Aerospace & Defense Technology - October 2024 - 10

Weapons & Armament
order of tenths of microseconds but
affects early pressurization rates.
The goal of the primer is to provide
rapid, smooth and symmetric ignition of
the propellant bed. In some cases, primers
can create pressure spikes that crush
grains and cause unpredictable surface
area and dangerous pressure spikes.
Experiments using thermographic imaging
can identify the causes of these dangerous
events and help scientists design
features to mitigate these risks.
Detailed thermal maps and time histories
of the ignition event will be helpful
for modelers to more accurately and
precisely predict propellant burn start
conditions. The modeling benefits are
likely more significant in large gun
chambers with large propellant grains
because of their more sizable temperature
gradients and longer timescales.
There are already plans to apply this
thermography diagnostic directly to
large-caliber gun chambers.
Once scientists develop a deeper
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understanding of the physics controlling
the ignition event, innovative ideas will
advance the technologies needed to
make ignition more consistent, homogeneous
and predictable. This research will
transform the reliability and safety of
gun systems while simultaneously
improving projectile velocity and range.
It is plausible that the new data will also
inform improved designs for primers or
ignitors. Currently, propellants are manufactured
with varying geometries to tailor
surface area for an ignition response
and burn rate. The thermographic flow
data will provide more insight into an
optimized geometric condition to
improve ignition and provide superior
ballistic performance. Fine-tuning of the
ignition process, in combination with an
evolution in propellant manufacturing
technologies can also extend the weapon
system lifetime by optimizing the temperature
and pressure conditions in the
breech and barrel that contribute to erosion
and deteriorated performance.
Internal ballistics and gun propellant
combustion have been studied for centuries
and modern guns have experienced
great strides in performance. The percussion
primer was a huge technology leap
from flint-lock powder trays or burning
fuses on canons. Observations and data
from this research may lead to great
innovations in propellant ignition and
overall ballistic efficiency, enabling the
next leap in gun system safety and performance
with both extended range and
improved weapon system longevity.
This article was written by John Granier,
Ph.D., Chief Engineer, Munitions & Energetics
at Element U.S. Space & Defense
(Belcamp, MD). For more information,
visit www.elementdefense.com.
10
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Aerospace & Defense Technology, October 2024
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Aerospace & Defense Technology - October 2024

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