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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Rails for electromagnetic hypervelocity launcher

Patent Number: 7,409,900

AbstractAn electromagnetic launcher is provided for accelerating a projectile from a breech end to a muzzle end. The launcher includes a container, a rail contained therein and a support. The container includes an inner surface along an axial direction. The rail is contained within the inner surface and includes a load surface to support the projectile and an interface surface. The support is disposed between the interface surface and the inner surface. The rail and the support provide a value to an expression for critical velocity V cr = 2 ⁢ EIk ρ ⁢ ⁢ A , where E is Young's modulus for the rail, I is moment of inertia for the rail, k is foundation modulus for the support, ρ is density for the rail and A is the cross-sectional area of the rail. The launcher is configured such that the critical velocity increases along the axial direction towards the muzzle. In particular, a material term √E/ρ of the rail increases along the axial direction, such for the rail being made from a first material being proximate to the breech and a second material being proximate to the muzzle, such that the material term √E/ρ of the second material being greater than that of the first material. Alternatively, the rail is made into a first shape being proximate to the breech and a second shape being proximate to the muzzle, such that a shape term √I/A of the second shape is greater than that of the first shape.
Patent Number7,409,900 Issue Date2008-08-12 Link USPTO website

Primary Category

Biographical Information


  • Nicholas V. Nechitailo,
  • Keith B. Lewis,


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

Executive Summary

This patent was granted in 1 year, 284 days, which is a much faster than average speed.

It has 15 claims, which is far 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, 284 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 far 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.