|McDonnell Douglas F/A-18 E/F Laser Guided Fuselage Join|
McDonnell Douglas is building the new F/A-18E/F Fighter for the US Navy. This is an entirely new aircraft, twenty five percent larger than it's predecessor and completely redesigned. The assembly and alignment tools were also new. As the sophistication of the new Hornet program had grown, so had the requirement for advanced assembly techniques. The company was looking for a measurement system with high accuracy for the critical fuselage join of the forward section and the aft section (manufactured by Northrop Grumman).
To select and implement an alignment system that could increase the precision of the alignment process, reduce the time and cost of the process, and provide critical data.
Research Technologies provided a laser based measurement system. Other team members provided positioners and a control console.
The tool operates in a closed loop fashion with three elements in the control loop, the measurement system, the positioner and the controller.
The rotating lasers describe a precise plane of light. Laser targets report their position, relative to this datum plane, to the computer.
The jacks are capable of powered or unpowered moves in all three axes. Load cells are an integral part of the positioners. All three axes, at each station are monitored. During alignment, the load cells register loads imposed on the airframe by positioner motion. "Protect the part" interlock logic shuts down motion in the event that the imposed load exceeds a pre-determined value.
Since the information generated by sensors and positioners is carried on a data bus, the host can be located remotely to maximize operator access. The system can be fully automatic, semi-automatic or manual. The results can be monitored for allowable thresholds, operator alerts and system diagnostics. Additionally, the as-built information can be output to Quality Control reports or logged to disk.
The computer controlled laser measurement and alignment system allows McDonnell Douglas to join the 60 foot long fuselage to near perfect accuracy. This tool improved the accuracy of the alignment process by a factor of ~30 times over the previously used method.
The combination of sophisticated software, accurate lasers and sensors provides the tool with a high precision measurement system.