The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 13, 1998
Filed:
Sep. 28, 1995
Peter L Langsjoen, St. Louis Park, MN (US);
James A Speck, Waterford, MI (US);
Alliant Techsystems Inc., Hopkins, MN (US);
Abstract
A hollow grain propellant for use in a lightweight training round. The hollow grain propellant incorporates multi-perforation propellant grain geometry. The hollow grain propellant is configured as a propellant grain having a center hole surrounded by uniform perforations. The center hole is larger than any one of the uniform perforations. The placement of the uniform perforations forms webs of equal length. The hollow grain propellant may include seven or more perforations. The perforations are arranged in a single ring around the center hole. The size of the center hole may be controlled to produce a wide range of bulk densities. The number of perforations may be dependant on the size of the center hole. The number of perforations may be controlled to vary with the size of the center hole to provide for a desired bulk density. The large center hole improves flame permeability through a propellant bed by increasing the porosity of the propellent bed and increasing grain diameter. The hollow grain geometry maintains good progressive burning characteristics at low bulk densities while retaining low mass fraction at slivering. The hollow grain propellant further eliminates the need to reduce ullage with costly spacers, fillers, or liners.