Engine noise forward of engines at mach 1+?

[RDoug]

This isn't true, sound's speed isn't constant like light. You would hear the horn, this is the same as the baseball on a plane.

I never said the velocity of sound was a constant. It most assuredly isn't. It varies according to the medium through which it is propagating and the temperature, density, and other factors of the medium itself.

What I said is since sound travels by wave propagation through a medium, it is limited to the medium through which it is traveling. A baseball, being a solid object, is not thus limited. You're attempting to apply Newtonian physics to a fluid dynamics problem.

This is a visual representation of precisely what I mean:

It's an F/A-18 passing through Mach 1. The condensation is developing in the sudden pressure drop in the shock cone developed at the precise moment the aircraft exceeds Mach. And, just as that condensation will never reach the cockpit as long as the aircraft exceeds Mach, neither will the rest of the pressure wave — which just so happens to also be carrying the sound of that aircraft. That's a bit of an oversimplification, but not by much. And if the aircraft continues to accelerate? Then the pressure wave behind it elongates into an even more distinct cone shape than what you see presented here. The longer that cone shape, the further behind the associated "sound" falls behind in ever reaching the cockpit.

 

[Ajax]

I never said the velocity of sound was a constant. It most assuredly isn't. It varies according to the medium through which it is propagating and the temperature, density, and other factors of the medium itself.

What I said is since it travels by wave propagation through a medium, it is limited to the medium through which it is traveling. A baseball, being a solid object, is not thus limited. You're attempting to apply Newtonian physics to a fluid dynamics problem.

This is a visual representation of precisely what I mean:

It's an F/A-18 passing through Mach 1. The condensation is developing in the sudden pressure drop in the pressure wave developed at the precise moment the aircraft exceeds Mach. And, just as that condensation will never reach the cockpit, neither will the rest of the pressure wave which just so happens to also be carrying the sound of that aircraft. That's a bit of an oversimplification, but not by much. And if the aircraft continues to accelerate? Then the pressure wave behind it elongates into an even more distinct cone shape than what you see presented. The longer that cone shape, the further behind the associated "sound" falls behind in ever reaching the cockpit.

Based on your logic above, the flight engineer on the concord wouldn't be able to communicate with the CA and FO because his voice would never reach them.

 

[RDoug]

And here's an even better depiction of a shock cone:

 

[RDoug]

And yet one more:

 

[Ajax]

So, horn in the trunk, FE on the Concorde, could nether of them be heard ahead using your logic?

Perhaps I misunderstood your point. That is what I understood your point to be, which is wrong.

 

[RDoug]

This link probably explains it better than I, because I certainly don't seem to be getting the concept across: http://www.physlink.com/education/askexperts/ae410.cfm

 

[Ajax]

This link probably explains it better than I, because I certainly don't seem to be getting the concept across: http://www.physlink.com/education/askexperts/ae410.cfm

You said a horn in the trunk when traveling mach 1+ wouldn't be heard, that is incorrect. That is what I was objecting to. Like I said, maybe I misunderstood your point. In which case. Ok.

 

[RDoug]

No, that is not what I said.

Matt13C brought up this precise scenario:

"So, if he was able to drive mach 1, and the horn was placed say on the trunk, not in the engine bay, would he not hear it, if it was placed on a poll so the sound couldnt be transmitted through the cars frame?

To which I correctly replied, given that the horn was behind the driver, that it was mounted in such a way as to not transmit vibration (sound) through the vehicle, and given that the vehicle was at Mach 1:

"That would be correct. The sound would never reach him."

The "him" being the driver seated in the vehicle ahead of the horn while traveling at Mach 1. I simply cannot make it any more plain than that.

 

[jynxyjoe]

I'd like this thrice if I could.

 

[knot4u]

No, that is not what I said.

Matt13C brought up this precise scenario:

"So, if he was able to drive mach 1, and the horn was placed say on the trunk, not in the engine bay, would he not hear it, if it was placed on a poll so the sound couldnt be transmitted through the cars frame?

To which I correctly replied, given that the horn was behind the driver, that it was mounted in such a way as to not transmit vibration (sound) through the vehicle, and given that the vehicle was at Mach 1:

"That would be correct. The sound would never reach him."

The "him" being the driver seated in the vehicle ahead of the horn while traveling at Mach 1. I simply cannot make it any more plain than that.

It would have to be awfully windy in that cockpit.

 

[Autothrust Blue]

And yet one more:

@ChasenSFO

 

[ChasenSFO]

@ChasenSFO

Faptastic.