May 26, 2007: Earlier this year, the U.S. Navy
officially named their new maritime patrol aircraft, the P-8A Poseidon, and put
development into high gear. The first P8As are supposed to enter service in
three years, and will be based on the popular Boeing 737 airliner. This almost
didn't happen, save for a clever PR stunt.
Three years ago, the navy was still considering a
competing design that, like the current P-3, used props, instead of jets.
Propellers were still a contender because maritime patrol aircraft, when
looking for submarines, spend a lot of time at low altitudes (200 feet or so),
in order to get the most out of their sensors. Jet engines operate best at high
altitudes, while propellers work much better close to the surface. Most sailors
who serve on P-3s, know what it's like to fly on a jet, and have always been
big supporters of propeller driven patrol aircraft. But the Boeing engineers
knew that a 737 could do the job. They came up with a clever plan to change the
minds of the thousands of sailors currently flying P-3s. Boeing equipped a 737
with the equipment found in a P-3 (some countries were already using navalized
737s as patrol aircraft), and went around to naval bases, where P-3s were
stationed, and took P-3 crews for a ride on the their P-8 mockup. They spent
most of the time at low altitudes. The P-3 users were convinced and, thanks to
the Internet, the word got around quickly.
Although the Boeing 737 based P-8A is a two engine
jet, compared to the four engine turboprop P-3, it is a more capable plane. The
P-8A has 23 percent more floor space than the P-3, and is larger (118 foot
wingspan, versus 100 foot) and heavier (83 tons versus 61). Most other
characteristics are the same. Both can stay in the air about ten hours per
sortie. Speed is different. Cruise speed for the 737 is 910 kilometers an hour,
versus 590 for the P-3. This makes it possible for the P-8A to get to a patrol
area faster, which is a major advantage when chasing down subs spotted by sonar
arrays or satellites. However, the P-3 can carry more weapons (9 tons, versus
5.6.) This is less of a factor as the weapons (torpedoes, missiles, mines,
sonobouys) are, pound for pound, more effective today and that trend continues.
Both carry the same size crew, of 10-11 pilots and equipment operators. Both
aircraft carry search radar and various other sensors.
The 737 has, like the P-3. been equipped with bomb
hard points on the wings for torpedoes or missiles. The B-737 is a more modern
design, and has been used successfully since the 1960s by commercial aviation.
Navy aviators are confident that it will be as reliable as the P-3 (which was
based on the Electra civilian airliner that first flew in 1954, although only
170 were built, plus 600 P-3s. About 40 Electras are still in service). The
Boeing 737 first flew in 1965, and over 5,000 have been built. The P-8A will be
the first 737 designed with a bomb bay and four wing racks for weapons.
