6,195 ml Capacity 8x68 Taras with LM-102 with 102 mm overall Length and 800 mm Barrel
LM-102, 55 mm long, 16 g heavy, BC1000 1,219, for 170 mm Gain twist barrel
| Powder | Mass [g] | Density [%] |
Pressure [bar] | Burn rate [%] |
V0 [m/s] |
Remark | |
| highest | @ muzzle | ||||||
| Alliant Reloder-22 | 5,16 | 98,5 | 4'500 | 627 | 100,0 | 906 | |
| Alliant Reloder-25 | 5,35 | 103,8 | 4'472 | 607 | 100,0 | 907 | |
| Hogdon H4350 | 4,86 | 94,3 | 4'519 | 590 | 100,0 | 888 | |
| Hogdon H4831 | 5,20 | 103,3 | 4'332 | 619 | 100,0 | 894 | |
| IMR 7828 | 5,17 | 100,9 | 4'508 | 634 | 100,0 | 912 | |
| IMR 7828 SSC | 5,17 | 97,2 | 4'508 | 634 | 100,0 | 912 | |
| Norma MRP | 5,20 | 97,2 | 4'477 | 631 | 100,0 | 910 | |
| Norma MRP 2 | 5,40 | 104,2 | 4'208 | 650 | 100,0 | 902 | |
| PCL 517 | 5,60 | 101,3 | 4'548 | 643 | 100,0 | 919 | |
| Rottweil R905 | 5,14 | 99,2 | 4'509 | 630 | 100,0 | 903 | |
| Path sighted in at 216 m for 265 m ± 5 cm Range | |||||||
| Range [m] | 0 | 50 | 100 | 150 | 200 | 250 | 300 |
| Speed [m/s] | 915 | 902 | 889 | 876 | 864 | 851 | 839 |
| Path [cm] | -5 | +1,3 | +4,6 | +4,7 | +1,7 | -4,7 | -14,5 |
| Wind drift [cm] | 0 | 0,1 | 0,5 | 1,3 | 2,5 | 4,1 | 6,0 |
| to 1200 m | |||||||
| Range[m] | 0 | 200 | 400 | 600 | 800 | 1.000 | 1.200 |
| Speed [m/s] | 915 | 864 | 814 | 761 | 707 | 655 | 605 |
| Path [cm] | -5 | +117 | +186 | +196 | +139 | X | -227 |
| Wind drift [cm] | 0 | 2,5 | 11 | 25 | 46 | 77 | 116 |
Here are the 8x68 Taras Dimensions in a PDF-File. It is a blown out 8x68S with 1° Body taper (full Cone angle) and 2° Throat, tailored for the LM-102. Cases may be neck turned. If so, Dimensions bust be accommodated to keep the 2° Throat at the same location with Respect to the Case, but for the LM-102 this extra Effort is not really necessary. See below, how the first two Drivebands fit in the 2° Throat:
They are dimensioned to fit with +0,01 mm Space Surface-to-Surface or 0,02 mm in Diameter. A Zero Tolerance cannot be designed, as all mechanical Parts are made with Tolerances, the LM-102 not excepted.
One Millimeter moved a 2° Cone changes 0,035 mm Diameter (above is 10(!) mm long). So to adjust for 0,02 mm Diameter either the Throat or the Bullet have to be moved 0,02/0,035 = 0,57 mm or roughly 0,6 mm. That is more than wanted, as the overall Cartridge length is fixed to 84 mm, hence the Name, so some Gap might persist. This Gap will allow to unchamber unfired Rounds, if for some Reason, the intended Shot cannot be fired. So a basic Safety requirement for Shooting ranges is met.
LM-102 950 m/s Pressure, click to enlarge
LM-102 950 m/s Pressure Iso-lines, click to enlarge
LM-102 950 m/s dynamic Pressure contour, click to enlarge
LM-102 950 m/s dynamic Pressure Iso-lines, click to enlarge
LM-102 950 m/s Velocity contour, click to enlarge
LM-102 950 m/s Velocity Iso-lines, click to enlarge
Estimated Drag, BC and Gyroscopic Stability at Standard ICAO Sea Level Conditions
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Möller LM-102 Cal. 8.200 mm, 16.0 g
Ballistic Coefficient Calculated for Drag Function G1
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Velocity Drag Coefficient RPM and Stability maximum Twist-
Factor of Form at a Twistlength lenght
and B.C. of 20,7 Cal. for s = 1.3
Mach m/s fps Cw i B.C. RPM s Cal. in. mm
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0,441 150 492 0,076 0,373 0,907 52941 1,11 19,1 6,2 157
0,514 175 574 0,075 0,373 0,907 61765 1,09 19,0 6,1 156
0,588 200 656 0,074 0,369 0,918 70588 1,07 18,8 6,1 155
0,661 225 738 0,074 0,356 0,951 79412 1,05 18,6 6,0 152
0,735 250 820 0,074 0,329 1,028 88235 1,00 18,2 5,9 149
0,808 275 902 0,074 0,289 1,172 97059 0,93 17,5 5,7 144
0,882 300 984 0,078 0,244 1,385 105882 0,81 16,3 5,3 134
0,955 325 1066 0,104 0,254 1,331 114706 0,56 13,5 4,4 111
1,000 340 1116 0,211 0,446 0,759 120104 0,62 14,3 4,6 117
1,102 375 1230 0,201 0,345 0,980 132353 0,67 14,9 4,8 122
1,175 400 1312 0,238 0,383 0,883 141176 0,76 15,9 5,1 130
1,763 600 1969 0,203 0,329 1,028 211765 1,14 19,4 6,3 159
2,351 800 2625 0,168 0,308 1,101 282353 1,28 20,6 6,6 169
2,939 1000 3281 0,141 0,278 1,219 352941 1,35 21,2 6,8 173
3,526 1200 3937 0,121 0,243 1,390 423529 1,40 21,5 7,0 177
4,114 1400 4593 0,105 0,214 1,584 494118 1,44 21,8 7,0 179
4,702 1600 5249 0,093 0,189 1,788 564706 1,47 22,0 7,1 181
5,290 1800 5906 0,083 0,170 1,996 635294 1,49 22,2 7,2 182
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Achtung! The LM-102 needs at least 900 m/s Muzzle velocity to fly stable from a 170 mm Gain twist barrel. This Note means, it will not fly stable from smaller Cartridges, yielding less Velocity, but from bigger ones. Bigger would not be better, as internal ballistic Efficiency would drop and too long Barrels would be needed.
That drag minimizing Tail introduced Mac. C. Adams in Langley, November 1951. M. A. Ramaswamy and S. Viswanathan optimized it December 1975 in Bangalore.
One may ask, why I design so many different shaped Projectiles. Aren't there optimal Solutions? Yes, there are, but the Conditions determine the Optimum. Different Conditions yield different Optimization shapes. This LM-102 is optimized for to deliver 900 m/s Muzzle velocity from a 8x68 Taras Cartridge out of a 80 cm Barrel. Other Projectiles exit for other Conditions. The Barrel shall have a progressive, or gain Twist with final 170 mm Twist length. This slow Twist start is meant to ease Drive bands requirements to reduce Engraving forces and Friction, but still withstand the Shear forces for such high Spinning. The LM-102 will handle that well.
Lutz Moeller, 6th February 2008
Currently (early 2008) Bisley limits fired kinetic Energy to 4'500 Joule. So watch out for local Range limits an Rules to obey.
See previous LM-101
Gönne Dir Lutz Möller Munition vom Erfinder selbst.
Du wirst keine bessere finden.
