Bow shock as a weapon

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>>32967504
SLAM could do it in theory, but the capability was never tested.

>>32967504
Case of using it as a tactic when they had nothing else is all I can think of.

https://youtu.be/DXbp2OyNYQ4

>>32967504

It's kind of an absolute last resort but yeah it can be done.

>>32967504
http://www.secretprojects.co.uk/forum/index.php?topic=2853.10

I can give a huge rundown of the science behind it and explain why it's theoretically possible, but not practical if people are interested.

>t. aerospace engineer

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>>32968462

>>32968462
well get to it

>>32968462
Would it be feasible if youre in...say...the Danger Zone?

>>32968814
What is this Zone of Danger you speak of?

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Aight here we go.

So sonic booms are measured in terms of two things:
>rise time - the time it takes for the wave to reach the peak intensity
>loudness - the peak intensity of the wave in decibels

To get the loudest - and thus most powerful - sonic boom, you want the shortest rise time and highest intensity. Because intensity's measured in terms of overpressure (see the pic), you need the shocks that coalesce in the front to produce the highest pressure differential. Same goes for the low pressure wave at the end - you need large expansion waves to produce large pressure changes at the end of the sonic boom.

Now there marks our first problem. Producing a large pressure differential like that means that the aircraft itself is going to be experiencing similarly large forces. And for those of you not getting it fully - you end up with high pressure in front of the aircraft and low pressure behind it. Gases want to go from high pressure to low pressure, meaning that the aircraft's effectively being "pulled" back by the pressure zones it's creating as it flies supersonically. Of course, there's a hell of a lot more to supersonic drag than that, but in terms of sonic booms those are the most important parts.

>cont

Israel used to use the sonic booms of jets over Cairo to knock the insulation off of the power-lines.

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>>32970128
>cont

Now, we'll look at the real math behind it. When an object flies through air at supersonic speeds, you end up with a series of shocks. Supersonic flight is effectively pushing something through a fluid faster than it can normally react - thus, instead of the flow being disturbed upstream in smooth streamlines, it reacts almost instantaneously in the form of shocks and waves. Shocks compress the flow, while waves expand it. However, compression shocks aren't isentropic, meaning you get some fucky behaviors.

For sonic booms, the important values are the pressure ratios. You have two types of pressure - stagnation and dynamic. Stagnation pressure is the ambient pressure, while the dynamic pressure is what the aircraft "feels" as it flies. Generally, the trend is
>stagnation pressure drops over shocks and stays constant across expansion waves
>dynamic pressure rises over shocks and drops over expansion waves

This right here is a good tool for looking at how things work.
http://www.dept.aoe.vt.edu/~devenpor/aoe3114/calc.html

Now, if we look the simplest shocks - normal, or detached shocks, which form ahead of the body in certain conditions - we see the greatest potential in terms of sonic boom strength. Say we have Mach 3 flow forming a normal shock. That produces a stagnation pressure ratio of 0.32834388 - a ~78% drop - and a dynamic pressure ratio of 10.3 - a 1000% increase.

So in theory, this seems like a good idea - that kind of pressure change at sea level would cause a change from ~15psi to 150 psi.

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>>32970252
>cont
There's tons of problems with that, though.

First of all, there's drag. That same huge pressure difference across the shock is going to be exerted along the entire forward surface of the aircraft. Thus, massive pressure changes are going to cause a huge amount of drag that the aircraft likely won't be able to overcome. Though drag is a function of density and thus drops off with altitude, so does pressure - so flying higher doesn't really solve that issue.

And then there's lift. Supersonic lift is produced by shocks staying attached to the wing. A normal shock not only produces a good amount of drag, but it also prevents the wings from producing lift. And without lift, you're not flying.

To actually get supersonic lift, you need your shocks to stay attached. This is done by using sharp, highly sloped surfaces. Angled surfaces allow the flow to stay "attached" to the surface by forming oblique shocks. Again, using the compressible aero calculator from that last post, you can look at the behavior there. Oblique shocks are just normal shocks happening at an angle. There's some weirdly simple trig involved that allows the flow to stay supersonic across the shock in the direction of the flow, albeit slowed down. But, because the slowing isn't as fast, you end up with lower pressure changes across the shock. This is almost always preferred - because you lose less stagnation pressure with oblique shocks, most supersonic engines tend to work with a series of oblique shocks instead of a single normal shock.

But for our purposes, this is a bad thing - you're reducing the intensity of the pressure changes, and you're spreading changes across multiple shocks. Depending on your height, they may still coalesce into single more powerful shocks, but this requires flying higher, which means lower pressure and thus reduced intensity.

>>32970128
>>32970252
>>32970372
>Actual intelligent response on /k/
Did I slip into the Twilight Zone or some bizarre alternate dimension?

>>32970423
>u intelligent
Don't know what kind of response you are fishing for. Thanks, I guess.

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>>32970128
>>32970252
>>32970372
Nice, thanks!

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>>32970372
Similar things happen at the back of the aircraft - as the aircraft "drops away," the air fills that space where plane used to be through Rayleigh flow - expansion waves. These are pretty much the opposite of oblique shocks - flow expands instead of compresses, and, though you don't lose stagnation pressure, dynamic pressure drops. Again, the more intense the expansion, the worse the drag will be but more intense the sonic boom will be thanks to the resulting pressure differences.

So now, let's summarize that. If we want some form of aircraft that can produce a lethal sonic boom, you'd need:
>Steeply angled flat lifting surfaces
You want to have oblique shocks as powerful as possible, so surfaces should be angled steeply enough that the flow is just barely staying detached. You don't want cones anywhere, because conical flow actually produces weaker shocks.
>medium altitude flight
You want to fly low enough that you're not losing too much pressure due to altitude, but high enough that the multiple layers of shocks that the aircraft will produce (everything that juts out produces a shock) can come together to form a single more powerful shock
>Short body
a shorter body will have the shocks spread across a shorter distance, and thus have a shorter rise time and more powerful boom.

Effectively, something like a hypersonic waverider would be a "good" design for that.

The real problem here is drag. Creating a powerful sonic boom goes against all real tenets of efficient supersonic design, so you'd need an absurdly powerful powerplant to get the thing running at all, and you'd be sacrificing every aspect of performance just for a marginally useful idea.

And then there's the question of what exactly *is* lethal. Though 2psi overpressure can be lethal with short enough rise times, the Concorde was something like 2.5 psi and it *only* broke windows. With the rise times you'd actually get, you'd need much higher overpressure to be lethal.

>>32970049
If you want to find out, you can take the highway to get there.

>>32970521
I believe West Germany tested this with a Tornado back in the 80s.

It was determined to be effective within a few hundred yards of the flightpath at about 100'; however, the level of risk involved made it very marginal as a practical weapon.

>>32970128
>>32970252
>>32970372
>>32970521
I read all of this and I want to thank you

>>32970628
That sounds pretty interesting. Got any links for that? It's definitely believable - even high-altitude supersonic flight can break windows.

>>32968814
What the shit, Archer?

>>32971184
Unfortunately, it was from an '80s book--it could have been The Third World War, but I think it might have been a different one.

There was a story of some pilots during the first gulf war that used sonic booms at night to make the Taliban think they were getting bombed when the planes were out of ammo.

>>32967524
Indeed. In time we will know. TRUMP

https://en.wikipedia.org/wiki/Project_Pluto

There are some 458 SOCOM cartridges that have the same effect.

>>32971343
>first gulf war
>taliban

>>32971488
>>32971343
This one?
>>32967710