US3528187A

US3528187A - Free-volume chamber for telescoped caseless ammunition

Info

Publication number: US3528187A
Application number: US769908A
Authority: US
Inventors: Joseph I Harrell
Original assignee: Hercules LLC
Current assignee: Hercules LLC
Priority date: 1968-10-23
Filing date: 1968-10-23
Publication date: 1970-09-15
Anticipated expiration: 1987-09-15

Description

Sept. 15,1970 v J. l. HARRELL 3,523,137

FREE-VOLUME CHAMBER FOR TELESCOPEIICASELESS AMMUNITIUN Filed Oct. 23, 1968 20 l4 I8 34 36 22 I6 IO 24 26 2730 32 I2 FIG.2

48 66 3 JOSEPH LHARRELL INVENTUR.

ATTORNEY United States Patent 3 528 187 FREE-VOLUME CHAMBER FOR TELESCOPED CASELESS AMMUNITION Joseph I. Harrell, Sparta, NJ., assignor to Hercules Incorporated, Wilmington, DeL, a corporation of Delaware Filed Oct. 23, 1968, Ser. No. 769,908

Int. Cl. F41c 21/00, 21/12; F41b 5/18 U.S. Cl. 42-76 6 Claims ABSTRACT OF THE DISCLOSURE A chamber designed for the firing of telescoped caseless ammunition is provided. The chamber has one or more cavities in its interior surface which provide areas of support and non-support at specific locations for the propellant charge of the telescoped round. Ballistic efliciency of telescoped rounds fired in this chamber is substantially improved.

This invention relates to a free-volume chamber for receiving a telescoped round of casel ss ammunition, said chamber increasing the ballistic efiiciency of the telescoped caseless round fired therein. More particularly this invention relates to a chamber having free volume which provides areas of support and non-support about the propellant charge of a telescoped round of caseless ammunition loaded therein to increase ballistic performance of the round.

Telescoped caseless ammunition is comprised of a propellant charge having an axial bore or cavity, a projectile housed entirely within the axial bore of the propellant charge and a primer. Various embodiments of telescoped caseless ammunition are disclosed in patent application S.N. 694,310, now Pat. No. 3,482,516; filed Dec. 28, 1967 by L. I. Farmer et al. and entitled Caseless Cartridges Having the Projectile Housed in the Propellant Charge.

When a telescoped round of caseless ammunition is loaded into the chamber of a gun, the projectile being housed in the propellant charge is not seated in the barrel of the gun as is the projectile of a round of conventional ammunition when in a loaded position. Upon initiation of the primer of the telescoped round, the projectile is forced forward into the barrel of the gun and becomes seated in the barrel. During the time interval from initiation of the primer until the projectile is seated in the barrel of the gun, some of the gases of combustion from the primer and from the initiated propellant charge can escape through the barrel of the gun ahead of the projectile resulting in a loss of propulsive gas. This loss in propulsive gas results in reduction in the ballistic performance of the round.

It has now been discovered that by providing various areas of support and non-support about the propellant charge in specific locations of the gun chamber that ballistic performance of telescoped caseless ammunition can be substantially improved. The areas of support and nonsupport provided by the free-volume chamber and their locations in the chamber are defined hereinafter in relation to a round of telescoped caseless ammunition loaded in the chamber. The round of telescoped caseless ammunition loaded into the free-volume chamber must be sized so that there is a close fit betwen the propellant charge and the inside walls of the chamber. Free-volume is provided by at least one aft cavity in the inside peripheral surface of the chamber. The portion of the propellant charge opposite the cavity is not supported, while the remaining portion of the propellant charge which by design is contiguous with the inside walls of the chamber, is supported. The location of the aft cavity or aft cavities in the free-volume chamber depends upon the position of the Patented Sept. 15, 1970 ice forward rim of the rotating band of the projectile housed in the propellant charge. It is necessary that the forwardmost edge of any aft cavity be located no farther forward in the chamber body than the forward rim of the projectile rotating band.

For a complete understanding of this invention, reference is made to the following detailed description and drawings.

FIG. 1 is an elevational view partly broken away and in section of a free-volume chamber with a round of telescoped caseless ammunition in the loaded position therein illustrating an annular cavity in the aft end of the chamber and the spacial relationships of the chamber cavity and the telescoped caseless round.

FIG. 2 is a longitudinal View partly in section of an embodiment of a free-volume chamber of this invention containing a round of telescoped caseless ammunition in the loaded position, said chamber comprised of a chamber housing and a chamber sleeve inserted into the housing, said chamber sleeve having both forward and aft cavities.

FIG. 3 is an elevational view partly broken away and in section of the chamber sleeve and telescoped caseless round of FIG. 2 further illustrating the chamber sleeve design and the spacial relationship of chamber sleeve cavities to the telescoped caseless round loaded therein.

In FIG. la free-volume chamber 10 and a barrel 12 are shown as an integral assembly. The chamber 10 has a cavity 14 in the shape of an annular groove in its aft end about the inside surface 16 of chamber 10, said cavity 14 having a forward surface 18 and an aft surface 20. A telescoped round of caseless ammunition 22 comprised of a projectile 24, propellant charge 26, and primer 28 is in the loaded position in chamber 10, with the forward edges 30 of the propellant charge 26 in contact with the forward surface 32 of the chamber 10. The projectile 24 is secured at the forward end of propellant charge 26 with a centering ring 27 and is secured at the aft-end of the propellant charge 26 with a propellant plug 29. Projectile 24 has a rotating band 34 having a forward rim 36. The forward surface 18 of cavity 14 is no farther forward than the forward rim 36 of rotating band 34. The longitudinal outside surfaces 38 of propellant charge 26 and the inside surface 16 of chamber 10 are contiguous over the length of propellant charge 26 with the exception of that portion of propellant charge 26 which is opposite the symmetrically distributed free-volume provided by cavity 14. The inside surface 16 of chamber 10 provides support for the propellant charge 26 contiguous therewith. The portion of the propellant charge 26 opposite cavity 14 is not so supported.

In FIG. 2 a free-volume chamber is shown comprised of a chamber housing 40 and a chamber sleeve 42 inserted into the chamber housing 40. The chamber sleeve 42 has an overall outside configuration coinciding with the inside surface 44 of the chamber housing 40 and has an outside diameter slightly smaller than the inside diameter of the chamber housing 40 to provide for ease of insertion of the chamber sleeve 42 into the chamber housing 40. A telescoped round of caseless ammunition 46 is shown loaded into the chamber sleeve 42. The chamber sleeve 42 has symmetrically spaced aft cavities 48 and forward cavities 50 about its inside surface 52 providing the free-volume for the chamber.

In FIG. 3, the telescoped caseless round 46 comprised of a propellant charge 54, projectile 56 and primer 58 is further illustrated as loaded in chamber sleeve 42. The projectile 56 has a rotating band 60 having a forward rim 62 and a rearward rim 64. The aft cavities as represented by cavity 48 of the chamber sleeve 42 are spaced about the chamber sleeve 42 so that the freevolurne provided by the cavities is symmetrically distributed about the propellant charge opposite the cavities, and positioned, in relation to the telescoped caseless round 46, aft of the forward rim 62 of rotating band 60. The forward edge 66 of cavity 48 and the rearward rim 64 of rotating band 60 are in alignment. The forward cavities are represented by cavity 50 are symmetrically spaced about the forward end of chamber sleeve 42. The forward cavities 50 are positioned forward of the forward rim 62 of rotating band 60 so that there is support provided by the chamber sleeve 42 directly forward of the rotating band 60. The propellant charge 54 is contiguous with the inside surface 52 of chamber sleeve 42 except for those areas of the propellant charge 54 opposite the forward cavities 50 and aft cavities 48, where no support for propellant charge 54 is provided.

ties. The spacial relationship of the cavities of the chamber sleeve and the telescoped round of caseless ammunition is as illustrated in FIG. 3. The total free-volume provided by the chamber calculated as a percentage of the total volume of the propellant charge of the telescoped caseless rounds is about 35%.

Eight rounds of telescoped caseless ammunition are assembled having like primers, propellant charges, and 20 mm. projectiles and are fired in the free-volume chamber described. Rounds 1-4 have the projectile manually seated in the gun barrel and the propellant charge loaded in the chamber prior to firing of the round to essentially eliminate gas loss past the projectile. Rounds 5-8 are fired as telescoped caseless rounds. Results of the firings are contained in Table II.

TAB LE II Charge Chamber Chamber Round Weight, Velocity, pressure pressure N 0. (grains) (ft./sec.) (p.s.i.) (p.s.i.) Round characteristic 732.1 3, 652 50, 300 62,000 Projectile seated. 732. 7 3, 674 50, 300 60, 000 Do. 732. 6 3, 687 52, 500 64, 000 Do. 723. 6 3, 647 51, 000 62, 000 Do. 724. 6 3, 683 64, 800 67, 000 Do. 729. 8 3, 638 51, 400 63, 000 Do. 724. 1 3, 667 55, 500 68, 000 Do. 731. 5 3, 609 50, 300 61, 000 D0.

1 Measured over a 10-foot interval beginning 31 feet from the gun muzzle. 2 Measured by copper crusher gauge. 3 Measured by transducer.

The following examples will further illustrate this invention. Example 1 illustrates the loss of ballistic efiiciency when firing a telescoped round of caseless ammunition in a conventional (close fitting) chamber.

EXAMPLE 1 TABLE I.CASELESS ROUNDS FIRED FROM A CONVEN- TIONAL (CLOSE FITTING) CHAMBER Round Round character- Propellant Velocity, Cherub e r N0. isties weight, grains itJsec. pressure,p.s.1.

1 Projectile 716.7 2, 998 63,000

telescoped.

2 Projectile seated... 716. 7 3, 650 63, 000

The loss of ballistic efficiency of the telescoped caseless round (round 1) due probably to gas loss prior to seating of the projectile of the round is illustrated by the decreased velocity for that round.

The following example illustrates the improvement in ballistic performance resulting from the firing of a telescoped round of caseless ammunition in a free-volume chamber of this invention.

EXAMPLE 2 A free-volume chamber designed for receiving caseless ammunition is prepared and is comprised of a chamber housing and chamber sleeve having forward and aft cavi- As can be seen from Table II, the measured velocity of the projectiles which are telescoped is substantially the same as the measured velocity for like rounds in which the projectiles are seated prior to firing. The substantially equivalent ballistic results from the firing of these rounds as compared to the ballistic results of Example 1 illustrate the efiectiveness of the free-volume chamber for increasing the ballistic efficiency of telescoped caseless ammunition.

The free-volume chamber of this invention provides areas of support and non-support about the periphery of the propellant charge of the round of telescoped caseless ammunition loaded therein. It is necessary in order that proper support be provided for the propellant charge, that the outside longitudinal configuration of the telescoped caseless round and the inside overall longitudinal configuration of the chamber, i.e., the configuration excluding cavities, be essentially the same so that the portion of the propellant charge not opposite a cavity is contiguous with the inside surface of the chamber.

The free-volume chamber of this invention can be prepared as a one piece or integral chamber or it can be prepared as a two piece chamber in the form of a chamber housing having a chamber sleeve insertable therein. When the free-volume chamber is comprised of a chamber housing and a chamber sleeve, the inside longitudinal configuration of the chamber body and overall outside longitudinal configuration of the chamber sleeve, i.e., the configuration excluding any cavities or voids completely through the sleeve, must be essentially the same. The cavities in the free-volume chamber can be made in any desired shape. These cavities can, for example, consist of pockets, or annular grooves in the integral chamber, or they can consist of pockets, annular grooves or complete voids in the chamber sleeve of the two piece free-volume chamber. The spacing of the cavities can be either symmetrical or non-symmetrical about the freevolume chamber. It is preferred, however, to space and size the cavities so that the free-volume provided is symmetrically distributed.

An essential feature of the free-volume chamber of this invention is that the chamber have at least one aft cavity wherein the forward edge of the aft cavity is located no farther forward in the chamber than the forward rim of the rotating band of the projectile. Other cavities can be located forward of the forward rim of the rotating band of the projectile. It is important, however, to provide some support around the area of the propellant charge opposite and forward of the forward rim of the rotating band. The amount of support area to be provided by the chamber forward of the forward rim of the projectile rotating band will vary depending on the overall configuration of the telescoped round, the physical strength of the molded propellant charge, and the size and distribution of free volume provided by the aft cavities of the free volume chamber. The purpose of the support area opposite and forward of the forward rim of the rotating band is to prevent breakup of the forward portion of the propellant charge until after the projectile has started to move into the barrel of the gun.

As will be evident to those skilled in the art, various modifications can be made or followed, in light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

What I claim and desire to protect by Letters Patent is:

1. A free-volume chamber designed for receiving a round of telescoped caseless ammunition, said free-volume chamber defined in relation to a round of telescoped caseless ammunition comprising a propellant charge, a projectile having a rotating band, and a primer, said round placed in a loaded position in said free-volume chamber; said free-volume chamber comprising a chamher body having at least one aft cavity in its inside peripheral surface whereby an area of non-support is provided for the propellant charge opposite said cavity, the forwardmost portion of said aft cavity located no farther forward in the chamber body than the forward rim of the rotating band of the projectile, the remaining portion of the propellant charge being contiguous with the inside surface of the chamber body which provides support for the propellant charge contiguous therewith, whereby increased ballistic performance results upon firing the telescoped caseless round in the free-volume chamber.

2. The free-volume chamber of claim 1 having at least one forward cavity in its inside peripheral surface whereby an area of non-support is provided for the portion of the propellant charge opposite said forward cavity, said forward cavity located forward of the forward rim of the projectile rotating band.

3. The free-volume chamber of claim 2 wherein the areas of non-support provided by the forward and aft cavities are symmetrically distributed about the propellant charge.

4. A free-volume chamber designed for receiving a round of telescoped caseless ammunition, said free-volume chamber defined in relation to a round of telescoped caseless ammunition comprising a propellant charge, a projectile having a rotating band, and a primer, said round placed in a loaded position in said free-volume chamber; said free-volume chamber comprising a chamber body comprised of a chamber housing and a chamber sleeve, said chamber sleeve being inserted into said chamber housing and having an outside longitudinal configuration corresponding to the inside longitudinal configuration of the chamber housing and an inside overall longitudinal configuration corresponding to the longitudinal outside configuration of the telescoped round of caseless ammunition loaded therein, said chamber sleeve having at least one aft cavity in its inside peripheral surface whereby an area of non-support is provided for the propellant charge opposite said cavity, the forwardmost portion of said aft cavity being located no farther forward in the free-volume chamber than the forward rim of the rotating band of the projectile, the remaining portion of the chamber sleeve being contiguous with the propellant charge of the round and providing support therefor, whereby improved ballistic performance results from firing of the telescoped caseless round in the free-volume chamber.

5. The free-volume chamber of claim 4 having at least one forward cavity in the inside peripheral surface of the chamber sleeve whereby an area of non-support is provided for the propellant charge opposite said forward cavity, said forward cavity located forward of the forward rim of the projectile rotating band.

6. The free-volume chamber of claim 5 having at least two aft cavities and at least two forward cavities symmetrically distributed about the chamber sleeve, said freevolume chamber providing symmetrically distributed areas of support and non-support about the propellant charge.

References Cited UNITED STATES PATENTS 2,866,412 12/1958 Meyer et al. 102-38 3,439,635 4/1969 Hensley 10238 BENJAMIN A. BORCHELT, Primary Examiner C. T. JORDAN, Assistant Examiner U.S. Cl. X.R. 10238 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. U.S.P, 3,528,187 Dated Inventor(s) Joseph I. Harrell (Case 1) I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

j Table II, Rounds 5 through 8, under Round Characteristic should read "Projectile Telescoped" SIGNED MD SEALED WI: 17m

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Auesting Officer Gel-1:31am 01' Patent: