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Self Harm

All war is tragic. Friendly fire, sometimes referred to as a blue on blue incidents, or fratricide, whilst becoming rarer with advances in technology,* is equally as tragic. Then there are the cases of self-inflicted harm (not all these incidents occur during war time): *More precision and accuracy of weaponry, better intelligence, electronic marking of Friend-or-Foe …

The jet plane that shot itself down

An F11F-1 Tiger, tail number 138620, is a plane that became famous as being the first documented incident of a jet plane that shot itself down!

On September 21st, 1956, Thomas W. Attridge Jr, a Grumman test pilot, was conducting test-firing of the aircraft’s four 20mm cannon (Colt Mark-12) at around Mach 1.0, aiming for a patch of open ocean off the coast of Long Island, NY.

Starting his run at 20,000ft, Attridge entered a shallow dive at 20° nose-down. When he reached 13,000ft, he pulled the trigger for a four second cannon burst, advanced the throttle to afterburner, steepened his descent, and fired a second burst to empty the magazine belts. Whilst firing, his plane continued in the descent, passing through to 7,000ft

About a minute (and 2.7 miles) after the first volley, he was hit by the first bullets he’d fired himself!

Even though the bullets were initially travelling well over 2,000 mph (the speed of the plane plus the muzzle velocity of the cannon), they slowed down quickly due to drag. Also, Attridge’s plane continued to accelerate in afterburner fueled descent, and the cruel consequence of these coincidences was that both entities ended up occupying the same space at the same time. Unlucky!

Attridge became aware of the incident when the plane rattled, and his windshield buckled inwards, He’d been hit.

Attridge throttled back to slow down and prevent cave-in of the windshield (His thoughts were that maybe he’d had a bird strike), and attempt to fly back to Grumman's Long Island field at 200 knots. He radioed that a gash in the outboard side of the right engine's intake lip was the only apparent sign of damage, other than for the glass but, more worryingly, only 78 percent engine power was available without severe roughness.

Two miles out, at 1,200 ft with flaps and wheels down, it became evident from the sink rate that the runway could not be attained at this low power setting. Attridge applied power, and is quoted as saying the engine made a noise like "a Hoover vaccum cleaner picking up gravel from a rug."

Shortly after, the engine lost power completely. He pulled up the gear and dead-sticked a landing, settling into trees, half a mile short of the runway. He gouged a path 300 feet long in the decelerating impact (losing a right wing and stabilizer in the process); fire broke out from the unburnt fuel. Despite injuries, Attridge managed to cut himself free of the plane and get far enough away from the crash. The Sikorsky S-58 helicopter dispatched to retrieve him also damaged its blades from contact with foliage during the rescue.

A post-accident investigation revealed that Attridge’s aircraft had been hit by three of the 20mm bullets he’d fired. The first penetrated his windshield, the second punctured the nose, and the third damaged the right engine intake, struck the inlet guide vanes, and lodged in the first stage compressor of the engine. This bullet was recovered and a picture of it is shown on the left.

Attridge survived the crash with a shattered leg, and three broken vertebrae. He successfully returned to flight status less than six months later, and continued on to a long and distinguished career in the aerospace industry, becoming the project manager of the LEM-3, the first lunar module rated for human flight (flown on Apollo 9), and later as VP of Grumman Ecosystems, the company’s environmental management and research venture.

Blue Angels

Interestingly, the F11F saw limited service as it was eclipsed by two more modern aircraft: F8U Crusader and F4H Phantom II. Tigers finished their service in the Naval Air Training Command and as demonstration aircraft with the Blue Angels, who flew the F11F during the period 1957-1969.

Propellers

The F11F is the first documented case of a jet powered aircraft shooting itself, but in the early days of fighter aviation, many propeller aircraft shot themselves with their own machine guns. On single engined aircraft, this problem was solved with the invention of a synchronization gear (sometimes called and interupter gear), which prohibited the guns from firing through it's own propeller disk when the spinning propeller was in the way on the muzzle! A great invention.

Missiles

The Tiger incident educated pilots of fast planes that maybe they should make gentle turns after firing guns (to remove the chance they’d fly into their own bullets). The next challenge is missiles.

Hollywood movies might show aircraft firing missiles and then, through some circumstance or other, getting "locked on" by their own ordnance and shooting themselves down, but I know of no reported incidence of this ever occuring.

For a simple explanation about how missile guideance systems work, here is an article.

What has happened (again to a Grumman Test Pilot), is a malfunction during a test of a Sparrow missile firing from an F-14. Normally when a missile is 'fired' it is released from the plane and drops a safe distance away from the aircraft before its motor starts.

On this particular test, the missile was to be released at transonic speed and under zero G load (so there would be no gravity assistance helping the missile seperate away from the plane. Small explosives help seperate the missile from the plane and gently push it away, but due to slight differences in the variant of the missile being used for this test, a smaller quantity of explosive than is normally used was installed.

An unfortunate consequence of all these circumstances resulted in a missile that released and then ignited whilst still too close to the launching aircraft. The missile severly damaged the plane, causing an engine fire, loss of control, and loss of the aircraft. Both crew succesfully ejected. There's a great write-up of the incident by the pilot Pete Purvis, entitled The Day I Shot Myself Down. It's a good read.

Submarines

Changing media, what about torpedoes and under water combat? Has a submarine every shot itself with it's own torpedo? In the Tom Clancy book (and subsequent movie) The Hunt for Red October, Topolev, the Captain of the Alfa-class submarine Konovalov ends up shooting himself after disabling the 'safety range' of the second torpedo he fires at Red October, but this is fiction. Has anything like this happened in real life? Actually, yes, a few times!

The most documented of these cases is the USS Tang. After a short, distinguished, and deadly service (sinking 33 ships, totalling 116,454 tons), on the 24th October, 1944, the Tang fired the last of her 24 torpedos which took on a circular arc and swept around to hit herself before she could maneuver out of the way.

If a (non-stearable) torpedo is fired and (due to gyroscope or rudder issue) does not run straight, then a fixed rudder error will cause the torpedo to travel on a circular path. If the radius of this path is tight enough that the torpedo does not run out of fuel, and it does not collide with something else along the way, it's going to end up at the same spot from which it was fired after a complete 360. If the submarine is still there, it's going to get hit.

It's probable that the USS Tullibee suffered a similar fate, as well as U-boats U-869, U-377, and U-962.

Torpedos can also be launched from surface vessels, and in 1942, a British cruiser, HMS Trinidad, was taking part in Arctic convoy duty when she engaged the German destroyer Z-26. Although she sank the destroyer, one of the four torpedoes launched by Trinidad had a faulty gyro mechanism (possibly having been affected by the icy waters), causing that torpedo to make a circular run and strike the Trinidad.



Kursk (K-141) Image: Wikipedia

Self-harm torpedo incidents have also occured before the torpedo has even left the launch tubes. On August 12, 2000 a tragedy occured on the Soviet submarine Kursk (K-141), when a dummy torpedo exploded in the launch tubes during a naval exercise. Speculation is that dummy torpedoes (no warheads), are manufactured to a lower safety standard, and a poor weld allowed the release of the highly concentrated Hydrogen Peroxide used for part of the propellant. The subsequent explosion caused the loss of the submarine and all 118 personnel perished.

Related incidents

Returning to planes, there are other accidents that have occured that, whilst not strictly self harm from self-shooting, are related.

During (yet another test flight) An F/A-18 Hornet accidentally hit a TA-4 Skyhawk with a (concrete filled) test bomb it released. The TA-4 was flying as a chase plane for the test, and was destroyed. Here's a video of the incident. Miraculously, the pilot of the TA-4 was able to safely eject from the fireball that his plane turned into. Here's a link to a video of more weapon jettisons (and an external fuel tank release) that went horribly wrong. Here's a photo showing a released bomb about to hit another B-17 flying below it.

Warthog

There is a US plane called the A-10, affectionately known as the "Warthog" (or sometimes "The Tank Killer"). It's not a pretty plane, but it has a really big gun* (it's almost as if they got a big gun, and built a plane around it). The gun is so powerful that there is an internet legend that the reaction of firing the gun can slow the plane down so much that it would stall. Therefore, the pilot has to fire the gun in short bursts. This is bogus! *The cannon in the A-10 is one of the most powerful guns ever flown. The 30mm cannon fires depleted Uranium shells at a rate of 3,900 rounds/minute.

Well, it's partially true, the gun is fired only in short bursts, but not for this reason (if you do the math you'll quickly realize that the mass of the plane is many thousands of times more than the mass of the projectile, so even with a high muzzle velocity and a high rate of fire, it's going to do very little to the momentum of the aircraft).

The reason for the burst firing is because of the products of cumbustion from the propellant of the shells. The gasses generated by the combustion of the propellents get sucked into the engines, reducing the partial pressure of oxygen, and this has the potential to cause flame outs (this actually happened in testing). In addition to recommending the gun be fired in bursts, the engine is now fitted with electric re-ignitors that come on when the gun is fired.

Shorter burst of fire also reduce the heat generated and help preserve the life of the barrel.

Don't shoot up!

Finally, if these things have not warned you enough, if you own a gun, please do not shoot it up in the air in celebration event.

Not only is it illegal in many states and countries (for good reason), it's really dangerous. What goes up, much come down, and each year there are many deaths and injuries from falling bullets (and property damage).

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