Maryland's Defense Patent Database

The defense community in Maryland is an R&D powerhouse. Use this database to see the innovative patents that are poised for commercialization.

Data is provided by DoD Naval labs in Southern Maryland. Database funding supported by the DoD Office of Economic Adjustment through a Defense Industry Adjustment grant program.

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Recoilless and gas-free projectile propulsion

Patent Number: 5,952,601

AbstractA recoilless and gas-free projectile propulsion device is provided. A hol pressure vessel is sealed on a first end to an aft end of a projectile in a launch tube. The pressure vessel is further open on a second end. A propellant charge-filled pressure chamber, defined in a forward portion of the pressure vessel, has holes venting to the pressure vessel aft thereof. A piston, sealed within the pressure vessel for sliding movement therein, is spaced apart from the pressure chamber to define a volume therebetween that receives gases produced during the burning of the propellant charge via the vent holes. A pressure valve divides the volume into a forward section adjacent the pressure chamber and an aft section adjacent the piston. The pressure valve remains closed until a threshold pressure is reached in the forward section at which point the pressure valve opens to join the forward section with the aft section. A countermass is positioned between the piston and the second end of the pressure vessel. When the pressure valve opens, the gases in the volume act on the pressure chamber and the piston. As a result, the projectile with the pressure vessel sealed thereto is propelled forward while the piston moves aft. The piston travels to the second end of the pressure vessel to drive the countermass (e.g., a fluid) out of the pressure vessel at its second end while the gases remain sealed in the pressure vessel which is launched with the projectile.
Patent Number5,952,601 Issue Date1999-09-14 Link USPTO website

Primary Category

Biographical Information


  • Matthew J. Sanford, Bel Alton, MD
  • Larry E. Crabtree, Falmouth, VA
  • Roger L. Ellis, Fredericksburg, VA
  • James F. Cahill, Fredericksburg, VA


  • The United States of America as represented by the Secretary of the Navy

Executive Summary

This patent was granted in 1 year, 144 days, which is a much faster than average speed.

It has 19 claims, which is fewer than average for this category.

Its proximity to basic research is much less than others in this category, and it displays a much slower than average technology cycle time.

This patent received far fewer citations from other patents, and references far fewer other patents, as compared to other patents in this category.

Grant Time

1 year, 144 days



Patent Grant Time

This patent had a much faster than average grant time compared to others in this category.

Patent grant time can be influenced by many factors. Activities within the USPTO that are beyond the control of patent attornies can influence grant time, but short grant times can also indicate well-written patents and dedicated efforts to respond rapidly to USPTO office actions with strong arguments. Shorter grant times are preferable, and the scores for this section are inverse measures — higher scores are better.

Patent Claims

This patent has fewer claims compared to others in this category.

The number of claims in a patent is correlated with its strength. Because greater claim counts increase the cost of a patent, more claims can indicate the importance an applicant assigns to a patent. Importantly, some may elect to file claims across multiple patents. A higher score in this metric indicates more claims, relative to others in this category.

Citations From Other Patents

This patent has received far fewer citations from other patents, than others in this category.

Citations from other patents are an important measure of the significance of a patent. More citations indicate that other technologies build on a patent. Higher scores in this metric are better, and indicate more citations from other patents.

Citations to Other Patents

This patent referenced many more citations to other patents, than others in this category.

A lower number of citations to other patents can be a sign of diminished patent strength. More citations indicate dependence on more other technologies. Higher scores in this category are better, and indicate fewer citations to other patents.

Research and Innovation Indicators
These are percentile ranks — they indicate the percentage of peers with lower scores.

Proximity to Basic Research



This patent has much less proximity to basic research compared to others in this category.

Proximity to basic research is measured by comparing the number of citations to non-patent literature among a cohort of patents. Because most non-patent citations are primary research papers, a higher count indicates greater proximity to basic research.