Projectile

Abstract

The present invention provides a projectile for use in a simulated fan-blade-off ballistic test. The projectile has an ellipsoid body having a blind axial bore extending from a first axial end. The blind axial bore is for housing a weight adjustment body which can be used to modify the weight and/or centre of gravity of the projectile. A sealing plug may seal the weight adjustment body within the axial bore and an insert may be provided to fix the position of the weight adjustment body and/or to control the sliding of the weight adjustment body within the axial bore.

Claims

1. A projectile for use in a simulated fan-blade-off ballistic test, the projectile having an open axial end and a closed axial end, the projectile being projected toward a target with the open axial end as a tail side of the projectile and the closed axial end as a nose side of the projectile, the projectile comprising: an ellipsoid body having a blind axial bore extending from the open axial end of the projectile to a blind end of the blind axial bore, the blind axial bore extending for a majority of an entire axial length of the projectile; at least one weight adjustment body housed within the blind axial bore separated from the blind end of the blind axial bore; and at least one insert housed within a space between i) the blind end of the blind axial bore and (ii) an end of the at least one weight adjustment body closest to the blind end in an axial direction of the blind axial bore, the at least one insert being made of a resiliently deformable elastomeric material with a spring constant, the spring constant being selected to control a sliding movement of the at least one weight adjustment body in the axial direction, such that upon impact of the nose side of the projectile on the target, the end of the at least one weight adjustment body moves further toward the blind end of the blind axial bore by compressing the at least one insert.

2. The projectile according to claim 1, wherein the at least one weight adjustment body is slidable within the blind axial bore.

3. The projectile according to claim 1, further comprising a sealing plug for sealing the blind axial bore.

4. The projectile according to claim 1, wherein the ellipsoid body is formed of aluminium or an aluminium alloy.

5. A kit for use in a simulated fan-blade-off ballistic test, the kit comprising: the projectile according to claim 1; and a plug for sealing the blind axial bore at the open axial end.

6. The kit according to claim 5, further comprising a plurality of weight adjustment bodies of differing masses.

7. The kit according to claim 5, further comprising a plurality of inserts of differing axial lengths and/or differing deformation properties and/or differing frictional resistance properties.

8. A simulated fan-blade-off ballistic test method comprising: firing a projectile towards a test item to be impacted, the projectile having an open axial end and a closed axial end, the projectile being projected toward the test item with the open axial end as a tail side of the projectile and the closed axial end as a nose side of the projectile, the projectile comprising: an ellipsoid body having a blind axial bore extending from the open axial end of the projectile to a blind end of the blind axial bore, the blind axial bore extending for a majority of an entire axial length of the projectile; at least one weight adjustment body housed within the blind axial bore separated from the blind end of the blind axial bore; and at least one insert housed within a space between (i) the blind end of the blind axial bore and (ii) an end of the at least one weight adjustment body closest to the blind end in an axial direction of the blind axial bore, the at least one insert being made of a resiliently deformable elastomeric material with a spring constant, the spring constant being selected to control a sliding movement of the at least one weight adjustment body in the axial direction, such that upon impact of the nose of the projectile on the target, the end of the at least one weight adjustment body moves further toward the blind end of the blind axial bore by compressing the at least one insert; and assessing damage to the test item after impact of the projectile.

9. The projectile according to claim 1, wherein the at least one weight adjustment body slides away from the open axial end of the projectile towards the blind end of the blind axial bore.

10. The projectile according to claim 1, wherein the entire axial length of the projectile is approximately 170 mm, and an entire axial length of the blind axial bore is approximately 164 mm.

11. The projectile according to claim 1, wherein the blind axial bore has: a first diameter section disposed at the open axial end, a second diameter section disposed inward of the first diameter section and having a diameter smaller than a diameter of the first diameter section, and a third diameter section disposed inward of the second diameter section and having a diameter smaller than the diameter of the second diameter section.

12. The projectile according to claim 1, wherein the blind axial bore is sealed so that the at least one weight adjustment body flies with the projectile and slides within the blind axial bore upon an impact of the projectile after the flight.

13. The projectile according to claim 1, further comprising: paint coatings or gridded lines on an outer surface of the projectile that are monitored by a camera as the projectile is projected and impacted on the target.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

(2) FIG. 1 shows a lateral view of a first embodiment of the present invention;

(3) FIG. 2 shows an axial cross-section through the first embodiment;

(4) FIG. 3 shows a radial cross-section through the first embodiment;

(5) FIG. 4 shows a perspective view of the first embodiment,

(6) FIG. 5 shows an axial cross-section through the first embodiment with an insert, weight adjustment body and sealing plug in situ; and

(7) FIG. 6 shows an alternative insert.

DETAILED DESCRIPTION AND FURTHER OPTIONAL FEATURES OF THE INVENTION

(8) FIGS. 1 to 5 show a projectile 1 for use in a simulated fan-blade-off ballistic test. The projectile has an ellipsoid body 2 having a blind axial bore 3 extending from a first axial end 4, the blind axial bore 3 for housing a weight adjustment body 9 (shown in FIGS. 5 and 6).

(9) The first axial end 4 is truncated where the axial bore is formed.

(10) The axial length of the ellipsoid body 2 (i.e. the distance from the first axial end 4 to the second axial end 5) is around 170 mm.

(11) The length of the axial bore 3 (i.e. the distance from the first axial end 4 to the blind end 6 of the bore 3 is around 164 mm.

(12) The diameter of the ellipsoid body 2 is around 90 mm.

(13) The diameter of the axial bore 3 is around 26.6 mm. The axial bore 3 has an enlarged diameter section 7 (e.g. having a diameter around 35 mm) proximal the first axial end 4. An intermediate diameter section 8 is provided between the enlarged diameter section 7 and the main axial bore 3. The intermediate section 8 is threaded for cooperating with a corresponding thread on the sealing plug 10 (shown in FIGS. 5 and 6). The sealing plug 10 is contained within the axial bore although in other embodiments, it could have an external portion which is positioned at the truncated first axial end 4 to form the projectile into a complete ellipsoid shape.

(14) The ellipsoid body 2 is formed of aluminium. The weight adjustment body 9 is formed of tungsten alloy.

(15) The aluminium projectile shown in FIGS. 1 to 4 has a mass of 1.84 kg with the centre of gravity located 81.2 mm from the first axial end 4.

(16) The ellipsoid body 2 has an outer surface provided with a pale-coloured/white, matt paint coating. The coating is provided with a grid of axially-extending and circumferentially-extending lines. The grid comprises four equally-spaced axially-extending lines and three equally spaced circumferentially-extending lines with the central circumferentially extending line extending around the position of the centre of gravity of the projectile (with the other two lines spaced 40 mm either side of the central line). This allows for easy observation of the projectile after release as discussed below.

(17) As shown in FIG. 5, an insert 11 is provided in the axial bore between the weight adjustment body 9 and the blind end 6 of the axial bore 3. The insert 11 initially holds the weight adjustment body in abutment with the sealing plug 10. The insert 11 is formed of a deformable material e.g. a resiliently compressible elastomeric material having a spring constant which can be selected to control the ease of deformation/compression of the insert.

(18) FIG. 6 shows an alternative insert which comprises a spring portion 11a and a damping mechanism 11b.

(19) In use, the projectile 1 is loaded into a gas gun and a sabot is provided around the projectile.

(20) The projectile 1 is fired from the gas gun at a speed up to 250 m/s towards a test item. The speed of projection of the projectile 1 after firing is measured using a light curtain. The projection and impact of the projectile after firing is monitored using a camera. The paint coating and gridded lines on the outer surface of the ellipsoid body 2 facilitates this camera monitoring. The camera is also used to monitor distortion of the test item during impact. A grid and/or speckle paint coating on the test item highlights any distortion during impact.

(21) Before impact, the weight adjustment body 9 is held in abutment with the sealing plug 10 by the insert 11, 11a, 11b. The weight adjustment body will remain in its initial position until impact and will then slide away from the first axial end 4 (towards the second axial end 5) towards the closed end of the blind bore 6. The impact of the weight adjustment body against the blind bore end 6 (via the insert) will simulate the second impact by the blade root portion.

(22) While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the scope of the invention.

(23) All references referred to above are hereby incorporated by reference.