Manufacturer could switch to larger 737-800 instead of original -700 offering following windtunnel tests

Boeing is looking at the 737-800 as an alternative to the smaller -700IGW as the platform for its proposal for the US Navy Multi-mission Maritime Aircraft (MMA) requirement, as the company plans a wider role for the system within the navy's network centric architecture.

"The navy is looking for something that is extraordinarily flexible and whatever is happening on the battlefield of the future, this aircraft will be able to help. It is going to be a bit of JSTARS [Joint Surveillance Target Acquisition Radar System], a little bit of AWACS [Airborne Warning & Control System] and a little bit of MC2A [Multirole Command and Control], but with the added ability to go and kill a submarine," says Jack Zerr, Boeing MMA programme manager.

The 737-800's advantage is a 5.9m (19.3ft)-longer fuselage on which to mount sensors. An option is to move the weapons bay from the forward lower hull to aft of the -800's wing, also helping to solve stability issues discovered during recent windtunnel tests.

"With the doors in their original configuration, there was a pitch-up that caused us a stability and control problem. There are a couple of ways to resolve this: one is to add dorsal fins, the other is to add folding doors. Moving the bomb bay aft also avoids the issue," says Zerr. Boeing is considering two different sized bays, one 3.5m long and the other 4.7m long, depending on internal stores carriage needs.

Boeing is trying to minimise aerodynamic changes to the 737 by retaining the existing nose. It is working with Raytheon to reconfigure the APS-137 radar to fit within the 737 outer mould line. To minimise development costs, the USN is looking at migrating Lockheed Martin P-3/EP-3 systems, such as the APS-137, to the MMA.

Boeing is planning high-speed windtunnel tests of the 737-700 and -800 MMA in September when it hopes to make a decision. Boeing, BAE Systems with the Nimrod MRA4, and Lockheed Martin proposing a new-build P-3, are expected be awarded MMA pre-development study contracts at the end of this month.

Source: Flight International