US2390635A - Torpedo launching mechanism - Google Patents

Description

Dec. 11, 1945. s, ER gr 2,390,635 I TORPEDQ LAUNCHING MECHANISM Filed Jan. 12, 1942 2 Sheets-Sheet 1 ec-v11, 1945. s. N. BARKER ETAL 2,390,635

-TORPEDO LAUNCHING MECHANISM Filed Jan. 12, 1942 2 Sheets-Sheet 2.

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Patented Dec. 11, 1945 UNITED STATES PATENT OFFICE 2,390,635 TORPEDO LAUNCHIN G MECHANISM of Great Britain Application January 12, 1942, Serial No. 426,406

' In Great Britain May 14, 1940 9 Claims.

The present invention relates to the launching of marine torpedoes by gas pressure generated by combustion of a smokeless powder propellent charge in a combustion-chamber which is separate from but communicates with a torpedo-tube in such a manner that the gases pass into the torpedo-tube from it.

The pressure required in a torpedo-tube to launch the torpedo is only a few atmospheres, and at pressures below about 20 atmospheres smokeless powders do not burn satisfactorily, but generate excessive quantities of nitrous gases.

According to the present invention, for launching a torpedo in the manner described, there is provided the combination with the torpedo-tube, of a separate combustion-chamber having a pressure-reducing connection therewith constituted by a permanently open but restricted aperture, and a propellent charge which comprises a fast-burning portion and a slow-burning portion so proportioned that the fast-burning portion rapidly builds up an adequate pressure in the combustionchamber, and the slow-burning portion maintains an adequate pressure during the discharge of the torpedo.

It desirable to keep the weight of the combustion chamber and of the torpedo-tube as low as possible but it will be appreciated that if a fast burning charge were employed alone a light construction would not be possflole owing to the high peak pressures which would be developed. Furthermore the high peak pressure in the torpedotube would be liable to collapse the tail of the torpedo. On the other hand if a slow burning charge were employed alone this would result in the production of highly corrosive gases owing to the inefficient combustion and it would be incapable of producing a sufficiently high pressure in the time available to launch the torpedo satisfactorily. The employment of both a fast burning and a slow burning charge of the kind hereinafter described to a large extent solves the abov problems.

It is found desirable in practice that the pressure in the torpedo-tube should rise to its maximum value as rapidly as possible, this value being of the, order of to 10 atmospheres, and this is achieved by the rapid production of a suitably high pressure in the combustion-chamber, which highpressure is reduced by the pressure-reducing orifice. The adequate pressure to be produced by the fast-burning portion of the charge is therefore one which is adequate for the two purposes of (a) producing the desired maximum initial pressure in the torpedo-tube, and (b) producing the. higher pressure in the combustion-chamber which is necessary for effective combustion of the remainder of the charge as above mentioned, whilst that produced by the slow-burning portion is such as will give in the torpedo-tube the pressure required to continue and complete the effective discharge of the torpedo.

According to another feature of this invention, the propellent charge is contained in a casing which ofiers no effective resistance to the emergence of the combustion gases into the combustion-chamber.

Another feature of this invention relates to the composition of the propellant charge used in the apparatus above-mentioned, and according to this feature of the invention, the quantity of the fastburnin-g portion of the propellent charge is such as to provide rapidly the maximum pressure in the torpedo-tube to effect the discharge of the torpedo. The actual amount will depend primarily upon the sizes of the combustion-chamher and the restricted aperture and the safe working pressure in the combustion chamber and to a smaller extent on the dead space in the torpedotube. The amount and the rate of burning of the slow burning charge and the size of the restricted aperture are so corelated as to permit a predetermined maximum pressure to be built up in the combustion-chamber which is required for ensuring sufficient gas to pass into the torpedo-tube to launch the torpedo at the desired velocity. Preferably, the fast-burning portion of the charge is in the form of cords (hereinafter referred to by the reference character 36) which are of considerably smaller web-thickness than the slowburning portion which is preferably in the form of rectangular strips or tubes (hereinafter referred to by the reference character 36a )which ar long in relation to their other dimensions and have a form characterized by a constant-burning surface. The term "web-thickness means the least dimension of the fast-burning or the slow-burning portion of the cartridge charge. In the tubular l form, this is the thickness of the wall of the tube; and in the cord form, it is the diameter of the cord.

The propellent charge is assembled in a cartridge of usual construction and according to another feature of the invention, the quantity of the slow-burning portion is from three and a half to five times the weight of the fast-burning portion. As hereinafter described in detail, the fastburning portion of the charge is so arranged with reference to the slow-burning portion of the charge that the flame from the fast-burning portion spreads over the inside and outside surfaces of the slow-burning portion and therefore ignites it over substantially the whole of its surface. Ac-

cording to another feature of the invention, the

cartridge-case is open ended and its closure is efiected by a Celluloid or like combustible disc,

whereby there is no effective resistance oifered to the emergence of the gases from the cartridge- 7 Figure 2 is a section to an enlarged scale on the line 2-2 of Figure 1;

Figure3 is a section also 'to an enlarged scale on the line 3-3 of Figure 1, and

Figures 4 to 9 are indicator. diagrams showing variation of pressure in the combustion-chamber andf torpedo-tube during" the burning of the charge.

The combustion-chamber comprises a main cy lindrical body portion I t! hemispherical at one end H and closed at the other end by a breechblock l2, and breech IS. The breech-block operates according to the well known interruptedthread princip e and slides into the open position along two guide rails 14, one being secured at each side of the chamber.

at; its open endby a Celluloid disc H. The cartridge-case I5 is held between the breech-block I2. and the'breech I3 by means of a split cartridge holder l8 facilitating the removal of the cartridge-case after firingg The base of the cartridge is fitted with a primer l9 which may be either an ordinary percussion primer or an electric primer" containing a resistance heating element, or a primer adapted for either percussion or electric firing.

V The firing mechanism is adapted for both pereussion and electric firing and to this end comprises a firing pin mountedin the breech-block by means of insulating bushes 2|. 2!! is electrically connected by flexible conductors 22 to the central electrodes 23 of one or more terminals 24 to which suitably armoured cables from the firingcontrol may be connected. For percussion firing a pistol bolt 25, provided with an insulated striker head 26, is driven towards the firing pin by a pistol-spring 21. Normalli, the pistol-bolt is retained in its retracted position by a transverse release pin 28, the latter being pulled out for firing. Greasing nipples 29 are provided for the lubrication of the moving parts.

The combustion-chamber is adiacent and connected directly to the torpedo-tube 30 at a point nearits rear end by a Venturi nozzle 3!, the entrance to thelatter being protected by a grid 32. having perforations about in diameter. The throat portion 33 of the nozzle is made separately from the main body portion so that it can be readily exchanged to provide larger or smaller nozzle openings according to requirements. The nozzle 3| is attached bybolts (not shown) to suitable facings provided on the combustion-chamber and torpedo-tube respectively, packing Inem bers l34, 35 being inserted to ensure a gas-tight joint. Thus the combustion chamber is in direct A cartridge-case l5 contains the propellent charge [6 and is closed The firing pin together with .55 lb. of a slow-burning composicommunication with the torpedo tube through a permanently open but restricted aperture.

A safety release device 45 is screwed into the hemispherical end of the combustion-chamber and comprises a bursting disc 31 and a protecting disc of asbestos 38 clamped between the screwthreaded members 39 and 40.

In putting this invention into efiect it must be borne in mind that the weight and dimension of charge used will vary with the size of the torpedo, and with the degree of gas-tightness achieved between the torpedo and the wall of the torpedotube. The optimum size of the Venturi nozzle will also vary according to the weight of charge used.

By way of example, in the particular case when it is required to launch a 1570 lb. torpedo of 17.7 inches diameter from a torpedo-tube in which it has an effective travel of 13 feet, the empty combustion-chamber may have a capacity of about 325 cubic inches, its weight, exclusive of the breech and firing mechanism being 25 lbs. The throat diameter of the Venturi nozzle is .49 inch.

The propellent charge in the cartridge 15 consists in this particular case of .107 lb. of a fastburning composition comprising nitro-glycerine 4.1%, nitrocellulose 50%, diethyl diphenyl urea 9% in the form of cords of diameter .047 inch,

tion comprising nitroglycerine 35.5%, nitrocellulose 51.5%, diethyl diphenyl urea 4.75%, diamyl phthalate 7%, mineral jelly 0.25% and potassium nitrate 1%, in the form of tubes each about 6.7

7 inches long and about .137 inch web-thickness.

As will be apparent from Figs. 1 and 3, the cords of fast-burning composition are arranged in parallel to form a core 36 and are also arranged so that they encircle the slow-burning tubes 36a which are made of the slow-burning composition, the said tubes being grouped around the fastburning core which extends from one end to the other end of said tubes. The purpose of this arrangement is to insure that the flame from the fast-burning cords will spread over the length i of the slow-burning tubes and thus ignite them throughout substantially the whole length of their inside and outside surfaces. In this way accidental influences on the ignition of the slow-burning charge consisting of the tubes 36a are reduced,

' and consistency of results is improved. Furthermore, the transverse arrangement ofv portions of the cords 35 around the tubes 36a serves the useful function of keeping the whole charge together as a unit.

The small size powder is inserted as a core 36 (see Figure 3) between the tubes 36a and also wrapped around them and the whole charge is loaded in a brass cartridge-case l5 of which the open end'is closed witha Celluloid disc I! and in the base of which a primer I9 is situated.

When fired, the cartridge builds up a maximum chamber pressure of 102 atmospheres which is maintained for about /6 sec., and gives a maximum pressure of about 5 atmospheres in the torpedo-tube. and ejects the torpedo satisfactorily within approximately half a second from the fir ingof the cartridge.

A method of launching during a second period, and during both: said periods allowing such quantity of the gas generated to pass into the tube as will build up a a torpedo from a tube consists in generating gas at a high rate during a first period so as to build up a pressure of the. order of a to atmospheres, then reducing; the rate of generation to maintain Said pressure maximum pressure of the order of to atmospheres during the discharge of the torpedo.

The following is a description with reference to. Figures 4 to 9 showing how the variation in the weight of the slow and fast burning charges and the diameter of the nozzle affects the pressures built up in the combustion chamber and in the torpedo-tube. The ordinates in these diagrams represent the pressures and the abscissae repre. sent time. The experiments were carried out in connection with apparatus having the dimensions above referred to and having a torpedo of the size and weight as set out above and having a length of 18 feet.

Figures 4, 6 and 8 represent the conditions set up in the combustion chamber while Figures 5, 7

and 9 represent the conditions set up in the tor-W pedo-tube.

In Figures 4 and 5 the diameter of the nozzle employed was .45 inch in each of the experiments and the weight of the fast burning charge was 48 grams in each case. The curves show the effect of varying the weight of the slow burning charge. The curves 50, 5| and 52 represent the conditions produced by employing 200 grams, 120 grams, and 180 grams respectively of the slow burning charge. The maximum pressures obtained in the combustion chamber by these charges were 1625, 850 and 1.300 pounds per square inch respectively, and in the torpedo tube 65 lbs., 53 and 70 pounds per square inch respectively.

In each diagram there is an initial phase of low, almost constant pressure during which the priming charge is igniting the fast and slow burning powders. 1y at a rate which is determined by the size of the combustion chamber and nozzle and by the surface area of the charge, and hence, for a given size of chamber and nozzle to a considerable extent by the weight of the fast burning portion since this latter has a relatively large surface area in proportion to its weight compared with the slow burning powder. When all the fast burning powder has been consumed the slope of the curve decreases and then remains substantially constant for a further phase at a value determined by the size of the nozzle and the surface area of the slow burning powder. When all the powder has been consumed the pressure falls away approximately exponentially. Other things being equal, the duration of the third phase would be proportional to the weight of the slow burning portion of the charge, but in the experiments in question it was not possible to vary the die size of the slow burning powder, so that variations of the weight of the slow burning powder also produced variations in the rate of burning of the charge as a whole owing to the variations in surface area.

Experiment 52 shows a desirable form of combustion-chamber curve with the pressure well maintained. Increasing the weight of slow burning powder as in experiment 50 results in the pressure rising to a peak at the end of the third phase, while reducing the weight of slow burning powder as in experiment 5| has the opposite effect, both being disadvantageous from the point of view that the combustion-chamber must be made stronger and therefore heavier, in proportion to the mean effective pressure. Figures 6 and 7 show the curve 50 compared with a, curve 53 obtained by increasing the diameter of the nozzle to .5 inch. The weight of the charges of the slow and fast burning material being the same as in experiment 50. This resulted in the maxi The pressure then rises rapidmum pressure in the combustion chamber being reduced to 1200 pounds per square inch, but the maximum pressure in the torpedo tubes was increased to 73 pounds per square inch.

The weight of charges used in experiment shown by curve 5! would be suitable for use with a nozzle of smaller diameter, if under these conditions sufficient gas were pr'oduced to launch the torpedo satisfactorily. Alternatively. better results might be obtained by using slow burning powder of smaller web size i. e., by increasing the rate of burning of this portion of the charge. It would not be suitable in this case to attempt to obtain a level topped diagram by reducing the weight of the fast burning portion since this would reduce the pressure below that necessary to ensure efiicient combustion.

The diagrams set out in Figures 8 and 9 show the eifect of varying the weight of the fast burning charge while keeping the nozzle size'and the weight of the slow burning charge constant. In this instance the diameter of the nozzle was .35 inch and the weight of the slow burning charge was 130 grams. The weight of the fast burning charge employed for the curve 54 was 4.8 grams and for the curve 55 was grams. The former resulted in the production of a combustion chamber pressure of 1500 pounds per square inch and the latter 1300 while the maximum torpedo tube pressure for the first charge was 56.5 lbs. per square inch, and the torpedo tube pressure for the second charge was lbs. per square inch. In the case of the experiment shown by curve the charge contained too little fast burning powder resulting in a comparatively slow rate of pressure rise during the second stage and a low pressure at the end of this stage. Experiment shown by curve 54 indicated that by increasing the fast burning charge from 30 to 48 grams resulted in a veryconsiderable improvement.

Amongst the advantages obtained according to our invention are the facts that the combustionchamber may be of lighter construction than the hitherto known combustion-chambers for torpedofiring charges and that an intermediate gas receiver is not required, whilst all uncertainty about the action of a valve between the firing chamber and the torpedo-tube is avoided, and the lag before the torpedo commences to move is reduced, and accuracy of aim is increased. Moreover, the cooling eifect on the gases in the combustion-chamber is diminished, and consequently, the amount of propellent powder required is reduced.

We claim:

l. A torpedo launching cartridge comprising a casing containing a fast burning charge in the form of cord about .047 inch in diameter and comprising 41% nitroglycerine, 50% nitrocellulose. 9% diethyl diphenyl urea and a slow burning charge in the form of tubes about 6.7 inches longand having a web-thickness of about .137 inch, which tubes comprise 35.5% nitrcglycerine, 5.5% nitrocellulose, 4.75% diphenylurea, 7% diamyl phthalate, 25% mineral jelly, and 1% potassium nitrate, the weight of which slow burning charge is from three and a half to five times the weight of the fast burning charge.

2. A method of launching a torpedo from a tube to which through a constricted opening is connected a combustion chamber which consists in generating gas in said combustion chamber by the combustion of a charge at a high rate during a first period so as to build up a pressure of the order of a to atmospheres, and then by connected a combustion chamber, which consists in generating gas in said combustion chamber by the combustion of a charge formed from smokeless powder, which combustion is arranged to take place at a high rate during a first period so" as to build up a pressure of the order of 100 to 150 atmospheres, and then by the combustion of a slow-burning charge, formed from smokeless powder, thereby reducing the rate of generation of the gas in said combustion chamber to maintain said pressure during a, second period, and during both said periods allowing such quantity of gas generated in' said combustion chamber to passthrough the constricted opening into the tube as will build up a maximum pressure of the order of 5 to atmospheres during the discharge of the torpedo.

4. A torpedo launching cartridge comprising a casing having therein a fast-burning portion of the charge in the form of cords arranged in parallel to form a core, a slow burning portion of the charge in the form of tubes grouped around said fast-burning core so that the core extends from one end to the other end of the tubes, and a further fast-burning portion of the charge in the form of a cord encircling the tubes transversely from one end to the other end thereof.

5. A torpedo launching cartridge comprising a casing having therein a fast-burning portion of the charge in the form of cords about 0.047 inch in diameter and arranged in parallel to form a core, a slow-burning portion of the charge in the form of tubes about 6.7 inches long and having a web thickness of about 0.0137 inch grouped around said fast-burning core so that the core extends from one end to the other of the tubes, and a further fast-burning portion of the charge in the form of a cord encircling the tubes transversely from one end to the other end thereof and having the same diameter as the first of said cords;

6. A torpedo launching cartridge comprising a casing having therein a fast-burning portion of the charge in the form of cords composed of nitro-glycerine, nitro-cellulose, diethyl diphenyl urea, said cords being arranged in parallel to form a core, a slow-burning portion of the charge in the form of tubes composed of nitro-glycerine and nitro-cellulose diphenyl urea, diamyl phthalate, mineral jelly and potassium nitrate, which tubes are grouped around the cords so that the cords extend from one end to the other end of Said tubes, and a further fast-burning portion of the charge in the form of a cord encircling the tubes-transversely from one end thereof to the other and of the same size and composition as the first of said cords.

7. A torpedo launching cartridge comprising a casing having therein a fast-burning portion of the charge in the form of cords arranged parallel to form a core, which charge contains about 41% nitro-glycerine and about nitro-cellulose, a slow-burning portion of the charge in the form of tubes grouped around said fast-burning charge so that the cords extend from one end to the other end of the tubes, which tubes include about 35.5% nitro-glycerine and about nitro-cellulose, and a further fast-burning portion of the charge in the form of a cord encircling the tubes transversely from one end thereof to the other and of the same size and'composition as the first of said cords.

8. A torpedo launching cartridge comprising a casing,' acharge in the casing having a fastburning portion of the charge in the form of smokeless powder fashioned into cords arranged parallel with one another to form a core, a slowburning portion of the charge fashioned from smokeless powder to form tubes, which tubes are grouped around the pore so that the cords extend from one end to the other end of the tubes, and a further fast-burning portion of the charge in the form of a cord encircling the tubes transversely from one end to the other end thereof and of the same size and composition as the first of said cords.

9. A torpedo launching cartridge comprising a casing containing a fast-burning portion of the charge in the form of cords of about 0.047 inch smallest transverse dimension and packed together to form a core, the composition of which cords is mainly nitro-glycerine and nitro-cellulose in the proportion of about 4 to 5, a slow-burning portion of the charge comprising a plurality of tubes each about 0.137 inch smallest transverse dimension grouped around said core and of a length substantially equal to the greatest di-" mension of the packed cords and composed mainly of nitro-glycerine and nitro-cellulose in the proportion of about 3 /2 to 5, a further fast-burn ing portion of the charge in the form of a cord encircling the tubes transversely from one end to the other end thereof and of the same transverse dimension and composition as the first of said cords, which fast-burning portion of the charges comprise from about 20 to 28%% of the total.

STUART NETHERVVOOD BARKER.

GEORGE SIDNEY SELMAN.

VICTOR GEORGE BULL.

VIVIAN CHARLES ERIC MARTEN-GWILLIAM. ROBERT WARK. THOMAS THOMSON.

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