Going back to the Alpha Project again—we had produced bomblets that would not detonate sympathetically if one happened to be set off by, say, an enemy bullet. Only a 100G shock could activate a pistol. Both characteristics gave protection against enemy fire and inadvertent mishandling of bomblets. In the case of Ian Donaldson’s crash, the Canberra fuselage had absorbed so much of the shock loading on impact that not a single bomblet had detonated; which is why all 300 ended up in Maputo.
New Frantans
MY PROJECT TEAM HAD SUCCEEDED in its most pressing task of providing the Canberras with an effective anti-personnel strike capability. By January 1977 we were already engaged in a number of new projects. These ran concurrently, imposing a huge load on Denzil and Bev who were still heavily involved in the production of Alpha bombs, officially designated Mk2 Fragmentation bombs. In spite of this they had been more than willing to take on new developmental work. Projects Bravo and Delta (pyrotechnics and 37mm Sneb boosters) had been finalised. Next priorities, Projects Echo and Foxtrot, were for new Frantans and high-pressure bombs.
To provide the Lynx with an effective Frantan, we chose to move away from conventional napalm bomb designs. All those in use in the western world were simply metal tanks, most with small fins designed to pitch the unit nose-down at the moment of release to ensure positive separation from the aircraft. Otherwise, none possessed flight stabiliser fins.
After release, the tanks behaved in haphazard ways causing them to follow unpredictable trajectories. Tumbling, flying sideways, oscillating and corkscrewing were characteristics that set napalm aside from aimable bombs and made accurate delivery difficult. For instance, if two tanks were released together, with one pitching nose-down and another nose-up, they could land so far apart that one might fall short of target whilst the other passed over.
When Americans took on a target they dropped four or more napalm bombs from each of a number of aircraft to saturate large areas with flame and intense heat. Absolute accuracy and high costs did not bother them whereas we needed units that would follow a repeatable trajectory to make each unit aimable, accurate and highly effective. This meant we had to produce an aerodynamically shaped unit with low drag characteristics for carriage, but incorporating efficient stabiliser fins to ensure longitudinal stability for clean release and alignment in free flight.
Metal containers were no good, as we had witnessed on hundreds of occasions. Burster charges coupled with unpredictable case rupture resulted in equally unpredictable distribution of burning napgel. Too often large quantities of the gel remained inside partially burst tanks or sticky blobs of unburned gel lay all over the ground and stuck to vegetation. This was no good at all! I decided we needed tanks that would shatter like glass on impact to free their entire gel contents in a huge fan-like spray of tiny droplets with inter-linking volatile gas. I had learned that the Hunter disposable long-range tanks were constructed from fibres with phenolic resin and that they shattered on impact. We followed this line and produced casings moulded from woven glass fibre and chopped asbestos set in a phenolic resin binder.
Prototype sixteen-gallon units were made and fitted with Alpha bomb fuses (suitably modified to function at low-impact levels) imbedded in the large pocket of flash-compound that ignited the napgel. From Day One the new Frantans were a great success and, with small modifications, were cleared for operational use on Lynx and Provosts.
Hunters used imported spun-aluminium fifty-gallon Frantans but these suffered all the limitations we sought to overcome. So I arranged comparative trials between our lowcost sixteen-gallon Frantan and the very costly imported fiftygallon units. The results were astounding. The Hunter pilots were able to deliver the local unit with great accuracy. In itself this was pleasing, but even more satisfying was the fact that the local unit, though only possessing one third of the napgel contents of a fifty-gallon unit, provided consistent coverage of ground that equalled the best of the imported variety. Foreign currency saving was another bonus.
Golf Project
IN PROJECT FOXTROT WE ATTEMPTED to produce fuel-air explosive (FAE) bombs, which American military journalists described as having ‘near-nuclear’ effect. One military article was supported by dramatic photographic records of the total destruction of an old US naval destroyer from just one of these FAE bombs. However, destruction of ships was not America’s real interest in FAE. The weapon had been developed to clear large pathways through enemy minefields by detonating hidden mines with excessive over-pressure of ground.
Ethylene oxide was the medium we employed. There were two reasons for the choice of this liquid gas. Firstly, it explodes with as little as 2% of air inclusion and as much as 95% of air inclusion, whereas most other gases will only detonate within a very narrow gas to air ratio. The second advantage of ethylene oxide is that, when ignited, it produces gas volumes many times greater than any high-speed explosive, such as TNT.
Each American FAE bomb was dropped at relatively low level and descended to ground on a parachute. A groundsensing device perforated a pressure disc to release the bomb’s pressurised liquid contents at about twenty feet above ground and simultaneously fired flares upwards. The upward and downward flight time of the flares allowed the ethylene oxide gas skirt to widen to around twenty-five metres in radius before the first of the flares contacted the gas skirt setting off a vicious explosion. Lethal over-pressure from a mere five gallons of ethylene oxide dispersed and detonated in this way extended way beyond the edge of the gas skirt.
Very often the precise positions of CTs firing from dense bush were not known and we had no single weapon that could produce lethal effect over relatively large areas to cater for such situations. FAE seemed to offer a perfect solution to this ongoing problem.
Considerable time, effort and cost went into Project Echo during which we succeeded in making huge expensive fireballs before, eventually, achieving two terrific detonations. The first of these broke many windowpanes in the Kutanga Range domestic area that was over 500 metres from the blast. What interested us about successful detonations were the sound effects they produced and the fact that they totally stripped vegetation, including substantial trees, up to forty-five metres radius from blast centre. The ground around was pulverised and powdered to a depth of several inches. The sound of each detonation was not a sharp bang, as from TNT, but a loud deepnoted ‘crruuump’ from an explosion, followed immediately by the ‘cruump’ of an implosion.
Ethylene oxide is a very dangerous substance to store and with Rhodesia being under UN sanctions it was also very expensive and difficult to source. Considering these issues, and realising that weapons that descend on parachutes would be difficult to deliver accurately, even in the lightest of wind conditions, we decided to drop the FAE project. Nevertheless, I was still determined to produce high-pressure bombs. Denzil was just as determined and acquired information on the gas-generating properties of every known explosive and combustible liquid compound. His hope was to identify a readily available safe-tohandle explosive that would exhibit similar characteristics to ethylene oxide. When he recommended ANFO we all studied the data before agreeing it exhibited suitable gas-producing properties. This was a pleasing discovery because we could produce ANFO very cheaply and easily.