US 5,097,743 A · Method and apparatus for zero velocity start ram acceleration

Abstract

A method and apparatus for initiating a ram acceleration of a projectile that is at rest. A projectile (34) is positioned in a starting chamber (14) of a launch tube (12). Starting chamber (14) is either filled with a gas at a relatively low pressure or is substantially evacuated. A wave reflection disk (42/42') is positioned a short distance behind the projectile. Downstream of the starting chamber are a plurality of segments, including a first segment (16), which is filled with a combustible gas mixture at a substantially higher pressure than that in the starting chamber. The first segment is separated from the starting chamber by a pair of thin membranes (20a and 20b). These membranes have a characteristic burst pressure that is about midway between the differential pressure in the first segment and the starting chamber. To initiate the ram acceleration process, fluid between the two membranes is exhausted to the atmosphere, sequentially exposing them to a differential pressure that exceeds their burst pressure. Bursting of these membranes enables the combustible gas mixture to expand unsteadily from the first segment into the starting chamber. An expansion wave produced by the expanding combustible gas mixture passes the projectile and reflects from the wave reflection disk as a shock wave. The wave reflection disk converts the kinetic energy of the expanding gas into thermal energy, at a temperature sufficient to initiate combustion of the mixture. The shock wave propagates downstream from the wave reflection disk, attaches to the projectile, and establishes a stable, thermally choked ram acceleration of the projectile down the launch tube. As the combustible gas mixture burns behind the projectile, the resulting pressure wave accelerates the projectile down the bore of the tube into successive combustible gas-filled segments.

Claims20

Dependent claims

Apparatus for accelerating a projectile using a ram acceleration process that starts with the projectile at rest, comprising:

(a) a launch tube that is longitudinally divided into a plurality of segments along its length, including a first chamber in which the projectile is positioned at rest, and an adjacent second chamber filled with a combustible gas mixture, the first chamber having a substantially lower fluid pressure than that of the combustible gas mixture within the second chamber;
(b) separation means for separating the first chamber from the second chamber;
(c) means for opening the separation means, allowing the combustible gas mixture to quickly expand into the first chamber from the second chamber, producing an expansion wave that passes the projectile within the launch tube at a supersonic velocity;
(d) wave reflection means, disposed behind the projectile in the first chamber, for reflecting the expansion wave as a shock wave back toward the projectile;
and
(e) means for igniting the combustible gas mixture behind the projectile as the expansion wave is reflected as a shock wave, the reflected shock wave starting the ram acceleration process as it reaches the projectile, so that the combustible gas mixture burns behind the projectile, continuously accelerating it longitudinally down the launch tube.

3 more elements

Apparatus for initiating a ram acceleration process to accelerate a projectile, comprising:

(a) a launch tube having a hollow bore extending longitudinally through it, the bore having a diameter greater than a portion of the projectile that is shaped to define a throat;
(b) a plurality of thin membranes, longitudinally spaced along the length of the launch tube bore, dividing the launch tube into a plurality of segments, the segments being filled with combustible gas mixtures of varying densities;
(c) a breech end of the launch tube bore including a starting chamber in which the projectile is disposed at rest as the ram acceleration process is started, the starting chamber having a substantially lower pressure than that of the combustible gas within an adjacent segment of the launch tube;
(d) means for perforating the membrane that separates the starting chamber from the adjacent segment of the launch tube, enabling the combustible gas mixture within the adjacent segment to expand into the starting chamber, producing an expansion wave having a supersonic velocity at a point where the expanding combustible gas mixture flows past the throat of the projectile;
(e) wave refection means disposed behind the projectile in the starting chamber, for reflecting the expansion wave produced by the expanding combustible gas mixture after it has passed the projectile as a shock wave, thereby converting the kinetic energy of the expanding combustible gas mixture into thermal energy that ignites the expanding combustible gas behind the projectile, thus initiating the ram acceleration process to propel the projectile into the adjacent segment of the launch tube, the projectile continuing to undergo ram acceleration through successive segments of the launch tube.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for zero velocity start ram acceleration

Life of this patent

Method and apparatus for zero velocity start ram acceleration

Life of this patent

Abstract

Claims20