Attachment B-Ported Tube Interface Control Document (ICD).DOCX

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Attachment B - Ported Tube Interface Control Document (ICD)

CANNON INSTRUMENTATION PORT INTERFACE CONTROL DOCUMENT AND MODIFICATION GUIDELINES

PROGRAM MANAGER SELF PROPELLED HOWITZER SYSTEM

10 October 2024

DISTRIBUTION STATEMENT A. Approved for public release: distribution unlimited.

1. PURPOSE.

This document contains interface control information, general modification guidelines, and inspection criteria for modifying a cannon system for use with three ballistic pressure transducers. The intent of these modifications is for live fire instrumentation and collection of internal ballistics data. Once a cannon system is altered using this document, it is highly recommended that the cannon is properly marked, and only used for engineering and development purposes. Any limitations to the fatigue life or strength of a cannon system once it’s modified should be documented and attached with the cannon assembly.

2. OVERVIEW OF PORTED CANNON TUBE MODIFICATION.

The general architecture of this modification consists of the addition of three instrumentation ports as shown in Figure 1 below. This architecture follows the practice used on the M776 cannon system when tested at Yuma Proving Grounds, AZ.

Figure 1: Instrumentation Port Architecture

The sections below will detail all interfaces and guidelines for placement, manufacture, and inspection of the Muzzle, Chamber, and Breech Ports.

3. MUZZLE PORT.

Location Guidelines: The muzzle port is located at the muzzle end of the cannon tube. The specific port location and geometry should be selected by the design activity. The port should be located approximately 12 inches axially from the end of the cannon tube. The port should be clocked radially, in a manner that it maximizes access and cable routing but does not interfere with functional geometry such as gunners quadrant flats. Example location shown in Figure 2 below.

Figure 2: Example Muzzle Port Location (inch units)

The port must be located so the entire diameter of the port through hole falls within a rifling groove. Due to manufacturing variability, the recommended practice is to select a port location that allows locational flexibility. During manufacturing preparation, the exact port location should be selected using ultrasonic equipment to ensure correct placement within a rifling groove.

Transducer: The Muzzle Port will use the RP120 pressure transducer provided by Yuma Proving Grounds. Geometric details on this transducer can be found below in Figure 3.

Figure 3: RP120 Transducer Geometry (inch units)

Port Geometry: Specific port geometry should be determined by the design activity for the cannon system. The port geometry can vary based on the thickness of the cannon wall at the muzzle port location. Two examples of port geometry for thin walled and thick walled cannons are shown below In Figure 4 to use for development of specific geometry.

Figure 4: RP120 Instrumentation Port Geometry Examples (inch units)

In the examples shown above the thread length and through hole diameter should not exceed the thick wall example and should not be less than the thin wall example. The counter bore shown in the thick wall example is to allow for tooling accessing for installation and removal of the transducer. The sealing surface is critical to functionality and should be controlled to a finish of Ra = 16 micro-inch. The design activity should also consider how the strength and fatigue life of the cannon will be affected with the addition of this port.

4. CHAMBER PORT.

Location Guidelines: The chamber port is located axially with a .5 inch standoff from the back of an M795 projectile base when the projectile is seated in the cannon tube. The distance from the front edge of the rotating band to the bottom of the projectile base on a M795 projectile is 3.876 inch (98.45 mm). A diagram showing the chamber port axis location in relation to the M795 projectile and cannon tube is shown below in Figure 5.

Figure 5: Axial Location of Chamber Port

The specific port location and geometry should be selected by the design activity. The port should be clocked radially, in a manner that maximizes access and cable routing but does not interfere with functionality. It may be necessary for a channel to be added along the surface of the cannon tube to allow for cable routing.

Transducer: The Chamber Port will use the E30F2 pressure transducer provided by Yuma Proving Grounds. Geometric details on the envelope of this transducer can be found below in Figure 6 below.

Figure 6: E30F2 Pressure Transducer Geometry (inch units)

Port Geometry: Specific port geometry should be determined by the design activity for the cannon system. The port geometry can vary based on the thickness of the cannon wall at the port location. An example of port geometry is shown below In Figure 7 to use for development of specific geometry.

Figure 7: E30F2 Instrumentation Port Geometry Example (inch units)

In the example shown above the minimum thread depth and through hole diameter should be adhered to. The counter bore is to allow for tooling accessing for installation and removal of the transducer. The sealing surface is critical to functionality and should be controlled to a finish of Ra = 16 micro-inch. The design activity should also consider how the strength and fatigue life of the cannon will be affected with the addition of this port.

5. BREECH PORT.

Location Guidelines: The Breech Port should be located on the spindle or equivalent breech component. The port’s axis should run parallel to the cannon tube axis. The specific port location and geometry should be selected by the design activity. The port location should facilitate access and cable routing and not interfere with functionality. It may be necessary to modify other breech components with channels or other geometric features to allow for cable routing to this port location.

Transducer: The Chamber Port will use the N5TS pressure transducer provided by Yuma Proving Grounds. Geometric details of this transducer can be found below in Figure 8 below.

Figure 8: N5TS Pressure Transducer Geometry (inch units)

Port Geometry: Specific port geometry should be determined by the design activity for the cannon system. The port geometry can vary based on the specific cannon configuration. An example of port geometry is shown below In Figure 9 to use for development of specific geometry.

Figure 9: N5TS Instrumentation Port Geometry Example (inch units)

In the example shown above the minimum thread depth and through hole diameters should be adhered to. The .281 inch diameter through hole is for the purposes of cable routing. The sealing surface is critical to functionality and should be controlled to a finish of Ra = 16 micro-inch. The design activity should also consider how the strength and fatigue life of the cannon will be affected with the addition of this port.

6. MANUFACTURING GUIDELINES.

The following points below are recommendations for manufacturing of any of the transducer ports. Alterations may be required due to local equipment and tooling availability. Dimensional conformance should be to shop tolerances, unless specifically called out by the design activity.

1. Prior to any cutting operations the final position of the muzzle port should be identified and altered if necessary. The entire diameter of the port’s through hole must fall within a rifling groove. It is recommended to use ultrasonic equipment for this.

2. It is recommended to use Cobalt tooling for cutting operations.

3. For muzzle and chamber ports, threaded features should be drilled initially with a traditional drill bit, and spot faced with either a spot facing tool or 4-flute end mill. The surface finish of this spot face is critical as it is a sealing surface for the pressure transducers. Surface finish for spot face is Ra = 16 micro-inch on all sealing surfaces.

4. When tapping threads use a 3 step tapping approach consisting of a starter tap, plug tap, and bottom tap. The minimum full thread depth must be adhered to for proper sealing of the pressure transducers. Ensure to not crash any tooling into sealing surfaces due to the surface finish requirements shown above. If any tooling does come into contact with the spot face, a smaller end mill or similar tool must be used to clean up the surface finish.

5. De-burr the holes inside the cannon bore using handheld scraper or rotating flap wheel attached to a pole extension or long shaft.

6. De-burr outside edges using crocus cloth, flap wheel, or similar device.

7. INSPECTION GUIDELINES.

The following points below are recommendations for inspecting the transducer ports. Alterations may be required due to local equipment and tooling availability.

1. It is recommended that inspection procedures 2 and 3 below are carried out (if possible) prior to un-fixturing of the cannon tube in the event that any rework is required.

2. Inspect the surface finish of the instrumentation gauge spot face sealing surface by using a small diameter video borescope inspection camera or similar device. The surface finish should be verified by visual comparison using a surface finish gauge or similar device.

3. Verify function and thread form by completing the following steps using a surrogate transducer or representative plug.

a. Mark the bottom of the transducer seal with engineers marking, machinists blue ink marking, tool layout marking or similar product.

b. Screw in the transducer by hand until it bottoms out or stops.

c. Removed transducer.

d. Confirm the seal fully contacts the spot face surface by inspecting with a small diameter video borescope inspection camera or similar device. There should be a solid uniform contact shown between the seal and spot face surface.

e. Clean any marking products.

f. If the seal does not contact the spot face surface, the thread depth will have to be increased until it does.

8. NON-CONFORMANCES AND DEVIATIONS.

Any non-conformances or deviations to the requirements and guidelines in this document shall be reviewed with PdM SPH-M.

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