Loading patent…
AssigneeThe United States of America as represented by the Secretary of the Army
InventorsRobert W. Milton, Lawrence B. Thorn
Estimating the term…
The hot spall tester comprises a tube furnace portion adapted for retaining a magazine portion for containment of a plurality of steel ball bearings which are heated and individually dropped through a feed tube member to a programmed or manually operated carrousel portion having a plurality of sample cups for receiving and containing individual solid propellant samples to be spall tested in accordance with the method. A torque rod is employed to facilitate rotation of the magazine portion and carrousel portion in a vertically aligned relationship with the magazine portion so that the heated steel ball is delivered by gravity through a feed tube to a sample cup of the carrousel portion positioned below the magazine portion. In operation the magazine portion and carrousel portion are aligned and vertically positioned to provide a calculated transit time for the steel ball bearing to drop by gravity to the propellant in the sample cup. Subsequent rotation of the carrousel of about 22.5 degrees positions the cup containing the propellant sample and hot steel ball bearing under a piston having about 0.0001 inch clearance with the carrousel whereby because of its close tolerance, the piston retains the propellant and hot steel ball bearing in a confined pressure relationship during any pressure buildup. For an eight unit capacity of the magazine portion and carrousel portion the sequence can be repeated either manually or automatically eight times to evaluate a solid propellant composition reaction to a hot spall.
A hot spall tester comprising:
A method of hot spall testing a solid propellant sample to determine a specific reaction of said solid propellant sample after being contacted with a heated spall dropped by gravity from a magazine portion aligned and timed with a feed tube member which is also aligned with a receiving cup of a carrousel portion, said specific reaction determined to permit a specific-reaction to be classified as one of three types of reaction including propellant igniting immediately, propellant not igniting, or propellant smoldering, gradually building up pressure, and then igniting, said specific-reaction serving to assess the survivability potential of a propellant to gunfire, shrapnel, or metal fragments thereof, said method comprising:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
No related US applications are recorded in the indexed filing history.
No references of this kind are recorded.
Term end not estimated
USPTO file history isn’t available for this patent, so only indexed dates are shown.
A potential hazard to many field based weapon systems is the threat of gunfire and shrapnel or metal fragments thereof. The safety of the soldiers and the survivability of the system is based on the ability of the weapons of the system to absorb these fragments without deflagrating or detonating of the propellant. In particular, missile systems that are based in hostile territory are prime candidates for targeting of bullets and mortar, and realistically, a certain percentage of any deployed missile system will, at one time or another, be the subject of a hostile attack involving gunfire, or artillery. For this reason, it is extremely important to know what kind and how much metal fragments these missiles can absorb before failure of the propellant system.
A major contributing factor to the deflagration of solid propellant relates to the heat transfer between a hot fragment and the propellant. In other words, the propellant is ignited by the hot fragment.
In a "real world" scenario, the hot fragment is shot and then imbedded into the propellant. As this happens, three things can happen: 1. the propellant does not react to the fragment; 2. the fragment causes the propellant to detonate immediately; or 3. the fragment smolders in the propellant, gives off exhaust gasses, builds up a critical pressure, and finally deflagrates or detonates.
FIG. 1 of the Drawing depicts a prior art hot spall testing device.
FIG. 2 of the Drawing depicts a side view of the programmable hot spall testing device of the invention.
FIG. 3 depicts a sectional view of the top plate with a piston positioned therein.
In reference to FIG. 2 of the Drawing, the hot spall tester 10 comprises a tube furnace portion 20 adapted for retaining a programmable magazine portion 30 supported by programmable magazine support plate 31 within a removable housing member 24. The magazine portion serves to retain a plurality of steel balls, which after being heated, are individually dropped through a feed tube 40 to a programmable carrousel portion which contains a plurality of sample cups 51 for receiving and containing individual propellant samples to be spall tested.
A data acquisition system 60 is employed for acquiring time to ignition, pressure and temperature during burn or other related information for the hot spall tester. Thus, a pressure sensor 61 and a thermocouple 62 indicate what conditions are taking place in the cup below piston 53. A quartz rod 59 described below transmits light from this cup for further output to sensors.
In further reference to FIG. 2 of the Drawing, the hot spall tester 10 structure is provided with a base plate member 11 having side plate members 12 secured thereto in an upright position and secure to a top plate member 13. Intermediate the top plate member and the base plate member is shown a carrousel support plate member 14. Between the carrousel support plate member 14 and the base plate member 11 is shown a support plate 15 for stepping motor 71. Stepping motor 71 is controlled manually or by computer command through collector 70. A support rod 23 is of a variable length to facilitate adjustment of the magazine height prior to connecting to a torque rod for operational rotation. The magazine portion and carrousel portion are connected to the stepping motor 71 by torque rod union 54 which couples torque rod 55 to the designated portions for rotation as described hereinbelow. Thus bearings 56 (Andrew's type) and bearing alignment plate 57 are employed to provide for operational support and to facilitate rotation of carrousel portion while achieving a control of the clearance of only about 0.0001 between an adjustable piston and the rotatable carrousel portion.