Remington, reliability, and the R51

I thought I'd write a bit about the Remington R51, because a lot of friends really like the look of it (and the original Remington model 51 it was based on) when they brought it out a few years ago, and they were very disappointed when it proved so unreliable that Remington had to discontinue production and recall all the shipped pistols.

Recently, Remington brought out a revised version of the R51, and it has come back to mixed reviews; some stating it had fine reliability, and some that it had better than the first production run, but still poor reliability.

TFB-TV, the video production side of the Firearms Blog, ran a full test of the weapon, on video, with 600 rounds of 8 different kinds of ammo... and really, the quote speaks for itself:

"After 600 rounds of testing, the [second gen.] Remington R51 is looking like the kind of gun I'd want my enemy to have in a gunfight" -- TFB TV

Watching the testing, I think I have a pretty good idea of what's wrong... and I thought I'd break it down here.

Basically, the only ammo it would run cleanly with, was the hot German 124gr NATO round nose FMJ stuff. It had just one total failure in about 200 rounds of that ammo.

That's very good ammo by the way, and my favorite factory load for breaking in difficult 9mm pistols, and for shooting through subguns and 9mm carbines. You used to be able to get it pretty cheap by the "battlepack", but I haven't seen any available lately.

The remainder of 8 ammo types tested were averaging one malfunction per every other mag of brass ammo, and the weapon wouldn't run any steel cased ammo at all, with one or more malfunctions per magazine.

Essentially all the malfunctions with brass cased ammo were nosedives, most of which the slide overrode. This normally suggests that the magazines are the primary issue... as is generally the case with MOST self loading firearm malfunctions.

Given the 124gr nato ran very well, and all of the other ammo did not... most of it was lighter, and if it wasn't lighter it was hollowpoint... It seems the weapon is extremely sensitive to cartridge OAL and nose profile.

The German 124gr nato ammo has a long ogive nose profile, making it a couple millimeters longer over all, than either a 124gr JHP, or lighter FMJ or JHP loads (its also longer than 124gr winchester white box, which has a shorter ogive and a rounder more spherical nose profile).

That NATO spec ammo is also hotter than most ammunition... in between an American +P and +P+... It will result in higher slide speeds and energy, even with the "Pedersen Hesitation Lock" blowback action, because it's a modified blowback system that locks the barrel and breech block together until pressure drops, but it still has much more energy hitting the slide earlier in the timing cycle, than a Browning or Walther style locked breech operation (and because it pressure dependent, it is much more sensitive to ammunition variability).

What this suggests to me (as an engineer, a gunsmith, and a shooter) is a combination of timing, and magazine issues.

Hesitation lock weapons are almost always going to run better with hotter ammunition, and may be unreliable with lighter loads. Also, cartridges that obturate differently, or that have different lubricity and stiction (such as steel cases vs. brass), may dramatically alter the timing of the weapon compared to brass test loads.

If  you tune an action to run reliably with lighter pressure ammunition, with hotter ammunition it's more likely to unlock too early, and possibly malfunction, accelerate wear, or even have a catastrophic failure.

If you tune it to run reliably with hotter ammunition, though it will be less likely to have safety and durability issues, and will wear less; it may be unreliable with lower pressure loads.

It's a delicate balancing act that's difficult to manage even with all other factors being perfect. Adding steel cases which obturate in the chamber very differently, and which have dramatically different friction characteristics, just adds another set of issues to the tolerance stack.

That's the timing issue. But, while the other +P ammunition also ran better than the standard pressure, it still had problems... thus the magazine issues.

Its likely that the magazine lips and follower are presenting the cartridge too far back, and too low, at too shallow an angle, and with too much friction on the cartridge.

This combination would cause the feeding cartridge to tilt nose downward too far... without moving forward, or at least before it moves far enough forward... thus a cartridge with too short an OAL may fail to engage the feed ramp, and instead slam into the front of the magazine.

Since the slide is overriding the cartridges instead of jamming on the rims, it also means it's pushing the cartridge stack down far enough, with little enough effort, to continue its stroke.

The failures with steel cased ammo were mostly nosedives as well, but there were also FTI failures, from light primer strikes.

They had nosedive failures every few rounds with steel, which doesn't surprise me, because steel is going to have higher feeding friction, against the mag lips, mag follower, and the rounds under it. Thus the nosedive problem would be exacerbated.

The light primer strikes are lightly due to inadequate force exerted on the firing pin, rather than any more complicated issue.

Both of these issues indicate to me that they used springs that are either too light by spec, or too soft by QC, both for the internal hammer, and for the magazine.

These spring issues are common failures in quality control for any manufacturer, and common problems with any self loading pistol... and frankly, are not surprising given the state of Remingtons manufacturing and quality control issues over the past few years.

When the geometry and timing of a design are just barely on the edge of being reliable, a slightly soft spring can easily make the difference between a weapon that runs, and one that doesn't.

So... what do you do to fix it?

As a manufacturer or a gunsmith, there some relatively simple changes that might help.

First, I would try a slight revision in the mags and mag catches, to make the magazine sit just a little bit higher could improve feeding function; as could a slight easing of the feed lips, reducing friction on the feeding cartridge, and presenting it in a slightly more nose up attitude, allowing it to move further forward with less pressure; thus making it easier for the cartridge to engage the feed ramp and jump up under the extractor, rather than nosediving (particularly for shorter OAL or steel cased cartridges).

If one has an R51 that is overly load sensitive, and has similar issues, and changing to a stronger mag spring doesn't resolve them, then one could try easing the feed lips slightly themselves, as well as polishing them with emery cloth, to reduce feeding friction.

Other than that... There's not much you can do, except to internally blueprint the gun... polish metal mating surfaces, deburr anything that would be in a feed path etc...; and make sure that your springs are good.

Self loading firearms are all going to be sensitive to timing, ammunition variability, magazine geometry, quality control in springs and mags, and quality control in general; and pistols doubly so over rifles, since you've got much less energy and much shorter distances and time windows to deal with.

Honestly, it's pretty easy to make one unreliable, and pretty difficult to make one reliable.

Using a locked breech design helps reduce the variables, and make them less sensitive, which is why you don't see many full power centerfire pistols that don't have a locked breech mechanism.

Even the original Remington model 51 was only available in .32acp and .380acp. There's good reason why blowback pistols... even modified blowback pistols such as the R51... above .380acp in power are rare.

You're already cutting your tolerances close and stacking them high... when you add questionable quality control on top of it... well... the results are... predictably unpredictable shall we say?

Significant Precision

Lawyers believe that they are trained to speak and write extremely precisely, particularly while in a deposition or courtroom.

It is pounded into their heads over and over again in Law School how important it is to communicate precisely. The law can be a very technical subject, hinging on very fine distinctions. They are shown example after example of the results of imprecise communication, and how it can be exploited.

Compared to "normal" people, they DO communicate precisely. After all, imprecision in a lawyers speech can lead to their clients losing a great deal of money, or going to jail.

They don't come within shouting distance, of the precision of communication required and regularly practiced, by either doctors or engineers.

When you internalize the notion that imprecision in your communication can kill someone... or lots of people... particularly after watching it happen... That changes things entirely.

At the same time, both engineers and doctors can be MADDENINGLY vague about anything they consider unimportant, irrelevant, uninteresting, or so basic as to be understood by them as unnecessary to explain.

Even... perhaps especially... when that is exactly what you are asking about, or need to know.

This can make for some... interesting... problems.

Many are aware of...

... the "old" proverb "do not meddle in the affairs of wizards, for they are subtle, and quick to anger".

Some few also know the vairant thereof "do not meddle in the affairs of dragons, for you are crunchy, and taste good ketchup".

Apparently, someone at DHS forgot the engineers corollary to this proverb:

"Do not irritate an engineer, for smiting you will amuse them, and make a good story over beer"

Five Years Later - Why bullpups aren't a great solution

In my ongoing series revisiting posts from five (or six) years ago, I thought I'd update one of my most read and linked posts, the one on bullpups.

In this case, I'm not doing a new post, but I've completely re-written (and corrected all the typos and dead links in) the old post. In particular I greatly simplified it, pulling out a bunch of wonkish detail on human mechanics and ergonomics which just about everyone ignored.

Oh and I renamed it; since I don't actually thing they're a BAD idea, but they aren't an optimal solution:

For some reason, the the bullpup rifle keeps being put forward as a good idea.

...Really, for the most part, they are not.

I'm an engineer and a firearms expert; by training, inclination, experience, and employment. I'm a veteran, a former security contractor, a former firearms trainer, and a class III armorer and light duty gunsmith (I don't have a barrel lathe or mill at the moment, and I don't want to be an FFL again; so I don't offer full gunsmithing).

I have a great appreciation for good engineering. Bullpups are, in general, not good engineering.

The bullpup rifle has one real advantage: bullpup designs allow for a shorter overall weapon, for a given length of barrel (typically between 4" and 7" shorter than a conventional rifle).

That's not an insignificant advantage. In some missions it's even a huge asset (particularly in urban combat, or infantry dismounted from armored vehicles).

In most missions though, that 4-7 inches isn't much of a plus.

On the other hand, the bullpup configuration has a number of disadvantages:

• Bullpup designs are mechanically more complex, requiring a long trigger linkage, and control system linkages. This seriously degrades both control feel, and reliability, and increases bulk and weight (there may be engineering solutions to this problem).
  
  If current munitions infrastructure and laws allowed for electronic trigger, feed, and ignition systems, this would be a non issue, and the bullpups advantage may outweigh it's several disadvantages; but for now, that's not an option (also, electronic systems have their own issues).
  
  
• If a bullpup has a catastrophic failure, instead of the explosion being six or eight inches in front of your eyes, it's right at your eyesocket, or touching your cheekbone or ear. The only good thing is, if the bolt flys back, it doesn't end up in your eye socket.
  
  Most bullpups also eject hot brass, and vent hot gasses in the vicinity of your eyes and ears (some eject downward or forward, which is a better solution for a bullpup, if it's engineered properly).
  
  
• Mag changes on most bullpups are slower (sometimes much slower) because they require more repositioning, that positioning can be awkward, and can be difficult to see (if necessary) without fully dismounting the rifle.
  
  A conventional rifle allows you to see your mag changes, and is more easily maneuvered with your dominant hand, which makes mag changes easier in general.
  
  More importantly a human being can naturally bring their hands together in the dark. As a basic design guideline, magwells should either be in your dominant hand, or just in front of it; because it is far more difficult to manipulate anything dexterously that is located behind your dominant hand.
  
• Because of the positioning of the magazine (usually the part of a gun extending lowest) close to your shoulder when the weapon is mounted, bullpups can be difficult to fire while prone (though this is common with some other rifle designs as well).
  
  Note in the pictures below, the magazine is by far the lowest point of the rifle; and being located behind the dominant hand and close to your shoulder; when you drop prone it will tend to strike the ground forcing the muzzle downward.
  
  This can also cause problems with mags being warped, ripped out of the magwell, having the baseplate broken off, or the rifle itself being ripped out of the users hand when hitting the deck.
  
  A conventional rifle with a long magazine can have issues with dropping prone as well, but because the mag is positioned forward of the dominant hand, instead of forcing the muzzle down, it will tend to force the muzzle up; and though it's not advisable to use the magazine as a monopod, it's possible. With a bullpup, it isn't.
  
  This isn't an issue for rifles that are generally fired off bipods, so in an SAW or LMG role, the bullpup may be an appropriate solution (though having the feed system in such tight quarters with your shoulder and cheek is its own issue).
  
  
• Charging the rifle and manipulating the operating handle is often more difficult, and sometimes can't be done without dismounting the rifle, or reaching over the rifle with your support hand (again, some conventional rifles do share this weakness; and this is a problem that can easily be solved with proper engineering).
  
  
• Bullpups are naturally balanced in a non-instinctive way.
  
  This is really the biggest problem, and the one that is hardest to solve with engineering.
  
  The balance point on most bullpups is in between your hand and your shoulder when mounted, which is unnatural. We have a natural tendency to try to balance things between our hands, not between our hand and shoulder.
  
  The only way to correct this is to put heavy things in front of your dominant hand, or to make the weapon short and light enough that this won't make a difference (and even then it will still be more awkward and less instinctive to point; but several modern bullpups have taken the second approach).
  
  This balance will tend to make a bullpup tend to shift its butt under recoil, unless it is very tightly mounted to your shoulder; particularly during rapid fire. This tendency is somewhat countered by the position of your support hand so far forward on the barrel,  by the fact that the overall leverage moment of the muzzle is lower (the muzzle isn't as far from either your shoulder, or your dominant hand), and by the fact that most bullpups have straightline recoil.
  
  A conventional rifle is balanced in between your dominant and support hands, and there are good reasons for that. A human being naturally handles things that balance in the palm, or in front of your dominant hand, better, because we naturally want to balance things between our hands.
  
  Under recoil, the muzzle of a conventional rifle rises, but just from gravity will fall into you support hand again without actually holding or pulling it down, because the fulcrum of the lever is in your dominant hand, and the balance point is in front of the fulcrum. 

Some of these issues can be solved, or mitigated with engineering (and most modern bullpup designs do resolve, or at least reduce, many of those issues). Also, a lot of this can be worked around with training.

What it comes down to though, is that bullpups are ergonomically incorrect for human beings. When you have the option, you don't train someone to do something ergonomically incorrect, you redesign the equipment to fit human ergonomics.

The only good thing about a bullpup is the short overall length in relation to their barrel length; and that is not advantage enough to outweigh the disadvantages for most missions.

Well, that and the fact that they look cool, which is the real reason so many people are enamored of them.

A lot of folks have watched a lot of stargate (or played a lot of stealth shooter video games). They use the FN-P90 PDW which isn't exactly a bullpup, but follows a similar concept; and they do just look kind of futuristic.

The Steyr AUG was designed in 1976, and it still looks like a space gun:

Several countries have adopted bullpup designes as their primary service arm, notably Austria, and Australia (the AUG above), France (the FAMAS),

and the UK (the SA80 system, now in the L85-A2 variant):

The reasons cited are usually overall length, the extra accuracy and velocity afforded by the longer barrels allowed by the configuration, and some medical or efficiency studies showing that the bullpup was actually ergonomically correct.

Here's the thing: every study that the British did showing that the SA80 design was ergonomically correct, or that the reliability issue was solved, has over the past few years been proven to have been "Unjustifiably optimistic", or some other such euphemism for fraud.

The SA80 has  proven to be ridiculously unreliable , though at least it is SA80 is quite accurate when it functions properly (also the HK refit and remanufacture of the A2 variant has dramatically improved reliability... Though it's still not great).

The SA80 in fact is so poorly designed, that firing it from your left shoulder will give you a black eye (and can even break your cheekbone) and send hot brass and gasses flying into your eyes. You also can't fire the thing from the left side of cover without exposing your whole head and torso.

I have tried the P90, the SA80, the Steyr AUG, the Bushmaster M17, the FAMAS, and the IMI Tavor (the latter two held and played with, but not shot), and I haven't found any of them but the P90 to be remotely comfortable, or anything but awkward. I've tried a couple of bullpup conversions from other weapons as well, same thing (excepting several bullpup sniper rifles, that I quite liked, and as I said, the P90 which is only sort of a bullpup... it's quite handy and nice to shoot).

UPDATE: Since I first wrote this, I've had a chance to shoot with the FN F/S2000 in both semi and full auto variants: 

While it looks like a heavy and awkward spacegun, it's actually very light, well balanced, and comfortable. Reports from the field are that it is generally reliable, but there aren't a lot out there yet to establish a useful sample.  

Mag changes are still less than ideal, and the trigger is still poor; but the handling of the gun is good, and it is reasonably accurate for an assault rifle. I do worry however about the forward ejection system. It seems to me like it would be easy to jam up in the field. 

Also, since I originally wrote this, Kel-Tec has introduced their RFB forward ejecting bullpup in 7.62x51: 

Unfortunately, not many of them are out in the world yet, so I haven't had a chance to fire one; but the design seems to address some of the issues above.  I have real concerns about the forward and up ejection system, and the inability to clear a jam without field stripping the weapon however. 

Until someone has shot thousands of rounds through them, had to change mags in the dark, and in cramped conditions, had to clear jams under combat conditions etc... they can't know how unsuitable bullpups are as anything other than a niche weapon, to be used only where OAL is the most critical factor (but where SMGs are not an appropriate choice).

For example, bullpup sniper rifles make a lot of sense, particularly in .50bmg and other anti-materiel chamberings. In fact, any weapon that you would normally fire off a bipod makes sense as a bullpup, because the ergonomic issues around balance, and lying prone don't really apply.

People say "Well the designs just aren't good enough yet, I'm sure as they mature they'll get better, isn't it the natural way to go eventually?"

First of all, why would it be?

Other than the fact that the Sci-Fi network likes featuring bullpups in their television shows, there is no reason why bullpups should be "the future". They have one design advantage, shorter length, and many design disadvantages.

Now, when we use caseless ammmo loaded in 1000 round blocks, and using electronic ignition systems... sure, bullpups make sense. At that point, all the basic engineering weaknesses are compensated for, and the advantage of a longer barrel for length of weapon offsets the balance issues... if they even exist then, given progress in materials.

But for now, so long as we are using relatively "conventional" ammunition and firing mechanisms, those engineering problems outweight the one real advantage; and the ergonomic issues simply compound the problem.

Engineers aren't miracle workers. We can refine a design until it's mechanically perfect within its design parameters; but the point I'm trying to make, is that at our current level of cartridge firing weapons development, there is no way to design an ergonomic bullpup.

So, bullpups are only slightly shorter than their conventional counterparts (maybe 7" in the case of an assault rifle), nothing to sneeze at, but not a huge advantage in most cases considering the missions they are intended for; they are less reliable and more mechanically complex than conventional designs, they are ergonomically incorrect, and they are more likely to injure their user.

I'm not denying there are missions where a bullpup is appropriate (as I said above), but I can't see any conventional situation where a bullpup assault rifle is the right tradeoff to make; even urban warfare and infantry dismounted from armor.

But they look cool...

Hallelujah, he's finally gone!

Today is a great day my friend. Today is the day that BMW begins its return to grace and greatness; because today is the day that CHRIS BANGLE RESIGNS.

Thank you god.

For those of you who don't understand why I am thankful for this blessed event, let me give you some examples, of both pre and post Bangle BMWs.

Pre-Bangle:





Those are examples of the E34 M5 (1989-1995) and E39 M5 (1996-2004); what I believe to be the two best examples of the classic BMW sports sedan.

Admittedly I'm biased, in that I've owned two E34 5 series; and would still love an E39 540is or M5 (the E34s are still great; but they are getting a bit long in the tooth. Plus the E39 has almost twice the horsepower, more room, and better handling).

Some might call the styling boring, but I disagree. They are smooth, but hard edged. Muscular, but not overblown. Classic, clean, simple, and balanced.

Simply, they are a pure expression of form and function in harmony. Antoine de Saint-Exupery famously said "Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.". With these cars, there is nothing left to take away.

Unfortunately, Chris Bangle decided that meant it was a perfect time to start adding stuff:


That, is called a "Bangle Butt"; because Chris Bangle insisted on adding it to all of his designs.

Who on earth could find that attractive?

Actually, just a more basic question, why on earth did BMW make this man head of design, when he admitted he didn't like how BMWs looked. He thinks the hoffmeister kink should be eliminated, and that the double kidney grill is old fashioned.

Bangle said repeatedly in interviews that he thought BMWs looked boring; and that he kinda liked ugly cars because they were interesting.

I guess these are VERY interesting then:


In case you were confused, no, those aren't Pontiacs; they are $40,000 to $90,000 BMWs... though you can certainly be forgive for the comparison. I for one think the recent 5 series looks an awful lot like a Pontiac Bonneville:


Here's a more explicit look at the similarities:

That would be a recent 3 series compared to a Pontiac G8 (what used to be the Grand Prix) of the same year. Striking resemblance wot?

Pontiac is of course famous for the "Excitement" look; achieved by taking standard GM three box products, and adding ridiculous plastic body cladding and pointless frippery.

Here's his latest, and "greatest" effort, the X6:


Which if you ask me, looks a lot like a slightly smoothed out Pontiac Aztek:


But maybe that's just me. I actually like good looking cars... I guess I'm not interesting.

Sometimes, I love the Internet

Laser Flashlight Hack!!

Turn a MiniMag flashlight into a powerful DVD laser pointer! This 245mw laser is powerufl and fits real cozy in a MiniMag! See the video at the end for the Test Results!

Disclaimer: CAUTION! As you know...lasers can be dangerous. Never point them at any living object!

Operating Systems

The question was recently asked "What's the difference between blowback and recoil operation?".

If you aren't a gun nut, those terms probably don't figure much into your daily conversation. In fact, you've probably never heard of them. Even if you are a shooter, unless you are into the technology and engineering of guns, you may not know the terms.

What they are, are labels for two of the most common methods of operating a self loading (meaning automatic, or semi automatic) firearm.

In a self loading weapon, the operating system uses the energy of a firing cartridge, to eject the spent casing, load the next round, and re-cock the weapon; ready to fire again with the next pull of the trigger (or if fully automatic, firing again as soon as the cycle completes).

There are three fundamental ways of using the energy of a firing cartridge to cause a weapon to cycle itself (weapons that cycle off of external power, like Gatling guns are not counted here).

1. Gas Operation
   
2. Blowback Operation
3. Recoil Operation
   

Gas operated systems tap the pressure of the expanding combustion gasses (through a piston, lever, gas trap, tappet, op-rod or direct impingement) to force the bolt, slide, or other breech mechanism back and cycle the action.

This system has physical complexities relating to regulating gas pressure (which can vary wildly), and timing of the operating cycle; but is less sensitive to firing position, weapon mounting, and cartridge power; as well as being less dependent on finely fitted moving parts; than other self loading systems.

As such, gas operation is the most common operating mechanism for assault rifles and light machine guns; as well as the operating mechanism for a large number of automatic shotguns (many are recoil operated instead). Some pistols also use gas operation, but because of the additional weight and bulk required for a gas system, this is uncommon.

The most prominent examples of gas operation, in its major variants (in order of mechanical simplicity) are:

1. The AR platform rifle (AR-10 and 15, M16, and variants) which uses direct gas impingement; where the gas from the barrel acts directly on the bolt carrier.
   
   This system has the most inherent accuracy of any gas operated system; but is also sensitive to fouling, and is the most difficult system to time properly.
   
   
2. The AK 47 and variants, which uses a short stroke linked piston op-rod design.
   
   In the AK system, the op-rod, piston, and bolt are mechanically fixed to each other and thus travel in a long stroke; but the gas only works on the piston for a short distance before it is vented, so it is a short stroke gas system.
   
   This system is mechanically very simple and reliable, but is detrimental to accuracy; because the gas system is physically linked to the bolt, and to the barrel; which induces unpredictable vibration into the barrel.
   
   
3. The M1 carbine, which uses short stroke tappet system to cycle the action.
   
   In a tappet system the gas piston and tappet, which may or may not be physically linked (or even a single part), move a short distance very rapidly under gas pressure. After the gas pressure is cut off (either through a mechanical limit to the piston stroke, or a gas port cutoff actuated by the pistons stroke) the tappet flies back through inertia imparted it by the gas piston. At this point the tappet may be in contact with the bolt or op-rod; or it may travel a short distance to strike an op rod, or travel further to strike the bolt directly; in either case imparting a great deal of inertia to the op-rod or bolt. The bolt then flies back against spring pressure without any further mechanical connection to the gas system.
   
   This system is a good compromise of mechanical simplicity, accuracy, and reliability; because it uses the reliable gas piston system which doesn't foul as much or have as sensitive timing as the direct impingement system; but it doesn't mechanically fix the gas system directly to the barrel and bolt; which reduces vibration.
   
   
4. The M1 Garand, which use a long stroke, long rod gas piston system which has a bolt, op-rod, and piston in three separate parts, not mechanically fastened to each other (but which remain physically connected to each other through spring pressure and friction fit). The entire system cycles for the full length of the operation cycle; thus "long stroke".
   
   This system is somewhat detrimental to accuracy (though not as much as in the gas system of the AK47), and is sensitive to very high or very low gas pressures (either bending the op rod, or short stroking the action); but is otherwise very reliable.
   

* It's not significant enough to be called a major variant; but the the M14 uses a design that combines elements of the tappet system of the M1 Carbine, and the long rod system of the M1 garand. It uses a short stroke gas piston that cuts the gas pressure off quickly, and an op rod that doesn't maintain continuous contact with the piston.

Blowback operation uses the reaction of the cartridge casing "blowing back" (the equal and opposite reaction to the bullet blowing forward) to push the breech mechanism back and cycle the action. It is mechanically the simplest type of self loading action, because fundamentally the only moving parts are the breech mechanism, and the cartridge case itself (not counting the spring which pushes the breech back into place after ejection). Effectively a blowback operated weapon is in fact a gas operated weapon; with the gas piston in this case being the cartridge casing.

There are two common major variants of the blowback system: Simple Blowback, and Delayed Blowback.

Simple Blowback operation is the most common operating system for pistols firing cartridges with less energy than 9mm parabellum (9x19). Without a delaying or supplemental locking mechanism, breech mechanisms have to be very heavy to handle higher energies; thus making pistols using simple blowback for more powerful cartridges very heavy and bulky. Many submachine guns, and pistol caliber carbines however use the simple blowback mechanism because the extra weight of the blowback bolt isn't a problem.

Delayed blowback is called this, because there is an inbuilt mechanism to delay the breech blowing back, until pressures have dropped to the point where the cartridge can extract safely. Common methods include roller lockers, gas delay, fluted chambers, friction locks (like the Blish lock, which proved ineffective), rotating lugs, or some combination of all of the above.

Delayed Blowback systems are somewhat common in assault rifles, battle rifles, and machine guns. Some pistols and SMGs also use delayed blowback, but this is uncommon.
The most significant examples of simple blowback systems are:

1. The Makarov pistol (9x18mm), which is by far the most manufactured centerfire blowback pistol, and which uses a textbook example of simple blowback.
   
   
2. The UZI submachine gun; which also uses a textbook simple blowback system; slowing down it's operation for use with high pressure 9mm nato and .45acp loads by using a very long, very heavy telescoping bolt design.

Also, it should be noted that almost all .22 auto pistols use a simple blowback operating system.

The most significant examples of the delayed blowback system are:

1. The HK P7 pistol, which uses a gas delay mechanism. This system is very rare; only used on a half dozen weapons in modern circulation.
   
   
2. The CETME/HK G3 series of rifles, and MP5 series of submachine guns (all based on the same design), which all use a roller delayed blowback system (the CETME/G3 also uses a fluted chamber to aid in the delay. The fluted chamber increases friction on the cartridge case as it extracts, slowing down the unlocking and blowback).

Delayed blowback systems are relatively uncommon, because they are extremely difficult to manufacture reliably. They require high precision machining, with very tight tolerances; and are very sensitive to differing operating pressures.

Recoil operated systems uses the energy of the recoil of the firing cartridge to cycle the weapon; by locking the breech and barrel together and causing the whole mechanism to be forced back (again an equal and opposite reaction to the bullet being forced forward).

There are two common implementations of this system Short Recoil and Long Recoil.

In the Short Recoil system, the breech and barrel are locked together only for a short time. As they travel back, a mechanism unlocks the breech from the barrel (typically a tilting link, or a sliding cam), which then stops moving; and the the breech continues moving back to it's full cycle length; extracting and ejecting the spent cartridge casing before being forced back into battery by the operating spring, or recoil spring (which may be the same thing).

A variant of the short recoil system uses a hybrid of short recoil and delayed blowback, by keeping the barrel and breech locked together through rotating or camming locking lugs that unlock as the mechanism cycles.

Short recoil is the most common operating system for centerfire pistols more powerful than 9mm Makarov (9x18mm); but is uncommon in most other types of weapons.

The most significant examples of this operating system are:

1. The Browning M1911 pistol, which uses a tilting barrel connected to the frame with a link pin, and locked to the breech with locking lugs machines into the barrel and slide
   
   
2. The Browning P35 Hi-Power pistol, which also uses a tilting barrel; but which connects the barrel to the frame with a machined cam lug that is an integral part of the barrel; and a cam pin which is fixed to the frame.
   
   
3. The Browning M2 machine gun, the basic heavy machine gun of the armed force of the United States (and many other countries) from it's introduction in 1921 'til the present day.
   

Almost all modern centerfire handguns in a major caliber use a variant of the operating system in one of these two pistols. Most heavy machine guns use a variant of the operating system of the M2 (or a long recoil mechanism)

*A minor, but significant variant, is the sliding cam system used only by Beretta currently, but introduced by Walther in the P38; the first successful double action auto service pistol. In this system neither the barrel nor slide tilt relative to each other. They remain rigidly locked by a sliding cam separate from both, until that cam is moved out of position by the rearward cycling of the slide. It is significant both because it is the only major caliber centerfire semiautomatic pistol operation system in common use not designed by John Browning; and because the Beretta M9 is the service pistol of our armed forces.

In the long recoil system, the entire barrel and breech mechanism remain locked together to the limit of the cycle; where the bolt is held back, and the barrel is then forced forward by the recoil spring. After the barrel travels forward (it may lock forward all the way first, or it may not), the bolt is then released, ejecting the round (some systems eject the round as soon as the barrel moves forward), stripping a new round, and slamming back into lock with the barrel.

This mechanism is common in machine guns, and automatic shotguns; but uncommon in all other types of weapon.


The most significant example of the long recoil system would be:

1. The Browning Auto 5 shotgun, which was the first successful semi-automatic shotgun design, and is the longest produced semi-auto shotgun by far at 98 years of regular production.
   
   Most automatic shotgun designs were based on this same principal until the introduction of the gas operated Remingtion 1100 in 1963.
   

You'll note, John M. Browning designed most of the significant recoil operated weapons I referenced. Though he did not invent the concept of recoil operation (Hiram Maxim made the first practical recoil operated gun), Browning perfected and popularized it; making it the most common system of operation for centerfire handguns and machine guns today.

Funny enough, Browning also invented the first successful gas operated gun, the Browning model of 1895; which was briefly adopted by the U.S. as a standard machine gun; and the first truly successful blowback semi-automatic pistol, the Colt model 1903.

Based on his experiences developing these (and other) weapons, Browning believed that blowback and gas operation were both inferior to recoil operation, from an engineering and physics standpoint.

From a pure mechanical and physical standpoint he is correct, in that recoil operation is the simplest and most efficient system capable of handling major power cartridges.

Unfortunately, to be reliable, durable, and accurate; recoil operation also requires very good production tolerances, fine machining, and excellent metallurgy. This is why most firearms manufactured in the third world, or former Com-Bloc countries are either simple blowback, or gas operated with a simple piston/rod system.

So what system is best?

Well, it really depends on what type of weapon you're talking about; and what you want to do with it. There isn't really a "best" system, or all guns would use it; but there are better choices for certain applications.

Clearly, gas systems are the most versatile for rifles (not necessarily best, but definitely most versatile); because they can be adapted to run most anything; but they aren't appropriate for most pistols because of their bulk. Also, gas systems are by their nature dirtier and more sensitive to fouling than other operating mechanisms. The most accurate gas system, direct impingement, is also the dirtiest.

Delayed blowback systems are more inherently accurate than gas or recoil operation (both for rifles and pistols, because there is no vibration induced by a gas piston, and no barrel motion in recoil), but in pistols they are more mechanically complex than recoil operation; and in rifles they are limited in the power and range of cartridges they can fire reliably.

Short recoil is certainly best for major caliber pistols; but it isn't necessary for .22s, and in fact the mechanical rigidity of the blowback system improves accuracy (no matter the chambering).

Just some general principles to guide you in figuring out an operating system:

Accuracy:

• Less motion is good
• Less mass in motion is good
• Slower motion is good (presuming sufficient energy)
• More consistent motion is good
• Fewer moving parts are good
• Fewer closely fitted parts required is good
• Better tolerances and tighter clearances are good
  

Reliability (all of the above 'cept the last, plus):

• Less sensitive to timing is good
• Less sensitive to pressure is good
• Less sensitive to firing position is good
• Less sensitive to weapon mounting or grip is good
• Less sensitive to fouling is good
• Less fouling overall is good
• Looser clearances required are good
  

Power and Versatility:

• Less sensitive to pressure is good
• Less sensitive to inertia is good
• Less sensitive to recoil is good
• Less sensitive to overall power of the cartridge (one way or the other) is good
  

Unfortunately, you can't have all those things at once. To optimize your choices, you need to look at what your needs are for accuracy, reliability, power, and versatility, and make your compromises.

Best of luck, no-ones come up with the perfect solution yet... Maybe when we have hand held plasma pistols with an instantaneous recharge rate, and unlimited power source...

...'Til then I'm pretty happy with a 1911, an AR, an M14, and my manually operated pump shotgun and revolver.

There's an old saying...

...Actually two. The first is "if it's stupid and it works; it isn't stupid", the second is "if it seems too good to be true, it probably is".

What's amazing, is that sometimes, the first, can contradict the second in some pretty fun and interesting ways... but most of the time, it doesn't. Let's talk about one of those times.

So, the first saying...

One of the first examples given to illustrate the operating principles of small engines, is usually that of an air compressor. An internal combustion engine sucks in low pressure air, mixes it with fuel and a spark at something approaching a 14:1 ratio (with the fuel, not the spark), blows it up; and high pressure air comes out the other end... along with water vapor, carbon, carbon monoxide, carbon dioxide, nitrogen dioxide, ozone, partially burned and unburned fuel, and other nasty bi-products of the combustion of hydrocarbons.

Like almost all other reductions of complex machines into simple models, it's a stupid comparison; but it works (therefore, according to the maxim, it isn't stupid).

Now, what would happen if you took the fuel out? Well nothing because there would be no release of energy to make the pistons turn... so lets not simplify things that much. What if we take the fuel out AND we reversed the flow of high pressure air?

Well, hopefully something like this:

Actually, I was hoping for something a little less ugly and stupid looking but... as the saying says...

So the basic concept is this: Instead of high pressure exhaust coming out, we pump VERY high pressure air IN, which pushes the pistons (or turbines if you're so inclined, but I'm pretty sure they're using pistons in this application), turns the crank (and thus the transmission, and the wheels) and then exhausts as low pressure air (and a little water vapor and lubricating oil); basically an air compressor in reverse.

Here's the company line:

"Many respected engineers have been trying for years to bring a compressed air car to market, believing strongly that compressed air can power a viable "zero pollution" car. Now the first commercial compressed air car is on the verge of production and beginning to attract a lot of attention, and with a recently signed partnership with Tata, India’s largest automotive manufacturer, the prospects of very cost-effective mass production are now a distinct possibility. The MiniC.A.T is a simple, light urban car, with a tubular chassis that is glued not welded and a body of fibreglass."

...snip...

"Most importantly, it is incredibly cost-efficient to run – according to the designers, it costs less than one Euro per 100Km (about a tenth that of a petrol car). Its mileage is about double that of the most advanced electric car (200 to 300 km or 10 hours of driving), a factor which makes a perfect choice in cities where the 80% of motorists drive at less than 60Km. The car has a top speed of 68 mph.

Refilling the car will, once the market develops, take place at adapted petrol stations to administer compressed air. In two or three minutes, and at a cost of approximately 1.5 Euros, the car will be ready to go another 200-300 kilometres.

As a viable alternative, the car carries a small compressor which can be connected to the mains (220V or 380V) and refill the tank in 3-4 hours.

The temperature of the clean air expelled by the exhaust pipe is between 0 - 15 degrees below zero, which makes it suitable for use by the internal air conditioning system with no need for gases or loss of power."

How does it work?

"90m3 of compressed air is stored in fibre tanks. The expansion of this air pushes the pistons and creates movement. The atmospheric temperature is used to re-heat the engine and increase the road coverage. The air conditioning system makes use of the expelled cold air. Due to the absence of combustion and the fact there is no pollution, the oil change is only necessary every 31.000 miles.

At the moment, four models have been made: a car, a taxi (5 passengers), a Pick-Up truck and a van. The final selling price will be approximately 5.500 pounds."

Okay...

The geek in me is saying "oh cool", the engineer in me is saying "OK, how the hell are they gonna make THIS work?"

Not that a compressed air car can't work, obviously it can. The principle is very simple; the problem, as usual, is in the details. Specifically that little detail of efficiency.

Let's assume they pressurize the tanks to about 6000psi (about 400 bar, the highest conventional cascade compressor sets can go, the highest a reasonable pressure tank can store, and about twice a scuba tanks pressure).

If I'm reading correctly, they are taking 90 cubic meters of compressed air, and pushing a 1400lb or so vehicle, up to 68mph (110kph), with a 300km range.

I say 1400lb because thats about the minimum possible for the smallest model to hold two passengers, carry the essential propulsion gear, and electronics, and still have enough strength and structure not to collapse, even with advanced composites.

That car is going to need something like 20hp minimum, maybe 30hp (about 20kw); just to be able to get up to that speed (and more importantly, to be able to pull away from a stop sign on a hill).

Looking at a similarly specced vehicle, the French 2cv (or technically the 3cv model, which had 33hp -24kw-, and a 68mph top speed - that it took three minutes to accelerate to ) weighed about the same, and had about the same horsepower, and was dimensionally quite a bit smaller, so I think it's a reasonable estimate given newer more efficient materials end technology.

You really just can't move that much weight without pretty close to that much horsepower, and you really can't have a car that size with much less weight. Laws of physics being what they are and all.

So, to the second saying...

The rest of this will be in metric because those are the units easiest to work with here.

Given the range they've specified of 300km, and the power needed; we're looking at about 72KW/Hours of power; or 2,600,000,000 joules of total energy. Either 24watts for three hours, or 7 watts for 10 hours, the total energy is going to be about the same.

That has to come out of 90 cubic meters of high pressure air. At 400 bar, 90 cubic meters of compressed air, has about one and a half times that amount of potential energy.

Now remember, you can't get out more kinetic energy, than you have in potential energy. In fact, you can't even get as much out (that's called unity); because all systems are inefficient at converting potential energy to kinetic energy, to some degree.

So, it's good that there's 1.5 times as much potential energy as the engine needs right?

Here's the problem though, there is no way in hell that the thing is even 50% energy efficient. In fact, it would be an engineering miracle if they got out much more than 25% of what they put in.

Not only that; but you've actually only got about 2/3 of that energy as usable, because even at 100% efficiency you're going to need to flow about 200bar of pressure to get that 24kw (and given the volume of air available and 3 hour range).

Ok, so once again, 90 cubic meters; only presuming a minimum 200bar operating pressure, and 25% efficiency: You'd need to pressurize the tank to at least 1200 bar, or almost 20,000 psi. That's 4 times the highest pressure scuba tank (some HPBA systems are at 300 bar) or six times a standard tank.

Now these are all just really rough numbers, and who knows, maybe there IS an engineering miracle here. Also, its entirely possible they ARE pressurizing the thing to 1200bar; there are plenty of industrial applications that use pressures that high. In fact, there are common industrial applications (and equipment) for low density fluids (very few substances remain a gas at such high pressures, and nitrogen which air is mostly made up of, isn't one of them) at up to 150,000 PSI. It's just that such high pressures are not easy (and not cheap) to deal with, to store, to distribute, and to create in the first place.

Speaking thereof, the energy required to pump the high pressure air is going to be tremendous; because typical air compressor systems are terrifically inefficient; never mind the transportation and distribution infrastructure, which at least double that energy cost for production.

So yeah, your three minute fill up may have no direct emissions; but you're using probably 1440 KWh of energy total (inc. manufacture and distribution of the high pressure gas). At bout 8 cents per KWh (American national average. In India, where the car will be made, the national average is about 6 cents per Kwh) that would be $115.

$115 ??? but the article says about $2.80 (1.50 euro, at about $1.87 per euro at the moment). At $0.05 per Kwh in India, they're saying that they are using 56kwh of power total.

Honestly, I don't see how that's possible. For one thing, there's no way you could get 700kg to 110kph on 18.5kw; even assuming 100% efficiency (which is impossible).

But wait, theres more: they say that the car will come with a compressor that will reach a full charge in 3 to 4 hours, off a 240v Indian standard socket (240v at 15amp, for 3.6Kwh per hour, 4 hours, total energy about 15Kwh). Once again, assuming 100% efficiency, thats only 5Kw of power to move that 700kg, 110Kph.

That is absolutely impossible. Even at 500kg, thats not possible... hell it's maybe just barely possible at 250kg, and thats lighter than any but the lightest motorcycles and riders.

Hell, it's not even possible for a small compressor operating off standard mains current to achieve anything close to the operating pressures required.

The best portable commercial systems can flow about 15cfm at 6000psi (about 4 hours to fill the cars tank to 6000psi), and require either a 40amp 240v circuit; or a 25hp diesel motor. They are also about the size of a desk, weigh several hundred pounds, and start at about $30,000.

Let's just go over this one more time.

1. It is impossible to get more energy out, than you put in (you can't reach over unity).

2. In fact, its impossible to get even as much energy out, as you put in (you can't reach unity).

3. The best possible energy efficiency for systems of this type might be 25%, or assuming a technological miracle let's say 50%.

4. Even at 100% efficiency (which is impossible), 20-24kw (28-33hp) would be required for the vehicle to reach 110kph.

5. Even at 100% efficiency (which is impossible) 20-24kw for three hours (the specified range) would require 60-72Kwh (or 5-7kw for 10 hours, requiring pretty much the s

6. Even at 100% efficiency for both the engine, and the compressor system, the MOST possible energy that could be stored by the compressor system specified (230v at 15amp) in 4 hours would be 15Kwh; or 5Kw per hour for the three hour range specified.

7. It is impossible that such a vehicle would weigh less than 500kg. In fact it is nearly impossible it would weigh less than 700kg.

9. 5Kw will not move even 500kg to 110kph, never mind 700kg. In fact, that power would only move such a weight to about 20kph.

So, what they are describing is flat out impossible. Either the company promoting this wonder care are outright lying (possible, but seems unlikely), shading the truth to a ridiculous degree (highly likely, but still not enough), the reporter is a credulous idiot (almost certain, but also not enough in and of itself), or all three.

Personally, I'm thinking all three.

UPDATE:

Reader Smitty gives us a link to the actual designer of the vehicles in question.

Thank you very much sir, I appreciate that. I must have been stupid and not seen that among all the clutter on the article page.; and believe me I was looking.

At any rate, the first thing to note is, the vehicle is not in fact exclusively powered by compressed air. Apparently the motor is a hybrid diesel electric, with a low speed circuit powered by compressed air. This low speed circuit can be boosted by the electric portion of the drivetrain.

The low speed circuit operates at up to about 36kph generally. Above that speed the diesel circuit kicks in, up to about 60kph, when the compressed air circuit kicks out and the diesel goes it on it's own until top speed of 110kph. In addition to primary power, the diesel circuit is used to recharge the compressed air tanks when the pressure gets too low, or there is extra capacity the engine doesn't need for propulsion.

The waste heat from the diesel circuit is also used to maintain operating temperature of the engine, and reheat the super cooled exhaust air (very high pressure fluid, being released into very low pressure, means vapor phase change refrigeration whether you want it to or not). It is unclear what the range is when traveling exclusively on the air circuit.

Honestly, that's great. It's a good idea for using the waste energy of a vehicle to do something useful. Of course, the marketing page for the vehicles, and the article, make no mention of any of this. They refer to the car exclusively as a zero emissions vehicle, say it produces zero pollution, and explicitly say it doesn't burn any fuel, therefore never requires an oil change.

Lesse, shading the truth just a bit hard, a little bit of outright lying, and a credulous reporter?

Yeah I think so.

Now, as to my engineering assumptions; I haven't been able to find specific details as to how much HP the engine produces while on compressed air circuit vs diesel circuit, but this page does give some basic tech specs (in spanish):

Empty Weight: 550kg
Horsepower: 25bhp
Range without refueling in city driving: 150km

Stick in two small people and you get, 700kg or so, which is right in line with what I was saying, and with 25hp they are getting their top speed of 110kph... but their range is half what the article said, and that's at their projected "city speeds" of 36kph.

That's OK, seriously it's a significant engineering achievement. That's a VERY light, comparatively roomy city car that's incredibly efficient. It uses every possible means of increasing that efficiency, and apparently does a damn good job of it.

...just don't advertise it as an absolute zero emissions, pollution free wonder car that runs on compressed air, because it isn't.

What it is, is a more efficient and better conceived hybrid... and for once a hybrid that isn't a net environmental detriment (look it up, the electrical systems in hybrids cost more energy to produce than they save, and they are terribly harsh on the environment to dispose of).

That's great; more power to them, and I hope the car is a huge success.

Just one thing though: please stop trying to convince us you can do the impossible. We engineer types really don't like it when you do that; it makes us all twitchy.

Engineering

What makes a good, or great engineer?

I'm an engineer; at heart, by education, by training, by experience, and by profession.

I have degrees in aerospace, and computer engineering; I have a large amount of direct materials, mechanical, electrical, and information systems engineering experience and training; but those things are not what made me an engineer.

I'm an engineer, because it's what I am, mind body and soul. It's wired into me at the very base level of my intelligence and personality. Sure I could have chosen to do something else, some other profession; and I've certainly held jobs that had little (on the surface) to do with engineering; but an engineer is what I am, no matter what I do. Even serving in the Air Force, and doing security work; I've always had an engineering mindset and method, because it's simply who I am...

Of course most people don't really understand what an engineer is, or does, or what that mindset means; they make an assumption based on their surface perceptions, that has little to do with what makes an engineer.

A competent engineer can be trained, or develop through experience; but a great engineer has to be born that way, AND develop through training, education, and experience.

All three are critical to good or great engineering.

Without experience, very little that you do will be useful, efficient, or just plain work right. Experience teaches you how to screw up less, how to do things easier, and how to recover from errors.

It's hard to get experience without at least some training (including self training); or at least it's hard to get useful and instructive experience. Training gives you the basic familiarity with systems, components, and methodologies that allows you to gain useful understanding, and do things efficiently.

It's hard to make anything new without education (including self education); and if you aren't building new things, or coming up with new ways of doing old things; you aren't an engineer, you're a technician. Education helps you to understand the theories and science and reasoning and motivation behind the training and experience you have accumulate; and helps you to understand those lessons, and how they apply to new and different components, systems, and methodologies.

Ok, but what is a good engineer? What is engineering?

Engineering is the art of HOW. How things work, how things are built, how things interact and react, how problems are solved.

Engineering is the fusion of the theoretical and empirical. Scientist understand WHY things work, technicians know THAT things work if they do certain things... but engineers understand HOW things work (and to do so must understand much of the other two), and this understanding allows them to do and build, and fix new things.

A great engineer is a great engineer, no matter what their discipline; no, not all knowledge and experience transfers, but if someone makes great mechanical engineer, they most likely could make a great aerospace engineer, or nuclear engineer with the proper motivation, training, and experience; because great engineering requires three fnudamental drives or abilities in edition to training, education, and experience:

1. The innate understanding of how components, systems, and methodologies interact with each other; and the ability to distinguish and determine causation, correlation, and effect.

2. The absolute drive to figure out the "how" of everything around them.

3. The ability to generalize knowledge, experience, and insight gained on one system, component. or methodology; to other systems, components, and methodologies; similar or dissimilar.

W call the synthesis of these things, ingenuity; and it's what makes engineers something other than technicians or scientists.

If you can do these things, you will be a good engineer; even if you are a poor scientist or technician. If you cannot do these things, you may be a competent engineer; but you'll never be great, or even good. If you can only do one or two of these things, you may end up a good scientist or technician, but you'll never be a great engineer.

When I interview engineers for a job, I ask them all the usual questions, and then a throw one out there from left field: "Tell me what devices or pieces of technology you have in your house. Ok, now tell me how they all work".

If they are a real engineer, they'll be able to do it for just about everything; because they couldn't stand to have something around them that they didn't understand the workings of. Then they'll be able t take the knowledge of how those systems work, and apply them to microwave transcievers, or production line control systems, or large dataset search routines.

Now, take what I've just said makes a great engineer; and stop thinking about mechanical systems like cars, and computers.

Engineers are not just mechanics, or machinists, or programmers; they understand SYSTEMS, and by that I don't mean computer systems, or tooling systems or anything else normal people think of when they hear the word system.

A system, is a set of inter-related and interacting components, actions, decisions, behaviors, results, inputs, outputs, and feedback; be it a machine, or a busy intersection, or a city, or a society, or a person; they're all systems.

Normal people look at the world and they see people and places and things going about their business; engineers see something entirely different. We see systems interacting at every level; every action, reaction, result, behavior... they're all interconnected.

This is one reason why engineers are so ... well... absolute about absolutes, and so fuzzy about those things that are not absolutes.

To illustrate, let me use an example I've used before in this blog: the Steven DenBeste canonical example of the difference between how engineers look at energy production, and how the non-engineer looks at it.

Any good engineer can tell you: no amount of engineering will produce an energy source that is more reliable, cheaper, more available, safer, more environmentally friendly, and as energetic, as fossil fuels. That is what it would take to completely replace them in our world, and it simply cannot be done; so it isn't going to happen; at least not until fossil fuels are so expensive that other alternatives make more sense, in which case the maket will dicate those other alternatives are developed... which of course will make fossil fuesl cheaper becasue demand will be reduced, which will mean less incentive to devlop alternative technologies until the cycle repeats itself a few times.

The primary energy source for the human race was wood from pre-history until the developement of technologies for cheaply extracting coal in the late 18th century. We first discovered oil was a useful fuel for lamps, and for destructive devices, back in classical greek times. It took us til the 1860s to really start working with petroleum as anything other than a nuisance. It was the 1890s before we started using it much as a fuel, and then it was mostly used for heat and light. It wasn't until the 1920s and the widespread rise of the automobile and the airplane before oil became our societies primary source of fuel; and we are STILL using coal for something like half of all our electircal power generation around the world. The technological cycle is accelerating, but it doesnt work overnight.

When a good engineer says something is impossible, they mean that for all practical purposes it cannot be done; not that it's very hard, or that "we don't know how to do it", which is what most people mean when they say something is impossible. If a good engineer thinks something is possible, but very very hard, they'll tell you.

Some people see, to think that every scientific or technical problem can eventually be solved if we jsut get enough smart people, working hard enough, with enough money and resources. Unfortunately, that just isn't true. Great enringeering can do amazing things... even do what is seemingly impossible, by doing things in ways that circumvent limitations. This ability to do amazing things with engineering has created the expectation I mention above in may people who should really know better. The thing is, no amount of engineering, no matter how brilliant, no matter how technically advanced, no matter how innovative; can change, or get around the laws of physics. In order to "do the impossible", the very laws of the universe have to change, or at least our understanding of them does.

It is impossible for solar technologies to economically replace fossil fuels; and even uneconomically the environmental impact would be far higher than that of the fuels they are replacing.

The exact same could be said about wind power, tidal power, geothermal power... really almost all of the so called "alternative energy" sources. It is impossible to entirely, or even substantially replace fossil fuels with the so called "alternative" energy sources being promoted as environmentally friendly; without either destroying our society through the massive increase in the cost of energy, or hurting the planet far worse than fossil fuels ever could.

Note I do not say "we don't know how to", or "it would be very hard to"; it is for all PRACTICAL purposes, impossible; because to do so would require a fundamental change in the way physics and the universe work as we know it. There is an infinitessimal chance that such a change would occure, therefore when going into detail I say "for all practical purposes".

Again, that one hedge, doesn't mean what non-engineers mean when they say it. A normal person say"for all practical purposes", and they mean "it would be very hard and expensive to do so"; when an engineer says it he's saying that it would require a change in the fundamental laws of the universe to work.

This isn't to say that some of these technologies are not useful, and desirable as supplemental to fossil fuels; just that we can't replace fossil fuels with them, either entirely, or even mostly.

There is one currently working technology, and two very promising future technologies to replace fossil fuels. The first is mature, stable, and useful technically; and will become more so as engineering develops the systems to take advantage of it. The other two, we don't really know how to do right yet, or in the case of the second, even if it will be possible to do so.

If you're an engineer, you already know what three technologies I'm speaking of: nuclear fission, large scale use of hydrogen as a fuel, and nuclear fusion.

Nuclear fission is a well understood technology. It is still an immature field and market; largely because of political considerations; but it's safe, it works, and given proper economies of scale and a favorable regulatory environment, it's relatively inexpensive.

Of course the primary problem there is political; in that the envriowhacko movement has made large scale nuclear power all but impossible for now, in most places. Secondarily, we haven't developed the technologies necessary to parochially replace our use of fossil fuels with electricity.

As to the first issue, as time goes on I believe that nuclear fission will become the dominant means of electrical power generation in the industrialized world; because we need more and more power to keep that world industrialized, and the generation of power through fossil fuels is dirty, and expensive; and will continue to become more so.

As to the second, well there's no certainty we'll ever be able to replace fossil fuels with electricity... in fact there's a near certainty we wont be able to entirely, but that we'll be able to replace enough, that fossil fuels will become a very small concern, or could be replaced with other alternatives.

Fusion, is a lot like fission on the practical technical side, in that we don't have the systems necessary to use electric power as a fossil fuel replacement yet; but in the case of fusion the problem is more fundamental. We THINK we can figure out how to make fusion useful, controllable, safe, practical, and efficient... but we don't KNOW yet. We BELIEVE that the physics of the question are understood, and do not prevent us from engineering the solution as time goes on.

The problem is, we've been working on it for fifty years now, and we're still crawling like babies. It's going to take a hell of a lot more work just to make sure it can actually be done; and then a hell of a lot more work to actually engineer the solutions to doing it.

In the mean time, we should be doing as much as possible to engineer the changeover to an electrical energy world; using nuclear fission as the power source.

The final technology I mention as being potentially useful, is hydrogen fuel. Hydrogen is great, because it's energy dense (by weight anyway), it's the most common substance in the universe, and the only byproducts from its use in an oxygen atmosphere are heat and water. There are two primary potential uses for hydrogen as an energy source: In fuel cells to generate electricity, and as a direct fuel for turbine, and compression engines (like gasoline or diesel motors for example).

The first requires that we once again come up with ways to replace fossil fuels with electricity... which of course means that we should be engineering more and better ways of doing that; after all, ALL of our promising technologies for replacing fossil fuels require it.

The second usage requires us to engineer engines that use hydrogen as their fuel; something that is very much doable; and in fact something that has been in nascent stages for over 100 years; but because of the cheap availability and usefulness of fossil fuels was never developed very much.

Of course the practical problems with hydrogen are substantial. First, how do you extract the hydrogen from its base sources (primarily water and natural gas using current technologies)? Second, how do you safely transport it and distribute it? Third, what do you do with all the water vapor and waste heat being created when the hydrogen is being used as a primary fuel source? Fourth, how do you solve all of these problems economically?

The good news is that these are all well understood technical issues from a scientific standpoint; what remains is to engineer the solutions, and then build the infrastructure; and THAT is a political and social problem not a technical one.

So what do I think is going to happen? Well I would guess that as I said, nuclear fission power will become the dominant source of electrical power; and we will slowly shift as much as possible away from fossil fuels and into electric power. As we do so, hydrogen power will develop very slowly, because with less demand, fossil fuels will become far less expensive, and less of an environmental problem. From there, the market will determine the solution; but unless someone comes up with a massive engineering and economic upside to hydrogen, we'll probably keep using fossil fuels for the foreseeable future.

Long digression there with a lot of maybes and could bes and caveats right? Like I said, if it's not an absolute, we're pretty fuzzy about it. Normal people will say "Yes we can do this if we work hard enough" or "No we can't do this"; engineers will say "We can do this if... and its going to be hard if... but maybe... let me try this..."

Of course this method of looking at the world, for all it's advantages and abilities, has a problem. When you look at everything as interconnected systems, you tend to expect that systems and behaviors will be at least marginally predictable or reasonable, or rational.

One problem with that, human beings aren't. People are very complex systems, and they don't have consistent rules or behaviors. They ahve motivations, and passions, and understandings, and misunderstandings, and chaos, and fear, and inspiration... but the one thing they don't have is consistenly understandable or predictable rules or behaviors.

The universe is perverse. Complex systems are simply not rational or predictable, except at the macro level (and sometimes not even then); because of chaos theory, because of the law of unintended consequences, hell even because of the second law of thermodynamics.

The truly great engineers of this world know and understand this, at as deep a level as their understanding of systems; and thus they can function in the world without isolating themselves, or destroying themselves; or their relationships with those around them.

In fact, through this understanding, they can produce and express true brilliance; and if they're lucky they can achieve that which so few do: happiness

Unfortunately, there're a hell of a lot of otherwise good engineers who persist and insist on treating complex systems, and complex people; as if they were predictable, and rational. Those people don't generally end up very happy at all.

Why bullpups aren't a great solution

For some reason, the bullpup rifle keeps being put forward as a good idea.

...Really, for the most part, they are not.

I'm an engineer and a firearms expert; by training, inclination, experience, and employment. I'm a veteran, a former security contractor, a firearms trainer, and an FFL, gunsmith and class III manufacturer.

I have a great appreciation for good engineering. Bullpups are, in general, not good engineering.

The bullpup rifle has one real advantage: bullpup designs allow for a shorter overall weapon, for a given length of barrel (typically between 4" and 7" shorter than a conventional rifle).

That's not an insignificant advantage. In some missions it's even a huge asset (particularly in urban combat, or infantry dismounted from armored vehicles).

In most missions though, that 4-7 inches isn't much of a plus.

On the other hand, the bullpup configuration has a number of disadvantages:

• Bullpup designs are mechanically more complex, requiring a long trigger linkage, and control system linkages. This seriously degrades both control feel, and reliability, and increases bulk and weight (there may be engineering solutions to this problem).
  
  If current munitions infrastructure and laws allowed for electronic trigger, feed, and ignition systems, this would be a non issue, and the bullpups advantage may outweigh it's several disadvantages; but for now, that's not an option (also, electronic systems have their own issues).
  
  
• If a bullpup has a catastrophic failure, instead of the explosion being six or eight inches in front of your eyes, it's right at your eyesocket, or touching your cheekbone or ear. The only good thing is, if the bolt flys back, it doesn't end up in your eye socket.
  
  Most bullpups also eject hot brass, and vent hot gasses in the vicinity of your eyes and ears (some eject downward or forward, which is a better solution for a bullpup, if it's engineered properly).
  
  
• Mag changes on most bullpups are slower (sometimes much slower) because they require more repositioning, that positioning can be awkward, and can be difficult to see (if necessary) without fully dismounting the rifle.
  
  A conventional rifle allows you to see your mag changes, and is more easily maneuvered with your dominant hand, which makes mag changes easier in general.
  
  More importantly a human being can naturally bring their hands together in the dark. As a basic design guideline, magwells should either be in your dominant hand, or just in front of it; because it is far more difficult to manipulate anything dexterously that is located behind your dominant hand.
  
  
• Because of the positioning of the magazine (usually the part of a gun extending lowest) close to your shoulder when the weapon is mounted, bullpups can be difficult to fire while prone (though this is common with some other rifle designs as well).
  
  Note in the pictures below, the magazine is by far the lowest point of the rifle; and being located behind the dominant hand and close to your shoulder; when you drop prone it will tend to strike the ground forcing the muzzle downward.
  
  This can also cause problems with mags being warped, ripped out of the magwell, having the baseplate broken off, or the rifle itself being ripped out of the users hand when hitting the deck.
  
  A conventional rifle with a long magazine can have issues with dropping prone as well, but because the mag is positioned forward of the dominant hand, instead of forcing the muzzle down, it will tend to force the muzzle up; and though it's not advisable to use the magazine as a monopod, it's possible. With a bullpup, it isn't.
  
  This isn't an issue for rifles that are generally fired off bipods, so in an SAW or LMG role, the bullpup may be an appropriate solution (though having the feed system in such tight quarters with your shoulder and cheek is its own issue).
  
  
• Charging the rifle and manipulating the operating handle is often more difficult, and sometimes can't be done without dismounting the rifle, or reaching over the rifle with your support hand (again, some conventional rifles do share this weakness; and this is a problem that can easily be solved with proper engineering).
  
  
• Most bullpups can only be operated from the right shoulder; or if switchable, can only be operated from one shoulder without being reconfigured (this is changing, with the adoption of forward ejection mechanisms).know of, can be fired from the left shoulder.
  
  Because of the way most bullpups eject their brass, and cycle their actions; attempting to operate the weapon from the wrong shoulder will result in hot brass being ejected directly into your face, and possibly injuring the user... or they my simply not be able to cycle at all.
  
• Bullpups are naturally balanced in a non-instinctive way.
  
  This is really the biggest problem, and the one that is hardest to solve with engineering.
  
  The balance point on most bullpups is in between your hand and your shoulder when mounted, which is unnatural. We have a natural tendency to try to balance things between our hands, not between our hand and shoulder.
  
  The only way to correct this is to put heavy things in front of your dominant hand, or to make the weapon short and light enough that this won't make a difference (and even then it will still be more awkward and less instinctive to point; but several modern bullpups have taken the second approach).
  
  This balance will tend to make a bullpup tend to shift its butt under recoil, unless it is very tightly mounted to your shoulder; particularly during rapid fire. This tendency is somewhat countered by the position of your support hand so far forward on the barrel,  by the fact that the overall leverage moment of the muzzle is lower (the muzzle isn't as far from either your shoulder, or your dominant hand), and by the fact that most bullpups have straightline recoil.
  
  A conventional rifle is balanced in between your dominant and support hands, and there are good reasons for that. A human being naturally handles things that balance in the palm, or in front of your dominant hand, better, because we naturally want to balance things between our hands.
  
  Under recoil, the muzzle of a conventional rifle rises, but just from gravity will fall into you support hand again without actually holding or pulling it down, because the fulcrum of the lever is in your dominant hand, and the balance point is in front of the fulcrum. 

Some of these issues can be solved, or mitigated with engineering (and most modern bullpup designs do resolve, or at least reduce, many of those issues). Also, a lot of this can be worked around with training.

What it comes down to though, is that bullpups are ergonomically incorrect for human beings. When you have the option, you don't train someone to do something ergonomically incorrect, you redesign the equipment to fit human ergonomics.

The only good thing about a bullpup is the short overall length in relation to their barrel length; and that is not advantage enough to outweigh the disadvantages for most missions.

Well, that and the fact that they look cool, which is the real reason so many people are enamored of them.

A lot of folks have watched a lot of stargate (or played a lot of stealth shooter video games). They use the FN-P90 PDW which isn't exactly a bullpup, but follows a similar concept; and they do just look kind of futuristic.

The Steyr AUG was designed in 1976, and it still looks like a space gun:

Several countries have adopted bullpup designes as their primary service arm, notably Austria, and Australia (the AUG above), France (the FAMAS),

and the UK (the SA80 system, now in the L85-A2 variant):

The reasons cited are usually overall length, the extra accuracy and velocity afforded by the longer barrels allowed by the configuration, and some medical or efficiency studies showing that the bullpup was actually ergonomically correct.

Here's the thing: every study that the British did showing that the SA80 design was ergonomically correct, or that the reliability issue was solved, has over the past few years been proven to have been "Unjustifiably optimistic", or some other such euphemism for fraud.

The SA80 has  proven to be ridiculously unreliable , though at least it is quite accurate when it functions properly (also the HK refit and remanufacture of the A2 variant has dramatically improved reliability... Though it's still not great).

The SA80 in fact is so poorly designed, that firing it from your left shoulder will give you a black eye (and can even break your cheekbone) and send hot brass and gasses flying into your eyes. You also can't fire the thing from the left side of cover without exposing your whole head and torso.

I have tried the P90, the SA80, the Steyr AUG, the Bushmaster M17, the FAMAS, and the IMI Tavor (the latter two held and played with, but not shot), and I haven't found any of them but the P90 to be remotely comfortable, or anything but awkward. I've tried a couple of bullpup conversions from other weapons as well, same thing (excepting several bullpup sniper rifles, that I quite liked, and as I said, the P90 which is only sort of a bullpup... it's quite handy and nice to shoot).

UPDATE: Since I first wrote this, I've had a chance to shoot with the FN F/S2000 in both semi and full auto variants: 

While it looks like a heavy and awkward spacegun, it's actually very light, well balanced, and comfortable. Reports from the field are that it is generally reliable, but there aren't a lot out there yet to establish a useful sample.  

Mag changes are still less than ideal, and the trigger is still poor; but the handling of the gun is good, and it is reasonably accurate for an assault rifle. I do worry however about the forward ejection system. It seems to me like it would be easy to jam up in the field. 

Also, since I originally wrote this, Kel-Tec has introduced their RFB forward ejecting bullpup in 7.62x51: 

Unfortunately, not many of them are out in the world yet, so I haven't had a chance to fire one; but the design seems to address some of the issues above.  I have real concerns about the forward and up ejection system, and the inability to clear a jam without field stripping the weapon however. 

Until someone has shot thousands of rounds through them, had to change mags in the dark, and in cramped conditions, had to clear jams under combat conditions etc... they can't know how unsuitable bullpups are as anything other than a niche weapon, to be used only where OAL is the most critical factor (but where SMGs are not an appropriate choice).

For example, bullpup sniper rifles make a lot of sense, particularly in .50bmg and other anti-materiel chamberings. In fact, any weapon that you would normally fire off a bipod makes sense as a bullpup, because the ergonomic issues around balance, and lying prone don't really apply.

People say "Well the designs just aren't good enough yet, I'm sure as they mature they'll get better, isn't it the natural way to go eventually?"

First of all, why would it be?

Other than the fact that the Sci-Fi network likes featuring bullpups in their television shows, there is no reason why bullpups should be "the future". They have one design advantage, shorter length, and many design disadvantages.

Now, when we use caseless ammmo loaded in 1000 round blocks, and using electronic ignition systems... sure, bullpups make sense. At that point, all the basic engineering weaknesses are compensated for, and the advantage of a longer barrel for length of weapon offsets the balance issues... if they even exist then, given progress in materials.

But for now, so long as we are using relatively "conventional" ammunition and firing mechanisms, those engineering problems outweight the one real advantage; and the ergonomic issues simply compound the problem.

Engineers aren't miracle workers. We can refine a design until it's mechanically perfect within its design parameters; but the point I'm trying to make, is that at our current level of cartridge firing weapons development, there is no way to design an ergonomic bullpup.

So, bullpups are only slightly shorter than their conventional counterparts (maybe 7" in the case of an assault rifle), nothing to sneeze at, but not a huge advantage in most cases considering the missions they are intended for; they are less reliable and more mechanically complex than conventional designs, they are ergonomically incorrect, and they are more likely to injure their user.

I'm not denying there are missions where a bullpup is appropriate (as I said above), but I can't see any conventional situation where a bullpup assault rifle is the right tradeoff to make; even urban warfare and infantry dismounted from armor.

But they look cool...