US2389846A - High velocity projectile - Google Patents

Description

Nov. 27, 1945. G. R. ERICSON HIGH VELOCITY PROJECTILE Filed Aug. 26, 1941 N w mm NR R W m Rgm E t G y R A m M G G 1 H Patented Nov. 27, 1945 res 'E'E'i' FFHE This invention relates to projectiles and particularly to projectiles intended to be fired at high velocities.

As is well known to those skilled in the art, the

exterior ballistic efiiciency of a high velocity pro-,

jectile depends to a great extent on a high ratio of projectile weight to cross-sectional area while the internal ballistic eificiency of the projectile depends on a high ratio of cross-sectional area to projectile weight. That is to say, the require-.

ments for internal and external ballistic efficiency are just the opposite.

In order to avoid the above mentioned difficulty it has been proposed to use a projectile having comparatively great length and comparatively small diameter but provided with a packing, plug or sabot to increase the cross-sectional area of the projectile so that it will fit into a gun of comparatively large diameter, the sabot being of comparatively light weight and detachable as soon as up to the present applicant does not know that: i

any sabot has been developed having the necessary characteristics which may be summarized as follows: First, it must form a positive and effective seal against leakage of gas around (or through) the projectile during the discharge of the gun; second, it must firmly engage the projectile and also the rifling of the gun during discharge through the barrel so as to give the projectile the proper spin; third, it must maintain the projectile co-aXial with the barrel and guide it so that the centrifugal force due to the spin of the projectile will not in itself cause undue precession or yaw of the projectile in flight; fourth, it must be promptly detached from the projectile as soon as it leaves the gun; fifth, it must be of comparatively light weight; sixth, the projectile itself must have a high ballistic coefficient when detached from the sabot.

I obtain the desirable results outlined above by the construction shown in the accompanying drawing and described in the following specification and claims.

Referring to the drawing:

Fig. 1 shows a complete round of ammunition embodying my improved sabot and projectile, parts being shown in section,

Fig. 2 shows the base of the assembled projectile and sabot detached from the cartridge case,

Fig. 3 shows the condition and relation of the projectile and sabot while traveling through the barrel of the gun,

Fig. 4 shows a slightly modified form of sabot and projectile,

Fig. 5 shows the condition of the device shown in Fig. 4 while traveling through the barrel of the gun; and

Fig. 6 shows the adaptation of certain features of the invention to a nozzle type projectile.

The reference numeral l indicates the projectile having an ogee shape at the front end terminating in a shoulder 2 which is shown somewhat exaggerated in the drawing for purpose of illustration. At the rear of the shoulder cylindrical portion 3 followed by a boat tail or conical portion 4. The projectile may be made of whatever material desired and may or may not carry an explosive charge and fuse.

The sabot 5 comprises a tubular central portion having a comparatively thin inturned front flange G separated by an annular groove 1 from a thicker inturned flange 8. The inside diameter of the forward flange 6 is such as to snugly fit the short cylindrical portion 3 of the projectile while the internal diameter of the flange 8 is of a slightly larger diameter so that it can not stick or wedge onto the projectile. The difference in internal diameter between the members 6 and 1 may be comparatively small especially in small projectiles. Fifteen or twenty thousandths of an inch difference is ample for a projectile in the order of .50 caliber. At the rear of the sabot openings 9 are provided for a purpose which will be hereinafter described. These openings are formed between prongs I 0 terminating in guide members H engaging the rear of the projectile to maintain the projectile in position coaxial with the barrel of the gun. The outside diameter of the prongs I0 is preferably a freely sliding fit on the lands of the rifling of the gun, the number and width of the prongs i0 is such that they cannot expand into the rifling grooves but will bridge the grooves.

The turning action is provided by a turning band l2 of soft material such as gliding metal which is adapted to be engraved by the rifling in the usual manner.

The projectile and sabot may be applied to cartridge case 4 as indicated in Fig. 1.

In operation the explosion of the propelling in Fig. 3 but also to hold this flange in rigid.

frictional driving relation with the projectile so as to transmit the necessary spin to the bullet. The shoulder 2 may be narrowed so as to dig into the softer metal of the sabot to cause a more positive driving engagement but this is not ordinarily necessary.

When the projectile reaches the end of the gun barrel the openings 9 permit the escap of gas from the gun before the prongs I of the sabot are clear of the gun barrel. In this manner the disturbing force of the muzzle blast is reduced before the projectile is free to be tipped sideways and the likelihood of a substantial amount of yaw being set up at the instant of discharge is greatly reduced.

As soon as the prongs H) are free from the gun barrel centrifugal force Springs the members In and l I outwardly vary slightly but still enough to insure frictional disengagement from the projectile. It will be noted that the deformation of the forward flange 6 to the position shown in Fig. 3 will necessarily have the effect of expanding the internal diameter of this member and forcibly cracking it away from the projectile portion of the projectile 3. The deformation of the annular portion of the sealing member .tends to cause the prongs ID to spring outwardly so that as soon as they are free from the gun barrel they also release the projectile. The elimination of the pressure in the gun barrel permits the whole sabot to fall back in response to air resistance so that it drops free from the projectile a few yards after it leaves-the gun barrel. The sabot being made of very light construction does not travel far and falls to. the ground.

In the form of the invention shown in Fig. 4 the annular groove 8 in Fig. 1 is not formed in the sabot but the limitation of deformation of the sabot I is accomplished by contact of the sabot with the shoulder I6, it being noted that the bending of the sabot'to the position shown in Fig. 5 causes expansion of the internal diameter of the sabot to disengage it from cylindrical surface 3 and the taper of the shoulder I6 is much too steep to permit sticking of the sabot on this shoulder.

In the form of the invention shown in Fig. 6 the outside of the projectile is cylindrical and the inside of the forward end is tapered inwardly with an ogee curve, the radius of which is preferably from fourteen to twenty times the thickness of the wall at the rear end of the taper. The annular sealing surface 3 is formed behind the shoulder at the rear of the ogee forms the same as with the projectile shown in Fig. 1. At the rear of the cylindrical portion 3 the projectile is tapered out to the rear end with a curved taper. The equation of the curve may readily be calculated as follows: The sound wave thrown off from the nose of the projectile striking the inner surface of the rear cone at any point should be reflected within a direction directly opposite to the line of flight.

I claim:

1. In combination, a projectile for use in a gun, said projectile including a shoulder, a sabot having portions engaging the barrel of said gun and said projectile including spaced annular flanges, at least one of which is in sealing engagement with said projectile rearward of said shoulder, the flange having sealing engagement with said projectil including an area capable of distortion under discharge pressure in said gun to weaken said sealing engagement, whereby said sabot and projectile may separate after discharge.

2. In combination, a projectile for use in a gun, said projectile including a shoulder, a sabot having portions engaging the barrel of said gun and said projectile including spaced annular flanges, at least one of which is in sealing engagement with said projectile rearward of said shoulder, the flange having sealing engagement with said projectile including an area capable of distortion under discharge pressure in said gun to weaken said sealing. engagement, whereby said sabot and projectile may separate after discharge, and means including a spaced annular flange for limiting the distortion of an adjacent flange.

GEORGE R. ERICSON.

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