Issue No 22 THE AVIATION HISTORIAN 35
Powerplant 2 x 13,800lb-static thrust Rolls-Royce
RB.142R low-bypass twin-spool turbofan engines
(22,500lb-s.t. with reheat)
Dimensions
Span 48ft 8in (14·83m)
Length 72ft 9in (22·17m)
Height
(standing attitude) 17ft 9in (5·4m)
Wing area 630ft² (58·6m²)
Wing sweepback
(leading edge) 42°
(quarter chord) 36°
Aspect ratio 3·76:1
Dihedral -2°
Thickness/chord
ratio 0·06:1 at root 0·04:1 at tip
Tailplane span 22ft 6in (6·86m)
Tailplane area 145ft² (13·47m²)
Tailplane sweepback
(leading edge) 41°
(quarter chord) 37°
Tailplane dihedral +10°
Fin area 75ft² (6·96m²)
Fin sweepback
(leading edge) 63·4°
(quarter chord) 56·4°
Wheel track 9ft 10in (2·99m)
Wheel base 27ft 5in (8·35m)
Weights
Empty (excl fuel) 40,600lb (18,416kg)
Normal all-up 63,825lb (28,950kg)
Max overload 79,125lb (35,890kg)
Performance
Max speed Mach 2 at 36,000ft/11,000m
Max cruise speed Mach 0·97 (with 300gal
tanks at 32,000ft/9,700m)
Ferry range 3,000 miles (4,800km) with
max external fuel and 300gal
tank in weapons bayHawker P.1129 data
the forward-facing radar dedicated to low-level
flying and target detection. The Doppler aerial
and the two sideways-looking X-band aerials
were situated on the underside of the forward
fuselage, their apertures covered with dielectric
material. For reconnaissance there was a Q-band
twin-aerial sideways-looking system installed
in a removable underbelly package, and it was
likely that two versions of this package would
be needed; 15ft (4·6m)-long aerials were required
for operation above 2,000ft (600m), but for low
flying (500ft/150m and below) an 8ft (2·4m)-long
version was considered necessary. The proposed
camera installation consisted of three F-95 oblique
cameras mounted permanently in the bottom of
the fuselage just forward of the cockpit, and two
F-100 and two F-96 vertical cameras included in
the reconnaissance pack.
POWERING THE P.1129
Two engines (placed side-by-side in the rear
fuselage) were considered desirable in order to
minimise the P.1129’s vulnerability to groundfire
and debris and to increase the chances of
completing a mission should one engine fail or
be damaged. The RB.142R was first choice on
grounds of economy, but the bypass turbojet
also had an added advantage in that it produced
a very large thrust boost with reheat lit owing
to the higher proportion of unburnt gases in
the jetpipe compared to a normal turbojet. (The
RB.142R had a moderate reheat temperature of
1,577°C/2,870°F, but this was sufficient to give a
60 per cent increase in sea-level static thrust.) This
particular feature of the bypass engine closely
matched the strike-aircraft requirements which
demanded large thrusts for short periods of
time at take-off and during a supersonic dash. In
addition the low unlit thrust ensured that during
prolonged periods of subsonic cruise the engines
were operating at an r.p.m. which gave low
specific fuel consumption. And it was essential to
have the twin fully convergent/divergent reheat
nozzles at the extreme rear of the aircraft to avoid
structural damage from jet noise.
Semicircular conical centrebody intakes on the
fuselage sides were dictated by the requirement
for supersonic capability, experience with the
P.1121 having shown that a speed potential
in excess of Mach 2 needed an automatically
controlled two-shock intake with half-cones (a
(^1) ⁄ 24 th-scale display model and later drawings
show that these were subsequently changed). The
P.1121 had received a typical supersonic intake
which had been tested full-scale under static
conditions in front of two high-performance
engines — the de Havilland Gyron and the Bristol
Olympus. Suction-relief doors were installed in
the P.1129 to ensure good recovery and to attain
the best possible velocity distribution at low
forward speeds. The alternative Bristol Olympus
was eminently suitable in regard to size and
weight and would fit the P.1129 with only minor
modifications to the airframe. A Rolls-Royce Avon
development, the RB.133R, had been considered
for the smaller P.1125 but this did not provide
sufficient take-off thrust for the P.1129. The latter’s
groundrun could also be reduced by some 28 per
cent with a 5sec burst of rocket-assisted take-off
(RATO) thrust, in the form of solid-propellant
rockets giving 20,000lb of thrust in all.
The nosewheel of the conventional tricycle
undercarriage retracted rearwards behind the
cockpit and the rearward-retracting fuselage-
mounted mainwheels went into recesses aft
of the weapons bay; the static wheeltrack was
9ft 10in (3·42m). As noted, the P.1129 carried
its largest store, the Red Beard nuclear bomb,
euphemistically referred to as a “Target Marker”