This is from the Wall Street Journal - but I'm pretty sure its a "subscriber thing."


Creating Bullets Safe for Use on Planes
Is a Tricky Job, but the Demand Exists

By PAULO PRADA

Staff Reporter of THE WALL STREET JOURNAL


The silver bullet in airline safety may turn out to be a new kind of bullet.

With governments adding air marshals to airplanes to subdue hijackers, and some U.S. pilots asking for permission to carry handguns, ammunition-makers are scurrying to produce an airplane-safe bullet. The ideal: a bullet that could kill an adversary, but not pass through a cockpit door and kill the pilot or wreck electronics.

"In an aircraft with people, hydraulics, pneumatics and electronics, you'd be foolish not to be concerned about a miss or the problem of overpenetration," says Bob Giuda, chairman of the Airline Pilots Security Alliance, a Warren, N.H., group that lobbies to arm pilots.

Ammunition makers are focusing on so-called frangible bullets, which disintegrate on impact with the first hard substance they hit, eliminating ricochet and reducing the chance that bullets will pass through a body. Frangible bullets usually consist of a copper cladding packed with ground metals or plastics. They were developed to meet new demands on the firearms industry: ammunition that is less deadly for use by police in urban neighborhoods and less polluting than lead.

Often Inaccurate

But frangibles are often inaccurate, because the ground materials inside tend to clump or break apart, throwing off bullet trajectory and making shots behave unpredictably upon impact. By contrast, a conventional bullet, generally a homogeneous slug of lead, flies straight and hits as a solid mass, although with too much power for the inside of an airplane.

SinterFire Inc., in Kersey, Pa., and Bismuth Cartridge Co., of North Hollywood, Calif., believe they have come up with better alternatives, using such materials as copper, tin and bismuth, a hard and lustrous metal. Packing frangible bullets with more consistently machined powder or crystalline metal reduces the problem of clumping and makes the shots more accurate, they say. The companies believe they could sell millions of these bullets a year.

Manufacturers also have fine-tuned the material to make sure the bullets are powerful enough to kill, but not so powerful that they penetrate metal. Technicians have tested the rounds against a variety of materials, including gelatin globs that model human tissue.

(cont.)

SinterFire says its frangible bullets are more airplane-friendly. Its rounds consist of a baked metal powder that is 90% copper and 10% tin. By pulverizing, compressing and heating the metals, the company says, it avoids the clumps in other frangibles, making the bullets more reliable. "Our bullet can penetrate a bad guy's head, but it won't come out the other side," says Dan Smith, SinterFire's director of technology.

SinterFire works closely with Sigarms Co., a handgun maker in Exeter, N.H., which sells firearms to the FAA. Air marshals work for the FAA and use government-issued weapons. The two companies are discussing a new gun designed specifically for the frangible bullets.

Ken Elliott, president of Bismuth Cartridge, says his company recently developed a bullet made of that metal. Those bullets shatter more easily on contact than lead, because bismuth, a metal slightly heavier than lead, has a brittle, crystalline structure.

Mr. Elliott, already sells bismuth shotgun shells in the U.S., and is the publisher of hunting magazine "Sports Afield." He began investigating new ammunition several years ago, when the Clinton administration began pressing bullet makers to move away from lead, which poisons groundwater and soils.

Most frangible bullets, he realized, were "sintered" -- that is baked, not melted into a single unit. But he cast his bismuth bullets from the molten metal, forming a solid, yet breakable mass. The result, he says, is a truer flight path.

But some pro-gun pilots fear the push toward fragile bullets will produce ammunition that wouldn't stop terrorists. Mr. Giuda, of the Airline Pilots Security Alliance, says he would prefer short-range versions of standard bullets, whose lethality is unquestioned, but which would be less likely to blast through cockpit doors.

Here's another idea.

Pass out combat knives to every able bodied passenger on the flight. No worries about decompression.

A highjacker tries something, he DIES by the knife. I think today's passengers are in a mood to kill, if need be. Killing with a knife is a bit messy but so what, when your life is being threatned you do what you must.

I may be mistaken, but don't people who wear turbans have knives stashed in there some place.  I heard it has some "religious" significance.  Kind of like the Irish dagger custom.  If the right to freedom of religion lets you keep a knive on your person, shouldn't the right to LIFE afford the same?

IIRC, this is why Glaser Safety Slugs were developed.  I've only seen a few dozen fired, so I don't consider that very extensive experience, but none of those came apart before hitting the targets.  

Pumpkins reacted very nicely.  Regular .357 maggies whistled right through, leaving a nice big exit "wound".  The Glasers actually made the pumpkin jump a little.  No exit wound, but when you cut it open, the whole inside was full of little pieces of shot.  Neat!!

I accidentally dropped a magazine full of (well only six) .45 glazer rounds.  Now they rattle like a set of maracas.  Does thid mean the rounds will come apart before impact?  These things were kind of expensive, can I get a refund?

[b]The Myth Of Bullet Holes In Aircraft[/b]

excerpted from [u]The Proficient Pilot II[/u], by Barry Schiff:

[i][b]Pressurization[/b]

There probably are more absurd misconceptions about aircraft pressurization than about any other aircraft system.

Consider, for example, the popular belief that a bullet shot through a pressurized fuselage will cause explosive decompression and loss of aircraft control. This is, after all, what happened to Pussy Galore and James Bond in Goldfinger when a stray bullet went through the cabin wall of their Lockheed Jetstar. Not only did they experience explosive decompression, but the aircraft went into a spin, forcing Pussy and James to parachute to safety. Totally ridiculous, but it made for good drama.

And how about the myth perpetuated by the motion picture Airport '77? After the Boeing 747 came to rest at the bottom of the Caribbean, the intrepid captain (Jack Lemmon) allayed his passengers' fear of drowning by proclaiming authoritatively, "Don't worry, folks; this airplane is pressurized!" Apparently pacified, the naive passengers headed for the piano bar to sip martinis until rescued.

Someone should have nominated this movie for the "Best Comedy of the Year" award.
...

Pressurizing an aircraft cabin (the pressure vessel) is similar to pumping air into a tire that has a controllable leak. In the case of piston-powered aircraft, pressurizing air is provided by the engine turbochargers. The "leak" consists of one or more outflow valves at the rear of the cabin. These valves allow air to escape continuously. This prevents excessive pressure from causing structural damage and provides an exit for venting stale air overboard. Pressurization is maintained by pumping in as much air as is allowed to escape.

Many believe that cabin pressure is determined by varying the amount of air pumped into the aircraft. Not so. The flow of incoming air is approximately constant. Cabin pressure is determined by the outflow valves, which modulate automatically to vary the amount of air flowing overboard and maintain the selected degree of pressurization.

[b]In effect, the cabin always has at least one open "hole." The addition of a bullet hole, therefore, would have no effect on cabin pressure.[/b] The outflow valve(s) would compensate by closing slightly and automatically to maintain a constant flow of air through the cabin. Larger holes in the structure, however, may result in depressurization.

[b]In the case of jetliners, the ouflow valves are so large that the loss of an entire cabin window may not affect cabin pressure significantly.[/b] (It would not be pleasant, however, to be seated next to such a window.)[/i]

With 20,000 hours in more than 225 types of aircraft, Barry Schiff has achieved worldwide recognition for his aviation accomplishments. A verteran captain with Trans World Airlines, currently flying the Lockheed 1011, he is a contributing editor of [u]AOPA Pilot[/u] and an award-winning author of eight books and more than 500 articles.