MINIMUM IMPACT ENERGY FOR KE-PENETRATORS IN RHA-TARGETS
LANZ W. (1), ODERMATT W. (2)
(1) Swiss Ordnance Enterprise Corporation, Allmendstrasse 86, CH-3602 Thun, Switzerland (2) Defence Procurement Agency, Feuerwerkerstrasse 39, CH-3602 Thun, Switzerland
Abstract : The Odermatt formula presented originally in 1992 [3] also allows to determine minimum energy impact velocities for penetrating inclined RHA plates. For plates of 800 MPa ultimate tensile strength (UTS) this velocity is around 1900 m/s. However this velocity may considerably be reduced by tailoring the sabots for specific rods, taking into account rod length, barrel caliber and maximum acceleration. Then the optimum velocity value drops to about 1700 m/s. To compensate the velocity drop at tactical range (typically 2000 m) about 80 m/s increase has to be considered. On the other hand the influence of the muzzle velocity dependent efficiency of solid propellant gun systems downshifts the optimum velocity to about 1540 m/s for 2000 m range. Jacketed penetrators and sabots using new high strength light materials (e.g. FRP), allow to reach the required penetration at even lower energy levels.
1. PENETRATION LIMIT FORMULA
1.1 Penetration limit definition
In a finite target penetration limit means that the projectile reaches the rear face of the target and spalling opens the penetration channel. The penetrator residue will have a length of one to one and a half diameters. In a few of our experiments the residue stuck in the exit crater or dropped to the floor in the immediate vicinity of the target. This result is observable at the target site, whereas a semi-infinite target first has to be cut up laboriously. The formula described below allows a quick estimation of the target inclination necessary for a penetration limit. This is then easily established with few projectiles, especially when using witness plates.
1.2 Governing parameters
D penetrator diameter [mm] λ,λW aspect ratio L/D, LW/D L overall tungsten penetrator length [mm] vT impact velocity [km/s] LW working length of penetrator [m] v0 muzzle velocity [m/s] 3 ρP penetrator density [kg/m ] θ angle of obliquity 3 ρT target density [kg/m ] mP penetrator mass [kg] d target plate thickness [mm] mG mass of penetr. and sabot [kg] UTS target material ultimate tensile strength [MPa] mL propellant charge mass [kg] P penetration channel length [mm] EP impact energy [MJ]
European Forum on Ballistics and Projectiles, St. Louis (F), April 2000 - 2 -
d
90° D ρ P v T θ
L w L P = d/cos θ
ρΤ UTS
Figure 1: Definition illustration
1.3 Penetration limit formula
The formula has been published in [3] and [4]. Here it is presented with a slight variation, ie. P/L as the independent variable instead of d/D. ⋅− UTSc 2 P m ρP ⋅ρ vTP w cos)f( ⋅θ⋅λ= ⋅e (1) Lw ρT A B C D A aspect ratio influence, a good approximation is obtained with the following equation 1 ⎛ w −λ 10 ⎞ w a1)f( 1⋅+=λ ⎜ −⋅ tanh1 ⎟ mit a1=3.94 a2=11.2 (2) λw ⎝ a2 ⎠
B target inclination influence, the best fit for the exponent is m = -.225
C penetrator/target density influence, this is the wellknown root ρ-law
D the dimensionless exponent is derived in [1] by applying the π-theorem, the coefficient c depends on target material strength
c = 22.1 + 1.274⋅10-2⋅UTS - 9.47⋅10-6⋅(UTS)2 (3)
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 3 - 1.4 Range of validity of the formula/results
The range of validity is defined by the bandwidth of 74 experiments with 19 different penetrators and calibers of 25 to 140 mm. penetrators: targets: L 90 - 950 mm d 40 - 500 mm D 8 - 32 mm UTS 800 - 1’600 MPa 3 λ 11 - 37.5 ρT 7’850 kg/m mP 0.1 - 9 kg θ 0 - 74 ° 3 ρP 17’000 - 17’750 kg/m vT 1’100 - 2’000 m/s
Since the formula is also based on theoretical analyses extrapolations are permissible, yielding results with only slightly reduced accuracy. This was confirmed by several experiments.
2. APPLICATIONS
2.1 Scope
The above formula allows the comparison of results from firing tests with different target inclinations/thicknesses/material properties, penetrator geometries and impact velocities. It also allows the evaluation of influences of penetrator aspect ratio, obliquity and other parameters. Penetrator performance is predictable. Reliable extrapolations from a single test result are possible.
2.2 Optimisations
The analytical solution permits optimisations. E.g. the optimum impact velocity (maximum penetration limit for a given energy) exclusively depends on target strength and penetrator density: ⋅⋅ UTSc3 vopt = (4) ρP
800
700
600 ]
500
400 Tensile Strength V optimum 800 MPa 1.897 km/s 300 900 1.999
Penetration [mm 1000 2.085 200 1100 2.156 1200 2.210 100
0 0123456 Impact Velocity [km/s]
Figure 2: Optimum velocity for 10 MJ constant impact energy
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 4 -
For a given penetration the optimum penetrator length is 1 3 P opt eL ⋅= (5) ρ ()cosf m ⋅θ⋅λ P ρT
It is independent of target UTS. High penetrator aspect ratios require notably less energy. For a penetration limit of 1000 mm an aspect ratio of 30 only needs 27 % of the energy an aspect ratio of 10 requires. 100
90 λ = 10 80
70
60 15 50
40 Energy [MJ] 20 30 25 20 30 10 40 0 500 600 700 800 900 1000 Penetrator Length L [mm]
Figure 3: Optimum penetrator length vs. aspect ratio for P = 1000 mm obliquity 60° / UTS 800 MPa / penetrator density 17500 kg/m3
It has to be noted that this optimum is purely theoretic, because neither the influence of the sabot nor the influence of the interior ballistics are considered.
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 5 - 2.3 Penetrator layouts
The graph below shows the projectile parameters for a future caliber > 120 mm with penetrator lengths between 750 and 2000 mm and diameters of 22 to 30 mm. This is a specific evaluation referring to a penetration limit of 1000 mm, 60° obliquity, 800 MPa UTS and penetrator density of 17500 kg/m3.
28
26 D = 30 mm
24
22 Minimum 1
20 m ]
18 m 30 m L = 1000 m 1000 = L 16 L = 1200 m 1200 = L
14 m L = 2000 m = L Impact Energy [MJ Energy Impact 12 40 L = 750 m 750 = L 50 m 10 60
8 D = 22 mm 800 m = L 6 Minimum 2 4 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 Impact Velocity [km/s]
Figure 4: Penetrator parameters for 1000 mm penetration limit
This graph confirms again the fact established by eq. 4 that for a given aspect ratio there exists an optimum velocity, in this case 1897 m/s. This optimum value is often cited by the experts. However this value is not necessarily an optimum. As shown an increased aspect ratio requires less energy, eq. 4 transforms to ⋅ UTSc v = (6) opt2 ρP For the above evaluation eq. 6 yields 1095 m/s. This value is not realistic, since a rod of 24 diameter would need a length of 1600 mm. The corresponding aspect ratio of 67 is far from practicable. Fig. 4 graphically shows that for an optimisation velocity is not the only governing parameter.
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 6 - 3. APPLICATION OF THE ODERMATT FORMULA IN A SYSTEM LAYOUT
3.1 Length and aspect ratio (L, λ) of minimum energy KE rods for a required penetration
This is a graphic optimisation as described in item 2.3. The Odermatt formula yields the penetration limits P for different projectile lengths L vs. projectile impact velocity vT. These curves are plotted in fig. 5. An infinite number of L/vT combinations may be found which attain a required penetration, e.g. P = 1000 mm in 800 MPa UTS RHA at 60° obliquity. The aspect ratio (λ) influence practically disappears at values above 30. However for an assumed λ (say 36) the projectile mass mP, the impact velocity vT and the impact energy ET are determined. According to the data given in fig. 7 these values are
Figure 7: Proportions of tungsten penetrators with titanium fins
L (mm) 1127 1042 977 926 885 852 825 802 783 vT (m/s) 1400 1500 1600 1700 1800 1900 2000 2100 2200 mP (kg) 15.24 12.06 9,95 8.48 7.42 6.63 6.02 5.53 5.15 EP (MJ) 14.94 13.56 12.74 12.26 12.02 11.96 12.03 12.20 12.46
These results are plotted in fig. 6. The analytically calculated minimum energy is confirmed at vT = 1900 with EP = 12 MJ. It has to be noted that this minimum is not very pronounced: in the region of 1700 to 2100 m/s the energy variation is not more than 2.5 % or below 150 kJ respectively.
3.2 Sabot design influence
The 140 mm caliber with a peak pressure of 750 MPa (7.5 kbar) is taken as a reference for investigating sabot design influence. The maximum acceleration determines sabot dimensions. Fig. 8 shows a conventional aluminium sabot design.
Figure 8: Sabot proportions
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 7 -
1600 L=1200mm 1500 L=1100mm 1400 L=1000mm 1300
1200
1100
1000
Penetration [mm] 900
800 L=900mm 700 L=800mm 600 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 Impact Velocity [m/s]
Figure 5 : Penetration limit P vs impact velocity in RHA (800 N/mm2 UTS / 60° obliquity) in function of length L
15 1150
1100 ] 14 1050
1000 Penetrator Length
13 950
900
2.5% Impact Energie [MJ] Energie Impact 12 850 Penetrator Length [mm Length Penetrator Velocity for 800 Minimum Energy
11 750 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 Impact Velocity [m/s]
Figure 6 : Penetrators with L/D = 36 with penetration limit of 1000 RHA (800 N/mm2 UTS / 60° obliquity)
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 8 -
For the penetrators mentioned above sabots were individually tailored, their energies ES are shown in fig. 9.
26 1200
24 1150
Optimal Velocity = 1700 m/s
22 1100
Energy of Projectile EG
20 1050
18 1000
16 950 Energy [MJ] Energy Length L of Penetrator 14 900 Penetrator Length [mm] Length Penetrator
12 850 Energy of Penetrator EP (L/D=36)
10 800
Energy of Alu-Sabots ES 8 750
6 700 1400 1500 1600 1700 1800 1900 2000 2100 2200
Velocity [m/s]
Figure 9 : Penetrators with 1000 mm RHA (800 N/mm2 UTS / 60° obliquity) penetration limit energy of projectile EG = energy of penetrator EP plus energy of sabot ES aspect ratio L/D = 36
The sum of penetrator EP and sabot energies ES is the total energy of the projectile EG. Taking sabot mass into account obviously leads to a minimum energy shift to lower velocities, not depending on λ. The new optimum velocity is at vT = 1700 m/s and again there is no distinct minimum. The total projectile energy variation is less than 2.5 % between 1580 and 1830 m/s.
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 9 - 3.3 External ballistics influence
The results presented so far refer to zero range, ie. at the muzzle. For a tactical range, typically 2000 m, the projectile velocity drop has to be considered. As shown in fig. 10 substantially more energy is required to keep a penetration limit of 1000 mm RHA.
27
26
25 Range 2000 m
Optimal Muzzle Velocity at 1780 m/s 24
23 Energy [MJ]
22 Range 0 m Muzzle Velocity = Impact Velocity 21
DE ca. 2 MJ 20
19 1400 1500 1600 1700 1800 1900 2000 2100 2200
Velocity [m/s]
Figure 10 : Muzzle energy for projectiles with 1000 mm RHA (800 N/mm2 UTS / 60° obliquity) penetration limit range 0 and 2000 m
Even though light and fast projectiles loose more velocity than slower but heavier ones the terminal ballistics are still better than expected. This is due to the Odermatt curves (fig. 5) becoming flatter at the upper end and due to sabot mass influence. In fact the energy loss is nearly constant over the entire scope apart from penetrator lengths extremes below 800 and above 1050 mm. The external ballistics influence reshifts the energy minimum to higher velocitites. In RHA plates of 800 MPa UTS this shift amounts to roughly 80 m/s, the optimum velocity then being 1780 m/s for 2000 m range.
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 10 - 3.4 Integration into a 140 mm high pressure gun
Tailoring the sabots as described is one important action, however to define the entire system the energy delivered by the gun has to match the minimum energy for obtaining the required penetration. Fig. 11 shows the internal ballistics functions for a big caliber high pressure solid propellant gun (ca. 50 cal barrel length).
2200 30
2100
2000 25
1900 V0 = 2802×tanh(0.3171×k + 0.3275)
1800 20
1700 =17 kg [kg]
1600 15 L [m/s] G 0 m V
1500 m for
1400 mG (for mL = 17 kg) 10
m : Mass of Projectile 1300 G mL: Mass of Charge
1200 5
1100
1000 0 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0
k=mL/mG
Figure 11
Depending on the propellant charge mass mL to projectile mass mG ratio the graph shows muzzle velocities and projectile mass for 17 kg charge mass corresponding to 85 MJ charge energy (combustible cartridge case included). Transferring these curves to fig. 12 allows the selection of projectile layouts which reach 1000 mm penetration with 85 MJ energy input of a 140 mm / L50 gun at 7.5 kbar peak pressure. Thus a rod of 1000 mm length and 36 aspect ratio penetrates 1000 mm RHA in front of the muzzle. The same penetration at 2000 m range will just be obtained by rod parameters lying on the intersection between the 85 MJ energy curve and the λ = 40/2000 m curve. This intersection point represents a rod length of 900 mm and a muzzle velocity of 1830 m/s (lengths > 900 mm permit penetration > 1000 mm RHA).
Conclusions: Conventional projectile technology requires very high aspect ratio rods to reach 1000 mm penetration in RHA targets even propelling them by a 140 mm gun with 85 MJ energy input. Some margin for performance increase is at hand using • jacketed penetrators as presented in [5] and • new sabot design technologies both of which lead to a considerable weight reduction.
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 11 -
28 1250
1 26 1200 Range 2000 m 1 24 1150
2 22 Range 0 m Range 2000 m 1100
2 20 Range 0 m 1050 Projectile
18 1000 System Limit 1 16 950
Energy [MJ] Energy 1 2 14 900 Penetrator Length [mm] [mm] Length Penetrator
12 2 850 Penetrator
10 800
1 8 750 2 Sabot
6 700 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400
Velocity [m/s] Figure 12 : Penetrators with 1000 mm RHA (800 N/mm2 UTS / 60° obliquity) penetration limit aspect ratio = 36 [1] and 40 [2]
The terminal ballistics characteristics presented in [3] of solid propellant guns covering all conceivable projectile designs show a further typical optimum or maximum (see fig. 13).
Optimum Velocity / Maximum Penetration
1050
1100 1000
L = 1200 mm 900 1000
800
950 D = 24 mm
28 Penetration [mm]
L/D = 40 32 900 L/D = 36 36
L/D = 32
850 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 Muzzle Velocity [m/s]
Figure 13 : Terminal ballistics characteristics for a 140 mm tank gun RHA (800 N/mm2 UTS / 60° obliquity) / range 2000 m
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 12 - For all penetrator aspect ratios there exists an impact velocity yielding maximum penetration. For 2000 m range this inherent velocity is around 1540 m/s, which can be confirmed analytically. Referring to fig. 12 the same fact can be extracted from the common tangent of the gun energy curve and the appropriate λ-curve.
4. JACKETED PROJECTILES
Conventional high aspect ratio penetrators (λ > 30) have drawbacks such as pronounced elastic bending vibrations when leaving the muzzle and multiple ruptures in skirted targets leading to massive performance drops. These drawbacks can be circumvented by jacketing a very slender heavy metal core with lighter material (preferably steel or titanium), see [ ].
Table 1 : comparison example Densities : tungsten 17.5 [g/cm3] steel jacket 7.85 [g/cm3] penetrator full core jacketed Length L 960 960 D 30 30 λ = L/D 32 32 core dia dW - 23.4 λW = L/dW - 41 core mass mW (kg) 11.9 7.5 (inkl. Fins) jacket mass mH (kg) - 1.9 mP (kg) 11.9 9.4 mP (%) 100 79
For determining the masses of jacketed penetrators see fig. 14.
Figure 14: Proportions of steel/tungsten jacketed penetrators
Note that in the comparison both penetrator types are identical in length and outer diameter. Therefore the jacketed one is considerably lighter and contains correspondingly less kinetic energy for equal impact velocity. Despite of this fact a jacketed projectile attains practically the same penetration in thick RHA as its full core counterpart, as shown in [5]. This is due to the more favourable hydrodynamic behaviour of the tungsten/steel composite which yields a definitely smaller crater diameter, thus compensating the energy reduction, as shown in fig. 20 and [5].
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 13 - Fig. 15 shows that a jacketed projectile with an overall aspect ratio of 36 reaches the 1000 mm penetration limit in RHA of 800 MPa UTS at 2000 m range. The projectile length is (at least) 928 mm with a corresponding core aspect ratio of 46.
30 1250
3 Muzzle Energy for Range 2000 m 28 1200
3
26 2 1150
24 1100 2
Muzzle Energy 22 1050 1 for Range 0 m
20 1 1000 Penetrator Length
18 950
Energy [MJ] Energy 3 16 System Limit 900
2 [mm] Length Penetrator 14 850
12 1 800
3 1 2 3 10 750 2 Penetrator Energy 8 700 1 at Target Energy of Sabots 6 650 1300 1500 1700 1900 2100 2300 2500 2700 Velocity [m/s]
Figure 15 : Energies for 1000 mm penetration limit in RHA , 60° obliquity [1] UTS of RHA 800 N/mm2 [2] UTS of RHA 1000 N/mm2 [3] UTS of RHA 1200 N/mm2 System limit : muzzle energy of 140 mm gun, 85 MJ propellant energy
Obviously RHA targets with 1000 MPa UTS cannot be penetrated with λ = 36 jacketed penetrators, driven by conventional alu-sabots.
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 14 - 5. NEW SABOT TECHNOLOGIES
For more than 20 years now the same sabot material has been applied. It's time for a change. Various R+D departments work on this problem, but so far no new application has materialised in the big bore business. Obviously the sabots designed according to fig. 8 are not optimised. For a rough estimate of the influence of fiber reinforced plastic (FRP) sabot on system performance we assume a possible weight reduction of 25 - 30 %. In the calculation this is simply accounted for by taking a density of 2.0 instead of 2.7 g/cm3. To evaluate the ultimate (theoretical) performance increase we set the density at zero. These results are presented in fig. 16 .
1400
1300 Sabot Mass 0 kg
1200
1100 Penetration [mm] Penetration 1000 ΔP = 195 mm
900
800 1200 1400 1600 1800 2000 2200 2400 2600 2800 Muzzle Velocity [km/s]
Figure 16 : Terminal ballistic characteristics for penetrators with aluminium sabots and "zero mass" sabots
The graph shows in one example an increase of 195 mm penetration for a rod (L = 1000, λ = 36) with "zero mass" sabot. In reality only about 30 % of that can be exploited, i.e. ∼ 60 mm, corresponding ∼ 6 %, referring to 1000 mm RHA.
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 15 - 6. ARMOR PLATE STRENGTH INFLUENCE ON OPTIMUM VELOCITY
In item 2.2 the influence of target plate strength has been derived analytically. The higher the target UTS the higher the optimum velocity will be. For 800 MPa UTS the optimum velocity is 1900 m/s, rising to 2200 m/s for 1200 MPa UTS. The overall system investigation yields very similar results as shown clearly in the terminal ballistic characteristics for 2000 m range (see figs. 17 to 19). However it has to be noted that all these system optima are situated distinctly below the generally cited level of far above 2000 m/s. As also shown in fig. 15, the UTS influence nevertheless is quite significant (fig. 17 to 19). • Whereas a target UTS of 800 MPa allows 1000 mm perforation at 2000 m range with L/D = 33.3 jacketed penetrators of 950 mm length and 1750 m/s muzzle velocity, • a target UTS of 1000 MPa requires L/D = 38.5, 950 mm length and 1900 m/s muzzle velocity; • a target UTS of 1200 MPa even requires L/D = 41.8, 1000 mm length and 1900 m/s muzzle velocity; this extreme layout is by far out of reach for todays technologies even for a 140 mm high pressure solid propellant gun system.
7. REFERENCES
[1] K. Hoog, ISL, "Ableitung einer Panzerformel aus dem analytischen Modell", CCG-Lehrgang : Panzerdurchschlag und Panzerschutz, 23.-27.10.1984, Weil am Rhein
[2] K. Frank, J.A. Zook, "Energy-Efficient Penetration of Targets", Memorandum Report BRL-MR-3885 February 1991, ARL Aberdeen Prooving Ground, Maryland US
[3] W. Lanz, W. Odermatt Penetration Limits of Conventional Large Caliber Anti Tank Guns / Kinetic Energy Projectiles 13th International Symposium on Ballistics, Stockholm 1992
[4] R. Jeanquartier, W. Odermatt Post-Perforation Length and Velocity of KE Projectiles with Single Oblique Targets 15th International Symposium on Ballistics, Jerusalem 1995
[5] W. Lanz, H.F. Lehr Craters Caused by Jacketed Heavy Metal Projectiles of very high Aspect Ratio impacting Steel Targets 16th International Symposium on Ballistics, San Francisco 1996
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 16 -
140 mm Gun , 85 MJ Propellant Energy : Terminal Ballistic Characteristics for Jacketed Penetrators and FRP Sabots RHA Plates , 60° Obliquity , Range 2000 m
12 0 0 12 0 0 12 0 0
115 0 12 0 0 1150 115 0 10 0 0
110 0 110 0 110 0
40 10 5 0 10 50 1000 10 5 0 1200 800 36 10 0 0 10 0 0 10 0 0 40 40 32 800 950 950 950 36 12 0 0 800 Optimal Velocity 1590 m/s 900 900 900 Penetration [mm Penetration [mm Penetration [mm 32 36
850 850 850
Opt imal Velocit y 1775 m/ s 32 800 800 800
Optimal Velocity 1875 m/s 750 750 750
70 0 70 0 70 0 1200 1400 1600 1800 2000 2200 2400 1200 1400 1600 1800 2000 2200 2400 1200 1400 1600 1800 2000 2200 2400 Muzzle Velocity [m/s] Muzzle Velocity [m/s] Muzzle Velocity [m/s] UTS Target 800 N/mm 2 UTS Target 1000 N/mm 2 UTS Target 1200 N/mm 2
Figure 17 : 1000 mm penetration: L=950 mm, Figure 18 : 1000 mm penetration: L=950 mm, Figure 19 : 1000 mm penetration: L=1000 mm, L/D=33.3 L/D=38.5 L/D=41.8
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets - 17 - Comparison of impact craters: Full core tungsten penetrators and steel/tungsten jacketed penetrators with the same impact velocity in the same RHA plate (800 MPa UTS)
Tungsten penetrator Steel/tungsten jacketed penetrator ∅ 22 x 680 ∅ 22/17 x 680 mean crater dia = 46.1 mm mean crater dia = 40.75 mm
impact velocity 1850 m/s impact velocity 1850 m/s
Figure 20 : Impact craters in RHA (800 MPa UTS)
European Forum on Ballistics and Projectiles, St. Louis (F), 2000 Minimum Impact Energy for KE-Penetratots in RHA-Targets