BAE Systems

The Aircraft of British Aerospace and BAE SYSTEMS 1977 - 2017 105

On 20 October 1981 BAe’s Chris Yeo
made a world first when he piloted
Jaguar S62 XX765 on its maiden flight as
a fly-by-wire experimental aircraft. It
used four independent computer-
controlled electrical channels to relay
instructions to the flight surfaces. It was
the first aircraft ever to fly with its
conventional control rod-controlled
control surfaces entirely replaced by
electrically signalled controls with no
form of mechanical back-up. Any
breakdown in the FBW control would
have left the pilot with no other
alternative than to have ejected.
From the start, the programme was
an outstanding success. The FBW Jaguar
was effortless to fly and handled superbly
at incidences which normal Jaguars
could not reach. Pilots commented on
the lightness of the controls and the
crispness of the response. In 1983 5cwt
lead ballast was added in the tail to make
the Jaguar unstable. Whereas aircraft had
to be stable for a pilot to fly them, this
natural stability worked against
manoeuvring but with the addition of
computers an unstable aircraft could be
safely controlled.
Following its initial trials as an
unstable aircraft it was then fitted with
large wing leading-edge strakes, to
further decrease longitudinal static
stability. It was retitled the Jaguar ACT
(Active Control Technology). It made its

first flight with these fitted in March 1984.

To yet further increase the aircraft’s

instability, in July it was flown with

destabilising ballast in fuel tanks on the

inboard wing pylons. In this configuration

XX765 was very unstable but the FBW

systems enabled the pilot to indulge in

EAP to EurofightEr tyPhoon

†

carefree handling, however hard he

pulled the control column the aircraft

never exceeded its flight envelope limits.

The Jaguar FBW/ACT made a total of

96 flights until its retirement in

September 1984 and is now on display at

the RAF Museum, Cosford.

‡ The P110 led to a design jointly produced by all the Tornado partners - the Agile Combat Aircraft (ACA) which was publicly displayed for the first time as a
full-scale mock-up at Farnborough 1982. (BAE SYSTEMS North West Heritage)

‡ As part of the research for the new fighter the MoD funded the conversion of a Sepecat Jaguar to prove the

benefits of ‘Fly by wire’ (FBW) technology and relaxed stability. Jaguar XX765 made its maiden flight as a ‘Fly-by-wire’

experimental aircraft. Note ‘FBW’ on the fin. (BAE SYSTEMS North West Heritage)