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Meeting	ACGS Committee Meeting 92 - Dayton - October 2003
Agenda Location	9 SUBCOMMITTEE A – AERONAUTIC AND SURFACE VEHICLES 9.2 B-47 FBW Development
Title	B-47 FBW Development
Presenter	Gavin Jenney
Affiliation	Dynamic Controls, Inc.
Available Downloads*	presentation
	Downloads are available to members who are logged in and either Active* or attended this meeting.
Abstract	Between August 1966 and December 1969, a Fly-By-Wire (FBW) development program was conducted at Wright-Patterson Air Force Base in Dayton, Ohio. The purpose of the program was to demonstrate that electro-hydraulic primary flight control systems (commonly called Fly-By-Wire) offer advantages over mechanical controls in meeting increasing performance and reliability demands for aircraft control. At that time, although the U.S. Space program and some foreign aircraft had incorporated FBW systems, U.S. aircraft had not. In order to evaluate the operational characteristics of Fly-By-Wire in a large U.S. military aircraft, a Fly-By-Wire system was designed and flight-tested in a B-47E aircraft. The Fly-By-Wire system was applied to the pitch axis of the test aircraft. Three different phases of evaluation were conducted, each phase corresponding to different pitch axis mechanization. The Phase I system operation was based upon using an electrical position transducer mounted to the normal control column. The position transducer drove an electro-hydraulic actuator mounted in parallel with the normal pitch axis actuator. The Phase II system operation was based on using a side-stick controller, pitch rate and nose acceleration feedback in combination with the components of the Phase I system. Roll control by the sidestick was accomplished by driving a modified aircraft autopilot channel and adding roll rate feedback. The Phase III system operation added a dual-fail operate redundant actuator with failure injection provisions into the Phase II system. The first flight occurred on 14 December 1967, the last flight on 21 November 1969. A total of over one hundred flight test hours (by over 20 evaluation pilots) were accumulated on the Fly-By-Wire system. An improvement in dynamic input response at high q was obtained from the Phase I mechanization. A general improvement in the handling qualities was obtained with the sidestick controlled Phase II and III mechanization. The quad-redundant Hydro-logic actuator removed all injected failures with negligible deviation of the aircraft and did not exhibit random disconnects characteristics. The author both designed the development system and flew with it as test engineer during the flight tests.