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Supersonic Shockwave as Weapon

Fly plane fast over enemy
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The shock wave from a supersonic aircraft is very powerful. Why not get a top pilot to fly over the enemy at full speed? The shock wave would be strong enough to be destructive.
kevinthenerd, Oct 05 2007

Project Orion http://en.wikipedia...clear_propulsion%29
[AbsintheWithoutLeave, Oct 05 2007]

Shock wave? What shock wave? http://www.dself.ds...roj/failproj.htm#p1
[Ling, Oct 09 2007]

(?) A nice video of a shock wave from an F/A-18 http://www.owlnet.r...ech591/TRANS_S1.mpg
[Ling, Oct 09 2007]

Boeing 777 on short final http://www.airliner...pen.file/0637494/L/
Condensation effect does not indicate supersonic flight [lurch, Oct 12 2007]

Mach angle http://exploration....rocket/machang.html
The "shock waves" shown are too flat [lurch, Oct 12 2007]

Sound wave angles http://www.grc.nasa...rplane/sndwave.html
Move the slider to just past transonic and look at the shape [Ling, Oct 12 2007]

Schlieren photography http://en.wikipedia...hlieren_photography
Shock waves produced by a T-38 Talon during flight. [baconbrain, Oct 12 2007]

[link]






       Might work once. The second time someone will have a shoulder fired missile to stop that foolishness. (-)   

       Also hard to aim. You are going to get your guys nearby as well. And everything down range and up range.   

       There are more precise ways to break windows.
Galbinus_Caeli, Oct 05 2007
  

       Shock wave damage is actually the means utilized by fuel air bombs.
jhomrighaus, Oct 05 2007
  

       //Shock wave damage is actually the means utilized by fuel air bombs.//So, fly slower and use the fuel you save to make more fuel-air bombs.
AbsintheWithoutLeave, Oct 05 2007
  

       Are you suggesting fuel air bombs be used as propellant?
bungston, Oct 05 2007
  

       A jet engine is basically a controlled fuel/air bomb. Well, actually any liquid fueled internal combustion engine is, actually.
Galbinus_Caeli, Oct 05 2007
  

       //Are you suggesting fuel air bombs be used as propellant//
I understand the concept beind Project Orion was tested with conventional explosives, so yes, why not?
AbsintheWithoutLeave, Oct 05 2007
  

       That's a pretty broad interpretation of the mode of damage of an FAE.   

       Shockwave = overpressure wave. eh. kinda.
Custardguts, Oct 08 2007
  

       I wasn't offering a technical description there just trying to make a general comparison. Both utilize a pressure wave as the destructive force.
jhomrighaus, Oct 08 2007
  

       "Fearless Leader, the infidels have destroyed our plate glass windows and bone china again!"   

       "Curse You, George Bush!!!"
RayfordSteele, Oct 09 2007
  

       Fly closer to the AAA batteries = bone.
elhigh, Oct 09 2007
  

       How about clapping really loudly, that can be quite annoying.
zen_tom, Oct 09 2007
  

       Yeah, we shouldn't be using AAA batteries when we could be using solar cells instead. (sorry, that may be a bit UK-centric: AAA is a small size of electric battery for toys, flashlights or whatever)
david_scothern, Oct 09 2007
  

       Never once have I seen James Bond bowled over by a near miss bullet going at supersonic speed, saying 'Dash it all Moneypenny, I was felled by the shockwave. And by the way where's my laserbeam watch?'
Brett-Blob, Oct 10 2007
  

       Based on [ling]s video up there I would say we have pretty well shown that this would not work as all those navy guys seem to be holding up pretty well from their shock wave experience.
jhomrighaus, Oct 11 2007
  

       Why not get a computerized drone to do that? Oh well, close enough. [+]
quantum_flux, Oct 11 2007
  

       //Why not get a computerized drone to do that?// (que nasally voice) 'I'm on my lunchbreak m'kay'.
Brett-Blob, Oct 12 2007
  

       [jhom] - the image of the F-18 does not actually show a shock wave, as the jet is not flying supersonic. It's just a pressure ridge. In the low pressure behind it, the humidity in the air momentarily condenses, causing the cloud.   

       Quick sanity check: a shock-wave propagates outward from the source at the speed of sound - no surprise there. If the aircraft were travelling at the same speed forward that the shockwave moves outward, the angle of the leading edge of the wave would be 45 deg. back from perpendicular to the flight path. (1 to 1 ratio of plane motion to sound propagation.) You can continue on and show that angle to be equal to asin(1/n) where n is the Mach number. (In reality, compression effects create a different result, but this is a good rule-of-thumb approximation.) The angle of the compression wave in the video is quite clearly less than 45°.   

       And - by the way - that's not an F-18. It's an F-14 Tomcat.
lurch, Oct 12 2007
  

       Get out your protractor and do the math. It's making about 300 - 350 kts.
lurch, Oct 12 2007
  

       I'll be back in a bit with a link to a picture of a Fed-Ex DC-10 doing the same thing. With the gear down. <edit> Ok, the one I thought I remembered didn't show it very well, as it was in clouds. This triple-7 does pretty good, though.</edit>   

       [21Q] - protractor measures angle, not size. Works just fine, as long as you have a good side view. It won't work on the Wiki link you posted, I admit, because we don't have a broadside view of the plane.   

       //You can also see the water ahead of the plane being agitated by its passing.// Quite right. If he were supersonic, what would be reaching out front to create the disturbance, eh?
lurch, Oct 12 2007
  

       lurch, take a look at the very fast bug in the link.
Ling, Oct 12 2007
  

       [lurch] that's a great picture, but it's not relevant to the (sidetracked) discussion. That shows the lower pressure above a wing causing vapor to condense out of nearly-saturated air--the plane is just above a cloud/fog, so conditions are just right, and the plane is flying slow (I like the vortices off the flap ends).   

       The video shows the reduced pressure behind a shockwave's high pressure, causing vapor to condense out of nearly-saturated air. The "disturbance ahead of the plane" is not ahead of the plane, it's below and behind, but the camera angle is bad. But it and other vapor areas are below the plane, which would ordinarily be an area of increased pressure.
baconbrain, Oct 12 2007
  

       Correct me if I'm wrong but isn't one of the key items to control of airplanes during transition through the sound barrier the design of the tail section such that the control surfaces are designed such that they are able to bridge the Shock wave front as it passes down the length of the jets body? In essence this says that the shock wave actually trails the plane and as such the pressure wave visible in the video could not be from a sonic wave in origin?   

       [lurch] my earlier comment was aimed more at the fact that though uncomfortable the sonic shock wave from an airplane is far less destructive than the author believes.
jhomrighaus, Oct 12 2007
  

       A shockwave can damage glass and other fragile objects (and has). But, as was implied above, it won't have much power--it can't cause any more damage in one second than could be caused by one second's worth of jet fuel used as a fuel-air bomb.   

       There are many shock waves coming off a plane, with the biggest off the front. See Schlieren link.   

       [jhom] I'm saying you are wrong, but not taking time to correct you. Sorry.   

       Again, the shockwave makes pressure in the air, but the air bounces back from that compression/pressure, creating an underpressure area (it's a wave). That underpressure/expansion causes water vapor in the air to condense, if conditions are right (humid, cool, almost foggy). The cone of vapor is not in the shockwave, it is behind it in the recovery/reaction/bounceback zone.   

       HEY! It just occurs to me that it may be possible to make this idea work better.   

       If the plane flew in a supersonic circle around the target, a lot of shockwaves would hit it. If the plane flew in an ever-tightening spiral, all the shockwaves could arrive nearly at once, which ought to make more of an impact. The math shouldn't be too hard to program into an autopilot.
baconbrain, Oct 12 2007
  

       Quite true, and what I meant. Thanks for clarifying.
baconbrain, Oct 13 2007
  

       Every action has an equal and opposite reaction. If you are rupturing enemy spleens at 90m with force x, you are going to need a initial force that radially dissipates in three dimensions, i.e dissipates under the inverse cube law. Fasten your rivet guns, we are building one hella plane!
4whom, Oct 13 2007
  

       I think you would probably be better off with a giant Airzooka.
rascalraidex, Oct 13 2007
  

       The tightening circle is a great idea!
kevinthenerd, Jun 22 2008
  
      
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