Path: utzoo!utgpu!cunews!mitel!testeng1!stanfiel From: stanfiel@testeng1.misemi (Chris Stanfield) Newsgroups: sci.space.shuttle Subject: Re: Shuttle computers break down during glide tests Message-ID: <7800@testeng1.misemi> Date: 3 May 91 15:27:20 GMT References: <1991Apr26.111139.1@vf.jsc.nasa.gov> <1991May2.200211.2157@aio.jsc.nasa.gov> <74602@eerie.acsu.Buffalo.EDU> Reply-To: stanfiel@testeng1.UUCP () Distribution: sci.space.shuttle Organization: Mitel CAE Services Lines: 33 In article <74602@eerie.acsu.Buffalo.EDU> stein-c@acsu.buffalo.edu (Craig Steinberger) writes: > >I remember reading that the autopilot/autoland was accurate to a >tolerance of about 20 feet or so. This tolerance is acceptable in flight >but a mistake of 20 feet while landing can put you underground. However, >I do recall some tests of an autoland capability being tested on some >airplane by NASA (LaRC?). That was in an AW&ST some time ago. There have been functioning autoland systems in existence for 20 years - I know because the first engineering job I had was working on a simulator for the first successful one, the Smiths Mk.Va autopilot system. This system was installed in the Hawker-Siddely(Sp?) Trident (a commercial passenger jet) and in the Short Bros. "Belfast" (an RAF transport). It was cleared to Cat 3b, which means basically a blind landing. This system took the aircraft right down onto the runway - the pilot took over after the wheels touched (braking, reverse thrust, rollout, etc.), although the pilot had to lower the landing gear and, if I remember correctly, set the flaps. For those who are interested, the entire system was analog (no computer!), and used a lot af magnetic amplifiers. The flight data computer was like awatch inside. The reference inputs came from the gyros and a radar altimeter for when you were getting close to the ground. The pitch and roll channels were fully triplexed and the yaw channel duplexed. The system worked well and was reliable, but it was HUGE by todays standards - there were about 40 boxes, 12 servo actuator/clutch units and miles of wire. The flight systems junction box (a giant terminal block affair) had about 1000 junctions (>>2500 connections). The modern systems are, of course, much smaller, are digital and the newest ones are an integral part of the digital flight control system. Chris Stanfield, Mitel Corporation: E-mail to:- uunet!mitel!testeng1!stanfiel (613) 592 2122 Ext.4960 We do not inherit the world from our parents - we borrow it from our children.