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Launch Dynamic Characteristic of High Initial Velocity Grenade Launcher with Low Recoil

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In order to reduce the recoil of High Initial Velocity Grenade Launcher (HIVGL) and obtain better firing precision, two reduction recoil structures - short recoil barrel structure and laval nozzle structure were used for HIVGL. Virtual prototype simulation model of HIVGL were established, the dynamics curves of automatic mechanism of HIVGL and human shoulder force curves were obtained when HIVGL was launched by dynamic simulation software - ADAMS. The motion characteristics of automatic mechanism and the variation regulation of the maximum shoulder force were analyzed with different combinations of HIVGL structures and nozzle chamber charge amount. The barrel floating spring stiffness, pre-pressure and the effect of barrel stroke on spring energy storage were also analyzed. As proved by the research results, the maximum recoil of HIVGL can be greatly reduced by introducing short recoil barrel structure and laval nozzle structure. This result provides a beneficial reference for structure design and optimization of HIVGL.
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Launch Dynamic Characteristic of High Initial Velocity Grenade
Launcher with Low Recoil
Jie Song
1,a
, Zhenqiang Liao
1,b
and Ming Qiu
1,c
1
School of Mechanical Engineering, NUST, Nanjing 210094, China
a
songj86@sohu.com,
b
zqliao1013@126.com,
c
njustqm@163.com
Keywords: low recoil, short recoil barrel, laval nozzle, dynamic simulation
Abstract. In order to reduce the recoil of High Initial Velocity Grenade Launcher (HIVGL) and
obtain better firing precision, two reduction recoil structures - short recoil barrel structure and laval
nozzle structure were used for HIVGL. Virtual prototype simulation model of HIVGL were
established, the dynamics curves of automatic mechanism of HIVGL and human shoulder force
curves were obtained when HIVGL was launched by dynamic simulation software - ADAMS. The
motion characteristics of automatic mechanism and the variation regulation of the maximum shoulder
force were analyzed with different combinations of HIVGL structures and nozzle chamber charge
amount. The barrel floating spring stiffness, pre-pressure and the effect of barrel stroke on spring
energy storage were also analyzed. As proved by the research results, the maximum recoil of HIVGL
can be greatly reduced by introducing short recoil barrel structure and laval nozzle structure. This
result provides a beneficial reference for structure design and optimization of HIVGL.
Introduction
Grenade launcher is far more effective in anti-personnel roles than other direct-fire fire support
weapons such as GPMGs and HMGs, while also offering a slightly superior practical engagement
range. However, there are a lot of gaps between QLZ87 Automatic Grenade Launcher(AGL) armed
in China and advanced AGL armed in other countries. For the contradiction between muzzle velocity,
power, emission chamber pressure and the quality of weapons, recoil, two reduction recoil programs
of short recoil barrel automatic mode and recoil structure with postposition laval nozzle[1] which can
greatly reduced recoil were presented in this paper. The virtual prototype model of grenade launcher
system was established by taking using of software ADAMS. The mode was then used to simulate a
firing cycle of mechanism, the curve of kinetic characteristic and shoulder force were acquired. To
study a variety of performance of firearms and master key technologies of reduction recoil programs,
the effects of different quality of the barrel, structural parameters of barrel spring and charge mass on
automatic mechanism motion characteristics and changes in shoulder force characteristics were
analyzed. The maximum shoulder force of grenade launcher can be limited under 2000N, the research
results provide a technological basis for performance prediction and performance optimization of this
grenade launcher.
The Establishment of Model
Fig.1 Model of grenade launcher
Advanced Materials Research Online: 2013-06-27
ISSN: 1662-8985, Vols. 712-715, pp 1455-1459
doi:10.4028/www.scientific.net/AMR.712-715.1455
© 2013 Trans Tech Publications, Switzerland
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Three-dimensional solid model adopting the two reduction recoil programs was imported soft
ADAMS, constrains and working load were added, the curves programming calculated using matlab
of muzzle recoil force and propellant gas thrust reverser were introduced virtual prototype mode of
grenade launcher. The virtual prototype model of grenade launcher was shown in Fig.1.
Assumptions. In order to facilitate the calculation, model of grenade launcher was established as
the following assumptions:
(1)The direction of impact load of grenade launcher on shoulder was main along the direction of
barrel axis, so the direction of movement of receiver was assumed to be along the direction of barrel
axis, the vertical and horizontal directions of receiver were ignored;
(2)Each component in the model was treated as a rigid body[2];
(3)In order to reflect the forces between shoulder support and human body more realistically,
muscle and soft tissue were replace by spring-damper system[3];
(4)Soil resistance replace the forces which was extremely complex between spade and soil, the
calculation model of soil resistance was provide by literature[4];
(5)On the premise that simulation results were reasonable, firearms parts which have no
considerable movement were combined.
The determination of the load. There were three types of force in the model of grenade launcher:
(1)Force of propellant gas[5], there were three types of force of propellant gas, including the
gunpowder gas force in the interior ballistics, trust reverser of airflow and muzzle recoil force. By
means of sensor created in ADAMS, force of propellant gas was loaded when the firing conditions
were satisfied;
(2)Spring force, including barrel return spring, machine frame return spring, recoil buffer spring,
cartridge supporting spring, shoulder force spring;
(3)Extraction resistance[6], it was defined as the resistance between primer case and barrel when
primer case was drawn out by extractor. The shell used in grenade launcher was considered as a
cylindrical shell having the same diameter and thickness, the calculation formula of extraction
resistance was provided in the document[7].
Model Simulation
Fig.2 The motion curves of mechanism Fig.3 The motion curves of mechanism and shoulder
and shoulder force force under different stiffness of barrel spring
a the velocity curves of mechanism
(b) the curves of displacement and shoulder forces
machine frame
barrel
bolt head
frame
barrel
bolt
force
a the velocity curves of mechanism
b the curves of shoulder forces
K
=100N·mm
K
=100N·mm
K
=200N·mm
K
=100N·mm
K
=200N·mm
K
=300N·mm
K
=300N·mm
K
=300N·mm
K
=200N·mm
1456 Advances in Manufacturing Science and Engineering
Combine with Fig.2, machine frame and bolt head began to accelerate with the help of return
spring of bolt carrier. When t = 0.0593smachine frame and bolt head reached maximum forward
speed which was 6.77 m/s, then bolt head began to slow down after pushing cartridge case into gun
chamber and finally finish breech closing action. Machine frame reach maximum forward moving
displacement which was 255.5mm and bolt head reached maximum forward moving displacement
which was 233.5mm after machine frame and bolt head finished free stroke. When t = 0.065s, firing
pin strike primer case so that powder in chamber in the rear was lighted by artillery primer. When
entering chambers of nozzle, the propellant gas was accelerated by laval nozzle. At the same time,
there was an interaction between bullet and shell caused by the propellant gas. Bolt head began to
recoil and pushed machine frame and barrel back together. When t = 0.0659s, the propellant gas
pressure in gas chamber had an interaction between gas chamber piston and machine frame so that
piston pushed machine back to unlocking. When t = 0.0667s, barrel reached maximum recoil speed
which was 9.62m/s and muzzle brake began to work. When t = 0.0687smachine frame reached
maximum recoil speed which was 12.52m/s and barrel reach maximum recoil displacement which
was19.9mm. When t = 0.0729s, barrel reached maximum forward speed which was 4.05m/s and then
barrel stopped moving at the limit stop. When t = 0.0992s, the attenuator began to work. The recoil
velocity of machine frame was reduced to 0 from 5.92m/s under the attenuator action. When t=
0.1072s, machine frame was stopped by hammer catch, mechanism finished a circular motion.
Combine with Fig.2(b), the maximum shoulder force was 1450N. The maximum shoulder force of
grenade launcher in whole launching process was decided by two collisions that one was the collision
between barrel and receiver and the other was the collision between machine frame and shoulder
support.
The effects of firearms structural parameters on shoulder force
The effects of parameters of barrel spring on shoulder force. Combine with Fig.3, in pace of
increasing stiffness of barrel retracting spring, the maximum shoulder force was reduced. The
maximum shoulder force that stiffness of barrel spring was 100N·mm
-1
was caused by the barrel
collision with receiver, while the maximum shoulder force that stiffness of barrel spring was
300N·mm
-1
was caused by the machine frame collision with receiver. It was predicted that the greater
the stiffness of barrel counter-recoil spring the lager the maximum shoulder force. Increasing the
stiffness cause bigger recoil resistance, the maximum velocity of barrel and machine frame get lower,
so it led to reduce firing frequency. The effect of stiffness of the barrel spring on shoulder force was
shown in Table 1. since the maximum recoil distance of barrel was only 20mm, the stiffness of the
barrel spring has little effect on shoulder force.
Table 1 The effects of stiffness of the barrel spring on shoulder force
Stiffness of the barrel spring/N·mm
-1
Maximum shoulder force/N
100 1450
200 1417.3
300 1388.6
The formula of spring energy was show as follows
( ) ( )
2 2
2 1 2 1 2 1 2 1
1 1 1 1
( )
2 2 2 2
U kx kx kx kx x x P P s
= = + = + ⋅
(1)
Where, U is the spring energy, k is the stiffness of spring, x
2
is the compress of maximum working
load, x
1
is the compress of spring preload, P
2
is the maximum working load, P
1
is the spring preload,
s is the maximum recoil distance of barrel. Suppose U
P
is the spring energy of changing spring
preload, U
k
is the spring energy of changing stiffness of spring, U
s
is the spring energy of changing
maximum recoil distance of barrel. The effect of spring parameters on spring energy is shown below.
'
1
10
10
P P
P
P
U n
n
U x
= − ⋅
+
(2)
Advanced Materials Research Vols. 712-715 1457
'
1
1
1 10
10
k k
k
U n
U x
= +
+
(3)
'
1
1
(1 10 )
10
s s
s
s
U n
n
U x
= + ⋅ + (4)
Where, P
1
=n
P
· P
1
, k
=n
k
· k, s
=n
s
· s, P
1
is the changed spring preload, k
is the changed stiffness of
spring, s
is the changed maximum recoil distance. Set n
p
=n
k
=n
s
=2, the ratios of U
/U are 1.375,
1.625, 3.25, it can be seen that it is remarkable effect of changing maximum recoil distance on spring
energy.
The effects of quality of the barrel on shoulder force. Combine with Fig.4, on the condition of
the same recoil impulse, the higher the quality of barrel, the slower the recoil velocity of barrel and
machine frame, the lower the firing frequency. In barrel collision with receiver, momentum was
conserved in the direction of the barrel axis. For the same quality of receiver, the heavier the barrel,
the faster the receiver after the collision. The effect of quality of the barrel on shoulder force was
shown in Table 2. Combine with Fig.4(b), there was only one crest in the curve of the shoulder force
of grenade launcher which the quality of barrel was 3.51Kg. The heavier the barrel, the slower the
machine frame, the smaller the second peak. The maximum shoulder force of grenade launcher which
the quality of barrel was 2.56Kg was appeared in the period of the collision between machine frame
and receiver. From a purely changing barrel mass to reduce recoil, it can be considered to adjust the
collision time of barrel strike receiver and machine frame strike shoulder stock.
Fig.4 The motion curves of mechanism and shoulder Fig.5 The motion curves of mechanism and
force under different mass of barrel shoulder force under different charge mass
Table 2 The effects of quality of the barrel on shoulder force
quality of the barrel/Kg Maximum shoulder force/N
2.56 1457
3.05 1450
3.51 1522
The effects of charge mass on shoulder force. For activities nozzle used in this paper, reaction
force caused by propellant gas, on the one hand, it make the barrel deceleration so that collision
caused by excessive recoil velocity of barrel between receiver and barrel was avoided, on the other
hand, it make receiver deceleration so that the impact load on shoulder coming from moving receiver
was reduced. When increasing more charge mass, propellant gas with high velocity coming from the
a the velocity curves of mechanism
b the curves of shoulder forces
m=2.56Kg
m=3.05Kg
m=2.56Kg
m=3.05Kg
m=3.51Kg
m=3.51Kg
m=3.51Kg
m=2.56Kg
m=3.05Kg
a the velocity curves of mechanism
m=15g
m=20g
m=15g
m=20g
m=25g
m=25g
m=25g
m=20g
m=15g
b the curves of shoulder forces
1458 Advances in Manufacturing Science and Engineering
bottom of nozzle get higher speed and more rate of flow so that greater reaction force to barrel was
obtained. Combine with Fig.5, with increasing charge mass, recoil speed of barrel and machine frame
was lower, pre-impact speed was lower after barrel was successful to recoil to position, which was
good for force status of receiver. The effect of charge mass on shoulder force was shown in Table 3.
The more charge mass, the better. However, as a result of increasing the thickness of barrel for
strength and the length of cartridge case for greater chamber volume, the quality of weapons was
increased. In addition, there were severe erosion and damage of barrel caused by the high temperature
and high velocity flow and the problem of big noise.
Table 3 The effects of charge mass on shoulder force
charge mass/g Recoil impulse/N·s
Maximum shoulder force/N
15 16.2 1607.9
20 21 1343.3
25 26.5 1038.5
Conclusions
Based on dynamic analysis software, the simulation model of grenade launcher using two
reduction recoil structures of short recoil barrel structure and laval nozzle structure was analyzed, the
dynamic characteristic of mechanism and the stress variation of shoulder was studied. The effect of
parameters of barrel spring, quality of the barrel, charge mass on the movement of mechanism and
shoulder force was analyzed. A number of avenues what can reduce shoulder were given. The
research results show that the maximum shoulder force can be limited under 2000N and provide
simulation foundation for the design of grenade launcher.
References
[1] Y. Chen, Z.Q. Liao, G.X. Liu and T. Wang: Journal of Ballistics. Vol. 20(2008), p. 88. (in
Chinese)
[2] J.F. Ni, C. Xu and Y.P. Wang: Journal of System Simulation. Vol. 29(2005), p. 430. (in Chinese)
[3] J.D. Bao, C.M. Wang, D.R. Kong and Y.F. He: Acta Armamentatii. Vol. 27(2006), p. 1095. (in
Chinese)
[4] Y.P. Wang, J. Zhao, H. Nie and Y.J. Wang: Journal of System Simulation. Vol. 20(2008), p.
5722. (in Chinese)
[5] Z.Q. Liao, T. Wang and S.H. Yu: Weapon and gas dynamics numerical method (National
Defense Industry PressBeijing 2005).
[6] C. XuY.P. Wang: Dynamics of artillery and automatic weapon(Beijing Institute of Technology
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[7] S.Y. YiJ. Zhang: Principle and tectonic of automatic weapons(National Defence Industry
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Advanced Materials Research Vols. 712-715 1459
Advances in Manufacturing Science and Engineering
10.4028/www.scientific.net/AMR.712-715
Launch Dynamic Characteristic of High Initial Velocity Grenade Launcher with Low Recoil
10.4028/www.scientific.net/AMR.712-715.1455
ResearchGate has not been able to resolve any citations for this publication.
  • Y Chen
  • Z Q Liao
  • G X Liu
  • T Wang
Y. Chen, Z.Q. Liao, G.X. Liu and T. Wang: Journal of Ballistics. Vol. 20(2008), p. 88. (in Chinese)
  • J F Ni
  • C Xu
  • Y P Wang
J.F. Ni, C. Xu and Y.P. Wang: Journal of System Simulation. Vol. 29(2005), p. 430. (in Chinese)
  • J D Bao
  • C M Wang
  • D R Kong
  • Y F He
J.D. Bao, C.M. Wang, D.R. Kong and Y.F. He: Acta Armamentatii. Vol. 27(2006), p. 1095. (in Chinese)
  • Y P Wang
  • J Zhao
  • H Nie
  • Y J Wang
Y.P. Wang, J. Zhao, H. Nie and Y.J. Wang: Journal of System Simulation. Vol. 20(2008), p. 5722. (in Chinese)
Weapon and gas dynamics numerical method (National Defense Industry Press,Beijing
  • Z Q Liao
  • T Wang
  • S H Yu
Z.Q. Liao, T. Wang and S.H. Yu: Weapon and gas dynamics numerical method (National Defense Industry Press,Beijing 2005).