A great riding group on a Baja ride: From left to right, it’s British novelist and world traveler Simon Gandolfi, Go Go Gear CEO Arlene Battishill, hunting buddy J Brandon, Baja John, and yours truly. John loves Baja so much he lives down there. This photo is in Santa Rosalia. That’s the Sea of Cortez in the background.
Yep, based on the Chinese zodiac, 2020 is the Year of the Rat. I suppose there are all kinds of jokes, organized crime and otherwise, that could be made of that, but let’s set all that aside. Good buddy Baja John (who wrote to me from Bahia de Los Angeles in Baja just a few days ago) had this much better suggestion:
Hey Joe,
So, I’m calling this year the “Year of Hindsight.” I was thinking that might be good fodder for a blog entry. Lessons to pass to younger readers or lessons that have helped you live happier in your senior years. Who knows. Popped into my head and thought I’d share.
John
I think that’s a grand idea, John, and I’m hoping our readers do, too. Hey, it’s 2020, and everyone knows that hindsight is 20-20. So, to all our readers (and our year end report tells us that our key demographic for ExhaustNotes readership is men aged 55 and over), you have the benefit of years of experience in all kinds of things. Let’s have your comments, please. What advice on any topic (love, life, money, politics, 9mm vs. .45, motorcycles, whatever) would you give younger folks?
The 147-grain 9mm Speer bullet next to a 124-grain cast roundnose bullet. Cool, huh?
Well, ol’ Gresh sure stirred up a hornet’s nest with that flat track blog yesterday. We nearly ran out of bandwidth!
On to a more metric subject: 9mm ammo.
I started the PRK 10-day cooling off period (you know, the People’s Republik of Kalifornia) for my new SIG P226 a couple of days ago. Let me tell you, if anybody thinks they are going to outlaw guns in California, they need to think again. I had to wait an hour and a half at our local Turner’s Sporting Goods store just to start the process. There were five guys working the gun counter and customers were lined up five deep. There were a ton of folks buying and picking up guns. Trying to outlaw guns in America is a nonstarter, even here in looney leftwing California.
This man had some of the best comments ever. “They know so much that just isn’t so” ranks high on my list.
Okay, enough of the rant about my friends who know so much that just isn’t so, to borrow a phrase from one of the greats, and on to the subject of this blog: Getting ready for the 9mm accuracy load development program I spoke about a few days ago. Like I said earlier, my standard 9mm accuracy load for years has been 5.0 grains of Unique behind a 125-grain cast bullet, but as part of my New Year’s resolutions I am moving in two directions simultaneously: I’m expanding my horizons in the 9mm world and I’m reducing my waistline. The waistline story can wait for another day; today’s topic is the loads I’m crafting for inclusion in the 9mm Comparo.
I’m going to evaluate three or four different 9mm handguns and several different loads, and I’ve started reloading the ammo for that. The first four loads I’ve already crafted are with two different bullets I haven’t tried before: The 147-grain Speer truncated metal jacket bullet, and the 115-grain Armscor FMJ bullet. The 147-grain Speer bullets are really cool looking. If they shoot half as good as they look I’ll be driving tacks with my new SIG!
A box of Speer 147-grain TMJ bullets. These are long bullets compared to what I normally shoot. They do look good.One of the 147-grain Speers ready for seating in a charged 9mm case.Another angle. Some of you folks get it. Stuff like this is beautiful. I mean, look at it: Polished brass, Unique propellant, and full metal jacket, heavy-for-caliber bullets. Life is good, folks. These loads are at 3.9 grains and 4.4 grains.
Seating the bullets is always cool, too. It’s where it all comes together.
On the way up, Rockchucker style……and on the way down. A new cartridge is born!
The finished rounds look great. Now the question is: Are they accurate? We’ll see. This is the first time I’ve tried a bullet this heavy in a 9mm.
You can’t think about the time you spend reloading ammo compared to the cost of factory 9mm ammo. It would be too depressing. We do it for the sheer enjoyment of making something. We’re recyclers. Maybe that’s why RCBS reloading gear is green. Al Gore and Ms. Thunberg have nothing on us!
I seated the Speer bullets to the recommended depth for an overall cartridge length of 1.120 inches. I’m trying a couple of different propellant charges. I can experiment with seating depth to find the best accuracy later if this combo shows promise.
I know. It’s an obsession. But it’s fun.
But wait: There’s more! I also picked up another bullet I had not tried yet, the Armscor 115 FMJ (full metal jacket) roundnose bullets. They are cool, too, and they were only $10 for a bag of 100 pills.
Armscor is the same company that makes Rock Island Armory guns, like my Compact 1911.
I’ve shot brass-jacketed FMJ bullets before, but that was in my .45 when I bought bulk Remington ammo just to get the brass cases (you know, so I could shoot them up and reload them later). These are good looking bullets, too.
Brass jacketed Armscor 9mm bullets. We’ll see how these do. I like the look..
The charges listed in my loading manuals for a 115-grain jacketed bullet with Unique propellant seemed to hover around a max of 5.5 grains with a minimum of 4.8 grains, so I prepped two loads, one at 5.4 grains and one at 5.0 grains.
5.4 grains of Unique in primed 9mm cases. You can’t load too much more; this charge nearly takes up the entire case volume. With the bullets seated, this will become what we call a compressed load. Unique is what is known as a flake powder…the individual grains are tiny flakes of propellant.
Here’s a cool shot of the finished Armscor load. I like the way these look. It’s like being the Lone Ranger, but with gold instead of silver bullets. Hi Yo SIG, away! (Cue in the William Tell Overture.)
Ready for accuracy testing. This, too, is nice looking ammunition.
If you are not a reloader yet, you might want to think about getting into it. To me, reloading is as much fun as shooting. And if you want to learn how to do it, take a look at our series on reloading .45 ACP ammo on the Tales of the Gun page!
Fresh off a couple years of record attendance and wild popularity for flat track racing the AMA has decided to destroy the successful formula that has created all that positive buzz. Whenever a race series becomes popular the AMA cannot stop itself from diluting and dividing it into numerically more, yet overall weaker championships. They are doing just that in flat track with the new Supertwins class.
The historic, fabulous, drama-filled heat race format is no more. You’ll not see a lightly sponsored privateer like No. 23 Carver on an obsolete XR750 whip the asses of the best factory riders and teams like he did a few years ago. You’ll not see it because the AMA has limited entries to 18 pre-approved teams. No more heat races, no more last chance qualifiers, no more excitement.
The AMA hopes that we won’t notice that the game is rigged but flat track fans know a setup when we see one. To get in the Elite 18 it will take lots of money along with co-branding with the AMA and your chances of getting picked are much better if you have a really nice race transport semi-truck and branded pit barriers. Rider talent only comes into play after all the other barriers have been surmounted.
The chosen few will run two semis and if I know the AMA and the power of money I’m guessing the first nine places of each semi will make the main. It’s NASCAR thinking run amok. The AMA wants a more professional product to sell to television audiences. They want recognizable teams and popular riders spoon fed to an audience they feel are too stupid to appreciate a couple of privateers pitching a heated battle for 8th place. They want us to be like NASCAR fans cheering on personalities and products rather than effort. To achieve this end they are tossing out the very things that have made AMA flat track the premier motorcycle race series in America.
The AMA has it backwards. Fancy transporters and branded awnings don’t mean shit to flat track fans when the flag drops. AMA flat track is popular because of the unpredictable rough and tumble racing, not in spite of it. It’s popular because of the lone wolf in his van taking on the biggest motorcycle manufacturers in spite of the fact that it seems hopeless. It’s popular because no matter how out-gunned any expert rider on any night can ride his ass off and make the main event or even win the whole shebang. It has happened more than once.
You haven’t heard a crowd roar like the throat-rattling cheer flat track fans make when an underdog rider beats the big guns in a main event. It restores your faith in hard work, man. I hear you when you tell me the same guys win all the races anyway. That’s because they are the best riders on the best bikes. It’s always been that way in motorcycle racing, but flat track fans still hope to see the improbable and we don’t need to dumb down flat track to make our hopes impossible.
The legalese mumbo-jumbo in the document above is the rider’s path to the Main Event now. Replace grit, determination and talent with money and you have the new rules pretty well down. Teams will need to be partners with the AMA, it’s so not like it used to be and frustrating as hell. What utter and complete bullshit.
The list of eligible engines for Supertwins is longer than the number of eligible teams!
Ah well, it was an exciting, if short-lived resurgence in American Flat Track racing. At least we still have the singles class and an interesting, if sporadic, ATF Production Twins class (the true Class C Championship). The powers that be cannot leave well enough alone. Success is not enough for today’s bottom-line economy. Branding, sponsorship and tight control of the final product are paramount. It won’t be long before the AMA sells the racing rights to an engine manufacturer and Supertwins becomes a one-design spec class. I guess nothing ever stays the same and we all get sold out in the end. Welcome to AMA Flat track 2020.
The Gatling Gun, a book that tells the story of the original Gatling guns, their transition to modern gun systems, and several of the weapons platforms currently using Gatlings. It has been one of my most successful books ever. The Gatling Gun was picked up as the Book of the Month by the Military Book Club shortly after its publication and that made for a very healthy sales spike (and that was okay by me). It seems that every job I had after finishing college had something to do with Gatlings. I was on the Vulcan gun system in the Army. I was on the F-16 design team, an aircraft that flew with a 20mm Gatling. I worked on the Phalanx Close-In Weapon System at General Dynamics here in California. I was the Director of Engineering in the company that manufactured 30mm A-10 ammo. There’s more, but you get the idea.
Writing The Gatling Gun was a hell of a lot of fun, including visits to the Connecticut State Library (where the original Gatling and Colt archives, and many of the early Gatling guns, are stored). I handled original documents prepared by Samuel Colt and Dr. Gatling (and in the process, I became a licensed State of Connecticut historian). It was a hoot.
Of all the modern Gatling-equipped weapons of war, the most powerful is the A-10 Warthog, an aircraft armed with the mighty 30mm GAU-8/A Avenger cannon. Working for Aerojet, the company that manufactured the A-10’s 30mm ammunition, was one of the best jobs I ever had.
Today’s blog includes The Gatling Gun chapter on the A-10. I think you’ll enjoy it.
Chapter 11: The A-10 Thunderbolt Story
As the column of Soviet armored vehicles rolled across the open Eastern European plain, the lumbering sound of diesel engines and clanking treads drowned out all else. Russian infantrymen struggled to keep up, shouting to (but not hearing) each other. Suddenly, a roar different than that emanating from the tanks engulfed everything. It sounded like a powerful internal combustion engine (perhaps that of a race car) running at full throttle. The infantrymen started dropping as the tanks slowed to a stop. From the rear of the column, and working toward the front at an incredible rate, the ground erupted all around in 10-meter-wide explosions. Three of the tanks burst into flames, one blowing its turret off the hull. Black smoke was everywhere. An A-10 passed overhead, its 30mm Avenger gun continuing to roar, throwing out high-velocity depleted uranium penetrators and a 20-foot-long muzzle flash. The aircraft swung low as it passed the column. One of the infantrymen not killed in the first pass realized that the devilish craft was circling for another pass, and in addition to feeling raw terror, he suddenly felt very ill.
Of all the Gatling-gun-equipped aircraft flying today, one of the most intriguing is the A-10 Thunderbolt II. Nicknamed the Warthog by the crews who fly it, the A-10 is the first airplane designed from the ground up around a Gatling gun. It carries the most powerful Gatling gun ever built.
The Close Air Support Problem
The need for the Thunderbolt II and its very specialized mission was recognized during the conflicts in Korea and Vietnam. In these conflicts, U.S. aircraft were the best in the world for air-to-air combat. In the Korean War, these superb fighters included the F-86 Sabre, F-84 Thunderjet, F-80 Shooting Star, and F9F Panther. The F-4 Phantom, the F-111, the F-8, the A-7, and several others saw action in the Vietnam War. Vietnam-era tactical aircraft included such features as supersonic speeds, terrain-following radar, computer-assisted weapon delivery systems, and even such things as exotic as wings with adjustable sweep angles. One problem with these aircraft, however, was that they were designed primarily for air-to-air combat. This made them less than ideal for close-air-support missions (which support ground troops by engaging enemy ground targets). Having been designed for air-to-air combat, they had to be fast and maneuverable, and capable of flying at high altitudes. This placed constraints on the amount and kinds of ordnance that could be carried. Their high speed also meant the airplanes had a high stall speed, which detracted from accurately delivering ground fire.
In the close-air-support role, where the pilot would be required to engage ground targets in close proximity to friendly troops, inaccurate delivery systems were unacceptable. Most of the aircraft that flew in Vietnam were designed with late 1950s and early 1960s technology. During that era, vulnerability to small-arms ground fire was not recognized as a key design parameter. Unfortunately, this is precisely the environment in which close-air support aircraft must operate. In the Vietnam War, more U.S. aircraft were downed by small-arms fire than by any other means. There is even a confirmed case of an F-4 Phantom being shot down by a single rifle bullet.
The A-10 Warthog firing its 30mm Avenger cannon. This aircraft was actually designed around its powerful Gatling cannon. Each 30mm round has more muzzle energy than a World War II 75mm Howitzer!
The most significant drawback of existing close-air-support aircraft (i.e., those used in the close-air-support role prior to the advent of the A-10) was that they were ineffective against tanks. With enemy armor being one of the main threats to NATO forces in the European theater, military planners recognized that an aircraft with new capabilities was required.
The A-X Requirements
The close-air-support deficiencies the United States had observed during the Korean and Vietnam conflicts defined the need for the A-X aircraft in the mid-1960s (A-X stands for “Attack Experimental”). The air force initially envisioned a turbo-prop aircraft. The idea was that a current-technology version of the World War II Thunderbolt would best satisfy the requirements (note that World War II vintage Thunderbolts were used in a close-air-support role in Vietnam). The A-X specification was based primarily on deficiencies in existing aircraft. One of the requirements was an extremely accurate ordnance delivery system, because friendly ground troops could be within yards of the enemy. A high payload was also needed. As explained earlier, most existing tactical aircraft had been designed to maximize either maneuverability, speed, altitude, or some combination of these parameters. Payload had necessarily suffered.
The A-X aircraft also had to be able to remain in the air near the target for long periods of time, which is referred to as “loiter capability.” Existing tactical aircraft had been designed to operate at high altitudes. When flying at the low altitudes associated with close-air-support missions, they consumed excessive amounts of fuel. This translated to short loiter capabilities, which detracted from the effectiveness of close-air-support missions.
The air force also stipulated that the new A-X aircraft needed to have good “survivability” characteristics, meaning it should be relatively invulnerable to small-arms fire from the ground. To ensure that the aircraft met this requirement, the air force specified armor protection, redundant flight-control systems, and fire-suppression equipment.
The Armor Threat
The main requirement for the A-X aircraft, however, was that it be able to contribute significantly to the NATO defense of Eastern Europe, and that meant it had to be able to defeat tanks. (The Soviet Union and its Warsaw Pact allies had tens of thousands of tanks deployed along the East-European frontier. In any European combat scenario, the United States and the nations of Western Europe would have had to be able to defeat these tanks.)
To meet this threat, the United States developed (and continues to develop) many antitank weapons. These include shoulder-fired antitank weapons, large-caliber recoilless rifles, aircraft-delivered missiles and bombs, smart munitions, and several other systems. No U.S. aircraft, however, carried a gun system capable of defeating Soviet tanks.
The Flyoff Competition
In 1967 the U.S. Air Force solicited proposals from twenty-one companies to build a prototype A-X aircraft. After evaluating all of the proposals, it selected Northrop and Fairchild Republic as contenders to enter the final phase of the competition. As part of a new procurement policy, it funded both companies to develop aircraft meeting the A-X specifications. After Northrop and Fairchild finished building the prototypes, the air force conducted extensive tests prior to making a decision. During the competition, Northrop teamed with Ford Aerospace and Communications Company. Ford built the gun used in the Northrop aircraft, which was designated the A-9. Unfortunately for both Northrop and Ford, the Ford gun experienced many problems during the test program, including blowing up on at least one occasion. The antitank gun was the primary weapon for the A-X aircraft, and because the Ford gun (which was also based on the Gatling principle) performed poorly, the outlook for the Northrop A-9 was bleak.
A tank struck by GAU-8/A ammunition from the A-10 Thunderbolt. The GAU-8/A ammunition includes a mix of high explosive and depleted uranium projectiles.
Fairchild Republic teamed with the General Electric Armament Division to build the A-10. The A-10 carried a new 30mm version of the Gatling gun named the “Avenger,” which was based on the older 20mm Vulcan but was much more powerful. When General Electric became involved with the A-X program, it had nearly twenty years of development and production history with Gatling guns of various configurations. This experience was apparent during the test program, and the 30mm Avenger performed superbly. The A-10 rapidly demonstrated that it was a superior aircraft. The prototype flyoff competition ended in late 1972, and the A-10 was selected for a planned production run of 600 aircraft.
The A-10 Thunderbolt II
The A-10 Thunderbolt II is unlike any aircraft in the U.S. inventory. It is quite unconventional in appearance when compared to other tactical jet aircraft, and for good reason. One notably different aspect of the A-10 is its unswept wings. The stubby wings are straight to allow flying at the very low speeds required for the close-air-support role. Another striking difference is the location of the engines, which are mounted high above the rear fuselage. There are two reasons for this. One is better protection from enemy small-arms fire. Another is that the rear fuselage masks the engines’ heat signature, providing better protection from heat-seeking missiles.
The GAU-8/A 30mm Gatling gun. The size and power of the Avenger cannon are obvious in this photograph.
The A-10 has many other unique features that are not as readily apparent. One is a high degree of component and subassembly interchangeability. To the maximum extent possible, left and right components of the aircraft are identical, which considerably reduces the number of spare parts needed to support it. The interchangeable components include the engines, landing gear, rudders, and many parts of the wings and tail. The landing gear design is also unique in that when it is retracted, the main and nose wheels protrude slightly beyond the outline of the fuselage. This permits the A-10 to make emergency gear-up landings without damage. The A-10 is designed to survive small-arms fire. Control cables and hydraulic lines are routed so that one projectile could not inflict enough damage to make the aircraft unflyable. Another survivability feature is the cockpit design. The lower portion is surrounded by lightweight titanium armor to protect the pilot. The A-10 payload is quite impressive. In addition to 30mm ammunition, the A-10 can carry missiles, bombs, cluster bombs, and other munitions, for a total of up to 18,500 pounds of ordnance. This is approximately equal to the weight of the aircraft and is about double the payload of other aircraft used in the close-air-support role. Yet the A-10’s most intriguing feature is undoubtedly its 30mm Avenger Gatling gun.
The World’s Most Powerful Gatling Gun
The heart of the A-10 is its 30mm gun. The military designation for this gun is the GAU-8/A (the GAU is pronounced “gow,” and is an acronym for Gun, Automatic, Utility), and the A-10 was literally designed around it.
The GAU-8/A is a seven-barreled 30mm Gatling gun that weighs approximately 3,900 pounds fully loaded (or about 20 percent of the total aircraft weight). The gun is hydraulically driven and is fed through a double helix drum and ammunition feed system similar to that of the 20mm Vulcan (more on the feed and storage system later).
One way to appreciate the power of this gun system is to consider it in relation to the A-10. The gun is mounted to place the firing barrel on the exact centerline of the aircraft, and for good reason. When firing at the maximum rate of 4,200 RPM (it can also fire at a reduced rate of 2,100 RPM), the GAU-8/A generates about 19,000 pounds of recoil. To put this in perspective, consider the power of the A-10’s two fan turbine engines. Each of these generates about 9,000 pounds of thrust. When both engines are at full throttle, they generate a combined thrust of 18,000 pounds, which is less than the recoil of the GAU-8/A. In other words, when firing at maximum rate, more recoil force is generated by the GAU-8/A than by both of the engines operating at full throttle! The effect is quite noticeable, as the gun actually slows the A-10 when it is firing.
The A-10’s Avenger Gatling fires when each barrel when it is aligned with the centerline of the aircraft, which is why the cannon is offset to the aircraft’s left side.
The high recoil of the GAU-8/A gun is also the reason the firing barrel is along the aircraft centerline. If it were not, the A-10 would turn away from the target each time the gun fired. Aircraft carrying the 20mm Vulcan in an off-centerline position are also susceptible to this phenomenon, but the recoil of the 20mm gun is small enough to allow for compensation by offsetting the rudder a few degrees. This is normally programed into the flight-control computer and requires no action by the pilot. That approach would not work on the A-10, though. The GAU-8/A gun simply generates too much recoil.
The GAU-8/A Gun System
The GAU-8/A Gun System is made up of four subsystems: the gun, the ammunition feed and storage subsystem, the drive subsystem, and the electrical control subsystem. Specifications for the GAU-8/A gun system are presented in Table 11-1 and explained below.
The GAU-8/A gun is a seven-barrel Gatling-based automatic cannon (see the illustrations above). The gun subsystem consists of the following nine major components:
Rotor assembly. The rotor assembly is made up of the forward rotor (which accepts the barrels and is geared to the gun drive shaft) and the mid-rotor (to which the bolt guide tracks are mounted). The rotor assembly operates in the same manner and provides the same functions as that of other Gatling guns.
Housing. The housing serves as the basic frame of the GAU-8/A and provides a mount for many of the gun components (including the lubricator, ammunition transfer unit, solenoid assembly, firing cam,
rotor, and other components). It also contains the elliptical cam path that drives the bolts back and forth.
Barrels. The GAU-8/A has seven barrels. Each is 93.1 inches long and has 20-groove right-hand constant twist rifling (unlike the 20mm Vulcan, which uses a gain twist rifling pattern).
Bolts. Seven bolts are used on the GAU-8/A. They are similar to those used on the 20mm Vulcan, except they are much larger and use a percussion (instead of an electrical) firing system.
Transfer unit. The transfer unit is mounted to the right side of the housing. It feeds ammunition into the gun and accepts fired and unfired cases from it.
The GAU-8/A cannon and ammunition. This seven-barreled Gatling gun fires several types of 30mm ammunition. The ammunition has an aluminum cartridge case, nylon rotating bands (to increase projectile velocity and decrease barrel wear), and (in the tank-busting role) a depleted uranium penetrator warhead.
Lubricator. The lubricator is mounted on the upper rear portion of the housing. It contains a reservoir of lubricant, and each time the gun fires a small quantity is injected onto the bolt tracks.
Solenoid assembly. The solenoid assembly is also mounted on the housing and is used to withdraw the firing pin safety when the firing signal is sent to the gun.
Mid-barrel support and clamp. The mid-barrel support and clamp provides the forward mounting point for the GAU-8/A. It also locks the barrels in position within the rotor.
Muzzle clamp. The muzzle clamp provides structural support for the cannon and maintains concentricity of the barrel cluster.
Ammunition Feed and Storage Subsystem
The ammunition feed and storage subsystem is used to store and convey live and spent rounds (empty cartridges are not ejected out of the A-10). The nine major components of the subsystem are as follows:
Ammunition storage drum. The ammunition storage drum is similar in concept to the drum used for the 20mm Vulcan. It consists of an inner and outer drum, two scoop-disk assemblies, two drum-cover assemblies, and two spacer rings. The inner drum has a double-helix that forces the rounds forward or backward when the inner drum is rotated. Ammunition passes through the drum-cover assemblies for loading, unloading, firing, and returning fired cartridge cases to the drum.
Entrance unit. The entrance unit is mounted on the rear drum-cover assembly. It receives fired cases from the conveyor elements (explained below) and passes them into the ammunition storage drum.
Exit unit. The exit unit is similar in concept to the entrance unit. It mounts on the front of the ammunition storage drum and is used to feed live rounds into the conveyor elements.
Ammunition chuting. The ammunition chuting provides a path for the conveyor elements that carry ammunition to and from the GAU-8/A gun.
Conveyor turnaround unit. The conveyor turnaround unit feeds live rounds into the gun transfer unit (explained in the description of the gun subsystem). The conveyor turnaround unit also accepts spent rounds from the gun transfer unit and places them in conveyor elements for return to the ammunition storage drum.
Ammunition conveyor elements. The ammunition conveyor elements are linked together to form an endless belt that travels to and from the gun through the ammunition chuting. Each element carries one round of ammunition going to the gun and one spent case or unfired round when returning to the ammunition storage drum.
Drum drive unit. Mounted on the drum exit cover, the drum drive unit drives the ammunition storage drum.
Equalizer. The equalizer is mounted on the ammunition chuting approximately midway between the ammunition storage drum and the GAU-8/A gun subsystem. It equalizes the tension between the feed and return ammunition conveyor elements.
Loading access unit. The loading access unit is used to load ammunition into the storage drum. It is accessible through a panel on the left side of the A-10 (just forward of the wing).
Drive Subsystem
The drive subsystem is a hydraulic drive assembly consisting of the following major components.
Hydraulic drive motors. Two identical hydraulic drive motors provide power for the GAU-8/A gun and the ammunition feed and storage system.
Accessory drive gearbox. The accessory drive gearbox is driven by the hydraulic drive motors. It provides output torque for the gun and drum drive shafts.
Gun drive shaft. The gun drive shaft provides power to the GAU-8/A gun subsystem.
Drum drive shaft. The drum drive shaft provides power to the ammunition feed and storage subsystem.
Electronic Control Subsystem
The electronic control subsystem consists of the electronic control unit. This “black box” contains the circuitry that controls all GAU-8/A logic functions.
System Operation
When the A-10 pilot engages a target, the first step is to bring the armament control system to a state of operational readiness. Once this is done, the pilot must get the target in the Heads Up Display screen,
commonly referred to as the HUD. The HUD is a transparent screen mounted directly in the pilot’s line of sight. A small pipper (or bright spot) is projected onto the screen, and the pilot maneuvers the airplane (and consequently, the GAU-8/A gun) until the pipper is directly on the target. This allows the pilot to engage the target without having to divert his vision. This capability is critically important in a close-air-support aircraft, which must fly at low altitudes.
When the pilot wants to fire the GAU-8/A gun, he presses the control-column-mounted trigger. The trigger sends a signal to the electronic control assembly, which subsequently sends a signal to two solenoids mounted on the hydraulic drive assembly. When these solenoids open, aircraft hydraulic pressure is applied to the two hydraulic drive motors, and the gun, ammunition storage drum, and chuting begin to move. One-tenth of a second later, the electronic control assembly sends another signal to the firing solenoid assembly, which is mounted on the gun housing. This solenoid withdraws the safing sector from the firing cam path in the gun housing, which allows ammunition to begin the classic seven-step Gatling firing sequence. Each round fires as it reaches the firing point.
When the trigger is released, the electronic control assembly sends a reverse signal to the hydraulic drive assembly. The hydraulic drive motors reverse and rapidly decelerate the gun system. The gun system cycles in a reverse direction until all rounds are cleared from the cannon. This is done to prevent a cook-off (the inadvertent firing of a round due to absorption of residual gun heat), which could occur if a live round remained in one of the GAU-8/A’s chambers.
The 30mm Family of Ammunition
The success story behind the 30mm family of ammunition used in the A-10 is as intriguing as the story behind the A-10 and the GAU-8/A. When the air force began the A-X program, the intent was to manufacture the 30mm ammunition in government arsenals. In the past, the government usually bought ammunition components from several suppliers and then did the loading, assembly, and packing operations in a government load plant. In the early 1970s, the government estimated that the cost of each 30mm round would be about $75.
Aerojet Ordnance Company and Honeywell, Inc. (two munitions manufacturers) convinced the government that it would be best to allow private industry to manufacture the complete round. Under this procurement concept, GAU-8/A ammunition production has been enormously successful. Private industry was able to deliver high-quality ammunition at about $6 per round instead of the $75 the government originally planned to spend. To date, more than 80 million rounds have been procured. The 30mm family of ammunition consists of three different rounds, as explained below:
Target practice. The target practice (TP) cartridge is used for training.
Essentially a slug, the projectile has an aluminum nose and steel body.
High-explosive incendiary. The high-explosive incendiary (HEI) cartridge fires an explosive warhead with a point-detonating fuze. The projectile body is made of steel and contains .124 pounds of a high
explosive and incendiary mix.
Armor-piercing incendiary tracer. The armor-piercing incendiary tracer (APIT) cartridge fires what is probably the most intriguing of the 30mm projectiles. The APIT projectile has a depleted uranium
penetrator sheathed in an aluminum sabot. The depleted uranium penetrator has two functions. Because depleted uranium is a very dense metal, it defeats enemy armor through kinetic energy alone (the combination of high velocity and mass allow it to break through armor). Depleted uranium is also pyrophoric, meaning it burns with intense heat after it breaks up. These two characteristics make it extremely effective against enemy tanks. The rear of the projectile contains a pyrotechnic fumer, which reduces aerodynamic drag and allows it to maintain high velocities.
The normal GAU-8/A combat mix of ammunition consists of one HEI round for every five APIT rounds (TP ammunition is used solely for target practice and is not usually mixed with HEI or APIT ammunition). All types of 30mm GAU-8/A ammunition use aluminum cartridge cases (to conserve weight) and either plastic or copper projectile bands (to engage the rifling in the GAU-8/A gun barrels). The projectile bands permit higher muzzle velocity and reduced barrel wear.
The A-10 Bottom Line
All things considered, the GAU-8/A 30mm Gatling gun is one of the most interesting and successful applications of ground-attack aircraft ever developed. The GAU-8/A gun system is the most powerful Gatling gun ever built. The extremely lethal 30mm family of ammunition is an amazing procurement success story. The A-10, the GAU-8/A, and the 30mm family of ammunition still make up an important part of the U.S. national defense and will continue to for quite some time.
So there you have it: Chapter 11 of The Gatling Gun. There are 15 chapters in The Gatling Gun touching on all of the early Gatlings, their Civil War and Indian war deployments, the transition to modern high-rate-of-fire gun systems after World War II, and contemporary Gatling systems like the A-10 Warthog. If you liked our chapter about the A-10, you might enjoy the rest of The Gatling Gun.
Fifty or so miles north of Las Cruces, New Mexico and just over the mountains from White Sands Missile Range lies a huge bet on the future. The bet was placed almost 20 years ago and it’s been a 200 million-dollar, back and forth political football game to get to where we are today: Spaceport America, New Mexico.
Depending on which major party was in charge of New Mexico’s state government Spaceport has been alternately starved, funded or sabotaged. Some politicians hoped the thing would fail and worked towards that goal. Other politicians hoped it would put New Mexico on the front row of the commercial space race and threw taxpayer money at the project. If that wasn’t enough a well-publicized disaster with major tenant Virgin Galactic’s space plane and the collapse of oil prices (New Mexico gets huge sums of tax money from the oil industry) only increased the headwind.
The very access road to Spaceport is an example. Paved only in 2018, 10 years after construction began. Before that, heavy equipment and materials had to be hauled to the job site 50 extra miles via the town of Truth or Consequences or attempt a direct route from Las Cruces over a rough dirt road impassable during the wet. As usual, political gamesmanship made the project harder, costlier and take longer.
Hopefully all that is behind us. Virgin Galactic plans on moving its headquarters to Spaceport in 2020. The White Knight, first stage of Galatic’s commercial flight system, rests snugly in Sir Richard Branson’s curvy-sexy Spaceport hanger. Boeing, UP Aerospace, EXOS Aerospace, HyperSciences and SpinLaunch have become tenants. At least 20 successful launches have flown from Spaceport. These enthusiastic space pioneers are basically wealthy kids, the same as we were with our Estes model rockets except they are using real rockets.
While the site is “substantially complete” at this time and ready for business you get the feeling there are a lot of loose ends to tie. The public has access to Spaceport but you’ve got to be with a tour group as they don’t want idiots wandering around falling into drainage ditches or accidentally pushing flashing red buttons and causing rockets to launch. Tours start from Las Cruces or Truth or Consequences. We took the Las Cruces tour because we were going to Deming’s Tractor Supply for a 3-point box blade. I like to mix cutting-edge Aerospace facilities with dirt moving equipment whenever I can.
Once past the security gate you wonder where that 200 million dollars went as there are only two buildings of any size on the property. My guess is the lion’s share went into the 2-mile-long, 200-foot-wide, 42-inch-thick, multilayer runway. This thing has crushed rock, several courses of varying density concrete, a layer of asphalt and a thick topcoat of concrete. It looks like you could land a battleship on Spaceport’s runway.
The first building we visited was the main office and flight control tower. This domed structure was constructed using an inflated bladder, which was then shot with sprayed concrete material. After the dome mud set up the bladder was deflated and the interior shot with more sticky goo. You can build a high ceiling without internal supports using this method but the ones I’ve seen in the past all cracked.
The entrance area shows signs of deterioration already. High overhead, ill fitting, water damaged sections of patched drywall look like a buttery layer cake that has slipped a layer. Gaping holes on the exterior of the building reveal wires and skeletal metal studs. It’s sloppy work that people like me notice. I mean, this is the very first place visitors to Spaceport see. I’d appreciate it if management pulled the maintenance crew off of life support projects and tidied up the front door.
The flight control room is a fairly simple set up. It’s nothing like Mission Control in Houston. One 3-dimensional curved desk with computer monitors spanning the width of the desk sits a few feet back from a large window. I find it amazing that there is no radar but the restricted airspace over Spaceport America means there are no obstacles to hit until you smack into the Andromeda Galaxy. Launches are easy here; no need to re-route airplanes or alert the local populace. They tell me flights can be scheduled in a couple days rather than months. That’s a big window of opportunity and one of the selling points of the joint.
We like to say you get the first mile free when you launch your spacecraft from New Mexico. At 4500 feet Spaceport is close enough and it’s a real fuel savings when you consider gravity is stronger the closer you get to the concrete I’ve poured in my backyard. There’s also a zillion acres of vacant land surrounding Spaceport so collateral damage from explosions and failures to launch will be limited to sagebrush and bunnies.
Behind the visitor center and incorporated into the same concrete dome is a 24-hour-a-day, 7-days-a-week fire-rescue operation. There are a lot of things that can go wrong with space travel before you even leave the ground so these guys are on call even when no flights are scheduled. The fire guys gave a great talk on their various duties and let us sit in the Big Mama fire truck. All their gear was spotless and ready to go. Full EMS capability with a beautiful 2-bay ambulance is on site. If I ever sever a limb during a routine training mission I want these guys taking care of me.
Sir Richard Branson’s space tourism company takes up most of Spaceport’s futuristic, crawling-out-from-the-earth hangar structure. We couldn’t see inside because the electrically controlled windows were set to opaque and our guide didn’t have access to the switch that makes them clear. Blurry photos of the Mothership were all I could get. A secret panel blended into the steel-walled entrance walk opened, leading us to a kind of waiting lounge/museum. It was real James Bond super-villain stuff. Here was the G-force spinner that takes potential astronauts up to 6 Gs in preparation for their flight. Passengers who fail the spin test can’t fly.
I didn’t take the spin test because I wanted to digest my breakfast in peace. At 2 Gs older folks crawled out of the machine slowly and appeared a little disoriented. A tall, skinny 14-year-old was having a ball in the machine wanting more speed all the time. You could have taken that kid to 12 Gs no problem.
Listen, lots of people think space flight is a waste of money. They believe that all earthbound problems should be solved before we wander off into space. Complaining about the government or rich folks spending their money on space adventures instead of those less fortunate is a popular pastime. I’m not one of them. I figure the rich can spend their money however they want. Helping the unfortunate is what taxes are for. Whatever is left over is yours to invest in cocaine, prostitutes or space travel.
By now you know I dig all things space related and believe the faster we blow this joint the better off the Earth will be. 2020 should be an exciting year at Spaceport because Virgin Galactic claims they will be firing some spacecraft high into the sky.
, a book that tells the story of the original Gatling guns, their transition to modern gun systems, and several of the weapons platforms currently using Gatlings. It has been one of my most successful books ever. 
