Farnborough Air Show

Boeing’s P-8 gets its wings

 - July 12, 2008, 4:01 AM
With the attachment of its wings and the hanging of the engines last month, Boeing’s first P-8A Poseidon reconnaissance aircraft is right on schedule and could soon be earning its first international order, according to the manufacturer.

The militarized 737 derivative–which Boeing describes as a form-fit replacement for the U.S. Navy’s venerable P-3 Orion–recently began power-on systems testing on its dedicated production line at its commercial aircraft factory in Renton, Washington.
According to Boeing, despite the Poseidon’s outward differences from its airliner cousin–including a bomb bay, raked wing tips, underwing and fuselage centerline weapons stations and nearly 100 antennas–the P-8 shares 60 percent commonality by part number with its airliner cousin and could be built on the same assembly lines.

The fuselage is supplied by Spirit Aerosystems in Wichita, Kansas, the same subcontractor that supplies the 737 bodies, and is based on the latest -800 model. The P-8 represents a radically different approach for Boeing, building Navy requirements into the airframe from the ground up, with no modification or stripping out of existing structures needed at the end of the airframe production.

Using the same tooling, processes and worker training, the program has required unprecedented cooperation between the company’s commercial aircraft unit and its integrated defense systems division. “This is the long-term vision of Boeing: to build tactical aircraft in the heart of our commercial operation,” said Mohammad Yahyavi, vice president and program manager for the P-8A, adding that this is now the blueprint for any military plane based on a commercial platform.

For a 737, a typical trip through the final assembly line takes 10 days. Boeing has allotted nine times as much time for each of the five test aircraft in the system development and demonstration contract, as the airframer is expecting a steep learning curve. Keeping the P-8s from clogging Boeing’s finely tuned 737 production system was a major motivation behind the establishment of a separate line (the former 757 wing to fuselage assembly line), which could also be used to manufacture derivative EP-8s.

Perry Moore, Boeing’s director of P-8A manufacturing operations, said he would be satisfied to see the line process a Poseidon in 45 days as the procedures are refined. Once the aircraft’s stay in Renton is complete, it will then move to the integrated defense systems division for a similar length stay in final completion. First flight of the aircraft is expected next year.

Military Characteristics
One of the features on the P-8 that hints at its future service in antisubmarine work is its wingtips. Unlike the popular performance-enhancing winglets found on many commercial and business aircraft today, the wingtips on the Poseidon are a continuation of the wing, raked backward to better shed ice, given the adverse weather and altitudes the aircraft will be expected to patrol.

According to Boeing, the wingtips–not offered to commercial customers because of the additional length they add to the wingspan–give about the same level of performance as the winglet-equipped airplane. The wing also includes additional de-icing equipment. To accommodate the new design and the four under-wing weapons pylons, each of which has a 3,000-pound weight limit, the internal wing structure has been specially strengthened. The aircraft is expected to easily meet the Navy requirement for 2.2-g sustained flight, along with certification for operations down to 200 feet.

Another departure from the standard 737 configuration is the bomb bay, which has five weapons stations, each with a 1,450-pound weight limit. While the bomb bay can handle the current stores, it was designed with some growth capabilities in mind. Boeing’s engineers said they based their dimensions on the weapons bay in the Joint Strike Fighter so the P-8 could accommodate the same munitions.

Internally, the P-8 features three times more wiring and ECS ducts than a standard 737 because of the electronics suite. The aircraft features Raytheon’s APY-10 radar, which includes several improvements over the APS-137, with network enabling to allow different users to access the same information at the same time.

Five identical electronic operator stations equipped with 24-inch high-resolution displays form the nerve center of the aircraft, with data freely transferable and accessible between them. The identical stations cut down on part numbers and maintenance training and can be customized according to operator duty. A mission commander can monitor smaller views of what the other stations are looking at, and crucial information can be filtered for each station operator’s job.

The system uses off-the-shelf moving map software from Raytheon that shows bottom topography, important data for implementing the P-8’s primary mission of anti-submarine warfare. It is linked to the aircraft’s flight management system.

Once an operator selects a pattern for the distribution of sonobuoys–the Poseidon carries 126 per mission, double the capacity of a P-3 Orion–it is routed to the flight management where it can be considered. If approved, the autopilot can then adjust the flight to match the pattern, basically allowing the aircraft to be flown “from the back of the plane.” As one Navy requirement was for simultaneous sonobuoy drop capability, the Poseidon features three rotary launchers, each holding 30 of the marine sensors at a time. Through the operator stations, sonobuoy inventory can be managed and loading orders can be sent to the ordnance specialist working the launchers.

With a mission profile calling for an outbound trip of 1,200 miles, four hours on station and a 1,200-mile return flight, the P-8 has a fuel capacity of more than 10,500 gallons, distributed between three main and seven auxiliary tanks. Overall, the aircraft has a 5,000-nm range unrefueled and a 22-hour duration with midair refueling capabilities.

While the initial requirements were for an anti-submarine/surface warfare and an intelligence, surveillance and reconnaissance platform, Boeing said it is delivering that and more. It said it is providing something along the lines of a command-and-control aircraft that can track thousands of contacts, communicate with and transmit data to a variety of platforms and act as a UAV controller managing broad area maritime surveillance (BAMS) aircraft.

The U.S. Navy expects to acquire 108 P-8As to replace its aging fleet of Orions, with an expected entry into service date of 2013. Boeing predicts a worldwide market for an additional 100 aircraft among 14 countries, including India, which issued a request for proposal for a maritime patrol aircraft in April 2006. As the competition concludes, the company is anticipating an order for eight P-8s to replace India’s older Russian-built aircraft. The P-8I will be similar to the Navy aircraft, but will include the magnetic anomaly detector (MAD) boom, which was removed from the U.S.
requirements late last year. Given that the aircraft was initially designed with the MAD boom, it will be simple to accommodate customers who want to include it, according to Boeing.