US2148808A - Light mortar - Google Patents

Description

- Feb. 28, 1939. O. DONNER 2,148,808

LIGHT MORTAR 1 Filed June 2, 1936 2 Sheets-Sheet l Feb. 28, 1939. o. DQNNER 2,148,808

LIGHT MORTAR Filed June 2, 1956 2 Sheets-Sheet 2 zoo foo

Patented Feb. 28, 1939 UNITED STATES PATENT cfs-Fries Application .lime 2, 1936,

Serial N0. 83,114E

In Finland March 28, 1935 2 Claims.

My invention relates to ordnance, and particularly' to mortars.y

It has for an object to produce a mortar of light weight, quick and simple in its operation 5 and having an adequate shooting range.

In the drawings, whichillustrate one embodiment ofthe invention,

Fig. 1'- is a part side elevationv and part vertical longitudinal section of mortar embodying the invention.

Fig. 2f is an enlarged detail view of a portion oi the structure shownin Fig-l.

Fig', 3 is a cross section on the Fig. 2.

A Fig. 4- is a diagram illustrating the action that takes place when my mortar operates.

In most armies the needV of a light 40 to 65 millimetre mortar has been long felt. To ull the requirements' of practice the operation of a gun or this kind on the battlefield should, however, be extremely simple andV quick. For this purpose eii'orts have been made, although with poor success, to fire a winged shell by the use of one single propellant charge placed in the base of the shell. It has, however, been found extremely difficult to obtain the large variety of shooting ranges simultaneoush7 required and varying between On regulating the shooting range by changing the angle of elevation it is necessary to direct the gun almost vertically for short shooting ranges. An elevation range of 75, corresponding to half of the maximum shooting range, oiers considerable practical drawbacks and in such constructions, in

which the shooting range is regulated by changing the elevation angle of the tube, one has to fall back upon the use oi four different auX- iliary propellant charges or relays, in which cases the shooting ranges are 800, 650, 350, 200 and 100 metres respectively. Various efforts have been made to simplify the operation of the gun by using a constant elevation angle. A deviation oi 10 or less of the angle of elevation from the 43 which correspond to the maximum shooting 45 range is not of material consequence because of the very small change in the shooting range caused by this deviation. In this case it is suicient to direct the gun in the direction oi the target and as, on this shooting range, the trans- 50 versal inclination of the pointing device has a considerably smaller influence than for large elevation angles, the operation oi the gun is thus considerably simplified while its accuracy in practice is greatly improved.

55 Leaving, therefore, the regulation of the shootline 3-3 of ing range by changing the angle of elevation and by usingl a variable propellant charge out of consideration as being impracticable, there is stillY available regulation byl the aidof the gas leakage opening and the gas chamber behind the shell. tion by the leakage of the gas was in use, among others, in the British and Polish armies, but after ashort period thev use of this construction was abandoned; The cause for this was that 10.. so far it has notY been possible to construct the rather complicated mechanism required for thev closing and opening of the openings fixed points along the tube so that the same would operate accurately in practice, even with 15;: frequent cleaning. Regulation by the use of a variabievolume ofthe gas chamber behind the projectile hasl likewise been' employed in a construction, in which the starting point oi the projectile was-pushed slightly forward to obtaina 2Q larger gas chamber.

As a slightly enlarged gas chamber reduces considerably the gas pressure, this systeml has certain advantages, among others, by reducing the dispersion in firing at medium shooting 2,5 ranges. Although aV slight displacement of the l" starting point ofthe projectile has, at the beginning, a relatively great influence on the shooting range, the continued displacement of the same is of less importance. tain accuracy, a certain expansion allowance will further be required and as the placing of the starting point of the projectile too near to the mouth oi the tube oiers other considerable drawbacks, the regulation according to this method 35 has been used only in connection with a variable propellant charge The present invention relates to a construction by which the poss'bilities of regulation by the aid of the gases for largely diierent shoot- 40 ing ranges are combined with the advantages of a variable volume of the gas chamber, of a low pressure and of the accuracy obtainable on medium shooting ranges without requiring any mechanism for the opening and closing of the gas openings and the drawbacks adhering therein. In principle the invention is based upon the fact that the starting point of the projectile in the tube may be changed, for instance, by the aid of an adjustable percussion pin. During the iirst stage of this movement the shooting range is regulated chiefly by enlarging the gas chamber, When the projectile is further displaced, the girdle of the same will close one or more of the gas openings which are, generally, con- 5| As, to obtain a cer- 30 I stantly open. If the starting point is near to the rear end of the tube, the speed of the projectile on passing theopenings will be great and the period of time during which the gases may leak through the openings will be relatively short; further, the gases are to some extent cooled by the work effected by them. The influence of the openings is, in this case, relatively small.

On the other hand, when the starting point of the projectile is near to the rst opening, the speed of the projectile is smaller and the influence of the openings many times greater. When, nally, the starting point of the projectile is still more advanced, the girdle of the projectile will, from the start of the movement, bare theopening or openings so that the projectile as a Whole will operate in the same manner as a plunger vane in a gas regulating device and thus enable the attaining of the shorter shooting ranges.

In the drawings T designates the tube of the mortar which is provided with the various leakage openings, O1, O2, O3, etc. The percussion pin is indicated by S, While V is a crank to turn the bevel gear a and thereby turn the bushing b through meshing gear g. P1 the various starting points of the tube. The pin S has a sleeve c which is caused to rotate by means of a stud and slot connection h between the sleeve c and the bushing b.

direction or the other.

In Fig. 2 the curves K illustrate the eiect vof the change of the starting point of the pro--V between and 700 metres.

I claim: 1. In a light mortar of the character described, closing the lower end of the will act to close selected leakage openings, said means comprising a rotatable bushing, a crank operated device for rotating said bushing, means to connect said bushing and said sleeve together in virtue of which the sleeve may be turned about 2. In a light mortar in erally effected with one simple principal powder said means including a loncated normally in advance of the shell to be red., and means sleeve to position yet be free to move longitudinally, and a xed screw spindle in threaded engagement With said sleeve, 1n virtue

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