4000 degrees and some considerations
Even if the temperature in the Russian Oreshnik missile can reach 4000 degrees Celsius, the total amount of energy would be limited after all. Although the temperature in a commercial
cigarette reaches 400 C during burning and up to 900 during a puff, the extent is local.
Below are a few considerations and calculations that might relate to the fast missiles that struck Dnepropetrovsk last week.
One possibility for materials that can withstand high temperatures are:
Ultra-high temperature ceramic
4000 degrees is one thing, but we don't know much about the
specific heat capacity of the materials used. A high heat capacity would be desirable, because then proportionately more mass of materials with much lower capacity could be heated and in the process damaged.
One
paper states that the specific heat capacity is higher for ceramic materials than for metals. What that means is explained:
Specific Heat Capacity
Heat Capacity is amount of heat required to raise material temperature by one unit.
Specific Heat Capacity is amount of heat required to raise temperature of unit mass of material by one unit:
c= ΔQ/(
mΔT)
Where
c -specific heat capacity;
ΔQ – amount of heat;
m – material mass;
ΔT – temperature rise.
Specific Heat Capacity of ceramic materials is higher, than that of metals.
Compare:
“c” of alumina = 0.203 BTU/(lb*ºF) (850 J/(kg*K)).
“c” of steel = 0.115 BTU/(lb*ºF) (481 J/(kg*K)).
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If there is a high heat capacity, it would help to deliver a high amount of energy in the form of heat upon impact and that appears to be a quality of ceramic materials
Another
paper explains that metallic ceramics have electronically conductive, which I take to mean that they can lead a current, but at the same time they do not conduct heat well, though it may be higher, at very low temperatures, which however isn't important in this context, but still worth mentioning, because it shows that physical properties of materials do not always develop linearly when the temperature changes.
Abstract
Transition metal carbides, nitrides, and borides can be called metallic ceramics because they are electronically conductive and extremely hard. Their various applications include cutting and grinding tools, thermal-barrier coatings, diffusion-resistant thin films, interconnects, and superconductivity devices. In each case, the ability of the material to resist or permit heat flow is important. Because of the high concentration of nonmetal atom vacancies in the carbides and nitrides, the carriers of heat—conduction electrons and phonons (the quanta of lattice waves)—are severely scattered, and the thermal conductivity, K, is strongly affected, although differently in high- and low-temperature regions. Measurements of both the electrical and thermal conductivity of single-crystal metallic ceramics at low temperatures and the application of the Callaway formalism help explain the puzzling temperature dependence of K. The finding of a large peak in K of NbC just below its superconducting transition temperature confirms phonon-electron scattering and could lead to a thermal switch. The single-crystal thermal conductivity behavior of TiC and WC is used to interpret the measured K values for cemented carbides TiC/Ni-Mo and WC/Co through a broad temperature range.
If the missiles had a cover of metallic ceramics it might help to prevent the electronics inside from being overheated, while at the same time making the missile able to withstand high temperatures generated from friction with the atmosphere and the result of the energy transformations needed for propulsion. Moreover if the ceramics are hard and resistant, they would penetrate well into an object upon entry and deliver the accumulated stored heat.
Some consideration of the kinetic energy contained in a fast moving object compared to that of a
TNT equivalent
Ekin= 1/2 * m * v^2
For one kg of mass at the speed of say 2000 m/s that gives
Ekin =1/2 * 1 kg * (2000 m/s)^2= 2,000,000 kg*m^2/s^2 = 2 MJ
1 g of TNT energy of 4185 J or 4.185 kJ This gives for one kg of TNT 4.185 MJ
From this perspective, one kg of material moving at the speed of 2000 m/s has an energy that corresponds to about half a kg of TNT, or if the warhead of the missile has a mass of 100 kg, then it has a kinetic energy of 200 MJ, or the equivalent of about 48 kg of TNT. 100 kg mass may not be much, but on the other hand if the density is even 10 g/cm^3 then 100 kg would not take up more volume than 10 liters.
However the energy consideration is not over, since the we don't now how much energy is stored in the warhead as heat, or for that matter if one day it is loaded with explosives how much energy they would be able to put out from that perspective. Time will show.
If it was easy to make weapons like Oreshnik, more would have done it, which does not mean the subject of kinetic weapons has not been studied. For instance, I found a report from 1996;
Systems Engineering Analysis of Kinetic Energy Weapon Concepts. It turns out that there are other factors when it come to evaluate the destructive capability than a mere consideration of energy, including how materials behave under extreme stress, as when they are impacted by a fast object. Also there may be effects and principles that are outside the traditional principles of kinetic weapons. We know that superconductivity can display amazing properties, so are there physical phenomena that hide behind the wall of high energy events which by nature can be difficult to study and utilize, unless there is a high level of knowledge?
A personal interpretation of the effect, is that just like a laser can create an effect that one would not expect from a simple consideration of how much energy it uses, similarly it may be that a lot of energy transmitted by a well engineered small impactor may have extraordinary properties.
