Intelligent Repeatable Release Hold Back Bar (IRRHB)
Navy SBIR FY2008.1

Sol No.: Navy SBIR FY2008.1
Topic No.: N08-014
Topic Title: Intelligent Repeatable Release Hold Back Bar (IRRHB)
Proposal No.: N081-014-0216
Firm: Michigan Aerospace Corporation
1777 Highland Drive
Suite B
Ann Arbor, Michigan 48108-2285
Contact: Jon Coffer
Phone: (734) 975-8777
Web Site:
Abstract: The Repeatable Release Holdback Bar (RRHB) is a device that is used to hold aircraft in place just prior to launching them with a catapult. These bars are about 3 feet in length and attach to the front landing gear and hold it to a cleat on the flight deck. Once the catapult is fired a pre-determined force is reached and the holdback bar lets go of the aircraft allowing it to be accelerated down the deck. There have been some problems in the past with these holdback bars letting-go of aircraft prematurely, caused by worn parts or a failure of the bar to be properly reset after a previous launch. The result is that the aircraft moves down the deck unexpectedly and too slowly for a successful launch. Michigan Aerospace Corporation (MAC) proposes a way to record the number of shots fired on the bar, read the force acting on it during each launch and monitor reset conditions. In doing so, money can be saved in preventative maintenance by detecting early signs of a failure. During use, the holdback bar goes through high shock loads, which MAC is well-equipped to address in the design of this new system.
Benefits: Intelligent RRHBs will increase crew safety by decreasing the need for crewmembers to be near the holdback bar for manual checks and inspections after each catapult shot and by preventing premature releases from occurring. Intelligent RRHBs will also decrease maintenance costs by indicating when maintenance is needed before an expensive and dangerous failure can occur. Civilian shipping, tractor/trailers, cranes, heavy transport, bulk containers, and manufacturing machines like drop forges are some of the markets that would benefit from the technology developed for the holdback bars. In civilian shipping, where cables are used to tow ships or barges, a rugged strain gauge could be implemented to obtain real-time loads on the lines, providing warning of sudden tensioning and guidance to the tugboat operator. For tractor-trailers, loads imposed on the trailer hitches could be fed directly to the trucks' on-board computer networks. Cranes would be another great application for measuring loads. Real-time data could be displayed to the crane operators of the amount of loads being subjected to the cable system during heavy lifts. A drop forge machine could use the intelligent holdback bar technology to keep a log of the force that it hits at as well as the number of times it hits the material.