ENGINEERING DESIGN OF SHIP-BORNE GUNNERY RADAR PANELS*

By T. C. FINNIMORE, Associate Member,f and W. D. MALLINSON, B.Sc.(Eng.), Associate Member.f

{The paper was first received 8th March, 1946, and in revised form 20th May, 1946.3rd April, 1946.)

It was read at the RADIOLOCATION CONVENTION

SUMMARYThe peculiar conditions under which ship-borne gunnery radar

panels have to be installed, to work and to be maintained are described,together with the design limitations imposed by having to allow fordifficulties due to manufacture and development under war conditions.

Illustrations are given of how the various requirements are generallymet, and particular reference is made to certain constructional featuresof two equipments developed during the war. A note is added onfuture trends in engineering design.

(1) INTRODUCTIONA naval gunnery radar set comprises:—1. An Aerial Outfit (usually containing the transmitting and

receiving equipment) which is necessarily in an external positionexposed to weather and gun-blast.

2. Panel Equipment for displays, modulators, etc., whichmay be externally mounted or housed between decks, dependingon its particular application.

3. Power Supply Equipment to convert the ship's mainssupply (220 V d.c.) into the voltages required by the set. Thisconversion equipment is normally housed between decks. Thispaper deals only with item 2—the Panel Equipment.

(2) THE DESIGN PROBLEMS AND THEIR GENERALSOLUTIONS

The design problem is that of specifying a form of constructionwhich embodies to a maximum degree a balance between thefollowing conflicting aims:—

1. High Performance and Ease of Operation.2. Durability.3. Lightness and Smallness.4. Ease of Maintenance.5. Ease of Installation.6. Ease of Modernization.7. Ease of Manufacture under War Conditions.

For his designs to be successful the naval radar designengineer must keep himself abreast of the latest developments incircuit techniques, component advances, conditions afloat, andengineering materials and methods. In addition, he mustdevelop a sense of discrimination in order to establish in his ownmind a balanced conception of his aims against the backgroundof these developments, and he must be ingenious in devising themeans of their attainment.

(2.1) High Performance and Ease of OperationThe high standard of performance demanded under battle

conditions requires that the equipment must be convenient andsimple to use, and that it must not interact with other sets, which,in ships, are installed close to one another.

To meet the first requirement the designer must study the com-position of the team which is planned to operate the equipmentand the manner in which this team functions under battle condi-tions. He must then place all controls and indicators in positions

• Radio Section paper. t Admiralty Signal Establishment.

which provide the maximum physical and mental comfort andconvenience to the operator.

Freedom from interaction with neighbouring sets is obtainedby attention to the filtering of supplies and screening.

(2.2) DurabilityThe performance must not suffer materially from the rough

treatment and climatic extremes which it experiences during boththe pre-service and the service phases of its life. The pre-servicephase is the more severe in respect both of shock and of deteriora-tion due to climatic conditions, because the equipment is firstman-handled (often upside down) during transport by road,rail, sea and air, through climatic extremes, and is then storedfor long periods under worse atmospheric conditions than thoseprevailing in ships. During transport the equipment is not pro-tected against damp by its own heat as it is when in service;moreover no maintenance work can be done on it.

The transport conditions are mainly allowed for by strongmoisture-proof packing: units are resiliently mounted in sealedpacking cases so that they will withstand the shock of beingdropped from a height of 4J- ft on to concrete, as often happenswhen the case is pushed off the tail-board of a lorry or out of arailway waggon.

Installation of the equipment is usually carried out underextremely cramped conditions and in the midst of workmenengaged on other heavy ship-fitting work such as welding,riveting and drilling, in the course of which the equipment islikely to be damaged. This is allowed for by making frame-works and chassis strong enough to carry a man's weight: pro-jections such as control knobs are shielded by temporary coversfixed over the fronts of the panels and secured by pillars orhandles which remain on the equipment to provide "fences"against damage by passers-by. All holes are closed by tem-porary covers to keep out rats. Studs projecting from panelsare not allowed because bent ones cannot be replaced.

The service phase of the life of the equipment involves with-standing continuous vibration, roll and pitch, concussion, saltatmospheres and very long periods of operation, as well asclimatic extremes.

(2.2.1) Ship's Vibrations, Roll and Gun-shock.Engine and propeller vibrations occur with double-amplitudes

varying from 0 • 5 in maximum at 3 c/s to 0 • 02 in at 15 c/s, andship's roll may amount to 30° from the vertical. Concussion inthe ship's structure where equipment is located may be equivalentto accelerations of 10 to 20 g in any direction from gun-shock,and considerably more from underwater explosions.

The designer can adopt either of two principles in order toensure that the equipment shall withstand ship's vibrations andgun-shock: either he can make every part so rigid that it isresonant above 15 c/s and can itself withstand an acceleration of10 g in any direction; or he can make the equipment of engineeringrobustness and then raise it off the ship's structure on rubbershock-absorbers.

The latter principle has been adopted for all radar equipment441 ]

442 FINNIMORE AND MALLINSON: ENGINEERING DESIGN OF SHIP-BORNE GUNNERY RADAR PANELS

except aerials. In the case of office equipment the panel standson rubber mounts of such stiffness that the whole assembly hasa resonant frequency above 15 c/s: these mounts also reduce theshocks normally experienced to values which are not damagingto the equipment. The top of the panel is stayed to the deckabove (to provide adequate support against roll and pitch) byresilient mounts and slanting arms which take care of the ten-dency of the deck to move apart from the deck above owing tocollisions or underwater explosions.

On gun-mountings and directors it is impossible to stay thetops of weathertight cabinets or nacelles. These are thereforeusually solid with the mounting, and the radar units are resiliencymounted within them.

In order to withstand the roll of the ship up to 30° from thevertical, contactors are designed so that they cannot be closedby gravity when tilted to that angle, and oil-filled components areeither sealed or made tall enough for the oil to cover the contentseven under a tilt of 30 \

(2.2.2) Marine Conditions.In addition to the efforts described below to prevent salt-

spray from reaching the equipments, non-corrodible materialsare employed wherever practicable, contact between metals withcontact differences of potential is avoided, and protective finishesare applied throughout.

In order to keep clear of water which may flood the compart-ment to a depth of several inches, office equipments are mountedat least 6 in off the deck and no live circuits are closer than 12 into the deck. In the case of equipments in exposed positions, theweathertight cabinets in which they are housed must be capableof withstanding the force of green seas breaking over them; andventilation intakes and outlets must be designed accordingly.

(2.2.3) Climatic Extremes.Climatic conditions range from deck temperatures of — 25° F

(— 32" C) in the arctic, up to 90° F (32J C) shade temperaturein the tropics with relative humidity of 85 %. The temperatureof metal-work exposed to the sun reaches 150° F (66° C). Con-ditions in ship's offices range from freezing point up to 110° F(43° C) with 90% relative humidity.

Such extremes are met by the use of high-grade tropic-proofcomponents, and by careful attention to the ventilation of theequipment.

The components have to be rated for surges as well as forcontinuous operation under climatic extremes, and are selectedfrom the range of types approved by the Inter-Services Compo-nents Technical Committee.

The ventilation of equipment in exposed positions has to dealnot only with the heat dissipated by the equipment itself, but alsowith that introduced into the weathertight cabinets by solarradiation; the effect of the latter is reduced by lagging thecabinets where possible with heat-resistant material. A closedventilation system is preferred (i.e. one in which the same air iscontinuously circulated from a blower to the cabinets, througha radiator and back again to the blower), because salt-spray andmoisture must be kept out of the equipment. In cold weatherthe radiator is by-passed, while heaters in the walls of thecabinets keep the equipment above the freezing point. Thesesame heaters are permanently connected to the mains whetherthe radar equipment is working or not and are controlled bythermostats to keep the temperature above the highest dew-pointlikely to be met, so that condensation cannot occur.

Open systems were used in the case of certain equipmentswhich had to be fitted to existing directors or gun-mountings, inwhich there was no room for a radiator. In these systems theradar cabinets were cooled by a forced blast of filtered atmo-

spheric air from which drops of moisture had been removed asfar as possible.

Office equipments of the most recent design arc forced-ventilated by drawing air from outside the office, guiding it pastthe various sources of heat, and letting it out at the top or backinto ducting which leads to a large suction fan outside the office.This fan must draw approximately 200 ft3/min of air through thepanels, for each kilowatt to be dissfpated.

The inside of wave guides are kept dry by blowing throughthem a small amount of air which has first been passed througha chemical dryer.

(2.3) Lightness and SmallnessThe space occupied by an installation in H.M. ships must be

a minimum (particularly on gun-mountings and directors, andstill more so in submarines), because of the demands on spacefor other equipment.

Lightness is of primary importance on gun-mountings anddirectors, where excessive weight may adversely affect theoperation of the control equipment or the stability of the ship.

The obvious method of obtaining lightness is to use lightalloys and miniature components, but these were difficult toobtain during the war and were therefore reserved for use inapplications where size and weight were of greater operationalimportance, e.g. portable or pack ssts. Conssqusntly restrictionof size and weight has been sought by devising layouts andmethods of construction which group components of normalsize closely together without losing accessibility.

(2.4) Ease of MaintenanceAll parts of an equipment must be repairable or replaceable

on board without the necessity for the ship to return to base ordepot ship.

Ease of such maintenance depends upon the degree of accessi-bility of components and upon the ease with which they may bedetached and replaced. In between-decks equipmsnts this ac-cessibility is required in the installed position, to allow for therepair in that position of all but the most complicated faults.For equipments installed above deck, however, it is impossibleto carry out any repair work in position, partly because of ex-posure to the weather, and partly because the equipment is soclosely surrounded by other fire-control apparatus: thereforedesigns provide for the rapid removal of complete units to aradio maintenance room between decks, and for maximumaccessibility to the units when they are out of the equipmsnt.

(2.4.1) Radio Maintenance Rooms.A radio maintenance room is equipped with test racks in which

a complete set of working units is normally held, together withappropriate test gear for the diagnosis and repair of faults; thisroom is used for all repair work on above-deck equipment, andfor the more complicated work on between-decks equipment.

A usual arrangement is to provide one radio maintenanceroom for four installations of a given type of set.

The test racks provide means of enabling the radar set to workas a whole, using a dummy load instead of the aerial. When afaulty unit is brought in from a working equipment, it is putinto the test racks in place of the corresponding spare unit, whichis then fitted in the working equipment, while the faulty unit istested at a more convenient time.

(2.4.2) Safety of Maintenance Mechanics.The maintenance of complicated electronic equipment cannot

be successfully carried out unless it is possible to operate theequipment when in the maintenance position, i.e. with its inside re-vealed. Safety considerations, however, demand that mechanics

FINNIMORE AND MALLINSON: ENGINEERING DESIGN OF SHIP-BORNE GUNNERY RADAR PANELS 443

should be protected against accidental contact with dangerousvoltages and to that end it is a rule that where access is gainedin a particularly simple manner, such as by the opening of acover or a drawer, an automatic trip shall cut the supply to allhigh-voltage circuits. In order to reconcile this safety switchingwith the need for being able to operate the equipment in themaintenance position, a device is provided whereby the mechaniccan deliberately re-close the safety switch after it has operated.The re-closing device is automatically made inoperative whenthe cover or drawer is returned to the normal operatingposition.

(2.5) Design for Ease of Installation

In order to get office equipment into the ship, the panels aredesigned in sections small enough to pass through hatches 30 insquare (or 30-in diameter in submarines) and having a volumediagonal of less than 6^ ft.

Panels are designed for easy re-assembly on to their resilientmounts and for bolting together without access to the back ofthe set. This work has to be done under the congested conditionsof a ship's fitting-out, when different departments in the dock-yards are simultaneously installing their gear. For the samsreason inter-panel cabling is designed to be produced in thefactory as cable-forms with plugs and sockets already connected,so that the amount of connecting up to be done at installationis reduced to an absolute minimum.

In the case of equipment on gun-mountings or directors, theinstallation of the radar is in some cases carried out in thefactory of the gun-mounting contractor, where an overall test ismade before the whole mounting is transported to the dockyardand hoisted on board as a complete assembly.

(2.6) Ease of Modernization

Panels are sectionalized to permit of the introduction of circuitchanges without affecting parts not directly concerned. Thisfacility is desirable so that the Fleet may benefit from new ideassuggested by Service experience or by technical advances.

(2.7) Ease of Manufacture under WarConditions

A design which is easy to manufactureunder war conditions is a primary aim, be-cause the production rate which depends on itis vital to meeting the ship-fitting programme.Unfortunately, the design may not be plannedfor production by any particular plant, becausethe contract has to be split in order to en-sure continuity of production in the event ofdamage to factories through ensmy action.

Other fundamental difficulties to be facedare the continually changing scarcities ofmaterials in war-time, and the need to avoidinflammable materials.

(3) PARTICULAR SOLUTIONS TO SOMEOF THE DESIGN PROBLEMS

This Section describes the methods of con-struction adopted as particular solutions tocertain of the problems in the case of twogunnery radar sets developed during the war.

The first set, a 10-cm equipment associatedwith high-angle long-range armament, had itsdisplay panels located between decks close tothe gunnery calculating table, and employed

VOL. 93, PART III A.

three operators for following the target in range, bearing andelevation.*

The second set, a 3-cm equipment associated with close-rangeweapons, had its display units located on the actual gun-mounting, which was completely self-contained, including thepredictor.* Only one radar operator was employed (for target-searching purposes), the radar set being able to follow fullyautomatically once it was locked on to its target.

The reasons for locating the display panels of all gunnery radarsets between decks (except those associated with close-rangeweapons) are as follows:—

1. Operators are more comfortable and work better insheltered and protected positions.

2. The equipment is protected, is sheltered from weatherextremes and is easier to maintain.

3. The reduction in weight of apparatus on the director re-sults in smaller and simpler director power-control gear.

These three reasons outweigh the operational advantages ofhaving the displays on the director. Such advantages appearwhen considering the working of a ship's complete radar systemof which the gunnery set forms but one part. The systemfulfils all the functions of searching for a target, indicating it tothe particular gunnery set which is to engage it, putting thatgunnery set on to it, passing the information of the target'spresent position and its rate of change obtained by that gunneryset over to the predictors which calculate the target's futureposition, and so to the guns.

Both of these equipments described below were designed andproduced during the stress of war, when the development ofexperience of Service conditions in the tropics was advancingrapidly, and in consequence certain features are not consistentwith present-day ideas.

(3.1) The Design of a 10-cm High-Angle Gunnery Radar DisplayPanel

(3.1.1) General Construction.Fig. 1 shows a general view of the equipment. The panel cir-

• See Sections 12 and 16 of the paper on "Naval Fire-Control Radar" (page 349).

Fig. 1.—10-cm high-angle gunnery radar.Corner of ship's office showing display panels fftounted above associated director- and gun-control equipment.

29

444 FIMVIMORE AND MALLIR'SON: ENGINEERING DESIGN OF SHIP-BORNE GUNNERY RADAR PANELS

Fig. 2.-Standard 10-cm circuit unit with sides opened up. 10. Side plates. 14. Fixing screws. 1 1 . Top plates. 15. Fixing claws. 12. Identification strip.

cuits were sectionalized and assembled in standard circuit units. (Fig. 2). These units were grouped into four distinct blocks (Figs. 1 and 3) each of which was assembled into a sub-frameworks. The units were carried on an inner framework or cradle (Fig. 4) which consisted of two horizontal frames joined by hinges at the rear and supported by two pairs of unequal links (2-2 on Fig. 4) from telescopic runners (3, Fig. 4) fixed to the outer framework.

(3.1.2) Detail Features of Design. 1. All circuit units were made from the same simpIe section,

and in the blank form they differed only in regard to their lengths which were restricted to a few standards. This permitted the ordering of supplies in advance of the main construction pro- gramme.

2. The method of component mounting made the side and top plates of the units (10 and 11, Fig. 2) the equivalent of com- ponent strips which could be handled as simple sub-assemblies.

3. The circuit unit side assemblies were fitted with identifica- tion strips (12, Fig. 2) along each row of tags, a feature which helped both manufacturer and maintenance mechanic.

4. When assembled, there was a gap between the adjacent edges of the circuit-unit top and side plates (13, Fig. 6) which allowed a natural draught to pass through the units right across the component strip.

5. The circuit units were secured by only two large captive screws at the rear, and by two spring claws at the front (14 and 15, Fig. 6): this greatly facilitated the removal and replacement of the units.

6. The cradle construction gave extremely good accessibility by providing the following modes of access:-

(a) When the cradle was withdrawn on its telescopic runners as shown in Fig. 4, access to the top of the assembly was provided.

(b) When the cradle was tilted so as to rock back on its links, its underside was revealed as shown in Fig. 5.

'3'

Fig. 3.-Front view of 10-cm display equipment with plug panels removed.

1 . Framework boundaries. 8. Cable channels. 9. Plug panels.

Fig. 5.-Equipment of Fig. 4 with cradle withdrawn and tilted. 2. Cradle supporting linbs. 7. Safety switch. 3. Telescopic runners. 9. Plug panels. 4. Safety pawl. 13. Ventilation gap. 6. Car-type handle and lock. 16. Cathode-ray-tube support in

stowed position.

Fig. 4.-Front view of 10-cm display equipment with cradle withdrawn on telescopic runners.

2. Cradle supporting links. 6. Car-Vpe handle and lock. 3. Telescopic runners. 7. Safety switch. 4. Safety pawl. 9. Plug uanels.

(c) When the cradle was split as shown in Fig. 6, the whole of the inside of the assembly was revealed. In this state the advantage of mounting the lower units upside down can be appreciated since it exposed the interiors of every unit at the same time.

Operations (6) and (c) were very convenient physically owing to the high degree of balance about the pivoting "point."

7. A safety pawl (4, Fig. 4) was pivoted from the top frame and operated against a peg on the long link when the panels were either tilted or split. This prevented the assembly from moving its position until the pawl was freed by hand.

8. The cradle construction avoided the long interc onnectors

FINNIMORE AND MALLINSON: ENGINEERING DESIGN OF SHIP-BORNE GUNNERY RADAR PANELS 445

Fig. 6.—Equipment of Fig. 4 with cradle withdrawn and split.2. Cradle supporting links.3. Telescopic runners.4. Safety pawl.5. Cathode ray tube in special

maintenance position.

9. Plug panels.12. Identification strip.13. Ventilation gap.14. Fixing screws.15. Fixing claws.

which would have been necessary with the equivalent two-drawerarrangement.

9. The cathode-ray tube could be re-positioned for viewingwhen the cradles were split (5, Fig. 6).

10. Car-type handles and latches were fitted for securing thecradles in the open and closed positions. This reduced theoperation of withdrawing or securing a cradle to the very simpleone of turning a handle and pulling (or pushing). The handlewas fitted with a lock thereby protecting the equipment againsttampering by unauthorized persons.

11. Safety to the mechanic was obtained by a switch whichbroke the main supply automatically when the cradle was with-drawn. This switch could be re-closed by hand when it wasnecessary to work the unit in the maintenance position; the re-closing was cancelled automatically by pushing the cradle backto the operating position.

12. At the top-front of each framework section a removablepanel (9, Fig. 3) gave access to a cable channel running fromleft to right, which provided a through way for running thevarious cables which interconnected the framework sections. Allinterconnecting cables were made as part of one or other of theframework sections. They were cut to length and fitted with endconnections during production so that the installation operationwas limited to feeding them through the cable channel and fixingthe terminations.

(3.2) The Design of the Display Units for a 3-cm Equipment(3.2.1) All the radar circuits for this 3-cm set (including its

transmitter-receiver, modulator and servo circuits) weresectionalized for accommodation within seven standard unitseach 12 in high by 18 in wide by 16 in deep (Fig. 7). They weredistributed between three weather-tight cabinets (Figs. 8 and 10)located in the only available spaces on the gun-mounting. Thedisplay and auto-strobe circuits occupied two of the units, butcertain of their power supplies were obtained from rectifiersforming part of a third unit.

The standard units slid like drawers into their cabinets, andmade electrical connection at the back through 8-pin socketsmating with plugs in the cabinets (Fig. 8). Since there were upto eleven such sockets on a unit, the force required to get theunit into or out of position in the cabinet was considerable andwas obtained by screwing (Fig. 9). This system of plugs andsockets ensured safety to the mechanic, because the unit becamedead with the first -\ in of movement in withdrawing it from thecabinet.

INCHES 14-;.,*_t-?- J 7< -"-*t- '? Ji'-4

Fig. 7.—3-cm close-range gunnery radar. Display unit, viewed frombeneath.

Fig. 8.—3-cm close range gunnery radar.Cabinet " B " with standard units withdrawn, to show wall heaters, 8-pin plugs and

non-return air outlet valve box.

Fig. 9.—Typical 8-in plug frame assembly showing also acme lockingscrew, and resilient mount for chassis.

446 FINNIMORE AND MALLINSON: ENGINEERING DESIGN OF SHIP-BORNE GUNNERY RADAR PANELS

Since the cabinets could not be resiliency supported on thegun-mounting, the components were insulated from mechanicalshock by mounting them on a tray which was resiliency sup-ported within the frame of the unit (Figs. 7 and 9).

Lightness was a requirement not only from the point of viewof the mounting, but also because it was desirable for one manto be able to carry the unit himself from the mounting down tothe radio maintenance room; this meant a limit for each unit ofabout 50 lb. It was not possible to meet that requirement, asthe units finally weighed between 60 and 100 lb, which necessi-tated the development of a canvas carrying bag with shoulderharness.

The ventilation system (Fig. 10) drew in atmospheric air

Fig. 10.—Layout of air ducting between blower and cabinets in 3-cmequipment.

through "eliminator" plates to remove solid moisture, followedby a brass-wool filter, and blew it through the cabinets out toatmosphere again through non-return valves (Fig. 8) designed toprevent rain or sea-water from being blown back into thecabinets. To prevent condensation on the components, therewere heaters in the walls of the cabinets, thermostatically con-trolled to keep the air above the highest dew-point temperaturelikely to be met.

(3.2.2) 3-cm Set Maintenance Facilities.The test racks in the radio maintenance room consisted of

three tall frameworks (Fig. 11) each containing three cradlescarried on telescopic runners and capable of tilting either up-wards or downwards. Standard units could be locked into theirparticular cradles (Fig. 12), which also carried a set of 8-pin plugsconnected to the test racks by flexible connectors capable of fol-lowing the cradles out to the full extension of the runners andto the full degree of tilt, thus enabling maintenance to be carriedout with the units alive. The safety of the mechanic was ensuredby the same sort of arrangement as was used in the 10-cmequipment previously described.

The test racks also contained apparatus such as the calibrator,oscillator, and oscillograph, which could be used to examine thefunctioning of any particular unit.

The ventilation of the radio maintenance room, in which 6 kWwere dissipated, was effected by a suction-fan located outside the

Fig. 11.—Test racks (empty) for radio maintenance room, showingdrawers for spare components.

Fig. 12.—Test racks showing test apparatus in posiiion, with displayunit in maintenance position.

room as discussed in Section 2.2.3, but the intake air of1 200 ft3/min was taken from inside the room, a practice nowdiscontinued.

(4) FUTURE TRENDS IN ENGINEERING DESIGNPresent equipments suffer from the following defects:—1. They do not obtain sufficiently accurate information.

FINNEMORE AND MALLINSON: ENGINEERING DESIGN OF SHIP-BORNE GUNNERY RADAR PANELS 447

2. They do not transmit their information to the user suffi-ciently quickly or sufficiently reliably, because of their de-pendence on the human element.

3. They take up too much space in the ship.Future trends must therefore be towards designing equipment

which is more accurate and more automatic, and yet smaller andmore reliable.

New materials and processes now being developed will enablebig steps to be taken in those directions. In particular, newdielectric materials will give smaller and better condensers, newmagnetic and insulating materials will give smaller and more re-liable transformers, non-corrosive light alloys will give lighterhardware, the use of hermetic sealing will give more reliable com-ponents, and the development of smaller air conditioning plantswill allow equipments to be smaller and will improve theirreliability.

The design of the supporting structures for equipment in ex-

ternal positions will always remain the interesting compromisebetween the requirement of infinite rigidity and infinitesimalweight.

(5) ACKNOWLEDGMENTSThe work described has been carried out at ths Admiralty

Signal Establishment and by various contractors to the Admiralty,notably Messrs. Electric and Musical Industries Ltd., Ths Gramo-phone Co. Ltd., Ferranti Ltd., The British Thomson-HoustonCo. Ltd., A. C. Cossor Ltd., and Richard Crittall Ltd. Theauthors wish to acknowledge the help and encouragement oftheir colleagues in the Admiralty Signal Establishment and ofthe design engineers in the above-named firms, in particular ofDr. A. K. Solomon and Mr. I. L. Turnbull. Finally they wishto thank the Board of Admiralty for psrmission to publish thepaper, and the Captain Superintendent for granting facilities forits preparation.

DISCUSSION ON"NAVAL GUNNERY RADAR"

Commander C. G. Mayer, U.S.N.R.: I am very conscious ofthe honour of being invited to take part in the Convention byopening the discussion on this naval occasion. The wealth ofdetail and the skilful way in which the material has been presentedmake these papers an outstanding contribution to the Con-vention, for which the authors are to be highly commended.For the past five years my duties have kept me in close touch withBritish developments, and I can therefore endorse at first-handwhat has been said concerning Anglo-American collaboration.

The story of the rapid expansion and shared responsibility ofthe development of radar has already been well told by SirRobert Watson-Watt. I cannot let this occasion pass, however,without paying an American tribute to British achievement, andI should like to add my own special appreciation of the remark-able co-operation and assistance which it has been my privilegeto experience in Britain throughout the war.

War conditions made it necessary for naval radar to beadapted to existing fire-control devices and guns. The practicalsolutions of the many problems in the two Navies were thereforeof necessity different. There were originality and inspiration onboth sides. We had the added benefit of British experience.Mr. Winant, the American Ambassador in London during thewar years, said in a recent address: "There was no phase offighting equipment, tactics or strategy that the British developedfrom their war experience that was not known to us before Japanstruck at Pearl Harbour." There has always been the friendliestand keenest competition for technical progress, and on the navalside the greatest admiration for what the Admiralty SignalEstablishment has accomplished under the able guidance andwith the encouragement of Captain Brooking and his staff. I amglad to see some of them here to-day.

The part that radar fire-control played in the sinking of theBismarck and Scharnhorst has been briefly mentioned. I shouldlike to remind you that radar has frequently been the only meansof seeing ships sunk. One of the first occasions on which thishappened was in the Battle of Guadalcanal in November, 1942,when, at a range of more than eight miles, an enemy vessel wasdiscovered by radar at night, engaged by one of our battleships,and sunk in the darkness, the only immediate evidence being thedisappearance of the pip from the face of the cathode-ray tube.By radar a ship has been discovered, identified, tracked, fired

upon and sunk, all within a few minutes and without visualobservation—such are the advances in naval gunnery.

In commenting on the papers I must confess to a feeling ofacute mental indigestion brought about by the great amount offood for thought which they contain. I propose, therefore, torefer to only some of the remarks of the authors which seem topoint the way to future developments.

First, there is the matter of target indication. As fire-controlradar becomes more precise and capable of higher resolution,the need for another equipment as a "putter-on" and fororganizational control becomes imperative. Mr. Prime hasindicated that a high speed of aerial-rotation is essential in orderto obtain up-to-date information on fast-moving targets. A highall-round-looking position must also be found for the aerial,which must not offend by reason of excessive top weight.Altogether it is not easy to meet the staff requirements.

Secondly, Mr. Coales and his co-authors have mentioned thedisadvantages of an increase in the time taken by a computer toreach a solution of the prediction problem. The great majorityof computers are mechanical devices developed before radar wasavailable to provide the continuous information which opticalrange finders could only give intermittently. Mechanical con-trivances are slow in responding by comparison with electronicmethods, and we must look forward to the use of electroniccircuits for the rapid solution of computing problems. In futurethe radar equipment, the computer and the weapon must beintegrated much more closely in the design of a fire-control system.

Thirdly, I should like to refer to automatic tracking. We areentering an era when the human variables in fire control mustbe eliminated. Time-constants are likely to be such that thehuman servo system cannot follow smoothly. In the automaticlock-and-follow set which has been described and which wehave seen demonstrated so ably, a volume of space 30' wide by3° high and 1 500 yd deep is explored every second, and theindicated target successfully locked on at ranges up to 5 000 yd.Such a performance requires a high degree of engineering dssignskill, and it can only be maintained by a corresponding highly-trained radar technician with adequate shipboard facilities forservicing the equipment. The Admiralty Signal Establishmentare to be congratulated on the measures they have adopted toprovide these facilities for both the 10-cm set and the 3-cm set.