Why don't fighter planes have backwards pointing guns?

December 23, 2006 2:16 PM

Why don't fighter jets (in real life or in those classic movies) have backwards pointing guns and missiles to shoot down their chasing adversaries in dog-fights?

I'm thinking in movies like Top Gun. When they are in the air fighting often one plane is chasing another one trying to shoot it down. The chased plane just tries to get away. But why couldn't they have backwards pointing guns or missile launchers to luck onto their enemy?

posted by names are hard to technology (33 answers total)

Remember the third Indiana Jones movie? Planes that could fire in 360 degrees existed, but I imagine someone decided that the ability to shoot your own plane's tail isn't necessarily a plus.
posted by MsMolly at 2:41 PM on December 23, 2006

I'm no expert, but I think the philosophy these days is that close quarters dogfighting is a thing of the past. Pilots can locate and attack thier enemies from so far away and with guided weapons that maybe it doesn't really matter whether they are directly in thier line of fire - the missles are guided to the target anyway.

I do know though that some planes from the wwI through wwII era had rear facing gunners - the Stuka Dive Bomber, for example.
posted by blaneyphoto at 2:42 PM on December 23, 2006

If you can shoot someone with your rear facing guns, they can more easily shoot you with their forward facing ones. You don't want to be in this position.
posted by smackfu at 2:44 PM on December 23, 2006

Not guns, because modern fighters often fly faster than bullets do. If you fired a machine gun out the back of a fast jet, the bullets would be traveling fast in relation to your jet, but slowly in relation to most other things (and in the same direction as your jet). Rockets don't need to be initially pointed toward their target. A rocket targeted on something behind your jet, and fired forward, would turn around and fly back to meet the target.
posted by Kirth Gerson at 2:45 PM on December 23, 2006

It's not a fighter, but here's a pic of a B-52's tail guns
posted by buggzzee23 at 2:51 PM on December 23, 2006

I imagine someone decided that the ability to shoot your own plane's tail isn't necessarily a plus.

I can't find the article (I thought it was on DamnInteresting.com), but planes that have guns that could hit the tail have a solenoid that prevents it from firing, muh in the same way the timing device worked to sync the gun and propellor.
posted by niles at 2:57 PM on December 23, 2006

Many planes used to have 'em.
posted by Exchequer at 2:59 PM on December 23, 2006

Wikipedia thinks tail guns are obsolete:

The tail gunner found heaviest use during the World War II and early Cold War years on large bombers, but the position has become largely obsolete due to advancements in ranged air combat armaments such as air-to-air missiles as well as modern detection and countermeasures against such armaments.

Here's a partial list of the plans that had 'em.
posted by Exchequer at 3:03 PM on December 23, 2006

Firefox in the Eastwood movie did
posted by A189Nut at 3:31 PM on December 23, 2006

As other people have pointed out missiles have basically made tail guns (and all gun turrets) redundant. But even before missiles a tail gun in a fighter would have reduced the planes ability to perform its primary mission. Fighter planes tend to be very specialised: you have fighters, interceptors, ground attack, recon, EW, wild-weasel and so on. They're not designed to do everything, nor are they designed to defend against everything.
posted by schwa at 3:32 PM on December 23, 2006

Note that only one of the planes on the list Exchequer linked to is supersonic. In fact, even forward-firing machine guns fell into some disfavor when planes became fast enough to shoot themselves down.
posted by Kirth Gerson at 3:38 PM on December 23, 2006

If you fired a machine gun out the back of a fast jet, the bullets would be traveling fast in relation to your jet, but slowly in relation to most other things (and in the same direction as your jet)

Still could work - the guy chasing you is moving at about your speed, and so that bullet that's basically hovering behind you (OK, falling) is still going something like mach 2 from his perspective. Of course, this doesn't address the other obsolescence issues people have brought up.
posted by rkent at 3:55 PM on December 23, 2006

It's worth noting that the target acquisition systems of modern AAMs rely on radar (some older AAMs were heat-seeking). Both radar and IR don't work very well through your fighter plane's jetwash, which is hot, extremely turbulent, and going through a mach transition if you are supersonic.
posted by ikkyu2 at 4:05 PM on December 23, 2006

Maybe someone with actual experience will chime in, but:

I'm not aware of many fighters that have had tail guns. The P-61 did, but it was a purpose-built radar-equipped night fighter that was very far from traditional fighters.

What fighters use to shoot down planes behind them is their front-firing guns, and maneuvering. There are a variety of ways that you can manage your energy to end up behind an unwary pursuer. Bombers had tail guns and other guns because they're big and ungainly and can't do a 9-gee yoyo.

A back-firing gun on a fighter seems bad for a lot of reasons. First, given the weight-restrictions that planes live and die by, having one gun firing backwards and its associated ammunition is one less gun firing forwards, or substantially less ammunition for each normal gun at the very least. It seems like this would be even worse with modern missiles and their associated radars.

Second, I'd guess that it would be a pure bitch to aim. You'd normally expect it to be a deflection shot of some sort, and that's hard enough firing forwards in the way that you've had lots of practice doing and without having to crane your neck around until it hurts.

Third, fighter combat is inherently aggressive. At least, pilots who survive do so by aggressively engaging enemies (and refusing to engage). If I were designing a fighter, I would assume aggressive rather than defensive pilots would do everything that I could in the design of the aircraft to enhance and focus the pilot's aggression. Not having a tail gun on a fighter is like putting the thickest armor on the front of a tank -- it reflects how the weapon is intended to be used.

Fourth, fighters don't fly alone, at least not in air forces that win aerial supremacy. You shouldn't need a rear-firing weapon if you have a wingman who can maneuver into a position where he can shoot down Mr. Bandit with his plain-old front-firing guns or missiles.
posted by ROU_Xenophobe at 5:23 PM on December 23, 2006

Read somewhere that there have been experiments with radar-controlled missiles that can launch normally, but turn to attack in any desired direction. Over-the-shoulder missile fire, if you will. But obviously, turning 180 degrees uses up a lot of fuel. Best to never have to get into this situation at all, and use advanced radars to see the enemy earlier and vector to his position in a more advantageous way.

After all, dogfighting is like using a bayonet. Sure, you might need to use the bayonet, so train for it. But better to shoot the guy from a distance in the first place...
posted by frogan at 6:28 PM on December 23, 2006

Not guns, because modern fighters often fly faster than bullets do.

coughBULLSHITcough

Military ammunition travels upwards of 1000 meters per second.

A jet travelling above Mach 2 is doing at least 2120 kilometers per hour. Now pay attention:

2120 kilo*1000= 2,120,000 meters per hour

60 minutes in an hour and 60 seconds in each minute = 3600 seconds in one hour

Thus, a jet at Mach 2 is doing 2,120,000 meters per 3600 seconds.

Or 589 meters per second.

You don't even need to do the math to realize the idiocy of this statement - how the hell could a jet fire bullets that travel slower than the jet is?

Seriously.

That said, I'm going with this guy:

If you can shoot someone with your rear facing guns, they can more easily shoot you with their forward facing ones. You don't want to be in this position.

In modern dogfight, the focus is on losing your tail and/or putting him in a compromising position with your wingman. Pilots have enough to focus on doing that, let alone shooting at something behind them.

That said, if they could design some kind of computerized target acquisition and firing mechanism - like the SeaBee anti-missle guns that some Navy ships have...that would be pretty cool.
posted by allkindsoftime at 6:31 PM on December 23, 2006

What a lot of other people said, but to emphasize why they were not used that much even by WWII.

1: Weight. Each extra pound cuts off a chunk of range, speed, maneuverability, and ammunition.

2: I don't think the actual mechanics of air combat often worked by getting on the tail of a target. Instead, the strategy involved strafing the areas where you expect the enemy to be sometime in the future and gambling that your target's path intersects that of at least one of the bullets. The attacker is more likely to be coming from above to take advantage of gravity or from the flank trying to cut off your direction of travel. Even in "tailing" another aircraft the two are not going to be in a neat straight line.

3: By WWII, air combat was less one-on-one combat, and more combat between teams. Defensive fighters attempted to protect a specific resource (such as a carrier) by controlling the airspace over the resource, and offensive fighters attempted to disrupt the defense. So your best defense is was often the other members of your squadron, friendlier airspace, or running in the hopes that your pursuer will break off to deal with a more critical objective.
posted by KirkJobSluder at 6:45 PM on December 23, 2006

Modern dogfighting occurs beyond visual range. Any aircraft that depends on closing to a range where guns (BTW, they are cannons -- at least 20 mm in the case of the F-16) would be effective would be knocked down early in the fight.

Missiles cannot be fired forward and loop back to engage a target. Almost every A-A missile I know of has the seeker on the front end. The body of the missile would block any target behind the missile. Since almost all A-A missiles lock on before launch, they can't be launched and expected to do a 180 and acquire a target.

As ROU_X notes, there are maneuvers designed to give a wingman a shot at someone on your tail. Failing that, that's what chaff and jammers are for.

The crap in Top Gun was pure movie fantasy. Fighters just don't get that close to each other anymore, but the camera shots would have been boring otherwise.

BTW, allkindsoftime, you forgot the aspect that the jet will sustain thrust indefinitely, but the shells from the cannon only have thrust when they are first fired. They will begin slowing down immediately after they leave the barrel, eventually slowing to below the jet's speed. The jet could then fly through them and suffer damage.
posted by forrest at 7:40 PM on December 23, 2006

The jet could then fly through them and suffer damage.

IIRC, this has actually happened on rare occasions.
posted by ROU_Xenophobe at 7:51 PM on December 23, 2006

The Russians have missiles that uses thrust-vectored exhaust for steering. The target is designated up to 45 degrees behind the pilot by a tracking system tied into his helmet that looks similar to the old TOW missile guidance system in the Cobra helicopter.

Russian AAMs, AGMs and SAMs have always had a slight lead on similar American models, in part because at the end of WWII, they got all of those German missile designers while we got von Braun and the V-2 gang. Hinted at here.
posted by atchafalaya at 8:45 PM on December 23, 2006

You don't even need to do the math to realize the idiocy of this statement - how the hell could a jet fire bullets that travel slower than the jet is?

Well, math aside, we are talking about firing backwards. If I throw a baseball backwards from a car moving at 60mph, the baseball's groundspeed (or airspeed) will be slower than the car's. If a 900m/s bullet is fired backwards from a plane moving at 550m/s forward (airspeed), that bullet's initial airspeed is going to be 350m/s.
posted by knave at 9:30 PM on December 23, 2006

Well, math aside, we are talking about firing backwards. If I throw a baseball backwards from a car moving at 60mph, the baseball's groundspeed (or airspeed) will be slower than the car's. If a 900m/s bullet is fired backwards from a plane moving at 550m/s forward (airspeed), that bullet's initial airspeed is going to be 350m/s.

When the pursuing aircraft then flies into the bullet at 550m/s, the damage is just the same. The thrown baseball might fly a short distance as far as a stationary observer is concerned, but it might go right through the windscreen of a following car if you've got a good enough pitching arm.
posted by tomble at 10:05 PM on December 23, 2006

Oh, and here is an interesting discussion of this very topic, in particular rear firing missiles.
posted by tomble at 10:09 PM on December 23, 2006

Since this thread is sort of branching out, it's worth pointing out that the WWII-era B-17 bomber, among others, had a tail gunner turret. The life expectancy of a tail gunner in combat was about 30 seconds; my father, an armorer-gunner on a B-17, lost 3 tail gunners over 12 missions.

One of the reasons for this was that the German Messerschmidts had .63 calibre guns with a range of about 1200 yards; they could fly a pursuit curve until they came in range of the B-17's .50 cals (about 1000 yards), then turn their armored belly towards the bomber and veer away. In the intervening 200 yards picking off the tail turret gunner was essentially like shooting a fish in a very small barrel.

My father, always an enterprising person with the head of a mechanical engineer, obtained a spare 20mm cannon from somewhere and jury-rigged it into the .50 cal waist gun mount of a B-17. He obtained a belt of high explosive armor tearing ammunition and dropped 12 German fighters on his next mission. None of the kills were confirmed and he was met on the landing field, hauled in before top brass, reprimanded, and lowered in rank when his plane returned to base.

The Millenium Falcon, from the Star Wars series, had laser turrets that would point towards her stern; in some of the derivative works, this was pointed out to be a consequence of her ability to outrun other vessels.
posted by ikkyu2 at 10:23 PM on December 23, 2006 [5 favorites]

That's awesome, ikkyu2. Thanks for that.

Answer to the question:
Modern air-to-air combat occurs so far out that the determining factors are radar range/strength and missile range. Check the stats on the AMRAAM. Everything else is really just kind of ancillary.

If it makes you feel better, modern thrust-vectored fighters have such maneuverability relative to the range combat occurs at that actual facing at the time of contact is almost a non-factor.
posted by Ryvar at 5:48 AM on December 24, 2006

None of the kills were confirmed and he was met on the landing field, hauled in before top brass, reprimanded, and lowered in rank when his plane returned to base.

I'm curious enough to further derail the thread (in my defense, the question has been pretty thoroughly answered): why the hell did he get in so much trouble for shooting down enemy planes? I can understand "Congratulations, but next time clear it with HQ first," but lowered in rank?? WTF?
posted by languagehat at 9:02 AM on December 24, 2006

The F-16 was mentioned.... it only has a few seconds worth of bullets (I think 10 seconds); the primary weapon is the AAM. However, there were enough cases of fighters during the Vietnam era that had no guns, only missiles (or rockets), that expended their missiles and had to break off engagements that when the F-16 came into service, it was decided to put the gun back in, just in case. (Guns are also used for ground attack.)

So forward-facing guns are of marginal use as it is. Rear facing guns are not more useful than missiles, and of no use in a ground attack mission.
posted by Doohickie at 3:47 PM on December 24, 2006

why the hell did he get in so much trouble for shooting down enemy planes?

I think the answer can be found somewhere in the pages of Catch 22.
posted by Pollomacho at 6:05 PM on December 24, 2006 [1 favorite]

why the hell did he get in so much trouble for shooting down enemy planes?

Possibilities include:

(1) The story is bullshit. This isn't to say that ikkyu2's grandfather lied to him, only that he told ikkyu2, a civilian, a bullshit story.

(2) He also made large holes in other B-17's.

(3) It was a damnfool thing to do because:
(3a) It fucked up the weight distribution of the plane
(3b) It meant he didn't have nearly enough rounds to last the mission
(3c) The greater recoil fucked up the gun mounts
(3d) Even if he didn't put holes in other bombers this trip, the longer range meant that he was very lucky not to have done so.

Of these options, I would pick (1) if I had to bet. I mean, 12 kills in a single mission? From a waist gunner? All of which were miraculously unseen by the thousands of other people on the mission?
posted by ROU_Xenophobe at 6:54 PM on December 24, 2006

I am not certain of anything; my father was very reluctant to talk about WWII, and he told me this story when I was very young (7?) and possibly badgering him for war stories. I may have remembered it wrong, too. Unfortunately at this time he is no longer available to correct my account.

I seem to recall him telling me that the sort of ammunition he loaded into the chain gun was intended for tactical use (i.e. anti-buildings); using it primarily against enemy soldiers violated the Geneva conventions?
posted by ikkyu2 at 10:35 PM on December 24, 2006

Also, he told me this story: His fourth tail gunner, a raw recruit, asked him to confirm a kill only a couple of hours into a mission.

He had shot down a British Mosquito, a friendly fighter escort out of Dover.
posted by ikkyu2 at 10:36 PM on December 24, 2006

In case you see this:

I seem to recall him telling me that the sort of ammunition he loaded into the chain gun was intended for tactical use (i.e. anti-buildings); using it primarily against enemy soldiers violated the Geneva conventions?

That's true of plain-old .50BMG rounds, IIRC. At least, there is a consistent urban myth that the .50BMG is theoretically an antimateriel round and not an antipersonnel round.

I didn't mean anything negative about your granddad, for what it's worth. Where I say "bullshit" you might think of "fable intended to illustrate some point that's itself true, even if the specifics used to illustrate it don't have to be."
posted by ROU_Xenophobe at 10:05 PM on January 8, 2007

He was prone to that kind of thing, Xenophobe - it was Dad, not granddad - so I don't know. In fact, I'm not sure now that he told me this story; I might have read it somewhere and talked about it with him. Long time ago.
posted by ikkyu2 at 1:47 AM on January 26, 2007