Focus Area 8: Agile Combat Support Pitch Day: Aircraft Tow Bar Technologies

Fighter aircraft are routinely moved on the tarmac with the use of the MD-1 universal tow bar. The tow bar has a rigid lunette ring that is attached to the tow vehicle though a pin; the ring – pin assembly has a gap, called a “hitch gap”, that allows rotational motion of the tow bar during turns. Analysis has shown the current allowable hitch gap, when combined with sudden stopping of the tow vehicle, can generate impact induced compressive loads that exceed the F-16 landing gear drag-brace assembly ultimate load strength and have consequently resulted in landing gear failures during routine towing operations.  These types of towing related failures have cost the USAF millions of dollars in repairs, and tens of thousands of hours of lost flight time.  Furthermore, it is feasible that this towing induced failure mode is present in other USAF aircraft and needs to be designed out to ensure safe towing operations. A solution to this towing problem is through design and development of a self-compensating shock absorber system that provides a consistent stopping force across the entire dampening stroke. This increased stopping time, and subsequent lower stopping force, will sufficiently remove the towing induced nose landing gear failures for all aircraft serviced by the MD-1 tow bar.