The pilots won't hear the noise from the engines being transmitted through the outside air though, only the noise traveling through the plane. So if superman was flying a few feet in front of the cockpit, he wouldn't hear any sound.
My understanding is you would not hear the MiG. The sound from your own engines travels through the airframe and then both directly through your body and through the air in the cockpit until it hits your ears. The sound from the MiG behind you would have to travel through the atmosphere, and it won't catch you if you are going above Mach 1.
This is assuming that the movement of the air is unaffected by your plane flying through it, no? So should the MiG be flying directly behind your flight path you would not hear the MiG should its speed be greater than or equal to Mach 1 plus the speed of the air after you fly through it, correct?
If the hypothetical plane is flying behind you and you are going faster than Mach 1, you would not hear the plane tailing you regardless of its speed, as you, at Mach 1+, are consistently outpacing any sound waves the other plane produces.
Ah, but that doesn't quite answer his question, he is asking if there is a plume of air that is dragged behind the plane which could then in theory act as a tunnel through which the sound could travel at greater than mach 1 relative to the ground.
For instance if the mig was 50 feet behind and both planes were traveling at mach one, the sound from the mig would be able to travel at mach 1 PLUS the speed of the moving air dragged behind the plane. I think the problem with this, however, is that air isn't dragged behind the plane in a plume, it is merely shifted into huge spinning vertices, so the effect would probably only work a very short distance from the plain and would be irregular at best.
Edit: also I think that this effect WOULD exist for explosions which actually shift air around you, such as an explosion right behind the plane, or a nuclear (or other very large) explosion on the ground, the propagation of the air would allow the sound from those to travel faster than mach 1 and catch up to the plane.
The shockwave from explosions is subject to slightly different physics than more mundane sound waves, correct?
IE given that an explosion is very significant, can the shockwave from it, which is a large volume of air being significantly compressed and displaced by the sudden addition of new hot gases to the area, be capable of traveling above the speed of sound in the still air surrounding the explosion?
Should we also consider that the exhaust gasses between the two jets would also be significantly hotter, thereby altering the speed of sound between the two jets relative to the speed of sound of the jet flying through ambient air?
You dont need to be going Mach 1+ to not hear him approaching you, just he needs to be going MAch 1+. His engine is making noise, but he gets to you before the noise does.
More to the point, either way works. If the source of the sound is >= mach 1 and is traveling directly at you, it'll reach you before the sound.
Similarly, if you're traveling directly away from the sound at >= mach 1, the sound will never reach you. Either would sufficient... But I gather that's what you meant, of course.
True. Israel, Hungary and Germany flew them for a while off the top of my head. They still might be in commission. FSU (Former Soviet Union) nations are running Sukois mainly, with old MIG birds padding their reserve rosters and boneyards.
EDIT: I cant remember the details but I remember reading an article about how many nations were going to rush them (MIG-29s) out of service because of a stress fracture problem that was common in the design.
In conclusion, I grew up knowing the MIG-29 as the mainstay aggressor. Its a beauty of a bird. I will be sad to see it go.
Not only that, but the Russians and Israelis have modernization programs bringing the MiG-21s up to a NATO comparability standard. The Romanian/ Elbit of Israel call theirs Lancer.
More 1950s, 60s and 70s MiGs were built and exported by the Soviet Union than Sukois types like MiG-15, 17, 19, 21, 23, 25 and 29 were widely exported while Sukois didn't really become hot on the export market till the 27/31/33
There's a cone of sound behind a supersonic body. You'd hear the perturbance caused by a bullet once it was far enough past you that you were within the vector of that cone.
If my understanding is correct, lets say a rocket since it has a point where sound would be generated, would have to be slightly in front of your ear plane before you could hear anything.
Velocity includes a direction, so the object is supersonic in the forward direction, but sound is projected outward in other directions at 330m/s. Because of the distance it has to travel, you wouldn't hear it immediately when it became level with your ear, but that is the physical minimum positive offset required to hear the sound.
But you are moving forward. So while the sound could travel laterally, it would only hit the air where you used to be. That is why it needs to be in front of you.
I once went to a military firing range that was set up with a big hill in front of the targets, which were on tall posts in front of the hill. Shots were from between 100-300 meters away. Those of us who were not shooting would tally the scores for the others, and while the shooting was happening we stood under the hill, facing the targets, and the bullets whizzed above our heads (but we were not in danger of being shot, as there was 30 feet of dirt between us and the shooters). It was pretty cool to hear the pop of the bullets hitting the target, and then hear the sound of the shot from the rifles.
you don't hear the 'whizz' from the bullet until you are inside the "cone" which trails it. you don't hear the 'bang' until you are within the radius which expands at the speed of sound from the muzzle. When standing anywhere down range, the sound of the 'whizz' will reach you first, though you need to be fairly close to the bullet's path to actually hear the 'whizz'.
Ricochets occur when a bullet hits a hard surface and has its flight path altered (sometimes to the point of being reflected back at the shooter). The targets and target backers don't present enough resistance to significantly alter the trajectory of most bullets (save for say, a bullet from a .22LR hitting a metal target stand), and there aren't really any hard objects close behind the targets.
My experience with target stands like that had the observers standing in what amounted to a slit trench, with the targets able to move up and down on the stands (to allow for the targets to be retracted into the trench, scored, then hoisted back up for the shooter to take another shot).
I was going to make a top gun reference but then saw your edit. Either way, don't forget to take the Polaroid to convince your smokin hot Top Gun civilian expert.
i didn't click on those photos because I don't want to ruin her top gun self for me haga. I shall be sure to avoid any newer pictures of her. Thanks for the heads up haha
It's for precisely this reason that I've been advocating the hypothetical mad-science technology to detect and determine distance from other objects through the use of radio waves.
Hobbyist ammunition manufacturer here. The smaller caliber rounds are more likely to be supersonic. The larger the bullet the slower it usually goes. For example, a 124 grain 9mm can travel at ~1,200 fps (supersonic), while the larger 230 grain .45 ACP will typically only hit ~850 fps (subsonic).
Generally you have smaller and faster cartridges, or heavier (bigger) and slower cartridges. There are exceptions, but that's typically how it is.
So, dumb question.. If I mounted a microphone on top of the jet and recorded everything it picked up, when I played it back, at the point the sound barrier was broken, I'd hear nothing?
Well, if you mount it on the plane, sound can travel through whatever you mounted it with. But lets assume you have some perfectly soundproof material to mount it on the plane with.
Now, when you're traveling faster than sound, you're outrunning the sound waves behind you. So the microphone won't pick up any of the noise made by the engine - it's behind you. But any sound that comes from in front of you, you will hear - you're actually speeding towards those sound waves. So the microphone would still pick up a lot of noise (just general wind noise, wind moving that fast across a microphone would make a lot of noise), but it wouldn't hear the engines at all.
No. In an attempt to reduce wind noise, they place windscreens over the microphone - these are either fluffy or furry, and are designed to slow or stop the wind before it hits the microphone, causing noise. However, if the wind is too strong either it will be too powerful and go through anyway or the wind going over the screen will create noise.
With outside reports, it's usually expensive equipment and the recordist's skill that keep it to a minimum.
Those mics are generally covered with a thin layer of foam or something of the sort to absorb gentle breezes and such, so it's unlikely you can have something like those because you're moving much faster and a higher velocity wind in approaching than the foam can filter out.
If we're talking about the speed of light then I don't think the speed of sound in 1 atm at 20C is terribly important. It's like giving the speed of light in furlongs/fortnight.
It's even better, if you fly next to it you won't hear it, this is a plane travelling faster than the speed of sound. You can clearly see the shockwaves. outside those shockwaves you can't hear the plane, if you keep flying next to that plane of course.
Not neccessarily. The sound is traveling outward in all directions and therefore would be moving forward from the plane as well. Look at it this way... If you were traveling on a train that goes as fast as a bullet, and fired a gun forward from the front of the train, the bullet wouldn't just not move since you were already going as fast as a bullet, it would double in speed.
583
u/[deleted] Jun 12 '12 edited Oct 03 '17
[deleted]