Na Wikipédia tem um artigo sobre...
Recoil myth
The GAU-8/A "Avenger" gatling gun next to a VW Beetle
A persistent urban legend is that the recoil force of the Avenger matches that of the A-10's engines and as such the plane would slow down, stall, and subsequently crash if the gun was to be fired for long periods of time (some even claim that the aircraft would begin to fly backwards). However, these claims can be demonstrated to be false through the use of simple mechanics.
The average recoil force, F, can be calculated using fundamental principles of mechanics. The operative principle is change in momentum equals impulse. mv = Ft, where m is the projectile mass, and v is the muzzle velocity, t is time. For a burst of fire,
which reduces to
F = mvr,
where
m is the mass of the projectile (0.425 kg),
v is the muzzle velocity (1067 m s-1),
r is the rate of fire in rounds per second (70 s-1).
At 4200 rounds/minute, 70 rounds are fired each second. A 0.425 kg projectile is accelerated to 1067 m/s every one seventieth of a second. This gives a recoil force of approximately 30 kN based on the relation above. On the GAU-8/A product homepage the recoil force is stated as 10,000 pounds-force, or about 45 kN, probably due to additional recoil from exhaust gas from the muzzle. The maximum combined output of the A-10 engines is 80 kN. Hence the recoil force of the gun is slightly more than half of the total thrust of the engines. While this is quite significant, it is not sufficient to stop the aircraft but it can noticeably slow the aircraft. In fact during test firing of the gun in the A-10 in the early 90's the USAF experimented with putting a muzzle brake on the end of the gun and extending the nose of the plane out around this muzzle brake to vent the gun gases backwards. It was decided during this testing that the effect of the gun was not significant enough to warrant the added expense and complexity of adding this to every plane in the inventory.
The recoil of the gun is also evident in the mounting position of the gun. The gun is mounted off the centerline of the plane as the bullets leave the gun when the barrels reach roughly the 9 O'clock position when looking at the nose of the plane, thus the recoil forces of the gun are directed down the centerline of the plane. This was done because it was discovered during development of the platform that having the gun mounted on the centerline and thus the recoil forces off the centerline was enough to push the plane off target when firing the gun.
According to 355th Fighter Wing Weapons and Tactics Chief at Davis-Monthan AFB in Tucson, AZ, there is no recoil problem with the GAU-8/A. The GAU-8/A utilizes recoil adapters. They are the interface between the gun housing and the gun mount. By absorbing (in compression) the recoil forces, they reduce the magnitude of the felt recoil, spread the time of the recoil impulse, and counter recoil energy transmitted to the supporting structure when the gun is fired.
Some claims have been made that the A-10 engines are susceptible to flame-out when subjected to gunpowder gases, such that when the GAU-8 firing, the smoke from the gun can make the engines stop, and this did occur during initial flight testing. Gun exhaust is essentially oxygen-free, and is certainly capable of causing flame-outs of gas turbines. However, the A-10 is now designed so that the gun exhaust passes underneath the fuselage, and never ventures near the high-mounted turbines, even during negative-G maneuvers.
http://en.wikipedia.org/wiki/GAU-8_Avenger
![8-]](./images/smilies/icon_cool.gif "Cool")
