If the aircraft were to fly at low level, what release manoeuvre would they use with a nuclear weapon, and escape the effects of their attack.

Vickers’ suggested profile Trial with B-47

At high level there was no great problem for the delivery aircraft, it would take the bomb approximately 50 – 60 seconds to fall depending on release height, this would allow time for the aircraft to turn away from the target and have its tail to the explosion.  The aircraft would also be some miles away at detonation. At low level it was a different matter.  At low level, assuming there are no delay devices, there is only a short time from release to detonation, the bomb will have little ‘forward throw’ because of the lack of height, and there will be limited time for the aircraft to get into the right attitude ready for the detonation.  The bombing profile and weapon used in the 1970’s is discussed elsewhere, this section is to look at the early (1950’s) thoughts on how the weapon should be delivered from low level.

To extend the forward throw and initiate an escape manoeuvre it was felt that some form of ‘Toss’ or ‘Loft’ bombing would do the trick, this would involve some fairly sharp manoeuvres for a large aircraft.  One of the papers in the PRO¹ file on low level operations suggested a ‘Loft’ bombing profile to Vickers.

“Method A. Bomber approaches target over pre-selected reference point on a single specific heading at maximum permissible speed; accurately executes a loop-entry manoeuvre, releasing the bomb at about 45^o and regaining level flight in the reverse direction to the approach in the most expeditious manner.”

The following is the recommendation from Vickers for the Valiant Mk. 1.

“The target is approached at a trimmed speed of 350 knots, bomb doors open.  On passing the identification point, the pilot immediately applies 2.7G, and concentrates on holding this value steady while the co-pilot opens up the throttle to take-off r.p.m.  As soon as the bomb is released, the pilot should release the excess ‘G’ and apply maximum aileron wheel load.  When about 60^o of bank has been attained, the aileron wheel load should be relaxed and the ‘G’ built up again.  When the roll has been finally checked, between 70^o and 90^o say, the ‘G’ should be brought up to the full value of 2.7 again. When the aircraft has turned through about 120^o, the ‘G’ should be released slightly, and the opposite aileron applied to roll out of the turn. The final heading should be approximately 150^o from that of the approach; the bomb burst will then lie directly behind the aircraft and the distance from aircraft to burst will be a maximum. When on the final heading, the bomb doors may be closed and the engines throttled back as convenient.

Optimum throw of the bomb is obtained if the bomb is released when the flight path angle to the horizontal is about 40^o.  However, such an angle is too great from the point of view of the subsequent manoeuvre, and the main object of the initial trials would be to determine the greatest angle which will allow the aircraft to perform the turn, the best associated angle of bank to apply, and the best point at which to start the recovery from the turn. The firm’s calculations suggest that 30^o should be practicable, but the first trials would be done at a lower angle, this being increased as the tests proceed.”

There is a letter in the file in the PRO¹ from Gp. Capt. Searby of the British Joint Services Mission in Washington, dated 25 September 1955 sent under ‘Secret Guard’ classification to A.V.M. Lees. In this he gives the results of trials of “Low Attack by B47 Aircraft”, and says that a high degree of accuracy was obtained, “ … in the final tests errors were reduced to the order of 100 – 300 feet.” I’ll quote in detail as it gives a good idea of the manoeuvres being considered, possibly also for the V Force.

“2. Initial trials on the B47 were carried out with the prototype and the Firm’s test pilot to ensure that the aircraft structure was sufficiently strong to take the acceleration forces involved.  These tests established the fact that the airframe could withstand up to plus 3G whereas the L.A.B.S. technique as evolved for the B47 requires only 2G.

3. The tactical trials with the B47 were made at Eglin and it is believed three aircraft of this type and some B57’s were used.  Preliminary trials involved investigation of associated low level navigation problems and in subsequent phases the feasibility of making L.A.B.S. attacks using instruments by night and in cloud were explored. The final phases involved bombing accuracy and it seems the B47 commences its manoeuvre at 2 – 300ft at a speed of approximately 420 knots: it pulls up to the top of its loop at between 7 – 8000ft and rolls out at 160 knots, although speeds as low as 95 knots in the inverted position have been reported. There appears to be little difficulty in performing these manoeuvres on instruments.

4. Whilst the feasibility of our V bombers making use of such tactics is not known here, the U.S.A.F. authorities regard this particular technique as a practical method of making medium bomber attacks.  Perhaps the greatest significance to be attached to the evolution of this technique lies in the possibility of fast medium bombers penetrating poor low radar cover and delivering bombs of much higher yield than that carried by fighter bombers.  In addition it brings within range certain targets which were formerly believed secure since they lay outside the range of hostile fighter bombers.

5. At the present time the official report on these trials has not been made available to us and we are anxious to ensure complete secrecy in regard to the source.” [My italics, J Dillon]

It is interesting to see that even good and close allies still like to do a little underhand information gathering.

The photo below shows a B47 variant which would have been similar to that used in the Loft bombing trials, though probably without the underwing pods.  The B-47 had a crew of three and I have to say it looks more likely that this could fly the L.A.B.S. profile than the Valiant.

Boeing B-47. Photo from the Boeing site.

I am not aware if any of these manoeuvres were adopted into squadron practice, maybe some older hands could enlighten me on that.  I suspect it may have been put on hold following the 1956 decision to hold back on low level trials on all three V Bombers. By the time that low level trials were brought back in, 1961, I believe Blue Steel was not far from introduction. Blue Steel was also before my time.  I was a straight WE177 laydown man.

The following is part of the text of a couple of emails from Tony Regan, ex Vulcan Crew Chief.

Your article dealing with LABS and the B47. It killed Group Captain John Woodroffe when he flew with Col McCoy in a B47 in November 1957 at Pinecastle; he is buried at Wittering (Pinecastle was later McCoy AFB and later still Orlando). Previously Col Mike McCoy was CO 321 Bombardment Squadron USAF at Pinecastle was flown in Vulcan XA900 by Squadron Ldr. Don Howard (of XA897 at London Airport 9 Sept 56). Eye witness (one of our Members of a crew chief site) tells me Howard's demo with the Vulcan, was a near vertical climb out. McCoy demonstrated the B47, but the wings folded and crashed in North Orlando.

Woodroffe was the Det CO also CO of Wittering. I was on 88 Squadron in Germany where we used an American weapon in the LABS role we mounted QRA in 1960.

regards

Tony Regan

Note.Sources

1. BAFS/S.505/ARM in AIR 2/14578