# Why don't combat aircraft have rear-facing weapons?

This excellent question addresses the role of dogfighting in modern aerial warfare. However it seems that most ACM concentrate on maneuvering into shooting position. Why don't combat aircraft have rear-facing weaponry?

Even WW-II bombers had rear-, side-, and downward cannons, albeit manned. Could a small electronically-controlled cannon be added to the stern dorsal part of a combat aircraft, for shooting rearward? I've personally seen remote-operated FN MAGS on vehicles, the whole system seems to weigh on the order of 100-150 KG including hundreds of rounds. The vehicle-mounted systems took up about a cubic meter or so of space, but a purposed-designed system could probably take up less than half that, and probably shave off a good portion of the weight as well.

Could a computer not point a barrel at a vehicle with a relative velocity approaching 0 and shoot, even in a +Mach 1 wind in the direction of the target? It may be enough to just get a few bullets in, shotgun style. The Uzi rifles famously don't shoot straight, they make a cone of bullets. Perhaps this cone, if aimed in the general direction of an aggressive aircraft, might be enough to either disable it or get it off your tail. A short barrel will make a wider cone, perhaps the rear-facing weapon could have an very short barrel. ACMs such as the Cobra maneuver seem to imply that there are a finite number of angles from which attack is most likely, the weapon could be limited in angular range to those angles.

I'm sure that piloting an aircraft while trying to avoid being shot is difficult enough, so I wouldn't assume that such a system would be of much help on a single-seat aircraft. However, in a dogfight presumably the ROI or navigator could operate the guns while the pilot does the aviation.

• Have you ever played a computer game with a rear-facing weapon? Complete waste of upgrade points. :-) – David Richerby May 22 '15 at 9:35
• @DavidRicherby: Actually, I haven't. Perhaps a computer could do better. Computers control fire in the Korean DMZ, for instance. – dotancohen May 22 '15 at 10:02
• I wonder why you don't mention missiles? It seems like launching a short range missile would be fairly easy (in my head), and it would certainly circumvent the recoil problem (just drop it before it fires). I only ask because the question title says "weapons" and the question mostly deals with the guns. – Jay Carr May 22 '15 at 22:56
• @JayCarr: I discuss guns as I'm more familiar with them and they are simpler. If you can address the issue with missiles, please do! – dotancohen May 22 '15 at 23:35
• Who control the rear gun? – Him Mar 14 '16 at 4:22

Machine guns were fairly effective weapons in WWII and shortly after. However, this was only because the attacking aircraft were also armed with machine guns. Even then, the fighter aircraft could be effective against not only the armed bombers, but also against the fighter escorts.

Bombers of the time did typically have tail gunners. However, this only resulted in a change of tactics, with fighters attacking from a different angle. Defending against one means of attack just means the attackers may choose a different attack vector.

However, the rocket age changed all this. Modern missiles can be fire-and-forget, automatically tracking a target from many miles away. Guns aren't very effective in this type of combat. In fact, it's debated whether fighter aircraft even need a forward facing gun anymore. The gun on the F-35 may not even be usable until after the first squadrons are operational.

At high speeds, the rear-facing gun would have to overcome the forward velocity of the aircraft, decreasing its effectiveness.

One could imagine something like a CIWS being helpful, but the weight and size would not justify the benefit for being included on a fighter, or even a bomber. Modern aircraft have chosen electronic defenses over mechanical ones. These can be lighter, easier to integrate, and are more effective in a wide variety of situations.

However, combining the two ideas and arming aircraft with lasers is still a possibility for the future.

• Slightly off topic, but... RE: aerial missile combat & the F35. Hasn't the USAF learned anything from Vietnam? The A6, F4 and others of that era weren't equipped with any guns because "missiles made them obsolete". A poor decision many paid dearly for. – FreeMan Jul 13 '15 at 12:54
• @FreeMan: There's such a thing as overcorrection. While missiles weren't good enough in Vietnam (especially since battlefield awareness and reliability were too low) 50 years of progress might very well have fixed that. With AMRAAM and AWACS, BVR kills became a reality in the 90's. – MSalters Jul 15 '15 at 19:04
• The unreliability of the missiles was only half the problem; rules of engagement often forbid firing missiles without visual identification of the target, which makes even reliable medium-range missiles worthless. – Russell Borogove Oct 5 '15 at 20:22
• Don't missiles have a minimum range? I don't think they would be effective in a dogfight (as much as the entire machinery is designed to avoid these). – Burhan Khalid Mar 14 '16 at 7:39
• "At high speeds, the rear-facing gun would have to overcome the forward velocity of the aircraft, decreasing its effectiveness." -- while that's true of course, if the following aircraft is at a similar velocity to the firing aircraft, the relative speed of the bullet would still be as high. Possibly higher, as bullet would experience less aerodynamic drag due to a relative "tail wind" of 500mph. – David Aldridge Jul 25 '17 at 12:35

If your opponent is directly behind you, you have lost the fight. The point of basic fighter maneuvering, or BFM, is to keep your opponent off your tail and hopefully get on his. Everything you would learn as a fighter pilot centers around ensuring you would never have to use a rear-firing weapon.

In addition, visibility directly behind the pilot is typically poor; humans can't turn our heads 180 degrees, and if we could we'd be staring at the headrest behind us. A few fighters have had rear-view mirrors, typically ones with a two-piece canopy including the Eurofighter, F-15C and F-14 among others, but the one-piece bubble canopy on fighters like the F-16 and F-22 give no good place to put a mirror that wouldn't further interfere with the pilot's forward vision. Rear-view cameras would be laughed at by pilots as a waste of an MFD.

A cannon firing backward would also be a pretty single-purpose weapon; in a multirole fighter you might get a chance to use it to add insult to injury when pulling out of a ground run, but in all likelihood you'll either have peeled off to one side as soon as you pickled your bombs, or you'll be toss-bombing and not even overfly the target. The only real reason you'd ever fire it would be to keep someone directly behind you on their toes.

• If your opponent is directly behind you, you have lost the fight. That is exactly why (I think) that rear-facing weapons are needed. And the device would be as single-purpose as the ejection seat and other safety systems are. – dotancohen May 22 '15 at 23:38
• @dotancohen Adding an extra 50kg of weight is a significant tip in the wrong direction in determining which plane gets on whose tail, and wins. Having two guns in different directions splits your focus, and has worked best for less maneuverable planes such as bombers. If you've got such good computer targeting that a computer tailgun would have you win that, then you might consider a turret mount instead. – Dronz May 23 '15 at 18:56
• Still, not needing to point the nose of the aircraft to your target to shoot him down is a dramatic change in tactics. You no longer need to be behind him, you just need to bank and yank a bit so that he's within your 120 degree field of fire. – slebetman Jul 14 '15 at 18:52
• Yes, and this was a frightening revelation to NATO forces in the years after the USSR collapse, when Western forces got their first close looks at the hardware left behind in Warsaw Pact nations. The AA-11 Archer was known to be a threat, but U.S. top brass didn't know just how outmatched they were until they watched mock dogfights with East German pilots. This new understanding led directly to the JHMCS and the next generation of NATO IR missiles like the AIM-9X, ASRAAM and MICA. – KeithS Jul 14 '15 at 19:30
• You can't have a camera system that tells you when something interesting happens and that occupies zero screen space the rest of the time? – curiousguy Oct 26 '19 at 16:22

When in a dogfight, you cannot shoot straight ahead without moving into a position which anticipates where your adversary will be when the bullets hit him. This means you need to turn tighter, to get into his circle. When both aircraft have similar specs, this is harder than it sounds.

The Russians once tested an idea which looked obvious at first: Svivel the gun upward, so it shoots into the circle without the aircraft needing to maneuver into the circle itself. They tested this on a MiG-15, but the results were disappointing. As soon as the gun was misaligned with the fuselage by more than a few degrees, the recoil from the gun would cause the MiG to pitch down; the last thing you need in a dogfight.

The lesson is easy: Shooting at an angle from a point far away from the center of gravity will cause control issues and might even be a greater danger to yourself than to your adversary. It might be that a modern FCS can compensate for this, but to my knowledge this has never been tried.

• But a gun pointing backwards will also shoot in line with the CoM like the forward facing guns. – ratchet freak May 22 '15 at 19:15
• @ratchetfreak: In a dogfight the rear-pointing gun will have to shoot into the circle just like the forward-facing gun. Only when the plane is ambushed in straight flight will the gun point along the longitudinal axis, but then I expect the pilot to be unaware of the threat. – Peter Kämpf May 22 '15 at 19:26
• It might be worth mentioning that the cannon on most aircraft actually does point slightly upward, giving the shells a parabolic arc to increase useful range. It's only 2-3 degrees in most cases though. – KeithS May 22 '15 at 22:49
• @KeithS: Correct, but it is not for range increase, but for making the bullets hit at the expected firing distance. The MiG-15 had three guns, one 37mm monster and two 23mm for smaller targets. They were designed to hit a B-29 at several hundred metes, and the higher nozzle velocity of the 37mm gun necessitated a shallower angle. When shooting at a F-86 from a much closer distance, the 23mm rounds would fly over and the 37mm rounds under the target. That is why their kill ratio was so poor. – Peter Kämpf May 22 '15 at 22:55
• I'm actually talking about newer aircraft; the F-16's Vulcan cannon is canted upward about 3 degrees from the stable "velocity vector" of the plane in clean configuration. This upward cant does produce an optimal range (something like 1500 feet), but the plane has some pretty sophisticated targeting modes including a truly ingenious "funnel" mode that account for range even without a radar lock, and with the plane having only one cannon, getting several different guns to hit the same place isn't a concern. – KeithS May 23 '15 at 0:02

Dismissing missiles for a moment, let's focus on fixed guns.

Rear-firing cannons simply make no tactical sense.

If you have an enemy fighter on your six, and in gun range, you need to pitch, roll, circle, and generally maneuver like crazy to throw off his lead aim to avoid getting shot out of the sky.

The very last thing you want to do is to fly in a smooth line lining him up in your (rearward) sights while he blasts you with his (forward) cannons.

That is not even taking into account that aiming the back of an aircraft at a (maneuvering) target behind you is an order of magnitude more difficult than aiming the front of the aircraft at a target in front of you.

So, fixed guns are out. What about remote-controlled, swivel-mounted guns?

This has actually been tried as early as in the Arado Ar 234, albeit in prototypes only. You still face the issue of wasting weight and space on a weapon that can only fire at the enemy if he's right where you do not want him in the first place. Speed, stealth, diversion, all these increase your chances of survival much more than pitting your rear-facing weapons against a fighter's forward-facing weapons.

So, bury the guns. At which point I'll say that I don't know enough about modern missile technology to say if modern air-air missles can or cannot actually engage targets to the rear, and bow out of the question.

Bear in mind this is all speculation:

Firing to the rear could be a bit optimistic; the pursuer won't be straight behind, he may be anywhere in a wide cone behind. (How wide that cone might be, we'd need to ask someone with experience in this area!)

A remotely swivelled cannon would probably be too slow to point anywhere within that cone, as the pursuer will naturally fire as soon as he has a position. Some heavy bombers have cannon (remote or manned) to the rear, but these are unlikely to be used in fast dogfights.

Also note most recent dogfights seem to have involved missiles, see gulf war engagements list. The preferred use for cannon on fighters might be in the ability to use a non-lethal show of force against heavy bombers or spyplanes, in a cold war situation. I recently found this mentioned while reading up about the old Lightning (search that link for "warning shots").

• How the use of cannon is non-lethal? Even tracer round is lethal if hit the right place. – vasin1987 May 22 '15 at 16:40
• @vasin1987: It's not lethal if you miss. Think "shot across the bow". – Fred Larson May 22 '15 at 17:24
• @FredLarson everything is not lethal if you aim to miss. Isn't the presence of escort fighter enough to prove a point more than the provocative firing a canon? – vasin1987 May 22 '15 at 18:53
• @vasin1987 Not necessarily. These confrontations can be a lot more complex than "we have a fighter, so we'll shoot you if you don't obey, so you will obey." Deploying an escort fighter doesn't mean you're willing to take actual action (and create an international incident), so it also doesn't mean the other side will immediately obey. Since actually shooting down an aircraft is typically the last resort, warning shots add a "we are very serious" factor; they aren't something to do lightly, and they are more effective than just a fighter in convincing someone to obey. – cpast May 23 '15 at 1:27
• As for missiles, you can't use missiles as warning shots, because it's much less clear that they aren't actually an attack (missiles having homing capability and all). It's the exact same principle as firing shots across a ship's bow. – cpast May 23 '15 at 1:28

Rear launching missile might be possible, but I think if you have the option of adding another missile, I imagine most pilots would prefer to have it forward facing so they can use it to aggressively attack and destroy an opponent. Dogfight tactics traditionally favour aggressive offensive tactics as opposed to defensive ones, and therefore forward pointing weapons makes more sense. If your enemy is behind you, you've already screwed up.

However the French actually managed to destroy a target behind the launching aircraft with a MICA missile (unsure if it was the radar guided or IR guided variant) https://en.wikipedia.org/wiki/MICA_(missile)#cite_note-4