Short range tubular projectile

• US 4,827,847 A
• Filed: 07/20/1987
• Issued: 05/09/1989
• Est. Priority Date: 05/30/1985
• Status: Expired due to Term

• Current Assignee: SNC Technologies, Inc. (General Dynamics Corporation)
• Original Assignee: Her Majesty The Queen In Right Of Canada (Government of Canada)
• Inventors: Evans, John R., Laviolette, Maurice A., Cheers, Brian
• Primary Examiner(s): Walsh, Donald P.
• Application Number:
  US07/075,731
• Time in Patent Office: 659 Days
• Field of Search: 102/503, 102/501
• US Class Current: 102/503
• CPC Class Codes: F42B 10/34 Tubular projectiles
• CPC Class Codes: F42B 10/54 Spin braking means

Abstract

A spinning tubular projectile (STUP) is subcalibre to reduce both retard and the gyroscopic stability. The total effect is to reduce crosswind sensitivity and to obtain a better ballistic match with an armour piercing fin stabilized, discarding sabot (APFSDS) round. To reduce the range to that desired for a limited range practice round, the STUP is equipped with spin-damping fins on its surface near the projectile center of gravity.

Claims

1. A short range practice projectile comprising a subcalibre hollow core tubular body having an annular leading edge with an internal wedge adjacent the leading edge, the area ratio of the smallest open area in the hollow core to the area of the core passage at the leading edge being such as to sustain a supersonic flow within the tubular body at projectile speeds above a selected supersonic speed and to produce a choked flow within the tubular body in response to reduction of the projectile speed to a speed lower than the selected speed;

spin damping means comprising a plurality of fins on the external surface of the tubular body for slowing the spin of the body during flight at a selected rate greater than the rate of velocity decrease, whereby the flight of the projectile becomes unstable, the angle of attack of the projectile increases, and the flow within the tubular body becomes choked at a projectile speed above said selected supersonic speed; and

a sabot carrying the body.

2. A projectile according to claim 1 including three fins spaced equally around the projectile.

3. A projectile according to claim 2 wherein the fins are located adjacent the projectile'"'"'s center of gravity.

4. A projectile according to claim 1, wherein the tubular body has a fineness ratio of substantially 4.

5. A projectile according to claim 1, including a bore in a trailing end of the projectile and a tracer material accommodated in the bore.

6. A method of controlling the range of a practice projectile having a hollow, tubular configuration and an internal wedge at the leading end of the projectile, comprising:

firing the projectile from a gun at a supersonic speed sufficient to cause supersonic flow through the projectile, and with sufficient spin to be gyroscopically stable;

slowing the spin of the projectile, whereby the gyroscopic stability of the projectile is reduced and the angle of the attack of the projectile is increased thus causing the flow through the projectile to choke in response to the increasing angle of attack.