Plane On A Conveyor Belt

[Dleg]

The treadmill is outside the airplane, and the airplane is white.

 

[matt267 PE]

What's the drag coefficient on the person, and are they plump or twiggy?

 

[Dleg]

Assume it is negligible.

Oh, and for anyone who has never read the original thread on this topic, it is EPIC.

 

[matt267 PE]

Are you saying they're in a perfect vacuum? If so, the plane wouldn't even be able to fly, making your question invalid.

 

[Dleg]

The person is running 5 mph on a treadmill, which is attached to the outside of an airplane that is travelling at 1 mph less than the speed of sound (for that pressure and temperature).  Someone else did the engineering necessary to get the situation to this point.

Now answer the damn question.

 

[Wolverine]

Not yet.  Is the white plane going 1mph slower than the speed of sound with a person on a treadmill on top accelerating or decelerating?

And is there any sort of power connection between the treadmill and the airplane, either absorbing power to run the treadmill motor or producing power from the motion of the running?

This is critical for my calculations.

 

[Audi Driver P.E.]

flight involves... nay... REQUIRES air movement to provide lift.

 

[matt267 PE]

This question is old news.  It's time to update the question.  Let's say there's a treadmill mounted on an airplane. If the airplane is flying at 1 mph slower than the speed of sound, but you are running on the treadmill at a speed of 6 mph, will your body be harmed when it breaks the sound barrier?

flight involves... nay... REQUIRES air movement to provide lift.

@Audi driver, P.E., have you considered Dleg's new question? I think it's invalid and Dleg is not providing enough info to Wolverine. What do you think? 

 

[Audi Driver P.E.]

@Audi driver, P.E., have you considered Dleg's new question? I think it's invalid and Dleg is not providing enough info to Wolverine. What do you think? 

I had not considered it.  But obviously there is information missing.  Is the treadmill moving at 6mph?  If not, then you're already beyond the speed of sound and obviously you survived.  But the bigger question is why would I be running on a treadmill on an airplane.  Am I sufficiently drunk?

 

[scatsob]

If the plane is flying that fast there would already be local flow in various locations already faster than sound, on the plane, person, and treadmill.  But yes, you will be very harmed and likely dead already as the plane accelerated to ~0.99 Mach.  Unless the person has some sort of suit on for protection. Is the person Spider-Man?

As a classically trained aeronautical engineer I find these questions disturbing. 

 

[Dleg]

Not yet.  Is the white plane going 1mph slower than the speed of sound with a person on a treadmill on top accelerating or decelerating?

And is there any sort of power connection between the treadmill and the airplane, either absorbing power to run the treadmill motor or producing power from the motion of the running?

This is critical for my calculations.

The treadmill is accelerating from zero to 6 mph, with the person matching that with his /her running speed.  So, the person and treadmill are traveling at 1 mph less than the speed of sound at the start of the scenario. 

Let's assume the person is wearing high speed running clothes that sufficiently protect him/her against the windspeed at 1 mph less than the speed of sound.

The treadmill is plugged in to a 120V AC outlet powered by the aircraft's electrical power system.

 

[FLBuff PE]

How much hair does the treadmill runner have? The amount of hair (both on the head and on the body) would increase the drag coefficient.

 

[Dleg]

none.

 

[wilheldp_PE]

The treadmill is plugged in to a 120V AC outlet powered by the aircraft's electrical power system.

Most airplanes use 115 VAC at 400 Hz.  If you use a treadmill designed for 115 VAC at 60 Hz, it's going to run ~7 times faster than it would in the US.  So now your 5 mph treadmill is going ~33 mph.

 

[jeb6294]

The plane will be fine.  The extra speed of the person on the treadmill will allow them to break the sound barrier and explode...but since they're going faster than the speed of sound, you won't hear them explode.

 

[Dleg]

Are you certain?  Wouldn't they cause a sonic boom, IF they accelerated through the speed of sound?

 

[matt267 PE]

Isn't there something about the theory of relativity that should be applied here?

 

[Dleg]

That's another topic.  The guy walking forward in the spacecraft traveling 1 mph less than the speed of light.

 

[csb]

Why's the plane gotta be white? 

 

[matt267 PE]

Why's the plane gotta be white? 

Because the other color plane didn't want to work.