Such a pod already exists. It’s the SPPU-22. A podded GSh-23-2 cannon which can be depressed. Developed for strafing runs, and for rear cover for a strike package (since it can be fitted to be fired rearward).

There are two similar Russian pods, one is the SPPU-6 with a 30mm cannon and one other I can’t think of.

Interesting, your post led me to an earlier post on this subject:

http://forum.keypublishing.co.uk/showpost.php?p=164688&postcount=3

From ‘Flying Guns: the Modern Era’ (due out sometime next year):

“Russia has developed by far the most interesting range of gunpods, as many of them permit the gun to be elevated and traversed in use. The best-known pod in which the guns stay conventionally fixed is the UPK-23-250, for one 23 mm GSh-23 and 250 rounds, which weighs 218 kg loaded. Pods with flexibly-mounted guns include the SPPU-22 which carries the same gun and slightly more ammunition (260 rounds) and permits adjustment in elevation only, from 0º to -30º, but weighs 320 kg loaded; the SPPU-6 for the GSh-6-23 rotary gun with 500 rounds, weighing 525 kg, which permits 0º to -45º elevation and plus or minus 45º of traverse; and the SPPU-687 (alternative designations found in some references are 9A-4071K or 9A-4273) pod for the 30 mm GSh-301 and 150 rounds, which weighs 480 kg loaded and permits 0º to –30º of elevation and plus or minus 15º of traverse.

. . .

The sideways-firing SPPU-6 is intended to be controlled by a second crew member, so is used with aircraft such as the two-seat Su-27IB.”

Tony Williams: Military gun and ammunition website and Discussion forum

If you can do 45º of traverse, is 90º really impossible?

So the principle seems to be there, now if they could just make it fully positionable . . .

KC-X: Questions Over Questions

The U.S. Air Force may keep industry waiting just a while longer than first expected concerning this year’s biggest defense program competition, the KC-X tanker.

At one point, November 12 was considered the likely award date . . . Even a few weeks ago, that date appeared to be slipping toward the end of the month. The question now is whether the delay will be even greater.

Industry officials on both sides note they have been surprised by the amount of questions the service has asked about their proposals — the dialogue began in August. Just sorting through the answers, some of them lengthy, is likely to take a while, they note, dimming hopes of an imminent announcement.

– aerodynamics: the turret will become problematic at any higher speed

for transit it could be locked in an ‘aerodynamic’ position

for CAS work, the plane won’t be at high speed anyways.

– volume: to store that “significant amount of ammo”, youll need big internal volume that will be wasted (figthers are littérally packed with electronics and various systems, and any part that isn’t is loaded with fuel…

I’m not talking about an internal, permanent system, i’m talking about an external pod. No different than any other pylon-mounted weapons.

how much of a gun + ammo could you actually hang off a pylon (or two) is certainly problematic though . . .

in the end, a good gunship is an aircraft that has big lift capability woth loads of available volume: converted transports, like the AC-130 for example…

obviously a dedicated gunship is preferred. The problem is that there are only a limited number of them. A gunship does you no good if it isn’t there.

a ‘turret-pod’ would allow standard fighters to offer higher quality CAS. Better aiming and more persistence than a traditional strafing run, and less ‘collateral damage’ than any missile or bomb, allowing it to be used closer to friendlies than is traditionally possible

http://www.dodbuzz.com/2010/10/19/kc-x-last-tanker-for-two-decades/

KC-X Last Tanker for Two Decades

Defense analyst and consultant Rebecca Grant said today that she believes there will not be any follow-on contracts for the KC-Y or KC-Z tankers, leaving the KC-X as the final plum for Boeing and EADS to pluck for at least 20 years.

. . .

Key to Grant’s argument is the Pacific theater. “Any air campaign will demand extremely long reach and heavy use of tankers. The distance from Guam to Taipei, for example, is 1,474 NM,” she wrote in her white paper, “Nine Secrets of the Tanker War.” In addition to distance, she said long range strike assets will be extremely thirty. A B-2 would require four refuelings of 100,000 pounds of fuel each, she writes. She says the “larger KC-Xs can handle the {Pacific bombing] scenario with four aircraft, However, the smaller notional KC-X would require a minimum of five and likely more tankers to meet both the offload and timing requirements for the mission.”

Grant appeared with retired Lt. Gen. Norm Seip, former 12th Air Force commander. I asked them who they would pick to win the competition. Grant hedged her bet, saying only that “additional fuel offload is of great value in the scenarios that concern me, especially the Pacific scenario.” Seip stayed much further away, saying he wouldn’t pick a winner “even if you put a gun to my head today.”

. . .

Both Grant and Seip told me they do not represent either Boeing or EADS.

Aeroplane upgrades could futureproof US Air Force fleet

And in July, two C-5Ms teamed up with eight older Galaxies for a comparative exercise delivering 100 US Army helicopters to Afghanistan from a Navy cargo yard in Rota, Spain.

The contrast between the new and old Galaxies was stark. The eight older C-5s together managed just 23 missions, compared to 23 missions for the two C-5Ms, according to Colonel Patrick Cloutier, one of the mission’s commanders. The C-5Ms carried 55 percent of the total cargo, despite flying one fewer mission than their older kin. The Super Galaxy ended the 30-day operation with a 96-percent reliability rate. The older C-5s scored 82 percent. “In short, the C-5M did what it was designed to do: deliver cargo more effectively and efficiently than its predecessor,” Cloutier said.

Alternative Future for C-5As?

Lt. Gen. Thomas Owen, Aeronautical Systems Center commander, thinks it would be “a good idea” to perform the C-5 Reliability Enhancement and Re-Engining Program modifications on the 37 C-5A aircraft that the Air Force intends to retain, but are not now programmed to receive this upgrade. He said the Air Force “will look at” the possibility of modifying these A models.

C-5M Rekindles Interest In Upgrading C-5As

With a program to re-engine the C-5B airlifter meeting cost and performance targets, the U.S. Air Force and Lockheed Martin are again looking at the possibility of upgrading older C-5As.

. . .

The three C-5Ms already in Air Force service, the former RERP development aircraft, include a single upgraded C-5A. This is achieving the same performance and reliability as the two modified C-5Bs

. . .

Congress directed the Air Force to study the potential for placing the retired aircraft with the Civil Reserve Air Fleet (CRAF) or international coalition partners. A report will be submitted soon.

Lockheed has approached CRAF carriers, international air forces and foreign airlines informally and believes there is some interest in the excess C-5As, says Mark Johnston, director of U.S. government air mobility programs. “We will know more in the next 6-12 months,” he says.