Super Sonic And Hyper Sonic In Sonic 1 Download
Oswald Lemus
The precise Mach number at which a craft can be said to be flying at hypersonic speed varies, since individual physical changes in the airflow (like molecular dissociation and ionization) occur at different speeds; these effects collectively become important around Mach 5-10. The hypersonic regime can also be alternatively defined as speeds where specific heat capacity changes with the temperature of the flow as kinetic energy of the moving object is converted into heat.[2]
While the definition of hypersonic flow can be quite vague and is generally debatable (especially due to the absence of discontinuity between supersonic and hypersonic flows), a hypersonic flow may be characterized by certain physical phenomena that can no longer be analytically discounted as in supersonic flow.[citation needed] The peculiarities in hypersonic flows are as follows:[citation needed]
As a body's Mach number increases, the density behind a bow shock generated by the body also increases, which corresponds to a decrease in volume behind the shock due to conservation of mass. Consequently, the distance between the bow shock and the body decreases at higher Mach numbers.[citation needed]
A portion of the large kinetic energy associated with flow at high Mach numbers transforms into internal energy in the fluid due to viscous effects. The increase in internal energy is realized as an increase in temperature. Since the pressure gradient normal to the flow within a boundary layer is approximately zero for low to moderate hypersonic Mach numbers, the increase of temperature through the boundary layer coincides with a decrease in density. This causes the bottom of the boundary layer to expand, so that the boundary layer over the body grows thicker and can often merge with the shock wave near the body leading edge.[citation needed]
High temperatures due to a manifestation of viscous dissipation cause non-equilibrium chemical flow properties such as vibrational excitation and dissociation and ionization of molecules resulting in convective and radiative heat-flux.[citation needed]
The "supersonic regime" usually refers to the set of Mach numbers for which linearised theory may be used; for example, where the (air) flow is not chemically reacting and where heat transfer between air and vehicle may be reasonably neglected in calculations. Generally, NASA defines "high" hypersonic as any Mach number from 10 to 25, and re-entry speeds as anything greater than Mach 25. Among the spacecraft operating in these regimes are returning Soyuz and Dragon space capsules; the previously-operated Space Shuttle; various reusable spacecraft in development such as SpaceX Starship and Rocket Lab Electron; and (theoretical) spaceplanes.[citation needed]
The categorization of airflow relies on a number of similarity parameters, which allow the simplification of a nearly infinite number of test cases into groups of similarity. For transonic and compressible flow, the Mach and Reynolds numbers alone allow good categorization of many flow cases.[citation needed]
Hypersonic flow can be approximately separated into a number of regimes. The selection of these regimes is rough, due to the blurring of the boundaries where a particular effect can be found.[citation needed]
In this regime, the gas can be regarded as an ideal gas. Flow in this regime is still Mach number dependent. Simulations start to depend on the use of a constant-temperature wall, rather than the adiabatic wall typically used at lower speeds. The lower border of this region is around Mach 5, where ramjets become inefficient, and the upper border around Mach 10-12.[citation needed]
This is a subset of the perfect gas regime, where the gas can be considered chemically perfect, but the rotational and vibrational temperatures of the gas must be considered separately, leading to two temperature models. See particularly the modeling of supersonic nozzles, where vibrational freezing becomes important.[citation needed]
In this regime, diatomic or polyatomic gases (the gases found in most atmospheres) begin to dissociate as they come into contact with the bow shock generated by the body. Surface catalysis plays a role in the calculation of surface heating, meaning that the type of surface material also has an effect on the flow. The lower border of this regime is where any component of a gas mixture first begins to dissociate in the stagnation point of a flow (which for nitrogen is around 2000 K). At the upper border of this regime, the effects of ionization start to have an effect on the flow.[citation needed]
In this regime the ionized electron population of the stagnated flow becomes significant, and the electrons must be modeled separately. Often the electron temperature is handled separately from the temperature of the remaining gas components. This region occurs for freestream flow velocities around 3-4 km/s. Gases in this region are modeled as non-radiating plasmas.[citation needed]
Above around 12 km/s, the heat transfer to a vehicle changes from being conductively dominated to radiatively dominated. The modeling of gases in this regime is split into two classes:[citation needed]
The modeling of optically thick gases is extremely difficult, since, due to the calculation of the radiation at each point, the computation load theoretically expands exponentially as the number of points considered increases.
I have been thinking about realistic sci-fi small arms of future. Usually authors make use of lasers and other vague laser-like rifles. But if you think about it kinetic projectiles have a lot of advantages over lasers. In the future people might have figured out how to store and apply energy efficiently enough to accelerate smaller projectiles at much higher speeds.
Another big advantage with this system is that it allows the user to decide how much energy to apply. If the target is not big or armored, you only apply little energy and accelerate the needle to lower speeds, and vice versa.
For this discussion let us assume that the needles are made of a material that doesn't immediately shatter at such high impact speeds and that the entire construction has no additional issues like energy, heat or recoil management.
My question is regarding impact and effectiveness. Say I fired one of those bullets at a human or a bear. Would they be immediately stopped and neutralized? On one hand I imagine a hypersonic bullet penetrating a biological body at such a high speed would cause shockwaves inside, and turn inner organs into a soup, but it is also possible that it will simply leave a clean tiny hole which might kill the target but not immediately, making this a pretty ineffective weapon.
UPDATE: I also want to add that the exact design of this needle is not set. If you think that it should be made larger or smaller to become effective, please don't hesitate to play around with the parameters. I am just brainstorming.
Disclaimer: This is all speculation. For obvious practical reasons, no one has conducted statistically valid studies on shooting humans or even animals with mach 30 hypersonic needles. (The entire science of wound ballistics has only stumbled gradually to its current level of knowledge on the effects of existing weapons by accumulating case studies.)
Before looking at possible effectiveness it is necessary to look at the problems with such a weapon. The first is that it needs truly extraordinary material science in order to launch the projectile without blowing up the weapon. With a conventional barrel that the needle is launched down, the air in front of the needle simply cannot get out of the way of the needle quickly enough. This means that without extraordinary materials the barrel will explode from the pressure built up in front of the needle, the same way a conventional firearm will blow up from excessive pressure behind the projectile if too much or the wrong type of powder is used.
Assuming that the barrel is made of indestructabilium, the air in front of the projectile being turned into plasma will result in increased energy usage (although the concept seems to rely on effectively unlimited energy anyway), extraordinary heating of the barrel that will necessitate a bulky cooling system, and the expulsion of the resultant plasma ahead of the needle, which will result in a high thermal signature.
Finally, it should be noted that both projectile energy and air resistance scale exponentially with velocity. This is a twofold problem - it means that even more energy is being wasted heating up air on the way to the target and that the actual impact velocity of a projectile will vary enormously with range. Which leads us finally to the downrange effects of the projectiles.
If a needle-like projectile drills a hole only a millimetre or two through a person, the chance of it swiftly incapacitating that person is pretty low. Yet it is quite likely to drill such a neat hole, since a needle which can remain intact while hurtling through the air at mach 30 will necessarily remain intact while pushing through a human body at lower speeds. The weapon somehow requires a projectile that can meet the following contradictory requirements:
Therein lines the problem - a projectile that can survive as required by points 1, 2 and 3 is going to punch a little hole in human flesh and keep going with most of its kinetic energy rather than disintegrating in it and creating wound effects. There are ways around this dilemma for slower, wider projectiles but I do not believe they could be engineered into a needle that can survive the extraordinary requirements of being accelerated to and travelling at hypersonic speeds.
It is worth noting that since switching from 7.62 mm to 5.56 mm projectiles that the US are now planning on switching to a 6.8 mm series of weapons due to insufficient combat effectiveness from 5.56 mm. (They considered a flechette-shooting version of the Steyr assault rifle a few decades ago in the advanced combat rifle trials and decided against it.) If you want your weapon system to be more credible then have your man portable gauss rifles shooting rounds with the same calibre and comparable velocities as those the US forces are looking at. They will have the advantage of being caseless, low signature weapons, meaning that even bullpups can be fired from either side of cover and ammunition capacity could be almost doubled (assuming the fictional power source has negligible weight).
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