The breakfast cereal manufacturer General Mills was the nation’s foremost developer of Biological Weapons of Mass Destruction in the early 1960s.

The Department of Defense has released small portions of several reports detailing the work in biological warfare performed by the Minneapolis-based company following a lengthy declassification review.

During World War 2, American consumer products companies were expected to come to the aid of their nation’s defense needs. After the war, many of these companies established small but lucrative defense contracting divisions.

General Mills set up a research division to tap into the long experience the company had in grinding or milling of fine particles, and in fabricating large thin films used for balloons, as well as making intricate electronics assemblies. The company made thousands of balloon systems for high altitude
reconnaissance purposes in a series of programs during the 1950s. High altitude balloons were used for various purposes, including taking photos of the Soviet Union and also to collect air samples to detect radioactive isotopes caused by nuclear weapons tests.

The success of the high altitude reconnaissance balloons suggested to the military possible use as a way to disseminate biological agents in remote locations. One of the problems with biological agents is that they can blow back to friendly troops. Dissemination by balloon offers a way to release these agents deep within enemy territory without requiring an aircraft overflight.

The Gopher mid-air recoverable reconnaissance balloon program was renamed Grandson in June 1953, and became ready for operational use after test flights in early 1954. A variant of Grandson, named WS-124A (Weapons System 124A), also called FLYING CLOUD, was designed and flight tested for the possibility of special warfare applications, but that effort was discontinued in late 1955. In reference books, WS-124A is listed as a Weather Reconnaissance Project, which was a cover story used to shield the aerial biological weapons program.

References to difficulties in milling, or grinding, of fine particles have surfaced recently in discussions concerning the anthrax sent to Congress through the mail. The fineness of the particles, considered critical in making the material easily dispersed by air, is a measure of the
technological sophistication of the anthrax manufacturer. Other types of biological agents also require fine grinding for maximum lethality.

George Whitnah, the project manager, died several years ago; his widow said that her husband and his colleagues had expressed some reservations about the work, but felt it was necessary because it was known that the Russians were working in similar directions. She said: “it was a different era back then”.

A company spokesperson disclaimed any knowledge of the bio-weapons program, and said that the defense unit was sold to Raytheon several years ago, taking with them any records from that era.

Below, you will find many of the reports that have now been declassified and released to The Black Vault.

Document Archive

blank Dissemination of Solid and Liquid BW Agents, Progress rept. 3 Jun-3 Sep 1960 [111 Pages, 4.7MB] – The problems of feeding and handling finely divided solid agents were studied along with applications of feeding devices such as screw feeders, piston feeders and pneumatic feeders. Progress was made in preparing for wind tunnel experiments on dissemination and deagglomeration and in the design of a special test section for these experiments. An isokinetic sampling probe was also designed. Progress on a study of the characteristics of finely divided materials is presented. This work includes literature search, theoretical analyses and experiments. A design study was initiated on an external aircraft store for liquid agent dissemination. Preliminary findings of an operational analysis to determine optimum design flow rates for several agents are presented and a summary is given of studies relating to specific aircraft store design problems.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 2, 4 Sep-4 Dec 1960 [111 Pages, 5.22MB] – Research on dissemination of solid and liquid BW agents was directed towards the development of weapon systems for the dissemination of these agents as a line source from high speed low-flying manned and unmanned aircraft. The results of experiments on feeding of finely divided solid materials with helical screws and piston devices are presented. Experiments on dissemination and deagglomeration are described including preliminary investigations of aerosol generation by erosion and also with a liquid CO2 system. Deagglomeration experiments were in a high-subsonic wind tunnel. Characteristics of finely divided materials are given. Aerodynamic data for wingmounted external stores and the effects of the external geometry and the pylon design on the incremental drag coefficients are discussed.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 3, 4 Dec 1960-4 Mar 1961 [113 Pages, 5.2MB] – Progress is reported on an experimental study of the effect of exposure to heated air streams on the viability of Sm aerosols. Results from experiments on the characteristics of powders are presented including investigations of frictional forces between powders and channel walls and dynamic angle of repose of Sm powder. Theoretical studies of load transmission in particulate materials and several specific cases of force transmission were analyzed. The properties of slurries, which include the thermal properties of egg slurry samples, were determined. Investigations were also made of the properties of slurries of Sm in a fluorochemical liquid. Wind tunnel investigations of the use of slip stream energy to deagglomerate finely divided solid materials progressed. Experimental results on the performance of a high velocity sampling probe and of an analysis of the influence of the effective agent filling density on the aerodynamic drag of solid agent disseminating stores are presented.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 4, 4 Mar-4 Jun 1961 [113 Pages, 15.2MB] – The viability of Sm subjected to air streams simulating a jet engine exhaust was radically affected. Compaction tests on Sm showed some viability reduction. Measurements were made of the coefficient of friction and the bulk density of various powders. A theoretical analysis of the force required to lift a disk embedded in a dilatant material was conducted. Thermal conductivity and viscosity measurements of egg slurries were carried out. Rheological properties of Sm slurries were investigated. Boundary layer studies are reported which indicated that wind tunnel tests on deagglomeration are slightly conservative as compared to actual flight conditions. High-speed motion pictures give an insight into the breakup of Sm agglomerates. Deagglomeration to primary particles of Sm was observed. An investigation of the store-carrying capacities of an unmanned aircraft and a preliminary design of a liquid disseminating unit is included.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 5, 4 Jun-4 Sep 1961 [137 Pages, 6.4MB] – Theoretical studies of the mechanics of particulate materials resulted in equations for predicting the force required to move a compressed plug of powder in a cylinder; theoretical limits on a resistance parameter are given. Wind tunnel studies of deagglomeration of finely divided compacted solids are covered. Particle size data and values for the frequency of occurrence of agglomerates, determined microscopically, are given. A design concept for the first dry-agent disseminating store to be designed and fabricated on this program is discussed. Studies of the jet-plume problem as it relates to loss of viability of biological aerosols are described. Experimental data on viability loss and a theoretical analysis of the fluid mixing problem are reported. Experimental results from a study of the rheological behavior of Sm slurries made with a fluorocarbon liquid are reported and a conclusion on the feasibility of this approach for disseminating solids is given.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 6, 4 Sep-4 Dec 1961 [123 Pages, 5.9MB] – Investigation on the dissemination of solid BW agents and the effort devoted to the design and fabrication of a liquid BW agent disseminating store for use as a weapon on high speed, lowflying aircraft is studied. The theoretical studies of powder mechanics are outlined. The distribution of energy during the process of compaction of a finely divided solid is discussed. Experimental measurements of the shear strength of powders are reported. The loss of viability produced by exposing dry biological aerosols to heated airstreams is presented. The simulants Bg and Sm were exposed to temperatures in the range of 30 to 130 C. Experimental studies of deagglomeration by slipstream energy are reported. The current emphasis is on assessment of the loss in effectiveness due to agglomeration. Feeding systems for dry agents is reported. A full-scale laboratory model of the feeding system for an airborne disseminator is described, and future test plans are outlined.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 7, 4 Dec 1961-4 Mar 1962 [123 Pages, 5.08MB] – Progress on the theoretical and experimental studies of powder mechanics is reported. The design and fabrication of a new aerosol chamber, equipped with light-scattering instrumentation is described. This chamber will permit studies of aerosol stability. The aerosol generation and sampling apparatus are discussed. Studies of the viability of Sm and Bg, in the bulk and aerosol forms, are presented. These are investigations of the effects of elevated temperature and additives. Wind tunnel studies of dissemination and deagglomeration are discussed. The results of further studies of small-scale agglomerates and a description of a new high-flow-rate disseminator model are given. New experimental work on metering and conveying dry powders is described and data are given on the performance of a fullscale laboratory feeding model. The results of computer studies dealing with the line-source dissemination of the agent UL-2 are given. The status of work on the design and fabrication of a liquid-agent airborne disseminator is reported.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 8, 4 Mar-4 Jun 1962 [235 Pages, 10.3MB] – This Eighth Quarterly Progress Report covers the work accomplished during the last reporting period on research and development related to the dissemination of BW agents. The progress in theoretical and experimental studies of the mechanics of dry powders is reported. This work continues to produce basic information which is being applied in the design and development of an airborne disseminator. Operation of the aerophilometer, with aerosols of dry powders, for the purpose of studying experimental techniques and determining operating parameters is discussed. This preliminary work is essential to carrying out the program on stability properties of aerosols. Data on the effects of compaction and additives on the viability of Sm powder are presented. The tests at Fort Detrick using the GMI-3 fixture and wind tunnel to generate aerosols in the 40-foot test sphere are described. Results with the full-scale experimental equipment for feeding and metering compacted dry powders are reported. The preliminary design of an airborne dry BW agent disseminating store is presented and described. Successful flight tests of the liquid BW agent disseminating store on an A4D-1 airplane are discussed.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progrss rept. no. 9, 4 Jun-4 Sep 1962 [120 Pages, 5.2MB] – Theoretical and experimental results relative to the studies of the mechanics of dry powders are presented for: (1) the applied stresses and energies required for the compaction of powders, (2) shear strength of compacted powders, and (3) bulk tensile strength and bulk density of compacted powders as a function of compressive load and distance from the face of the piston. Data on aerosol decay as affected by relative humidity are reported for five powders. A statistical analysis of the behavior of aerosols is presented to explain the phenomena observed in the aerophilometer. Tests on dissemination and deagglomeration, using the wind tunnel, are described which establish an upper limit of approximately 0.58 g/cc density for compacted Sm which can be aerosolized efficiently by the aerodynamic breakup mechanism. Wind tunnel evaluation of a shroud for the discharge tube of the airborne dry agent disseminator is discussed.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 10, 4 Sep-4 Dec 1962 [256 Pages, 12MB] – Compaction characteristics of dry powders, and the behavior of powders in the compacted state are discussed. Purely theoretical studies are presented which agree with results of experimental investigations. Flow rate data are presented from tests in which the full-scale experimental feeder was used to feed powdered sugar, flour, and talc, with a rate of 91 lb/min being achieved with compacted talc. Experiments are described in which foamed plastic was used to encapsulate cylinders of compacted powder which were subsequently fed through the experimental feeder. A sufficiently strong package has not yet been obtained. Successful laboratory and field testing of the E-41 Spray Tank for dry agents is discussed. The structural test report and a preliminary report of the air-worthiness flight tests are presented. Laboratory functional tests are described. Plans for biological flight tests with both the E-41 and E-42 Spray Tanks at Dugway Proving Ground are discussed.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 12, 4 Mar-4 June 1963 [195 Pages, 8.4MB] – In reporting on the continuing study of the mechanics of dry powders, data are presented which were obtained with the improved multipurpose test unit in which shear strength, tensile strength and bulk density are measured within the confines of a single isolator lab. Initial findings are discussed for an investigation of three supposedly identical Sm samples which exhibit distinctly different compaction characteristics. Particle-size distributions (Whitby) are included, which show a smaller MMD for saccharin after compaction to a compressive stress of 2.84 x 10 to the 4th dynes/cubic centimeters. Tests showing that the addition of Cabo-Sil to powders increase the stress required to produce a given bulk density are described. An investigation of the effectiveness of graphite in reducing side-wall friction of compacted powders sliding in cylinders is reported. A 50 percent reduction in the force required to eject the compacted powder has been observed when graphite is used as compared to the force required using a bare aluminum surface. Progress on the fabrication of the second E-41 spray tank is discussed. Minor design changes in the E-41 are described. Plans to flight test the E-41 at Eglin AFB on the F-100D and the F-105 are mentioned.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 13, 4 June-4 Sep 1962 [123 Pages, 5.08MB] – Information on the properties of powders, both biological simulants (Sm and Bg) and non-biological simulants (such as dried egg albumin and cornstarch), aided in the development of the E-41 spray tank for the line-source dissemination of dry solid BW agents. Tensile strength of powders as a function of bulk density and particle size was studied, using the segmented column method. The sliding-disk shear-strength method was used to measure shear characteristics of a number of powders. A methods study was made to determine the relative merits of preshearing or not preshearing the powder prior to the shear test. Surface area of powders was measured by the BET absorption method and a mathematical determination of microspore structure of powders was made from these data. Effects of electrostatic charge and humidity conditions upon aerosol formation and decay were studied with results sufficiently consistent to define the operating range of relative humidity. Storage of compacted Sm samples was continued with viability assays being made on 2-month and 4-month samples. There was no significant difference between compacted and uncompacted Sm.

blank Dissemination of Solid and Liquid BW Agents, Quarterly progress rept. no. 14, 4 Sep-4 Dec 1963 [107 Pages, 4.7MB] – Current theoretical investigations relating the interparticle contact energies to mechanical properties of compacted powders are described. Bg (lot SCH-63-109) used in flight tests was found to be more difficult to compact than Bg (lot 17). A new approach to obtain the energy of compaction from Instron data is presented. Agent LX, like other highly elastic materials, was found to be difficult to compact, has a comparatively high compaction shear strength, and a tensile strength too low to measure. An evaluation was made of the buoyant force corrections for the BET adsorption method to measure total surface area. Total surface area and rugosity measurements were made for spray-dried saccharin, agent LX, and egg embryo. A study of the effects of humidity (from 0 to 100 percent R.H.) upon the formation and decay of a ground powdered sugar aerosol is reported.



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