Episode 10: Explosive Decompression, Frog Giggin’, Rear Axle

Air Date: January 18, 2004

Explosive decompression can occur when a bullet is fired through the fuselage of a pressurized airplane, causing the hole to grow dramatically and possibly cause the plane to break up as seen in movies.

busted

The pressure is not high enough and the hole is too small. Explosive decompression only occurred when a hole the size of a window was made with explosives. Even then, the rush of air could not suck Buster completely out of the hole. Lastly, there are proven instances of explosive decompression where the plane was still able to maintain control and land.

(This myth was revisited in episode 38 and it was re-busted.)

A group of hillbillies use a live .22LR cartridge as a makeshift replacement for a burned-out fuse in their truck, but while the truck is driving, the bullet heats up enough to discharge, hitting driver in the groin and causing enough damage to require surgery.

busted*

The bullet did work as a replacement fuse, however when a short circuit was created, the wiring fried and the bullet did not fire. When the wiring was upgraded to a higher gauge, the bullet did fire out of the fusebox, but not with enough velocity to cause any serious injury.

*Though both Adam and Jamie admitted that the myth was plausible from their tests, they had to call it busted due to a lack of conclusive evidence, and the fact that they didn’t have a "plausible" verdict during the first season.

A steel cable, attached to both a street light post and the rear axle of a police car, will be able to yank the rear axle clear out from under the car when it tries to drive off, as seen in American Graffiti.

busted

The rear axle was able to be pulled loose, but only after several bolts securing it were removed. Additionally the axle was caught along the underside of the police car and could not clear the trunk. Adam and Jamie theorized that, in the movie, a ramp was used to give the car and axle enough of a boost to wrench the axle completely free.

37 Comments

  1. Lara says:

    Would the outside pressure of the plane not be the cause for a decompression on the inside.

    From my understanding of planes is that the pressure on the inside is set to that of being on the ground, where you can breathe normally. But if you are at a high altitude the pressure on the outside is substantially lower. If you puncture that pressure, because the outside is so much lower and so much more in quantity it would be like a vacuum sucking it out??

    If you reversed the scenario thus making the pressure on the inside substantially lower and you fire from the outside – you might have an explosion into the plane – if that makes sense … either that or I’m just not thinking logically and losing my mind.

    • Don Ramsey says:

      As Lars says, your experiment was done at ground level where the air pressure was the same inside and out side, if the experiment had taken place at 35.000ft the aircraft decompression would drag anything near the rupture of the aircraft out of the aircraft making the hole bigger. (but not an exlposion).

      • Chris says:

        Airplanes are NOT pressurized to match the pressure at ground level. Normally, an airliner has pressure that is maintained at 6,900 feet (2,100 m) when cruising at 39,000 feet, the Boeing 787 Dreamliner is 6,000 feet, the Airbus A380 features 5,000 ft and the Bombardier Global Express business jet features 4,500 ft.

        • MTP says:

          It is all about pressure differential!!!! Did these people sleep through basic science class? No wonder why we are in so much trouble.

          • Patito says:

            I love storys like this bcuz she’s lived it and been thru it all right down to linvig on the street. I know Ally personally and can tell you that what she’s saying to you on this bloog is real and truthful. Her and Jimmy are survivers and are recovering addicts who still struggle to get thru each day, one day at a time! And whats even more amazing is that they are useing their past experiences to reach out to others and try help them with whatever means is available to them which is the reason for this blog. So if your homeless or need help plz know that they are here for you. Keep up the good work u2!

  2. Roy Ford says:

    Police Car. It happened some years ago at Tamworth there was a highway patrol office that always was upsetting the locals. They padlocke a chain to a power pole and put a chain arounded the back axle. They also put the chain around over the tail shafte. When the ofice took of in pusuit the back axle was compltely removed from the police car

  3. Barry Schroeder says:

    Police car. I’ve never heard of it happening but it may happen with a 1960s period car a late model car has alot more support bars than a 1960s period car which only had leaf springs

  4. Shawn says:

    I’m in agreement with Lara. A plane at altitude would have low pressure outside so the outward rush of air would be greater.

  5. Ekrem says:

    I agree With Laura and Shawn:
    The matter is not the outside air speed that makes low pressure. At this altitude (plane cruise) the outside air pressure is already very low (even if the plane isn’t moving).
    Their argumentation is deeply wrong.

    THIS MYTH ISN’T BUSTED (yet)
    try harder next time.

  6. Aaron Wyse says:

    I agree with Barry; When I first viewed the episode; I saw the late model car with the locating arms and knew it wouldn’t come free. A basic leaf spring rear suspension would stand a much more realistic chance of ripping out. Needs to be redone.

  7. Michael says:

    Plane:
    I think the myth was not really busted.
    In my opinion the speed of the plane causes a much more suction. When you drive your car and open the window, it´s possible that some loose things will flow out of the window…. and a plane is much faster than a plane (and there is the pressure difference)

  8. GRANT says:

    Rear Axle. I agree a period car should have been used as these have a leaf spring set up which can actually rip out.( I hit a tree stump at about 60KM/hr and tore out the front spring mounting points). The car they useed has what is called a four link setup these are more robust and have stronger mounting points than the leaf setup. Needs to be redone

  9. Shona says:

    If you watch the episode, they increased the internal pressure of the plane while on the ground to an equivalent internal to external pressure as a plane at altitude. Don’t assume they’d be dumb enough to forget the pressure difference.

  10. nutwrench says:

    I have been working on cars since 1972. I have seen cars go from points&codensors to distrbutorless sequential port fuel injection systems with anti-lock brakes&front&side airbags. I agree with Grant. The car in the movie was a early 60′s Ford, the car you tested was a late 90′s(or newer)Ford. I say this is like apples&oranges. The older car only had 4 u-bolts &2 shocks holding it, wereas the newer car had a 4-link rear suspension with coil springs & a sway bar & oh yeah 2 shocks holding it in place. I say you need to re-do your test with an older model car that has a leafspring rear suspension to find out if this really did happen in the movie, I think you will find out that it really did happen, because the older suspensions were’nt as stout as the newer ones we have today. Thanks Nutwrench(ASE master auto. tech. since 1981)

  11. D Jorgensen says:

    The decompression myth was busted before it began. The B-24 Liberator was the first Allied military aircraft to benefit from a pressurized cabin. Hundreds of them were damaged by enemy fire, depressurized violently in flight, and survived, 20 years before a movie gave birth to the myth.

  12. rocketscientologist says:

    Of course, I believe it is the outside pressure that has an effect on the depressurization, and I believe it is an element that has not been properly investigated on the show. I know how they could test it properly though, email me if you need the details…

  13. rocketscientologist says:

    and I think the test they did was not to crash the plane but at least suck out a window9shot out from inside by a bullet) plus a buster or so…

  14. rox says:

    rear axel, i worked in a suspesion shop for 12 years on everything from cars to cranes i agree with everyone else this one needs to b redone using a period car the one adam and jamie used is a lot newer and stronger lets do it again guys

  15. Stan says:

    The myth that was busted Re:Rear axel, from the movie American graffiti needs to be revisited because the car used in your show had coil suspension and the police car used in the movie had leaf spring suspension. Cars from the 50s-60s era were made alot simpler. Give it another go guys !

  16. Bill says:

    Redo the american grafiti car stunt with an old school leaf sprung car. IF it got enough velocity it would likely work. It would at least pull apart the drive shaft slip yolk anf likely wrench the axle free, if not tear the spring shackles.

    (Journeyman mechanic and wannabe mythbuster)

  17. Kim says:

    Plane: The fact remains that explosive decompression does occur. see: TV series “Mayday”, British Comet, Hawaian Airlines, others. Try explaining the “myth” to the family of the airline attendant or to the pilot that was partially sucked out the window.

  18. Paul T. says:

    the explosive decompression can only be proved it the boys get a commercial jet, go to a altitude of 30,000 ft, and shoot out the window. There is no air pressure at that altitude. So if you have pressure on the inside greater to the outside, then you will get a vacuum effect. Remember, a plane pressurized at sea/ground level will not vacuum out. It will just equal out.

  19. What? says:

    Planes don’t hold the sea level pressure. They have a higher pressure than the outside, but only enough to keep you comfortable. You know when your ears pop? That’s pressurization. Or do people still think that is the magic pixie fairies that do it.

  20. josh stephens says:

    jamie this is josh a gine i like you ok but i thank adam is a litte bit cooler jamiecan you to emil me back bye.

  21. Randy N says:

    I found this online: >>>The scene in which the rear axle of a police car is pulled completely off was proven unlikely to actually happen in an episode of MythBusters. The hosts of Myth Busters theorized that a ramp was used in American Graffiti to give the car and axle enough of a boost to wrench the axle completely free. Lucas was able to achieve the stunt without a ramp as the hosts of Myth Busters had surmised. The act of damaging the patrol car in the film was meticulously planned. The entire rear axle of the car was cut away from the frame and body and the cable. The real event involved a heavy cable being attached. The other end of the metal cable was not attached to a light pole (as in the story) but rather to a winch on a heavy-duty 10-wheel tow truck that was parked in the darkness at the far end of the lot. As the car sped away from its parked location, at the exact moment when it crossed the sidewalk, the winch was activated. The pulling of the cable along with the force of the forward moving car caused the axle to be effectively yanked from beneath the car.[4].<<<

  22. Ben says:

    It seems to me that almost all of the failed experiments were due to lack of details oriented planning. Every time I watch this show I get frustrated with the apparent disregard to planning. I’ve personally seen better planning and mechanical expertise in my industrial arts class in high school. I hate to say it but these guys are amateur and will never appear to be anything but unless they have good help.

  23. AndyB says:

    Explosive decompression…
    I can’t comment on the explosiveness… but did the ‘bust’ allow for the presure difference between inside (usually at 0.8 – 0.9 bar or atmos.) and pressure at 30 -40,000 ft?
    There’s also the possibility that the Bernoulli effect: jet planes are travelling at mach 0.8… that’s a huge amount of air rushing past a hole in the fuselage to cause a good deal of lowering of the effective pressure outside… was THAT taken into account? -I imagine not…

  24. leon says:

    Hi about the axils being yanked out, this happened to me twice. I had a 72 for pickup with no rear bumper, I was in the process of pulling out a palm tree with a heavy cable attached to the axil, I performed slow tries with the granny gear only to leave tires smoking and spinning, I had the bright idea to use my truck’s weight using distance and speed, I ended up destroying my leaf springs parking cable and shocks the axil bounced back into the tree. the second time I was driving my jeep wrangler on the San Diego highway in California, was going 80 when I saw several stopped cars and a flipped over tow truck, my big tires whent over the trucks mechanical equipment and sent me atop the center divider , the center divider tore my rear axil off, the jeep ended up in the center of the other direction , I was able to drive/drag to the side with my front axil. I still drive that jeep.

  25. Bertie the Bunyip says:

    One, the B24 was not pressurized, the B29 was, however.
    Pressurisation can compound damage suffered from a gun or explosive device. Typical modern aircraft are pressurised to around 8.5 PSI or so, and while this may not seem much, if you translate that into something the size of a passenger entry door, say 3200 sq inches, you’re looking at a considerable amount of force. In this example, about 27,500 lbs, which gives some idea of the forces involved.
    Several airplanes with structural design flaws were lost this way in the early days of pressurised flight, most notable the Dehavilland Comet, two of which were lost when a fracture occured at the corner of a panel used to cover a navigation antennae.More recently, a fatigue crack expanded rapidly on a Boeing 737 in Hawaii causing the top half of the fuselage to seperate. This airplane survived, incredibly, but most that had similar serious damage did not. A JAL 747 for instance as well as a Taiwanese 747 both bet their doom because of a poor repair done on the pressure vessel of the aircraft. The speed of the passing airflow is not a significant factor in the differential of the inside and outside of the cabin and a ground level test where the cabin is pumped up to the pressure experienced in flight is valid as near as makes no difference.
    The preceding statements, notwithstanding, a bullet hole or even small explosion in a non critical area of aircraft skin is unlikely to cause enough structural damage to allow the hole to cause a massive rupture of the pressure vessel. Like most of these things, though, hit it in just the right spot under just th eright conditions and add in a bit of fatigue or damage in the area and it is entirely possible that the aircraft will break up in flight.

  26. Jim Dixon says:

    I know that “frog gigging” means hunting frogs with a “gig,” or forked spear. Does it have another meaning? Why is frog-gigging mentioned in the title of this episode? I don’t see any connection.

  27. troy martin says:

    rear axle should work just like in the movie if a leaf spring car is used.

  28. Gord says:

    James Bond got it wrong again: “Goldfinger” really sucks!

  29. Lorne says:

    I agree with Don Ramsy. The feusalage used was not full size it was done on the ground without air travelling passed it at typical jet pace. Although at low pressure there would be so much more air to be forced out of a small hole while a vaccum would be created by the air rushing past it on the out side. Some things just need to be done full scale to be busted or confirmed.

  30. Tim Buell says:

    My dad and a couple of his friends ripped the axle from a police car in Williamston,MI sometime between 1940-1950. I wish I could find an article about it in the Lansing State Journal.

  31. Aaron says:

    Bertie the Bunyip knows what hes on about

  32. Brien Cranford says:

    Dear Jamie and Adam please revisit this, it’s not the decompression that would be the problem, it’s the fact that there is hydraulics and electronics as well as fuel in various area’s of a aircraft that could cause serious damage to a airplane if there was a gun discharged within it. So while explosive decompression is not what Hollywood would like us to believe there is still ample reasons not to fire a finishing the confines of a aircraft,and if the plane is above 15k ft then you could face altitude esfixiation, due to the low oxygen levels at these altitudes and above, or at least let the viewers know about the other issues that could arise from foolish use of a gun on a plane.

    • Brien Cranford says:

      Dear Jamie and Adam please revisit this, it’s not the decompression that would be the problem, it’s the fact that there is hydraulics and electronics as well as fuel in various area’s of a aircraft that could cause serious damage to a airplane if there was a gun discharged within it. So while explosive decompression is not what Hollywood would like us to believe there is still ample reasons not to fire a gun while in the confines of a aircraft,and if the plane is above 15k ft then you could face altitude esfixiation, due to the low oxygen levels at these altitudes and above, or at least let the viewers know about the other issues that could arise from foolish use of a guns on a plane.

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