Preliminary experiments were carried out by ASR Section but it soon became apparent that the technical requirements were of a magnitude that meant that further development work could not be undertaken with the limited resources available to this group. Consequently, from April 1944 the main work on this project was handed over to RAE, although at all stages the ASR Section kept in close touch with its progress, including the planning and observation of trials at Farnborough. It acted, in effect, as a coordinating body between SOE as the client and RAE.
Three main lines of development were pursued. Trials of a Quilter delay opening mechanism (which had originally been designed for delaying the opening of personal parachutes) modified to increase the delay time to 30 seconds showed that it was unsuitable for use with containers. Secondly, it was proposed to modify the Middle East delay opening device to overcome problems which had arisen in the original design. Finally, the use of the American M111 altimeter fuse was to be tested. An assessment by RAE indicated that a container fitted with a stabilising parachute and an M111 fuse set to release the main parachute at a nominal height of 900 feet above the DZ would probably give sufficient accuracy; however, ASR Section felt that release at 600 feet would be preferable. A 35-second mechanical clockwork delay was also considered but in the form available was deemed to be unacceptable. In RAE’s view the Middle East device was also insufficiently accurate. One suspected that this was because it looked too much like a do-it-yourself job, which it was, and did not have the professional touch to which RAE devices would be expected to conform. In fact, SOE continued independently with the improvement of the Middle East device.
From April 1944 onwards pleas from the Polish Section became increasingly urgent. In the period April– July, 318 sorties had been mounted of which 174, or 55 per cent, were successful in dropping 114 men and 219 tons (222,500 kg) of stores: a tiny fraction of what would be required to supply the needs of the Polish Home Army. The situation was aggravated by the refusal of the USSR to allow aircraft to land and refuel at Russian bases in reconquered areas. Although by June trials of the RAE device incorporating the M111 fuse were underway, progress was slow. Among other things RAE’s other major commitments meant that it was difficult to get flying time for testing at Farnborough. But time was getting short as the Russians advanced towards Warsaw. The Poles were desperate to liberate their city from the Germans ahead of the Russians. For a short time the hazards of air supply to Poland from the Middle East were judged to be too high. On one sortie fifteen aircraft set out, four were lost and two crashed on landing. Operations were suspended for one or two weeks. By the time of the Warsaw uprising on 15 August the final trials of the RAE device were almost complete. It is not clear to what extent the Middle East device was used in this period but it was reported later that in a series of sorties from Italy some 40 per cent of the devices failed. This gave added urgency to attempts to improve the Middle East device. The ignition system was redesigned and a short length of instantaneous fuse was added to boost the parachute release mechanism. Progress was slow with the RAE device. The main problem was with icing of the mechanism at high altitudes and in one trial one out of three main parachutes failed to open at the assigned height.
Neither device was in a state to use operationally during the crucial period in August/September. In an operation on 13/14 August 54 sorties were launched from Italy. Twenty-three succeeded but eleven aircraft were lost, mainly brought down by fire from the ground as they swept in at low level to make a drop, and many aircraft were seriously damaged: it was in this period that the need for HADDA was most cruelly felt. At one stage after a sortie in which half the aircraft were lost only two or three serviceable supply dropping aircraft remained in Italy. In an attempt to relieve the situation the US Air Force reached an agreement with the Russians which allowed them on 10/11 September to send 110 B17 Fortresses to drop stores from 15,000 ft with the loss of only one aircraft. However, with the great spread due to wind drift from more than fifteen times the normal height of a stores drop, only 30 per cent of the containers were recovered. The feelings of desperation and anguish felt by the Poles in London reacted strongly on members of the ASR Section who were helpless to influence the RAE programme. It was not until the end of September that the RAE trials were completed and 500 devices were about to be despatched. But Warsaw fell on 2 October and the operational need for HADDA in that sphere ceased.
Nevertheless, interest in the high-altitude technique continued, especially in the Far East and with Airborne Forces. SOE continued independently to work on the development of the Middle East device to improve the ignition system and to waterproof it adequately for use under tropical conditions. By February 1945 the RAE device was in full production and was being issued. However, further tests showed that there were still problems of icing which it was proposed could be overcome by the use of an anti-freeze grease. And the static line broke on a number of occasions and failed to withdraw the arming device. Snags also arose in the fitting of the device in the Stirling aircraft. Some further trials were to be held to assess the use of a modified Mark IX bomb sight for aiming the containers. This work was in hand when the war in Europe ended. The work of ASR Section was summarised in two reports, Nos. 19 and 20, but these do not appear to have survived. Further development was handed over to RAE and Airborne Forces when the ASR Section on HADDA was disbanded in August 1945.
Free-Dropping of Stores
The possibility of dispensing with the use of parachutes was considered seriously early in 1944 when the supply of parachutes gave cause for concern. The ASR Section was given the urgent task of examining the feasibility of free-dropping stores and ammunition. The central problem was that of upgrading the methods of packing to ensure minimum damage on impact at speeds much higher than those experienced when a parachute was used. It was soon established that even with improved packing the free-dropping of C- or H-type containers was impossible. Moreover, it was clear that free-dropping would be feasible only with a limited range of more robust stores and equipment, and that the weight of each package would have to be limited.
Preliminary trials were carried out in December 1943 by dropping from a height of six feet onto concrete. When these proved promising, further tests were carried out on 26 May 1944 from a tethered balloon at Henlow. Drops were made from 3,000 ft onto grass. In these trials the simplest and most readily available packing materials were used. It was found possible to free-drop without damage ammunition and Sten guns firmly wrapped in blankets and enclosed in a mailbag or flour sack. It was thought possible that if the packages were designed to fall in a predetermined manner, then most of the packing material could be placed round the area of impact, with an overall saving of material. To achieve this the packages were fitted with a vane-type drogue which controlled the fall and impact satisfactorily. However, difficulties were seen in obtaining adequate supplies of these drogues. The use of improvised ‘flour sack’ drogues was investigated. These were made by inserting a wire ring into the mouth of the sack and linking this to the package with four rigging lines. These gave good results, not only because they controlled the direction of impact but also because the gyration or ‘spinning leaf’ effect reduced the speed of fall. With this technique 9 mm ammunition wrapped in blankets and Sten guns packed in corrugated paper and Koran fibre were dropped successfully from heights up to 3,000 ft from a balloon, and from aircraft flying at 135 mph and an altitude of 200 ft. An alternative was to use standard ammunition boxes fitted with a crash head and with a drogue to control the angle of impact. Drops from the balloon were promising but the ballistics of the load were erratic when dropped from an aircraft.
Furthermore, in these and other trials the presence of the drogue tended to interfere with the handling of the loads in the aircraft. Further development of the use of crash-heads was handed over to AFDC, while simpler methods of improving the packaging were pursued by ASR Section. This led to the specification of the methods of packing of seven standard load
s including besides ammunition, Sten guns and grenades, blankets, battledress, boots, shirts, and socks. Standard food packs included dehydrated rations, flour, 50 lb (22.7 kg) sacks of rice each containing one tin of corned beef, baked beans, milk, sardines and margarine. For reasons not apparent, no satisfactory means was found of dropping packs of .303 ammunition. No attempts were made to free-drop explosives or incendiary devices. The free-dropping of liquids raised some problems. The simplest method developed by AFDC was to place a liquid-proof bag of water or petrol inside a larger bag. A 5-gal. rubberised skin bag for use with an outer canvas bag was approved for use in Europe but doubts about the ageing of the components under tropical conditions meant that it was not acceptable in the Far East. The free-dropping of clothing and similar items by themselves was considered wasteful since they were better used to protect more vulnerable items.
Attention was also given to the despatching techniques. In conjunction with the RAE at Farnborough it was shown that a good concentration of sacks could be obtained by linking them together with webbing in strings of four (sausages) and dropping through the despatch hole. With an appropriate aiming technique the whole load of 64 sacks (1½ tons or 1527 kg) from a Halifax could be dropped accurately. In two separate sorties dropped from 1500 ft and 200 ft all the sacks fell within a circle of 75 yd radius. But it was possible to drop only eight sacks on each run in, so that eight runs, taking 30 minutes, were necessary to drop the full load. These figures could, no doubt, have been improved by the use of roller conveyors.
Since it was anticipated that the free-dropping of supplies might be needed to the Maquis areas of South-west France, it was important to check that the methods developed for dropping on grass or farmland were equally applicable for dropping onto rough and potentially rocky terrain. It was thus important to test the packings against more severe conditions.
It was decided to simulate these conditions by dropping onto a rocky hillside near Fishguard where SOE already had a base (Station IXc). This trial, carried out in conjunction with the Radio Communications Division (RCD), would also provide the opportunity to test their procedures for using the S-phone to indicate the release point over the dropping zone. It was also the first occasion on which direct verbal contact between the aircraft and the ground was monitored using the recently developed magnetic wire recorder, the forerunner of the tape-recorder.
The aircraft to be used was the RCD Halifax based at Hatfield. Incidentally, this was said to have been one of the six pre-production models of this aircraft and had been used extensively by RCD in their trials of homing systems using Eureka/Rebecca, S-phone and other devices.
On the morning of Saturday 3 June 1944 one party of the ASR Section had travelled to Fishguard by road while another group assembled at Hatfield and loaded the aircraft with the test packages. It was a brilliantly fine summer morning, so it was a little puzzling that the take-off was delayed. After some time the pilot, a Handley Page civilian test pilot, announced that he had been trying unsuccessfully to file a flight plan but had been unable to get through to Flight Control: his phone calls had been unanswered. He remarked jokingly that as it was Saturday morning the staff must be having a lie-in. He decided that even without flight clearance he would proceed with the trial. The flight was uneventful and a succession of packages – some linked like sausages – were despatched successfully through the jump hole. At the conclusion of the trial a course was set for home. However, very soon one of the engines caught fire and was shut down. So they limped back on three engines.
On approaching Oxfordshire flying at a few thousand feet, those on board had a magnificent view of the peaceful, rolling, checkered countryside basking in the warm afternoon sun. This sight, now familiar to anyone who has travelled by air, was an experience not often enjoyed by many outside the airborne units of the armed forces. But superimposed on this peaceful scene there soon appeared the airfields of Kemble, Fairford and Brize Norton. And here was an amazing sight. Laid out on all the airfields were close-packed herringbone formations of gliders. Very soon the pilot’s radio began to crackle. What was a limping Halifax doing in this airspace on an unscheduled flight over operational airfields and with a civilian pilot? A fighter came up to investigate and buzzed the Halifax. Presumably the pilot was able to satisfy ground control and the Halifax was allowed to fly on to Hatfield. No doubt the pilot had a severe dressing down for ignoring the need to file his flight plan. What no-one in the aircraft appreciated was that what they had seen was the glider armada preparing for D-Day. On Monday morning it was clear that, unbeknown to the ASR Section team, they had been privy to the last preparations for D-Day. It was no wonder that their flight had caused so much consternation on the ground. As it turned out this was the last flight of the RCD Halifax, which was deemed unairworthy and was disposed of.11
Examination of the packages which had been dropped confirmed that, by and large, the free-drop packing had been satisfactory. The main casualty was a package of six .38 revolvers which had been issued by Station VI on a ‘test to destruction’ basis. Five of them were unserviceable but the sixth was undamaged. It became something of an embarrassment since there seemed to be no mechanism for returning an item which was listed as destroyed. A night-time free drop was held up by weather and lack of aircraft, but eventually a successful drop using a Stirling aircraft was made on 19 October. Meanwhile, RAE, on the basis of air-to-air ciné films, had cleared the free drop technique for packages of between 30 and 50 lb (13.6 and 22.7 kg) and recommended the use of linked packages.
Free drop research had occupied a high proportion of the time and effort of the ASR Section and had been carried out in close liaison with the Airborne Forces. A healthy rivalry existed between the two groups of workers to the benefit of the overall programme. In the event, by the time the free drop technique became operational the parachute problem had eased and the US Air Force was dropping supplies in daylight to the Maquis areas. The free-dropping technique was therefore not used in north-west Europe but was applied to some extent in the Mediterranean and Far East theatres.
The pioneering work of ASR Section was not wasted. Free drops were used by Air Despatch for the delivery of medical supplies and food to the starving people of Holland in the months after their liberation. And since then free-dropping has been one of the main ways in which humanitarian aid has been delivered throughout the world. But curiously, the linking of packages to prevent their dispersal does not seem to have been widely adopted.
Pigeon Containers
At various stages during the war homing pigeons were used to send messages from the field, especially in north-west Europe. But the problem was that of delivering to agents pigeons which had been kept in lofts at Tempsford. At first a standard British pigeon-dropping container was used. But early in 1944 the Belgian Section reported that in an extensive series of operations a large number of pigeons had been killed or incapacitated in the drop. Considerable effort was devoted, in collaboration with Henlow, to design a suitable container incorporating a device to delay the opening of the parachute. This was tested for use from the practice bomb racks of the Mosquito. Successful drops using live pigeons were carried out.
It was said that, in fact, no container was necessary and that, using the technique adopted by Callow in India (Chapter 4) a pigeon packed in a brown paper bag and dropped through the jump hole had time to break out of the bag and flutter down!
Man-dropping Container
Early in 1944 the ASR Section was involved in a feasibility study, in collaboration with MAP, of a man-carrying container to enable an agent to be dropped from the bomb bay of an aircraft not fitted with a jump hole. Difficulties were foreseen in accommodating such a container in existing aircraft. There were other problems and, although regular contact was maintained with MAP, it appears that this scheme was not pursued. However, it was reported that the Germans were working on a much more ambitious project to design a container for three men and their equipment. This was a huge contain
er 9 ft long and 6 ft in diameter dropped on four parachutes. Presumably it was to be carried outside the aircraft. The SAS expressed interest in developing a similar, improved, design but there is no record of this ever being completed.
Dropping of Dogs
For some reason which is not clear, a suggestion was made that dogs should be dropped by air. At first sight it is difficult to see what advantage a dog might be to an agent since it would be another mouth to feed, might inadvertently give away its master or mistress to a search party and generally was an extra liability. But the clue lies in a comment by the Army School of Dogs who in April 1943 were asked by Col H.H. King at Station IX to meet with Flt Lt Bunn for discussions on the subject. The School suggested that any trial drops should perhaps be done with less valuable mongrel dogs rather than Huskies. We know that Station IX devised a collapsible ski-sledge for dropping by parachute for ad hoc operations and it seems likely that the dogs were seen as a useful adjunct to this in attacks on targets in sub-arctic regions such as parts of Norway. When one realises that this was a couple of months after the highly successful Gunnerside operation against the heavy water plant at Rjuken when the escaping attackers skied for many exhausting miles across snow-bound wastes to reach neutral Sweden, the possibility of dog-sledge transport must have been very attractive.
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