designs. His patent US 1798430 A for an "inflatable safety device" (scroll down for more info) eventually emerged into the navy's Mk-1 wraparound life vest. A navy representative had seen Markus marketing his device at a sports equipment show. The Mk-1 became standard equipment for naval and marine corps aviators and was used through the 1930's until the end of WWII. It was made of bright yellow rubberized canvas and features an automatic inflation system (also designed by Markus) using CO2 cylinders. The two air chambers are inflated when the two USN marked cylinders are perforated by activating the mechanism by pulling down the attached cords. Two rubber tubes can be used to top up the air pressure orally. The waist strap is latched by means of a hook and D-ring, and lead through a loop in the vertical neck strap.
The inflatable collar is proudly marked U.S.N. while stencils on the vest include the navy anchor, the name of the manufacturer - in this case Hodgman rubber Co. (the two other manufacturers who produced the vest were New York rubber corp. and United States rubber co.) and the Markus patents under which it was manufactured:
1694714 - inflatable life preserver (pat. December 11, 1928)
1766182 - inflating device (pat. June 24, 1930)
1772674 - inflating device for safety belts and the like (pat. August 12, 1930)
1798430 - inflatable safety device (pat. March 31, 1931)
The last contract was reportedly awarded in March 1942, the Mk-1 being replaced in May 1942 by the Type B-4 as standard equipment, but still in use until the end of the conflict.
Here's an extract from Mr. Markus' patent no.1798430: P. MARKUS, INFLATABLE SAFETY DEVICE. March 31, 1931.
"This invention relates to inflatable appliances designed for sustaining a person safely in water, and consisting essentially of a chambered vest or equivalent article or garment, a compressed air cartridge, and means for effecting the discharge of the compressed air from the cartridge into the chamber of the garment so that it shall safely sustain the wearer in water. (...) it is very desirable that a practically instantaneous inflation shall occur (...)
The vest is preferably of one chamber construction so that the chamber shalt be unbroken along the neck portion as well as at other points. It is to be understood however that the garment may be in two chambered type, preferably separated at the middle of the neck portion at the back thereof and adjustably connected (...) , it being understood however that the chambers of the last-mentioned type should terminate sufficiently close together to insure such engagement with the back portion of the head that the latter shall be pressed upwardly by the neck portions when the garment is inflated, and the wearer is on his back in the water." (...)
The full patent can be found under the following link: