sharrken

Have you looked at colonic irrigation / bowel management systems? My mother in law uses one, she has a very similar case of paralysis to what you describe. Seems to work very well for her.

For some reason they don't seem to be too widespread, and I suppose not everyone would get on with them anyway, but it does provide an alternative to digital stimulation.

Here is a YouTube video I found that explains the concept. http://m.youtube.com/watch?v=nvLQb2KZuUE

Accidentally broke them then had to dispose of the evidence.

The Rheinmetall L55 vs the L44 is simply a barrel length difference. The earlier L44 is 44 calibers (the width of the barrel bore, 120mm) long - so 5.28 meters long. The L55 is 55 calibers, so 6.6m long. Longer barrels mean higher muzzle velocities, so greater range and penetrating power. The only very minor drawbacks are the slight difference in length possibly impacting manoeuvrability in cramped areas, and the extra weight from the longer barrel.

The bigger difference is between the smoothbore Rheinmetall vs the rifled L30. From the mid 1800s to the 1960s, rifling was relied upon to impart spin into the projectile from a gun - which is necessary to keep it stable in flight and therefore accurate over long distances.

However, anti-tank rounds have moved away from high explosives to kinetic-energy penetrators. These are essentially extremely hard and heavy thin darts (usually depleted uranium or tungsten), fired at very high speeds, to give maximal energy onto the smallest possible point on a target - the more force into a smaller area, the more likely it will be to penetrate through the enemy tanks thick armour. To get the most force behind such a small projectile, a sabot is used - a casing that comes off in flight that fills the extra space in the barrel between the projectile and the bore. This allows you to use a very thin penetrator with a much larger barrel, so you can get more explosive charge behind the projectile while concentrating that force on a very small area of the target.

Now the bit of this that is important to the smoothbore/rifled difference is that once the sabot comes off, the effectiveness of rifling to impart spin on such a long thin projectile is greatly reduced, so the penetrator has fins to keep it spinning and accurate (just like a spin-stabilised rocket does). Now the rifling's spin is essentially redundant, and can actually harm performance due to it working out of sync with the penetrators fins. The Soviets first made this change with the T62 tank having a 115mm smoothbore gun.

Every other modern MBT other than the Challenger II now uses a smoothbore gun because of this. But the British have long used a special type of high explosive anti tank round, called High Explosive Squash Head, or HESH - which requires traditional rifling for stability. Rather than trying to penetrate the enemy tank at all, it simply squashes itself onto the exterior of the tank - like throwing putty at a wall. Only after it is squashed onto the exterior, it explodes - pushing a shockwave through the tank's armour that will cause bits of the inside face to fly off in shards at high speeds, known as spalling - which is generally extremely deadly to crew and equipment inside the tank, without having to actually penetrate it.

However, modern tanks have anti-spalling liners, which essentially catch the fragments when they come off, stopping them from flying around the inside of the tank. Also, modern tank armour uses multiple layers, often including ceramics, which will absorb or disrupt the shockwave as it passes through. Explosive or reactive armour is even more effective against HESH, as it pushes the explosive away before it detonates.

But although it is no longer very effective against modern tanks, HESH is still very effective against structures - if you fire one at a bunker (or house, or truck, or anything else for that matter), it is essentially like strapping a large lump of C4 to the outside and detonating, except you can do it from a mile or two away inside a nice safe metal box. This is a pretty desirable capability for infantry support, to the extent that the British army valued it higher than the slight anti-tank improvements that a smoothbore kinetic-energy penetrator would provide over their rifled ones (the sabot will still work, just not quite as well). They've since thought about switching to the smoothbore 120mm more just to standardise with the rest of NATO, but the cost/benefit was seen as unsuitable at the time.

TL;DR: Smoothbore is better because you can fire anti-tank kinetic penetrators a bit further, rifled is better because you can still fire squishy high explosives that are good for demolishing things, but overall it's not a massive difference, mostly just different priorities/traditions in the design phase.

Earlier Leopard 2's and the later Abrams (M1A1 and later) use the same 120mm/L44 Rheinmetall smoothbore gun. That got upgraded to a higher performing longer barrelled version on later Leopard 2's. This version (the longer smoothbore 120mm/L55) did get tested on the Challenger 2, but the British army chose to keep their own 120mm/L55 rifled gun, the Royal Ordnance L30.

The Chieftain, Leopard I and early Abrams (as well as a lot of other AFV's) did all share the same gun though, the 105mm Royal Ordnance L7.

Well as an interceptor, high speed with good loiter time are the important characteristics (along with suitable weapons obviously). The F3's radar was advanced for its time as well. Russian Bombers aren't exactly cut out for a dogfight, so it's not like manoeuvrability is all that important for an interceptor.