In the mid 1950’s there was a recognition that the V Force would probably have to fly low level if they were to penetrate to their targets.  Unfortunately the aircraft had not been designed for the low level role, nor had thought been given to a low level bombing profile that would allow the aircraft to escape the effects of its own weapon.

Problems of bombing and navigation Fly on 2 engines at low level? Result of trials on H2S at low level Valiant fatigue problems and their effect Restart low level trials Obituary for Jimmy Harrison, test pilot on the Vulcan

By the mid-50’s there was active discussion at Air Staff level into the feasibility of operating the V force at low level in its nuclear role, specifically against Russia. 

“1.Of all the possible methods that can be employed to prolong the useful life of a subsonic bomber low level penetration and attack is the one which offers the best chance of success even into the era of sophisticated guided missile defence systems.

2. The low-level penetration which can be achieved with V-bombers is limited but careful routing and optimisation of flight profile together with flight refuelling, offers the possibility of attacking a fair proportion of important targets.

3. One important consideration is the navigation, location and bombing of targets from low level.  Although little has been published on this aspect a great deal of information is available as a result of trials which have been carried out by Lincoln and Canberra aircraft of Bomber Command, and data from special trials with U.S.A.F. RB-45 aircraft.” ¹

The discussions were focussing on three or four main areas;

• The ability to navigate and bomb at low level.
• The flight profile for the release of the weapon
• Vulnerability of the bomber force during attack
• Airframe fatigue

Problems of bombing and navigation.

The H2S that I used in the early 1970’s must have been a considerable improvement on that available in the mid-50’s, judging by many comments in some of the documents in the National Archives.  One that deals particularly with the Operation of the ‘V’ Bombers at low level is AIR 2/14578, most of which was designated as SECRET or TOP SECRET when the documents were raised, but which have since been downgraded and put into the public domain.

In August 1955 the Chief of the Air Staff proposed trials using a Valiant to look into the possibility of low level flight profiles, and recognised that it would involve compromises over airframe fatigue life as the aircraft had been designed as a high level bomber. To limit the impact on fatigue life it was suggested that attacks would be made at night so reducing speed and fatigue. This was presumably based on the idea that the aircraft would be harder to detect at night, and so could afford to cut back their speed on the low level sectors.

Two engines out. A further suggestion around this time was that “distinct advantages may result from stopping one or two engines in low altitude operations of the ‘V’ bombers.  The Air Staff wish this question to be closely examined.” Not sure how popular this would have been with crews!  Some questions were stipulated as needing an answer on this question, I quote a couple of them;

(f) Rate of descent if one of the two engines fails?

(h) If one engine fails when flying on two, will the electrical power required be available to relight another engine?

On file there is a Loose Minute from April 1956 which comments on a response back from Vickers regarding two engined flight at low level; “…they go on to say that an engine failure with the aircraft flying at low level would therefore present a considerable risk and do not recommend proceeding with any trials on two engines. I think we must agree with their recommendation. …..” So by early 1956 this suggestion was dead.

The Valiant used for the low level trials was fitted with H2S 4 (I believe H2S 9 was the model I used, see separate page) and in these early days there was considerable skepticism regarding the use of H2S below 1,000ft.

It is important to remember that these were early days in the operation of the V Force, and that some of the data on which these operations would be based were coming initially from Canberra and indeed Lincoln squadrons. Lincoln aircraft with H2S 4A had done trials in East Anglia at heights between 500ft and 5000ft but as these heights were below the limits of the bombing computer, bombing had been done using time delays after overflying a point on a particular heading.

The trials showed that over the East Anglian type terrain (pretty flat) the radar could be used below 1000ft, but not down to 500ft “…the critical point of change over seemed to occur at around 800ft.”  The determination that came out of this was that; “Regarding airfields the optimum chance of detection of actual runways appeared to be about 2,500ft whilst the overall optimum height of operation from all points of view was about 5,000ft.” This may have been the optimum height for the operation of the radar, but could not be considered as low level in terms of operational flying.

Trial conclusions. As a result the trials group decided that no new radar needed designing, providing low-level operations were carried out at around 1,000 – 2,000ft; “At 800ft the use of the display is marginal whilst at 500ft, save in exceptional circumstances, it is unusable.”  Bombing would not be by use of the normal bombing computer, “…instead a simple manual computer would be provided.” There were obviously considerable improvements between then and 1970.

The conclusions in the report can be summarised as;

• The radar does not provide “any worthwhile operational performance” below 800ft.
• “Within present knowledge, there is no possibility that a radar could be designed to provide a satisfactory performance at heights below 500ft.”
• Using H2S 9 and flying at about 1,000ft “Track-keeping to +/- 5 miles and a bombing accuracy of 500 yards should be achieved.” (this would not be using the automatic computer)
• The essential modification needed is “…to provide cooling air to permit its continuous use at low-level for periods of up to 2 hours.”

Another paper in the same file picked up the point about radar and Bomb Computer performance and suggested that as the NBC could not be used below 7,000ft  and that the optimum height for the radar was 5,000ft then the low level phases could be flown at 1,000ft but “… it should be possible to climb to that height [5,000ft] every 4 or 5 minutes to get an H2S fix. This constant ‘pop up’ profile would be difficult against an effective radar network.

Cancel trials

By August/September of 1956 the fatigue problem had manifested itself on the Valiant and there were serious questions about the ability of the bomber to ‘get through’, “Blue Steel” was also on the horizon and this ‘stand-off’ weapon could possibly change the whole need for low level penetration.  

On 22^nd August A.V.M Lees wrote regarding a suggestion that the trials should stop; “Although I agree that we should cancel further trials and development work on the Valiant for the low altitude bombing role, I believe it is too early to make such a decision with regard to the Victors and Vulcans.  Such evidence that we have suggests that these aircraft are also likely to run into serious trouble from enemy defences in the next few years and that “BLUE STEEL” may not greatly help the situation. My staff are at present engaged in an assessment of their vulnerability and until this is complete I recommend that we hold the question of the Victors and Vulcans in the low level role in abeyance.”

In September he became convinced that the trial should stop for all three V’s. “…. Trials and development work on the Valiant and other ‘V’ bombers for the low altitude bombing role should be canceled, to enable all our efforts to be concentrated on clearing them for their primary role.”

The government were put in an embarrassing position by the fatigue problems discovered on the Valiant, it meant that the aircraft had to be withdrawn from operational service, so reducing the number of targets that the RAF could cover as part of the NATO plan.  There is quite a lot in the PRO files discussing how they would break the news to the Americans.

Restart low level trials.

In September 1960 Air Marshall Sir Kenneth Cross (C-in-C Bomber Command) was wanting to reinstitute the low level trials and suggested that there should be some leaked information to the press regarding low level flying by the Vulcan, he felt that “…. Controlled leakage of this sort could well contribute towards keeping the Russians guessing as to our intentions.” By April of 1961 aircraft of the Bomber Command Development Unit would be planning low level flight trials from Goose Bay in Canada and Offutt in Nebraska.  The photo below shows a Decca roller map that was fitted for trials to help overcome the low level navigation problem. I don’t know if these were ever used outside the trial group, I certainly never saw them in use. Anyone know?  There is a separate page on low level as I knew it.

Decca Roller Map Type 9033 as viewed from 2nd Pilot’s position in Valiant. Taken from B.C.D.U. report 21st September, 1961. Photocopied from file AIR 2/14578 in PRO.  J Dillon.

Note. Sources;

1. AIR 2/14578 “Operation of ‘V’ Bomber at low level” National Archives

At the beginning of May 2007 the Daily Telegraph had an obituary for Sqn Ldr Jimmy Harrison.  I have taken the liberty of adding a few extracts from their column.  Maybe there are some out there who remember him.

Squadron Leader Jimmy Harrison, was one of Britain’s most accomplished post-war test pilots, being known for his testing of the Vulcan bomber and the Nimrod maritime patrol aircraft. [The photo on the right is taken from the Telegraph article.]

After a successful career in the RAF as a night fighter pilot and graduate of the Empire Test Pilots’ School, Harrison joined AV Roe as a test pilot in 1953.  His arrival coincided with a difficult time during the development of the unique delta-wing Vulcan. The programme had reached a critical stage and Harrison spent much of 1954 testing one of three third-scale models of the Vulcan, the Avro 707A, designed specifically to test some of the characteristics of the delta-wing design.  The flying was crucial to the eventual success of the strategic bomber and Harrison’s contribution was enormous.

Emergencies were not unfamiliar in the test flying business and Harrison had his fair share of them. On July 24 1959 he took off with a crew of five and climbed eastwards from the airfield at Woodford, near Manchester. The aircraft suffered a complete electrical failure and every attempt to save the aircraft failed. He climbed to gain sufficient height for the three rear crew members to bale out - they were not equipped with ejector seats. After they successfully left the aircraft, he headed for the Humber estuary before he and his co-pilot ejected.  He landed in a remote field and limped to a narrow road still wearing his helmet and pressure suit.

Harrison started in the RAF as a Halton Apprentice in 1934, but went pilot when the war started, and turned out to be an exceptional pilot.  He was an instructor before going to an operational squadron where he flew Mosquitoes on night intruder sorties over Germany. After the war he started his test pilot career, flying many types including the Hawker P1052 jet.  It was the well known Roly Falk who encouraged him to join AV Roe in 1953.  In 1952 he had been awarded the AFC.  Jimmy Harrison died on April 16, aged 88.