SA,
Spinning shaft is defintely not a do-able idea for underwater projectile. The projectile must be in a 100% fully enclosed barrel in order to spin, how are we going to propell the shaft and the shooting line attachment will not work. Also by the 1000s?? times more drag in water than air, introducing other movement to the shaft/projectile aside from going forward will be a waste of energy. The best will be to have fins on the shaft that can be set/designed as such, it has a correction effect of an airplane airleron/flaps ( spelling ??? ). This way we can counter the going-to-low shoots effect by gravity for a specified distance.........say 10 meters effective. So we have a flat shooting gun...in theory.. I wish.
Jay deplete Uranium rod might be a good idea if u want the one of the heaviest metal there is on earth, I think the price and getting it might be a problem. Imagine a 6mm shaft so stiff and so heavy like a 11mm .........must check the DU specific gravity, here is the list. I just surf this especially for you dude .......
SPECIFIC GRAVITY OF METALS :
Aluminum, cast-hammered 2.55 - 2.80
Brass, cast-rolled 8.4 - 8.7
Bronze, aluminum 7.7
Bronze, 7.9 - 14% Sn 7.4 - 8.9
Bronze, phosphor 8.88
Copper, cast-rolled 8.8 - 8.95
Copper ore, pyrites 4.1 - 4.3
German silver 8.58
Gold, cast-hammered 19.25 - 19.35
Gold coin (U.S.) 17.18 - 17.2
Iridium 21.78 - 22.42 ================ 1st
Iron, gray cast 7.03 - 7.13
Iron, cast, pig 7.2
Iron, wrought 7.6 - 7.9
Iron, spiegeleisen 7.5
Iron, ferrosilicon 6.7-7.3
Iron ore, hematite 5.2
Iron, ore, limonite 3.6 - 4.0
Iron ore, magnetite 4.9 - 5.2
Iron slag 2.5 - 3.0
Lead 11.34
Lead ore, galena 7.3 - 7.6
Manganese 7.42
Manganese ore, pyrolusite 3.7 - 4.6
Mercury 13.546
Monel metal, rolled 8.97
Nickel 8.9
Platinum, cast-hammered 21.5 ============= 2nd
Silver, cast-hammered 10.4 - 10.6
Steel, cold-drawn 7.83
Steel, machine 7.80
Steel, tool 7.70 - 7.73
Tin, cast-hammered 7.2 - 7.5
Tin ore, cassiterite 6.4 - 7.0
Tin, 100% Pure 7.29
90 Sn & 10 Pb 7.54
63 Sn & 37 Pb 8.42
60 Sn & 40 Pb 8.52
50 Sn & 50 Pb 8.89
10 Sn & 90 Pb 10.50
5 Sn & 95 Pb 11.00
Tungsten 19.22 ============== 3rd
Uranium 18.7 ================ 4th
Zinc, cast-rolled 6.9 - 7.2
Zinc, ore, blende 3.9-4.2
I THINK TUNGSTEN IS STILL CHEAPEST FOR THE WEIGHT/MASS, PLATINUM & IRIDIUM MUST BE TOO EXPENSIVE.
Try this engineering link :
http://www.resonance-pub.com/mechanic.htm
Here is some idea of the contents :
* I am still trying to find if any info which is good for recoil absorbers, too much too read.*
Structural Damping Techniques
Significant progress is also being made in the development of novel structural damping techniques that could have a significant effect on how helicopter rotor blades and weapons systems are designed. New schemes currently under investigation include magneto-rheological and electro-rheological fluid based damping devices, active constrained layer damping treatments, piezoceramic actuators bonded to a structure and coupled to a shunted electric circuit, and nonlinear controller facilitated energy dissipation through an electronic circuit. Other new approaches, such as distributed control techniques (in contrast to controllers for discrete systems), localization and isolation of modal response, delayed action vibration absorbers, and neuromuscular-like control for absorbing structural vibration energy, may offer opportunities for progress in vibration control in the future.
OK SA, me need to go clubbing now ( 8 PM local here ) . Will continue again soon.
ENJOY
IYA
