Btw
The h&s guys at Tata are not Tata employees.
slowlane:
Don’t really know, Grumpy Dad, I’m FAR too much of a wimp to have ever been in the forces, but whether AP means Armour Piercing or Anti Personnel, the rest of what I wrote should make sense!
AP stands for Armour Piercing e.g. APDS (Armour Piercing Discarding Sabot)
slowlane:
Carryfast:
Franglais:
Carryfast’s shell hitting the tank is a good point. The tank will rock back because of the impact, but it won’t get pushed over by it. It will however get it’s armour melted as he says.
The tank is not rolled over or pushed back by many metres because the Momentum is the product of the weight of the shell times it’s speed. It is going very fast but is quite light compared to the tank.
As he said before the Kinetic Energy is dependent on the square of the speed. Stopping a shell (even without explosives in it) involves dissipating huge amounts of energy. The armour melts because of the energy in the projectile.
High velocity rounds are much more damaging than larger but slower rounds.
Here’s another one. Remember that lump of rock that fell on Russia? It wasn’t more than a couple of tons was it? But because of the sheer speed it hsd massive amounts of energy.
This is why we always have film stars saving the planet fron asteroids. Not because their momentum is so great, but because their speed means that a two ton lump of inert rock travelling at very high speed will have more energy than an A bomb!So on the basis that we’re agreed at the point when an AP shell actually smashes/melts its way through the armour of a tank there is no velocity difference relative to the tank and is at that point just transferring its kinetic energy into the armour ?.
Which therefore leaves the the question of the conundrum should the relevant calculation,for the loads applied to the lashings and anchorages of a steel coil for example,be based on transferring all/most of the kinetic energy contained in it,according to its actual speed,relative to the outside world,to the brakes where its dissipated as heat and/or transferring resulting inertial loads when changing direction ?.
Or is it just a case of cancelling out the potential ( g force ),based on the speed differential between the load and truck,by an equal opposing pull ?.
Bearing in mind the totally different formulas and the resulting final sum figures respectively.
Quite why we’re talking AP shells - an object moving, hitting a stationary object… so completely different to a load on a trailer, I don’t know. Until the shell hits the tank there is no problem, both systems are independent of each other. When the AP shell hits the tank there is a mismatch between the energy stored in each of them, and it will have to equalise. The shell is so light in comparison to the tank that very little energy can be balanced by transferring movement, so the only other way to balance the energy in the (now single) system is through deforming both the shell and the armour, but that will only use up a relatively small amount too, leaving heat as the final method of balancing the energy.
The entire time that an object is secured to the bed of trailer, it behaves as if it is an integral part of the trailer. This is why, so long as the object is secured in such a way that it doesn’t move, the force it experiences under panic braking is the identical to the rest of the truck. 1g, or in VOSA handbook terms 100% of the load’s weight. The object doesn’t have any kinetic energy of it’s own, in this scenario. The brakes will have to generate more heat because the whole think is heavier, but that’s the only change.
As soon as the object moves independently of the trailer bed, that is when you get serious problems. That is when you are trying to dissipate the kinetic energy of the load by itself (which results in things getting smashed up) because, as with the AP shell, the energy in the two systems must balance when they make contact. Unlike the shell, a 10ton top hat weighs more than the headboard and cab of the unit, so could balance the kinetic energy mismatch by moving and by deforming both of them.
At the point when the shell hits the armour of the tank it’s in a similar state as a steel coil is against its lashings during an emergency stop for example.IE there is no speed difference between the tank and the shell.The resulting damage is all caused by the result of the kinetic energy within the shell just like the energy stored in the coil.Which is all based on the energy used to fire it/accelerate it up to its velocity relative to the outside world not relative to the tank.That energy can’t just be magicked away.It either has to be absorbed in the form of capable armour,or in this case transmitted through the load security and vehicle component chain to be dissipated in the form of heat by the brakes. 
Unless I’ve missed something. 
All I know is I’ve been on coils for two months and am treating them with even more respect from those pictures
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Mrs B has a coil fitted.
She tripped over her slippers earlier and it wasn’t restrained correctly
(Fortunately she has beef curtains tougher than leather and was wearing heavy duty Primark knickers with extra arse cheek reinforcement so the coil was recovered and reinserted with a rubber mallet).
eagerbeaver:
Mrs B has a coil fitted.She tripped over her slippers earlier and it wasn’t restrained correctly
(Fortunately she has beef curtains tougher than leather and was wearing heavy duty Primark knickers with extra arse cheek reinforcement so the coil was recovered and reinserted with a rubber mallet).
My Mrs used to use a Dutch Cap, …but she still got pregnant… even though I took my turn wearing it when ‘doing the business’ . 
Then we discovered it was the wrong type. 
My missus went to get a coil fitted, after a quick once over the Doc recommended getting carpets fitted instead.