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Posted: 2/1/2006 6:52:54 PM EDT
[Last Edit: 2/1/2006 6:53:18 PM EDT by christ0ph]
So...IF a fighter jet is flying SUPER FAST, and fires it machinegun whether it be .50 BMG or 20/25/30mm.................does the resulting ft/lbs energy of the projectile end up higher because the gun itself was moving forward at MACH X/2000 fps,etc ?
Link Posted: 2/1/2006 6:54:26 PM EDT
how would wind resistance factor in?
Link Posted: 2/1/2006 6:55:21 PM EDT
good point, that is why im asking. questions get answered around here and i like it :)
Link Posted: 2/1/2006 6:55:47 PM EDT


The muzzel velocity is relative to the environment it was fired from. So it would be the muzzel velocity of the gun/round plus the velocity of the firing a/c...

Relative to the ground it would be moving at that much faster...

How do you think the term "emparting energy" to missiles came about? Accelerating to supersonic speeds before firing a missile so the missile starts out moving faster before accelerating.
Link Posted: 2/1/2006 6:59:25 PM EDT

Originally Posted By christ0ph:
So...IF a fighter jet is flying SUPER FAST, and fires it machinegun whether it be .50 BMG or 20/25/30mm.................does the resulting ft/lbs energy of the projectile end up higher because the gun itself was moving forward at MACH X/2000 fps,etc ?



yes but im guessing the target is moving at about the same speed as the laucher so it evens out
I would guess there would be some increase on stationary targets
or thats my story and im sticking to it
Link Posted: 2/1/2006 7:00:55 PM EDT

Originally Posted By LonePathfinder:


The muzzel velocity is relative to the environment it was fired from. So it would be the muzzel velocity of the gun/round plus the velocity of the firing a/c...

Relative to the ground it would be moving at that much faster...

How do you think the term "emparting energy" to missiles came about? Accelerating to supersonic speeds before firing a missile so the missile starts out moving faster before accelerating.



+1

No offense guys but this is something you should have learned in high school physics .
Link Posted: 2/1/2006 7:01:25 PM EDT
The Muzzle Velocity would be the Stationary Muzzle Velocity + the Velocity of the Air Craft.

As the Machine Gun is firing the Figther will slow down somewhat (due to Conservation of Momentum)

The Projectiles speed will rapidly decay once it leaves the Muzzle.
A Projectile when supersonic: its speed will decay linearly until it approaches the speed of sound, as it slows down past the sound barrier, the decay is no longer linear, but becomes quadratic.

The Speed of Sound varies due to a Medium's density, its temperature and humidity.


Link Posted: 2/1/2006 7:11:53 PM EDT
that why ya need friking lasers
Link Posted: 2/1/2006 7:12:06 PM EDT
The answer is yes. One reason that .50 cals were so effective in the ground attack role during WWII.

Air resistance (drag) does play a part in slowing the bullet, but the overall energy is certainly increased by the speed and altitude of the aircraft.
Link Posted: 2/1/2006 7:15:21 PM EDT

Originally Posted By Bostonterrier97:
The Muzzle Velocity would be the Stationary Muzzle Velocity + the Velocity of the Air Craft.

As the Machine Gun is firing the Figther will slow down somewhat (due to Conservation of Momentum)

The Projectiles speed will rapidly decay once it leaves the Muzzle.
A Projectile when supersonic: its speed will decay linearly until it approaches the speed of sound, as it slows down past the sound barrier, the decay is no longer linear, but becomes quadratic.

The Speed of Sound varies due to a Medium's density, its temperature and humidity.






Smart Dog!
Link Posted: 2/1/2006 7:15:36 PM EDT

Originally Posted By christ0ph:
So...IF a fighter jet is flying SUPER FAST, and fires it machinegun whether it be .50 BMG or 20/25/30mm.................does the resulting ft/lbs energy of the projectile end up higher because the gun itself was moving forward at MACH X/2000 fps,etc ?


Yes, the MV of the projectile is added to the speed of the aircraft.
Link Posted: 2/1/2006 7:16:28 PM EDT
Link Posted: 2/1/2006 7:31:56 PM EDT
[Last Edit: 2/1/2006 7:33:03 PM EDT by Col-Kurtz]
How about the old what if you shot backwards, into the direction you came from as opposed to going towards .
Link Posted: 2/1/2006 8:13:23 PM EDT
What about fighters that shoot airsoft?
Link Posted: 2/2/2006 6:02:14 AM EDT

Originally Posted By Miracle_Pants:
No offense guys but this is something you should have learned in high school physics .


You assume that high schools still teach physics. . . .
Link Posted: 2/2/2006 6:17:16 AM EDT

Originally Posted By www-glock19-com:
that why ya need friking lasers



The rule only applies to projectiles. Since the speed of light in a given medium is constant, there would be no additional KE in a laser fired from a moving aircraft.

Regarding the original question, the KE would be higher, but the energy imparted to the target depends on the target's velocity as well.
Link Posted: 2/2/2006 6:22:03 AM EDT
This reminds me of the discussion about whether the gun on an A-10 had enough recoil to stop the airplane in flight.
Link Posted: 2/2/2006 6:44:58 AM EDT
I think the B-58 Hustler had a prototype gatling gun in the tail, but it didn't work well and was discontinued.

Imagine if the B-58 was hauling ass at about 2900 fps, and the gun fired rearward also at about 2900 fps, wouldn't the bullets fall to the ground?????

2900forward
-2900 rearward
-------------
zero

Link Posted: 2/2/2006 7:04:44 AM EDT
Physics? I know most of my numbers and letters but I just don't know them in order.


____________________________________________________________
A warriors greatest joy is to drive his enemies before him and slay them. Burn his fields and sack his villages, then gather his wives and daughters as his own.
Link Posted: 2/2/2006 7:15:12 AM EDT
Ask the Lockheed Skunkworks guys. They tried to put MG's on the YF12A (the prototype SR-71).

The bird came home with bullets in it.

So, in answer, yes, for a short period.

Get going too fast, and you will overcome any benefits the projectile gains.
Link Posted: 2/2/2006 7:17:47 AM EDT

Originally Posted By mr0w1:
This reminds me of the discussion about whether the gun on an A-10 had enough recoil to stop the airplane in flight.



If the A10 were going real slow, maybe, but there is probably a safety system that doesn't allow the gun to fire under a certain airspeed.

The Harrier cannot fire any of it's weapon systems while in hover due to configuration of the landing gear system and the safties related to it. If the gear is down, it locks out the weapons.
Link Posted: 2/2/2006 7:37:24 AM EDT

Originally Posted By 71-Hour_Achmed:

Originally Posted By Miracle_Pants:
No offense guys but this is something you should have learned in high school physics .


You assume that high schools still teach physics. . . .



I did go to a public school. Do you really think I learned ANYTHING?
Link Posted: 2/2/2006 7:42:43 AM EDT

Originally Posted By H46Driver:

Originally Posted By www-glock19-com:
that why ya need friking lasers



The rule only applies to projectiles. Since the speed of light in a given medium is constant, there would be no additional KE in a laser fired from a moving aircraft.

Regarding the original question, the KE would be higher, but the energy imparted to the target depends on the target's velocity as well.



Technically, the laser would be slightly "blue shifted" and have more energy due to the airplane's velocity.
Link Posted: 2/2/2006 7:55:08 AM EDT
[Last Edit: 2/2/2006 7:57:00 AM EDT by metroplex]
When your aircraft is going Mach 2, all of the objects attached to the aircraft is also going at Mach 2. So when you fire the 20mm cannon, the bullets have an initial velocity of Mach 2, starts to pick up speed from the powder ignition inside the chamber and bore, and starts to decelerate as soon as it leaves the barrel due to wind resistance, gravity, mass of bullet/frictional forces, etc... You also have to remember that Mach 2 for bullet projectiles isn't that significant. Mach 2 around sea level is only 2230 fps (55 gr M193 is around 3200-3400 fps sea level).
Link Posted: 2/2/2006 8:06:27 AM EDT
Culled from the web:

Tom Attridge flying F11F-1 138620 on September 21st, 1956. While in a (slightly) supersonic dive, he fired his 20mm guns. Seconds later, the accelerating aircraft had overtaken the shells one of which was ingested into the intake.
Link Posted: 2/2/2006 8:49:53 AM EDT

Originally Posted By LonePathfinder:


The muzzel velocity is relative to the environment it was fired from. So it would be the muzzel velocity of the gun/round plus the velocity of the firing a/c....




What's a "muzzel?" And does it have a "break?"
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