Exercising ‘The Dog’

John Self recalls his RAF days with the Bristol Bloodhound surface-to-air missile.

For more than three years I worked on the Bloodhound Mk 2 missile system in the RAF: first with training at RAF Newton, then a bit of hands-on experience at RAF North Coates before a posting to an Australian base at RAAF Butterworth, near Penang, in Malaysia. Here the task was to turn a swampy ‘green’ field site into an operational squadron (number 33). 

The missiles were shipped to us, and we built them up and tested them in the newly-built MOTE (Missile Overall Test Equipment) facility.  Meanwhile, fleets of earthmoving equipment were creating the site for the installation of the four radars each with 16 launch pads, and other ancillary buildings.

When the infrastructure was complete, missiles were electronically and mechanically tested and either armed with warhead and boosters and installed on launchers, or put in the ready for use stands.  They spent 90 days being baked solid out in the tropical heat – quite enough time for birds to nest in the open aft end, but luckily nothing dangerous was found.  After that, they were disarmed and brought in for test and overhaul.  

The worst servicing problem was the high humidity affecting the magnesium castings in each of the two fuel bays. Bristol Siddeley (now in BAE Systems) had contoured the fuel bays with felt and balsa wood and this combination wicked up moisture nicely, causing quite serious corrosion of the magnesium.

History

A contract was placed in 1947 with the Bristol Aeroplane Company to develop a surface-to-air missile system, initially known as “Red Duster”, later re-named Bloodhound.  Bristol designed and developed the missile hardware and Ferranti Limited provided the radar guidance and control electronics.  After ten years in development, which included test firings at the Woomera Missile Testing Range in Australia, the first Bloodhound Mk.1 missile was handed over to the Royal Air Force in 1958.  The Bloodhound was used to protect key national assets, such as the V- bomber bases, which at the time held Britain’s strategic nuclear deterrent role.

The Bloodhound Mk.1’s radar proved to be very susceptible to enemy jamming and performed very badly against low-flying targets, so an up-grade development programme was undertaken, resulting in the Bloodhound Mk.2.  The Mk.2 first entered RAF service in 1964 with a more powerful radar and engines.

The Bloodhound Mk 2, or ‘The Dog’ to those working on it, was intended to counter the assumed threat from Russian bombers carrying nuclear bombs.  It’s an amazing testimony to the efficacy of the whole system that the original Mk1 became the improved Mk 2, with solid-state electronics and updated radar, lasting until 1991 with the RAF, and 1999 when the last international operator (the Swiss) decided to decommission it.  Equally amazing that, not only did it see long service in Switzerland, but also in Sweden, Singapore and Australia.  UK Aerospace Ltd must have been doing something right for all those years, in spite of Ferranti, who made the radar, guidance and launch control post (LCP) computer, being accused of making huge profits.  After an enquiry, Sebastian de Ferranti agreed to pay back £4.25 million to the government.

Bloodhound remained in service as long as it did simply because it was an effective system. Initially dedicated to high-level interception, later, with the Mk2, it was able to engage lower-altitude targets with little fuss other than mounting its radars on towers to give them an improved view.

The missile

Numbers Built	783 (incl. Mk 1)
Type	Surface to Air Missile
Wing Span	9.28 feet
Length	27.76 feet
Diameter	21.50 inches
Weight	5,000 pounds
Speed	Mach 2.5
Range	115 miles
Propulsion	Two Thor ramjet engines and four Gosling boosters
Guidance	Semi-active TIR Type 87 radar
Warhead	Continuous-rod warhead, RDX explosive

The missile was a long cylinder of magnesium frames and aluminium alloy skin with a prominent nose cone at the front and some boat-tailing at the rear.  Small aluminium-covered, cropped-delta wings with a plywood core were mounted mid-point, providing pitch and roll control. Two smaller rectangular fixed surfaces were in-line with the main wings, almost at the rear of the missile.

Two Bristol Siddeley Thor ramjet engines were mounted above and below the body. Four Royal Ordnance Factory (RoF) Gosling solid fuel boosters were wrapped around the fuselage, lying above and below the wings on either side. The Goslings had rather large fins of their own, which aided separation on burnout.

Small air intakes just under the ramjet intakes ducted air to a turbine that generated hydraulic pressure for the flight controls, and to a smaller turbine for the fuel pump. There was also a small pipe intake to pressurise the two fuel bags.

So, how did it all work? 

A surface-to-air missile allocator would assign a target to a missile flight operations room, where it was allocated to a missile section’s engagement controller in one of the launch control posts (LCP).  The engagement controller would then begin to track the target using the Type 87 target illuminating radar (TIR) and the associated missiles would automatically move to face the target.

Once the reflected signal from the target was strong enough, the computer would flash the `free to fire’ message on a screen and the engagement controller would be authorised to fire.

At launch, thermal batteries are fired up to power the electronics and cartridges blow off the two Bristol Siddeley Thor ramjet intake covers.

After the boosters are fired, and there’s enough thrust to break shear pins holding it to the launcher, it’s off, accelerating the missile before burning out. The Thors ignite and sustain the speed for up to 80 seconds of flight.

Think on this: by the time the missile has just cleared the launcher, it was doing 400 mph and achieved 0 to 760 mph (the speed of sound) within the 25ft of its own length. A 0 to 60 mph time of…? Four seconds later, the four Royal Ordnance Factory Gosling solid-propellant boosters have accelerated the missile to Mach 2.5 and fallen away.  By then, the two Thor liquid-fuel (kerosene) ramjets are working to sustain the missile during a flight of up to 80 seconds.  

Each booster generated 28,000 pounds of thrust for four seconds – that’s a total of 112,000 pounds, no wonder it’s quick! Peak acceleration 40g.

Radar energy (continuous wave, replacing the Mk l’s pulsed) reflected from the target is received by a dish antenna under the missile’s nose cone, and the Bloodhound is directed towards a point in the sky at which the enemy aircraft is predicted to be intercepted (proportional navigation).  Changes in direction are achieved by moving the two wings in the centre of the missile body either differentially or in unison: the so-called ‘twist and steer’ (or bang, bang) principle.

During the twist and steer commands the lower ram jet would be operating in the turbulent shadow of the missile body and would run rich, but a vane at the nose cone sensed the new angle and turned the wick down on the lower engine.  On the launcher, the vane was held in a neutral position by a wax sleeve so as to provide equal feed to both jets, and after a few seconds of flight the wax was burnt off and the vane held in position by the airflow.

The missile was kept on track by a receiver dish in the nose that picked up a signal generated from the TIR and reflected from the target aircraft.  But commands could also be issued from the Launch Control Post during flight.

The enemy’s tricks for making the Mk 1’s pulse-Doppler radar break its lock do not work for the Mk 2’s continuous wave radar; attempting to jam the radar can be counter-productive unless done with great skill and lots of power, because the Bloodhound has a ‘home-on-jam’ facility if lock with the radar is lost for a certain time. If the jammer isn’t the same as the intended target, no matter – there’ll be another Bloodhound along shortly.  Either way, a bad hair day for someone!

Detonated by a proximity fuse, the RDX warhead explodes to scatter a shower of metal rods which form an ever expanding 120ft circular-saw spinning through the air at Mach 2.5.  The Mk 2 carries more fuel than the Mk 1 and can reach target heights at more than 60,000 feet and well below 1,000 feet.  However, in low-level flight kinetic heating could be a problem for longer range intercepts, and there were pressure relief valves in the hydraulic system to allow for the expansion of fluid. At low level and Mach 2.5, things get a bit hot.

The published performance erred on the side of caution.  Range easily exceeded 100 miles, and maximum height was over 80,000 feet, depending on flight profile.

Servicing

When the missiles were removed from the launchers after their 90 day period, they were de-armed and taken to the test facility.  Here, any modifications were carried out and the whole missile system was put through exhaustive testing on the AHEPS – Air, Hydraulics, Electronics, Power System.

The electronics were housed in the forebody, just behind the radar dish.  Circuit boards with discrete components were arranged in three rows fixed to a central tube that also supplied cooling air. 

To fix electronic faults, the Bloodhound technician pulls the affected circuit board and reaches for his soldering iron. Throw-away technology has yet to reach the squadrons, and the technician can follow a fault through from diagnosis to rectification with their own hands.

Weapon, Airframe, Propulsion, Air Radar and Air Defence technicians pass to and from the Bloodhound Force during their service careers, just as if it were an aircraft operating unit. Similarly, though volunteers to ‘pilot’ a Bloodhound in the accepted sense of the word are notoriously scarce, the closely-approximating Engagement Controllers were previously drawn mainly from the same General Duties (Air) Branch.

Test firings

During my tour at RAAF Butterworth, two missiles were test-fired: one at the Aberporth test range in Wales, and the other at Woomera in Australia.  They used Jindivik target drones and there was a programmed miss distance of 25 feet in order to save the drone; this mostly worked but one of our test rounds passed a bit closer so that its supersonic shock wave took out the drone.

Unfortunately, I didn’t get to see one fired – it must have been an awesome experience – imagine the noise of those four fireworks going off.  I only managed to be involved in a fuel flow test of a Thor ramjet in their supersonic wind tunnel at Bristol Siddeley in Bristol.  It was a noisy experience even behind glass and with ear defenders. Impressive, though.

Old sites

By the way, if you search for North Coates and Bawdsey using Google Maps hand-select the satellite view you can still see the concrete pads where the radar and missiles were installed, right on the coast.  Also, try RAAF Butterworth in Malaysia.

The closest location where you can still see a poor condition Type 87 radar and a Bloodhound Mk 2 missile is at the Muckleburgh Collection on the north Norfolk coast – And the café sells a great apple pie and cream.

Author:: John Self

---

Bloodhound Mk 1

To see a Bloodhound Mk 1 Missile visit the Norfolk and Suffolk Aviation Museum where we have one on display. 

A short video tour of our exhibit is below.  More video tours and video blogs can be found on our YouTube Channel by clicking on the button here.  

 

 

Follow us on Social Media, email us or visit our Main Website.

• 
• 
• 
• 
•