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Concorde Vs Bullet



 
 
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  #1  
Old February 17th 06, 03:14 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

A friend and I were having a debate on a rumour that we once heard.
The rumour went along the lines, If concorde (or and other supersonic
aircraft for that matter) was fitted with guns then the bullets would
not be able to leave the muzzle or it would shoot itself if it fired
them while cruising. Assuming that the bullets velocity and the speed
of the aircraft are the same, what are your thoughts on what would
happen?

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  #2  
Old February 17th 06, 03:22 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

Next time you're on a plane, toss a bag of peanuts to someone in front of
you.

Never knew you could throw a bag of peanuts 500MPH, did you?

"rick_little99" wrote in message
oups.com...
A friend and I were having a debate on a rumour that we once heard.
The rumour went along the lines, If concorde (or and other supersonic
aircraft for that matter) was fitted with guns then the bullets would
not be able to leave the muzzle or it would shoot itself if it fired
them while cruising. Assuming that the bullets velocity and the speed
of the aircraft are the same, what are your thoughts on what would
happen?



  #3  
Old February 17th 06, 03:24 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

rick_little99 wrote:
A friend and I were having a debate on a rumour that we once heard.
The rumour went along the lines, If concorde (or and other supersonic
aircraft for that matter) was fitted with guns then the bullets would
not be able to leave the muzzle or it would shoot itself if it fired
them while cruising. Assuming that the bullets velocity and the speed
of the aircraft are the same, what are your thoughts on what would
happen?


Only if it's on a conveyor belt also going the speed of sound in the
opposite direction. ;^)


  #4  
Old February 17th 06, 03:37 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

OK, i think you are looking at the problem a little too simply. It is
not just a relative motion issue. Air travelling towards the aircraft
would not be able to enter the muzzle (as it has nowhere to go). The
bullet would then travel down the muzzle at the speed of sound say (I
know it has to accelerate but lets just say it travels at a constant
speed) relative to the muzzle (i.e. the bullet would be travelling its
velocity plus that of concorde). Upon reaching the end of the muzzle
it would hit a wall of air travelling at the same speed as it so would
effectively instantaneously slow down to the speed of concorde. It
then could go one of 3 ways, it could bobble about in the space between
the end of the muzzle and the air around (the boundary layer), fly back
past the aircraft and possibly hitting the aircraft on the way past or
it could go bounce back down the muzzle.

  #5  
Old February 17th 06, 03:49 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

In article .com,
"rick_little99" wrote:

A friend and I were having a debate on a rumour that we once heard.
The rumour went along the lines, If concorde (or and other supersonic
aircraft for that matter) was fitted with guns then the bullets would
not be able to leave the muzzle or it would shoot itself if it fired
them while cruising. Assuming that the bullets velocity and the speed
of the aircraft are the same, what are your thoughts on what would
happen?



It could happen, but not in the way described. The bullets will have an
initial velocity (in air) of aircraft velocity + muzzle velocity.

The problem arises after they leave the gun barrel and are exposed to
drag. The bullets will slow down, due to high supersonic drag and fall
downward. At some time, the aircraft velocity will exceed the bullets'
velocity. There was a case of a Grumman F-11F Tiger shooting itself
down when it fired at a target and dived into its own rounds.
  #6  
Old February 17th 06, 03:55 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

NOt quite.

The bullet would not 'instantaneously' slow down. It has a given amount
of energy and is capable of supersonic speeds. The question would be
how long would it take to slow down to the Concorde's speed. If you
guess a second, and the bullet was fired along the flight path of the
airplane, it would have fallen 16 feet be the time it was traveling the
same speed, and another number of feet before it slowed down enough for
the airplane to catch up to it.

During WW2 some airplanes were said to have hit themselves with their
own bullets, but I think you can work out how that might happen with an
airplane diving under its own line of fire.

Finally, if you think you knew the answer, why did you post the
question?

  #7  
Old February 17th 06, 03:55 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

If concorde (or and other supersonic
aircraft for that matter) was fitted with guns then the bullets would
not be able to leave the muzzle


I don't think there's anything special about being supersonic to the
basic physics involved (though it will add some wrinkles). Before
firing, there will be ram air pressure in the (forward facing) muzzle.
When the bullet is fired, there will be explosive chemical pressure
behind the bullet which will exceed the ram air pressure in the muzzle -
this difference will cause the bullet to accelerate down the muzzle. At
some point the pressure behind the bullet will begin to decrease (as the
reaction ends and the volume continues to increase), while the ram air
pressure will increase further up the muzzle (due to the bullet pushing
the air away). Given a sufficient charge, the bullet will exit the
muzzle and become a projectile. The speed of exit depends on the size
of the charge - obviously a dud would not eject the bullet (but this is
true of anything).

Once the bullet exits the muzzle, it will slow down and descend at a
rate typical of a bullet. The plane flying behind or next to it is
independent and largely irrelevant, though it will maintain speed and
altitude due to its engines.

Bullets typically are supersonic to begin with, so there's nothing
special here. Coming out of the concorde it will have an initially
higher airspeed than a typical bullet shot from the ground, so it will
decelerate more quickly. My gut feeling (I have never shot a gun
however) is that the bullet will have enough excess forward speed that
by the time it slows down to the concorde's speed, it will be way ahead
of the plane.

Do fighter planes have guns that fire at supersonic speeds? I suspect so.

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.
  #8  
Old February 17th 06, 03:58 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

If its travelling at its own velocity plus the velocity of Concorde,
why would it instantly slow down to the speed of Concorde after exiting
the muzzle? Seems to me it would continue out the muzzle at whatever
its combined velocity was.

  #9  
Old February 17th 06, 03:59 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

I posted the question because i wanted to canvas opinion and spark
debate.....the very reason that these groups exist!

  #10  
Old February 17th 06, 04:04 PM posted to rec.aviation.piloting
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Default Concorde Vs Bullet

The F-104, armed with a high velocity 20 mm Vulcan cannon
shot itself down during flight testing ground attack. It
passed the hail of bullets while in a dive. So, the bullets
will leave the barrels, but they slow down since they have
no continuous propulsion. The aircraft can pass the
bullets, something that is handled by training.


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But government sees it as an obstacle to be overcome.
some support
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"rick_little99" wrote in message
oups.com...
|A friend and I were having a debate on a rumour that we
once heard.
| The rumour went along the lines, If concorde (or and other
supersonic
| aircraft for that matter) was fitted with guns then the
bullets would
| not be able to leave the muzzle or it would shoot itself
if it fired
| them while cruising. Assuming that the bullets velocity
and the speed
| of the aircraft are the same, what are your thoughts on
what would
| happen?
|


 




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