The engineers quickly sketched profiles of four units comprising two hoppers each to establish the internal volume of each hopper. Having done this, they established that the external diameter of each Alpha bomb would be 155mm. From this the size of the rubber balls and inner bomb core were also determined.
The very next day preparations were in hand to press the metal blanks into half spheres. By Day Three the welding of half-spheres for inner cores and outer casings was already under way. The first hundred outer casings were taken off-line and filled with concrete for initial proving trials.
At New Sarum Warrant Officer John Cubbitt had his Drawing Office staff busy finalising the hoppers design and within two days Station Workshops were fabricating prototypes for preliminary drop trials of the concrete-flled Alpha bomblets. The concrete units approximated very closely to the calculated final weight of explosive ones.
At my insistence flight trials commenced with the fitment of a camera into a Canberra bomb bay to record the release characteristics of the old 28-pound bombs from the ‘bomb box’ unit. The bombs we used were practice units that had the same shape and ballistic characteristics as live ones. Two full-load tests of ninety-six bombs each were made. In addition to the bomb-bay camera, each drop trial was filmed from a formating Vampire.
What we saw was very disturbing. Bombs exiting the bomb box into the very high turbulent airflow, particularly at the rear of the bomb bay, gyrated, tumbled and jostled with each other. Some bombs were even blown back into their compartments before emerging again to join other wildly twirling and twisting bombs. Why film recordings such as these had not been made and studied previously, I cannot say; but it made us realise that the Board of inquiry into the Canberra disaster had not come up with the correct reason for the premature detonation that destroyed the Canberra.
First drop tests of the Alpha bombs were recorded in the same way and we were delighted to see how cleanly they dropped away and how rapidly they spread out and trailed back from the aircraft. Because the concrete Alphas suffered little damage on impact, we were able to gather them up for repeat drop trials, including releases at low level. All low-level runs were filmed from the bomb bay, by a chase Vampire and from the ground. The results were very encouraging. Impact with the ground was occurring well behind the aircraft, lateral spread was better than expected and every unit skipped back into flight.
Bev had designed and produced a small number of multidirectional fuses for first non-explosive trials. Our first live trial only involved five Alphas fitted with delay fuses amongst concrete units. No explosive was included to allow post-strike inspection of each fuse. Two of these fired instantly on impact with the ground, two functioned correctly and one failed to fire. Inspection of the latter showed that the initiating cap had fired but the delay link failed to transfer to the detonator cap. In the case of the two instantaneous bursts, initiating caps’ flame had flashed past the delay links directly to the detonator caps.
Modifications and rectification followed rapidly and we were soon testing whole clusters of Alphas charged with explosive. During this time we established that the Alpha bomblets exhibited two unexpected but highly desirable characteristics due to the rubber balls interface. The first was discovered when one bomblet had been deliberately detonated in the midst of a pyramid of unexploded bomblets (UXBs). It failed to cause a sympathetic detonation of any of the other bomblets as occurs with other explosive units—our problem was to find the widely scattered survivors for independent destruction. The second peculiarity was that we were finding hundreds of thin 20mmround shrapnel pieces that propelled like spinning saws and sliced their way into the hardest of trees. Formed by the 147 rubber balls that pressed out discs from the outer casing they spun like crazy saws aligned with their direction of flight.
By the seventh week, one week behind schedule, the engineers were totally exhausted from their intense work schedule and many sleepless nights. However, we were ready to demonstrate to the Air Staff a full-scale Alpha strike on a 1,200 x 200-metre target that had been prepared by the Range Warden, ‘Kutanga Mac’. Hundreds of cardboard and steel targets were set above ground and in trenches throughout the length and breadth of the target.
OC 5 Squadron, Randy du Rand, had not been too interested in our work at the start of Project Alpha, probably the consequence of my early tests with lead balls. However, once the project started to show positive results, nobody could have given greater support and assistance to the project team than Randy.
The Commander and his senior staff officers flew to Kutanga Range to witness the demonstration and see for themselves if the Alpha system was ready for ‘the real thing’. The project team had witnessed many trials but this was to be the first full-scale drop. We had reduced the original 400 Alphas per Canberra load down to 300 to facilitate easy loading and because we had come to realise that the reduced load covered a greater strike length than the original 800 metres we had set for ourselves. The 25% cost savings was not the reason for the reduction, but it was a huge bonus.
There was great anticipation and mounting excitement as Squadron Leader Randy du Rand opened his bomb doors late on his run-in at 400 feet at a speed of 300 knots. None of the Air Staff expected such a spectacle of dust and multiple airburst flashes as 300 bomblets did their thing. That the Alphas were bursting at perfect height well behind the Canberra was obvious to all before the sound of the explosions reached the observation point. This came as a thrilling continuous thundering of overlapping explosions.
The Commander was quite overcome by what he witnessed and showed it by shouting, “Bloody marvellous. Absolutely bloody marvellous!” Everyone present congratulated everyone else before we all set off to walk the full length of the prepared target area.
First inspection made it clear that the Alpha bomb system was just what we needed. When the visitors left, the project team commenced the detailed study that showed that the effective coverage of 300 Alphas was 1,100 metres in length by 120 metres in width. We had achieved more than we planned for! Fourteen unexploded bombs (UXBs) were defused for inspection in our ongoing attempts to reach 100% efficiency but, with 5% bomblet failures, the system already rated slightly better than the USA and UK guidelines for acceptable UXB rates in any cluster-bomb system.
The important thing was that the Alpha system was cleared for operations and the Canberra had been given the antipersonnel punch it deserved. Training of crews had been done but it was considered necessary to prepare for formation attacks, initially by three Canberras. This involved flying a very flat echelon with the aircraft spaced 100 metres apart. In this way a strike length of better than 1,000 metres and a width exceeding 300 metres could be assured. The reason for the very shallow echelon was to make certain that formating aircraft did not fall back into the curtain of shrapnel rising from the exploding bombs dropped by adjacent aircraft.
