Author Topic: Here’s why the B-58’s Tail Gun Rounds moved Backwards when They Left the Muzzle  (Read 285 times)

Offline Arlo

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The tail gun of the B-58 boasted many firsts for an aircraft defensive gun including the first fully automatic defensive gun fire control system.

The U.S. Air Force’s first operational supersonic bomber, the B-58 made its initial flight on Nov. 11, 1956.

The four engine delta winged aircraft was the world’s first bomber designed to sustain supersonic speeds during its mission profile. In addition to the Hustler’s delta wing shape, distinctive features included a sophisticated inertial guidance navigation and bombing system, a slender “wasp-waist” fuselage and an extensive use of heat-resistant honeycomb sandwich skin panels in the wings and fuselage and the first fully automatic defensive gun fire control system.

As JP Santiago explains in an interesting article appeared on his website Tails Through Time, the Convair B-58 Hustler’s tail cone that enclosed the tail gun was composed of tapered, concentric aluminum rings nested within each other and spring-loaded against each other to form a flexible aerodynamic shell for the gun system.

After looking at various options including rear-firing missiles and twin 30mm cannons, the General Electric T171 (first designation of the M61 Vulcan cannon) 20mm rotary cannon was selected in early 1954. According to Jay Miller’s book Convair B-58 Hustler: The World’s First Supersonic Bomber, the tail gun of the B-58 boasted many firsts for an aircraft defensive gun including the first fully automatic defensive gun fire control system for a production aircraft, the first aircraft gun unit to use a 3-axis inertially-stabilized platform to increase the gun’s accuracy, the first aircraft gun to use a self-contained environmental control unit for the gun and ammunition storage, first aircraft gun to use a solid state analog fire control computer for fire control and the first to use a hinged turret arrangement for maintenance work.

The forward muzzle velocity of the 20mm T171 cannon was lower than the forward velocity of the B-58 when it was flying at Mach 2. So relative to the ground, the cannon round would be moving backwards when leaving the muzzle!



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Offline Vulcan

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Well duh, it's a tail gun.

Offline FLOOB

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Not sure where you found this info, but no.
till he spouts black blood and rolls fin out


Offline APDrone

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 :rofl

Backward relative to a fixed point.

Assuming the jet had a velocity of 2000fps and the cannon shell had a muzzle velocity of 1600fps, then, relative to a ground observer, the shell would still be traveling at 400fps in the same direction as the jet.

Not taking into account friction, aerodynamics and such.

Almost hurts the head to think about it.

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Offline Arlo

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Backward relative to a fixed point.

No confusion here, regarding.  :)

Offline Vulcan

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:rofl

Backward relative to a fixed point.

Assuming the jet had a velocity of 2000fps and the cannon shell had a muzzle velocity of 1600fps, then, relative to a ground observer, the shell would still be traveling at 400fps in the same direction as the jet.

Not taking into account friction, aerodynamics and such.

Almost hurts the head to think about it.

 :salute

You're assuming wrong, the jet is like 2000fps (max) and the cannon rounds are just over 3000fps.

Offline APDrone

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You're assuming wrong, the jet is like 2000fps (max) and the cannon rounds are just over 3000fps.

I sit corrected!  I was not aware of the actual fps for the vulcan ( funny how you'd know that ) ..

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Offline Arlo

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Offline Puma44

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I sit corrected!  I was not aware of the actual fps for the vulcan ( funny how you'd know that ) ..

 :salute

Wiki states a velocity of 3,450 FPS and a rate of fire of 6,000 rounds per minute.  The F-4E carried 640 rounds of 20mm.  At that rate of fire, pilots could plan on three 2 second bursts of fire before the cannon was empty. 



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