Castle design assumes the enemy will reach the walls

Thursday, December 1st, 2022

The battlements along the top of a castle wall were designed to allow a small number of defenders to exchange fire effectively with a large number of attackers, and in so doing to keep those attackers from being able to “set up shop” beneath the walls:

The goal is to prevent the enemy operating safely at the wall’s base, not to prohibit approaches to the wall. These defenses simply aren’t designed to support that much fire, which makes sense: castle garrisons were generally quite small, often dozens or a few hundred men. While Hollywood loves sieges where all of the walls of the castle are lined with soldiers multiple ranks deep, more often the problem for the defender was having enough soldiers just to watch the whole perimeter around the clock (recall the above example at Antioch: Bohemond only needs one traitor to access Antioch because one of its defensive towers was regularly defended by only one guy at night). It is actually not hard to see that merely by looking at the battlements: notice in the images here so far often how spaced out the merlons of the crenellation are. The idea here isn’t maximizing fire for a given length of wall but protecting a relatively small number of combatants on the wall. As we’ll see, that is a significant design choice: castle design assumes the enemy will reach the walls and aims to prevent escalade once they are there; later in this series we’ll see defenses designed to prohibit effective approach itself.

Among the subjects was 17-year-old Ted Kaczynski

Monday, November 28th, 2022

I remember first finding out about the Unabomber in 1995 and being shocked that I hadn’t heard about a real-life mad-scientist supervillain mysteriously blowing up professors and industrialists.

I recently watched Unabomber: In His Own Words — in which Ted Kaczynski sounds like a bitter nerd, not Doctor Doom — and learned that his origin story involves another character who could have come out of a pulp novel, one Henry Murray:

During World War II, he left Harvard and worked as lieutenant colonel for the Office of Strategic Services (OSS). James Miller, in charge of the selection of secret agents at the OSS during World War II, said the situation test was used by British War Officer Selection Board and OSS to assess potential agents.

In 1943 Murray helped complete Analysis of the Personality of Adolph Hitler, commissioned by OSS boss Gen. William “Wild Bill” Donovan. The report was done in collaboration with psychoanalyst Walter C. Langer, Ernst Kris, New School for Social Research, and Bertram D. Lewin, New York Psychoanalytic Institute. The report used many sources to profile Hitler, including informants such as Ernst Hanfstaengl, Hermann Rauschning, Princess Stephanie von Hohenlohe, Gregor Strasser, Friedelind Wagner, and Kurt Ludecke. The groundbreaking study was the pioneer of offender profiling and political psychology. In addition to predicting that Hitler would choose suicide if defeat for Germany was near, Murray’s collaborative report stated that Hitler was impotent as far as heterosexual relations were concerned and that there was a possibility that Hitler had participated in a homosexual relationship. The report stated: “The belief that Hitler is homosexual has probably developed (a) from the fact that he does show so many feminine characteristics, and (b) from the fact that there were so many homosexuals in the Party during the early days and many continue to occupy important positions. It is probably true that Hitler calls Albert Forster ‘Bubi’, which is a common nickname employed by homosexuals in addressing their partners.”

In 1947, he returned to Harvard as a chief researcher, lectured and established with others the Psychological Clinic Annex.

From late 1959 to early 1962, Murray was responsible for unethical experiments in which he used twenty-two Harvard undergraduates as research subjects. Among other goals, experiments sought to measure individuals’ responses to extreme stress. The unwitting undergraduates were submitted to what Murray called “vehement, sweeping and personally abusive” attacks. Specifically tailored assaults to their egos, cherished ideas, and beliefs were used to cause high levels of stress and distress. The subjects then viewed recorded footage of their reactions to this verbal abuse repeatedly.

Among the subjects was 17-year-old Ted Kaczynski, a mathematician who went on to be known as the ‘Unabomber’, a domestic terrorist who targeted academics and technologists for 17 years. Alston Chase’s book Harvard and the Unabomber: The Education of an American Terrorist connects Kaczynski’s abusive experiences under Murray to his later criminal career.

In 1960, Timothy Leary started research in psychedelic drugs at Harvard, which Murray is said to have supervised.

Some sources have suggested that Murray’s experiments were part of, or indemnified by, the US Government’s research into mind control known as the MKUltra project.

The totokia was intended to peck holes in skulls

Thursday, November 24th, 2022

The Tusken Raiders in the original Star Wars wield a peculiar weapon that Luke calls a gaffi stick. It turns out that the gaderffii is based on the Fijian totokia:

According to Fiji material culture scholar Fergus Clunie who describes it as a beaked battle hammer (in Fijian Weapons and Warfare, 1977: p. 55), “…the totokia was intended to ‘peck’ holes in skulls.” The weight of the head of the club was concentrated in the point of the beak of the weapon or kedi-toki (toki to peck; i toki: a bird’s beak). The totokia “…delivered a deadly blow in an abrupt but vicious stab, not requiring the wide swinging arc demanded by the others.” (Yalo i Viti. A Fiji Museum Catalogue, 1986: p. 185) It was a club that could be used in open warfare or to finish-off or execute warriors on the battlefield.

Totakia and Gaffi Stick

They would verify the treaty without on-site inspections, using their own assets

Monday, November 7th, 2022

In 1972, the United States and Soviet Union signed the Anti-Ballistic Missile Treaty and the Interim Agreement, collectively known as SALT I:

This was an agreement by the two parties that they would verify the treaty without on-site inspections, using their own assets. Both sides also agreed not to interfere with these “national technical means.”

“National technical means” served as a euphemism for each country’s technical intelligence systems. Although these assets included ground, airborne, and other intelligence collection systems, the primary intelligence collectors for treaty verification were satellites, which both countries had been operating for over a decade, but neither country publicly discussed, certainly not with each other.

[…]

Surprisingly, there appears to have been little initial skepticism on the American side about the ability to verify strategic arms control treaties using satellites. In fact, there are indications that by the early 1970s there was an overestimation of their capabilities, although the people who developed and operated them were concerned about their limitations, as well as the misperception about what they could do versus their actual capabilities.

I’ve mentioned before that I always assumed that spy satellites used TV cameras, and it was a real shock to learn that they didn’t start out that way:

The first successful American photo-reconnaissance mission took place in August 1960 as part of the CORONA program. CORONA involved orbiting satellites equipped with cameras and film and recovering that film for processing. The early satellites orbited for approximately a day before their film was recovered, and it could take several days for that film to be transported and processed before it could be looked at by photo-interpreters in Washington, DC. Although the system was cumbersome, the intelligence data produced by each CORONA mission was substantial, revealing facilities and weapons systems throughout the vast landmass of the Soviet Union.

CORONA’s images were low resolution, capable of revealing large objects like buildings, submarines, aircraft, and tanks, but not providing technical details about many of them. In 1963, the National Reconnaissance Office launched the first GAMBIT satellite, which took photographs roughly equivalent to those taken by the U-2 spyplane that could not penetrate Soviet territory. Both CORONA and GAMBIT returned their film to Earth in reentry vehicles. By 1966, CORONA was equipped with two reentry vehicles, and GAMBIT was equipped with one, increased to two reentry vehicles by August 1969. The existence of multiple reentry vehicles on satellites and missiles was to become a source of concern for NRO officials as new arms control treaties were negotiated.

The two satellites complemented each other: CORONA covered large amounts of territory, locating the targets, and GAMBIT took detailed photographs of a small number of them, enabling analysts to make calculations about their capabilities such as the range of a missile or the carrying capability of a bomber. These photographic reconnaissance satellites provided a tremendous amount of data about the Soviet Union. That data was combined with other intelligence, such as interceptions of Soviet missile telemetry, to produce assessments of Soviet strategic capabilities. Signals and communications intelligence, collected by American ground stations around the world as well as satellites operated by the NRO, also contributed to the overall intelligence collection effort.

By the mid-to-late 1960s, these intelligence collection systems, particularly the photo-reconnaissance satellites, had dramatically improved American understanding of Soviet strategic forces and capabilities. A 1968 intelligence report definitively declared, “No new ICBM complexes have been established in the USSR during the past year.” As a CIA history noted, “This statement was made because of the confidence held by the analysts that if an ICBM was there, then CORONA photography would have disclosed them.” This kind of declared confidence in the ability of satellite reconnaissance to detect Soviet strategic weapons soon proved key to signing arms control treaties.

It can hear tracked vehicles and feel them coming

Thursday, October 20th, 2022

The US Army is developing a smart anti-tank mine that detects the sounds of enemy vehicles and then destroys them with an armor-piercing slug — from above:

“It can ‘hear’ tracked vehicles and feel them coming,” an Army researcher said in a press release. “When it does, it uses a mechanism that starts tracking the vehicle. When the threat-tracked vehicle is a certain distance away, the XM204 will shoot a submunition into the air to fire the warhead down at the target within its zone of authority.”

A Textron executive told Jane’s that each XM204 weighs about 80 pounds. The acoustic sensor detects oncoming vehicles and a Doppler radar pinpoints a vehicle’s exact location.

It turns out there wasn’t a next Palantir or SpaceX

Friday, October 7th, 2022

Anduril is a rare, paradoxical creation, Mario Gabriele argues: a defense contractor that moves like a startup, a software business disguised as a seller of hardware, and a weapons manufacturer, in pursuit of peace:

Anduril is a company that few in Silicon Valley thought needed to exist. Because of the foresight of Trae Stephens and Palmer Luckey, America and its allies have a software-first defense provider capable of impacting current conflicts.

[…]

Before joining Palantir in 2008, Stephens had spent time at the offices of Ohio congressman Rob Portman and the Afghan embassy in Washington D.C. His public sector work seemed to skew towards the technical, with Stephens “building enterprise solutions to Arabic/Persian name matching” for the Intelligence community. Stephens used and bolstered this experience as part of his six-year stint at Palantir.

While venture capital rarely draws from defense backgrounds, there is an exception: Founders Fund. Established by Peter Thiel, Ken Howery, and Luke Nosek in 2005, Founders Fund holds a unique position at the nexus of Silicon Valley and Washington D.C, thanks to Thiel’s co-founding of Palantir and particular geopolitical worldview. The firm was early to back SpaceX (one of the few recent startups to secure meaningful governmental contracts), while Ken Howery went on to serve as ambassador to Sweden during Donald Trump’s presidency.

Stephens was a neat fit at Founders Fund, as was his mission to find the next great defense business. SpaceX and Palantir had made significant impacts, but they were the rarest of exceptions. By and large, venture-backed startups had failed to disrupt the established patterns of the public sector in general and military in particular. Stephens was hopeful a new generation of entrepreneurs would change that.

Despite his best efforts, Stephens came up empty-handed. “I didn’t find anything,” he said. With the benefit of hindsight, the investor noted there wasn’t a business he had overlooked: “There was nothing to miss. It turns out there wasn’t a next Palantir or SpaceX.”

Though Stephens didn’t find a ready-made defense startup during this period, he did meet a founder who would play a starring role in Anduril’s creation: Palmer Luckey.

A year before Stephens started his venture career, Luckey set out to raise a Series A for his virtual-reality startup, Oculus. He found a willing partner in Founders Fund, who became the company’s “first institutional investor,” per Stephens.

It took little time for that faith to pay off. By March the following year, Facebook announced it had acquired Oculus for approximately $2 billion in a mix of cash and stock. Barely twenty years old, Luckey was suddenly a wealthy man.

Around the time of that acquisition, Stephens and Luckey got to know one another, discovering themselves to be somewhat kindred spirits. “He was super interested in national security,” Stephens said of Luckey. That fascination pre-dated Luckey’s creation of Oculus. Indeed, while working at Bravemind, an organization that uses VR to treat veterans with PTSD, Luckey first created a prototype of his revolutionary headset.

For the next three years, Stephens and Luckey stayed in touch. By 2017, much had changed for them both. In March of that year, Facebook fired Luckey, a decision he claimed was politically motivated, catalyzed by a $10,000 donation he had made to pro-Trump “shitposting” organization, Nimble America.

Meanwhile, Stephens had reached an impasse in his search for a modern defense prime contractor (a “prime”). It was increasingly clear that if he wanted such an organization to emerge, he would have to build it himself. He made his pitch to Luckey, explaining the status quo as he saw it. In particular, Stephens saw two major shifts to which America’s military had failed to adapt:

  1. The shift to software. Defense technology had traditionally been hardware first. Stephens was confident that future wars would be defined by software that worked in concert with intelligent devices and machinery.
  2. The brain-drain. In previous eras, the military could reliably attract the best technical talent. Historic minds like John von Neumann lent their abilities to branches of the armed forces. That is no longer the case. Today, many of the best technologists work at companies like Google and Meta. “We’re not in a position where our best and brightest are working on national security,” Stephens said.

Luckey was impressed with Stephens’ diagnosis and proposed cure. “He was super excited about it,” the investor recalled. The two began work on the company that would come to be called “Anduril.” As with many Thiel-affiliated entities (see: Palantir, Valar, Mithril), the business took its moniker from Lord of the Rings. In Tolkien’s books, “Andúril” is the name of a mythical sword which means “Flame of the West” in elven tongue.

[…]

On June 6, 2017, Anduril’s founders officially set to work on its first product: a sentry tower that leverages artificial intelligence to monitor border crossings. “It was totally Palmer’s idea,” Stephens said, noting that Luckey had sketched prototypes before Anduril had gotten off the ground. It can take years for a defense contractor to ship a new product; Anduril had its sentry tower in the field within six months.

[…]

Despite the unpopularity of its work, Anduril kept shipping. It followed the sentry tower with sensors, drones, and autonomous submarines. Though these products represented hardware innovations, the heartbeat of Anduril’s work was its orchestrating software system, Lattice.

[…]

The software system acts as a command hub, pulling in information from sensors, drones, and other field assets. Using artificial intelligence and computer vision, Lattice constructs a live, detailed view of a battlefield, accessible via computer, tablet, or VR headset. Critically, Lattice is built such that it can sync with assets made by other companies. It is an open system that seeks to play nicely with third parties.

In addition to intuitively presenting important information, Lattice streamlines decision-making. It does so by offering potential next moves. For example, if a field sensor identifies an enemy drone, it will show up on Lattice along with a prompt to intercept it. In the push of a button, an operative can decide to send an asset to meet and disable it.

That date marks one of the most creative periods of conceptual design for any fighter aircraft

Wednesday, October 5th, 2022

When the F-22 design team struggled to meet its weight and unit-cost goals, it decided to step back and open up the design to more fundamental changes:

“After a bloody debate, we agreed to trash the current design and start over,” says Mullin. “Over that weekend, we brought in a new director of design engineering, Dick Cantrell, flew in people, and started a ninety-day fire drill. Work started on Monday 13 July. That date marks one of the most creative periods of conceptual design for any fighter aircraft. We looked at different inlets, different wings, and different tail combinations. One configuration had two big butterfly tails and looked somewhat like the F-117, though people did not know that since the F-117 was still highly classified. The configuration search was wide open, but the biggest single change that resulted from it was to go with diamond-shaped wings.”

The concentrated configuration search began with a slew of possible designs. The search complicates the numbering scheme considerably, as diamond wings, twin tails (two tails instead of four), various inlet shapes, and various forebody shapes were all considered and reconsidered simultaneously in the summer of 1987.

[…]

“The fundamental reason for going to a diamond wing was that it provided the lightest configuration and gave us the best structural efficiency and all the control power we needed for maneuvering,” Mullin explains. “The biggest consideration was its light weight. Weight drove the decision.”

“A diamond wing has more square feet of surface area, but is more structurally efficient,” adds Renshaw. “The longer root chord provides a more distributed load path through the fuselage. Multiple bulkheads carry the bending loads. The design provides more opportunity to space the bulkheads around the internal equipment. It also provides more fuel volume.”

“The structural engineers wanted a diamond wing because it provides a larger root chord, which carries bending moments better,” Hardy notes. “The aerodynamicists wanted a trapezoidal wing because it provides more aspect ratio, which is good for aerodynamics. Dick Heppe, the president of Lockheed California Company, made the final decision, and he was right. The aerodynamics were not all that different, but the structure and weights were significantly better. So we went to a diamond shape. The big root chord, though, moved the tails back. Eventually we even had to notch the wing for the front of the tails. If the tails moved farther back, they would fall off the airplane.”

Once the wings were set with Configuration 614, subsequent configurations dealt with the tail arrangement. “We spent a lot of wind tunnel time looking at the tails,” recalls Lou Bangert, the chief engineer for engine integration from Lockheed. “From late 1987 to early 1988, we were engaged in what we called ‘the great tail chase.’ We knew we would have four tails, but where they would go was a big deal. A small change in location often made a huge difference. We had to look at performance effects, stealth effects, stability and control, and drag at the same time. The tail arrangement and aft end design were important design considerations for all of these effects.”

Wind tunnel results showed an ultra-sensitive relationship between the placement of the vertical tails and the design of the forward fuselage. The interactions could not be predicted accurately by analysis or by computational fluid dynamics. The airflow over the forebody at certain angles of attack affects the control power exerted by the twin rudders on the vertical tails. Getting the airflow right was critical.

The cant and sweep angles of the vertical tails could not be altered too much because such changes increased radar signature. In finding a suitable arrangement, the control system designers were constrained by the radar signature requirements to moving the tail locations laterally or longitudinally and to shrinking or enlarging them while holding the shape essentially constant. By the end of the dem/val phase, the team had accumulated around 20,000 hours in the wind tunnel. A lot of this time was devoted to tail placement studies.

Everything wants to be at the center of gravity

Monday, October 3rd, 2022

The basic challenge of designing the F-22 was to pack stealth, supercruise, highly integrated avionics, and agility into an airplane with an operating range that bettered the F-15, the aircraft it was to replace:

“One problem we typically face when trying to stuff everything inside an airplane is that everything wants to be at the center of gravity,” Hardy explains. “The weapons want to be at the center of gravity so that when they drop, the airplane doesn’t change its stability modes. The main landing gear wants to be right behind the center of gravity so the airplane doesn’t fall on its tail and so it can rotate fairly easily for takeoffs. The fuel volume wants to be at the center of gravity, so the center of gravity doesn’t shift as the fuel tanks empty. Having the center of gravity move as fuel burns reduces stability and control. We also had to hide the engine face for stealth reasons. So, these huge ducts had to run right through the middle of real estate that we wanted to use for everything else. The design complexities result in specialized groups of engineers arguing for space in the airplane. That was the basic situation from 1986 through 1988.”

Corbett regarded total command of the sea with skepticism

Sunday, October 2nd, 2022

Ukraine’s success in contesting the skies turns the West’s airpower paradigm on its head, because it offers an alternative vision for pursuing airspace denial over air superiority:

In rethinking America’s approach to airpower, pundits should look to Mahan’s contemporary, the British naval theorist Sir Julian Corbett. Corbett regarded total command of the sea with skepticism, arguing the “most common situation in naval warfare is that neither side has the command.” He favored a relative, rather than an absolute, interpretation of command of the sea, calling for a “working command,” delimited in time or space — “sea control” in today’s parlance. Similarly, Douhet’s absolute rule of the skies may be desirable, but air forces may get by with more limited control of the airspace, or temporary and localized air superiority.

For Corbett, the corollary of sea control is sea denial. If a navy is not strong enough to gain command of the sea, he argued, it could still attempt to limit or deny the other side ability to make use of the sea. He referred to this concept as “disputing command,” and offered two main methods: a “fleet in being” and “minor counterattacks.” He envisioned an active defense, in which a smaller navy could avoid battle but still remain threatening as a “fleet in being” by staying active and mobile. “The idea,” he explained,” was “to dispute control by harassing operations, to exercise control at any place or at any [opportune] moment … and to prevent the enemy from exercising control in spite of his superiority by continually occupying his attention.” Additionally, an inferior navy could conduct minor counterattacks, or hit-and-run strikes, to try to take undefended ships out of action.

Corbett’s strategy of denial in the naval realm is pertinent to the air domain as well. Ukraine has used mobility and dispersion to maintain its air defenses as a “force in being.” Operating a mix of Cold-War era, Soviet-made mobile surface-to-air missile systems Ukrainian defenders on the ground have kept Russian aircraft at bay and under threat. To do so they have used the long range S-300 family, medium range SA-11s, and short range SA-8 Gecko systems. Exploiting dispersion and mobility, as Corbett advised, Ukrainian air defenders have used “shoot and scoot” tactics, firing their missiles and quickly moving away from the launch site. “The Ukrainians continue to be very nimble in how they use both short and long-range air defense,” a senior Pentagon official concluded. “And they have proven very effective at moving those assets around to help protect them.”

Mounted on tracked vehicles, Ukraine’s surface-to-air missile systems are fleeting targets. Given the danger of flying over Ukraine, Russia relies largely on standoff sensors to find radar targets, lengthening the time required to engage Ukraine’s mobile systems. After firing, the defender can turn off the radar, pack up and drive away to hide in the ground clutter — forests, buildings, etc. During the Gulf War in 1991, the U.S.-led coalition hunted Iraq’s truck-mounted Scud missiles, but even with the advantage of air superiority, it still failed to achieve a single confirmed kill. In the skies over Ukraine, Russian aircraft are not only the hunter but also the hunted, further complicating the task of finding and destroying them.

As a result, there is a deadly “cat-and-mouse” game between Russian aircraft and Ukrainian air defenses. The Oryx open-source intelligence site reports that, since the start of the war, 96 Russian aircraft have been destroyed, including at least nine Sukhoi Su-34 and one Su-35 — equivalents to the American F-15. Ukraine started the war with a total of 250 S-300 launchers, but 11 weeks later, the Russians have only managed to knock out 24 of them, at least so far as Oryx has confirmed with photos and videos. Given how Ukrainian officials carefully manage information about their losses, caution is needed in drawing conclusions from our limited information about them. Still these figures suggest that the Russians are only able to attrite a small portion of the threat, and, compared to radar and battery command vehicles, the less important part at that. The best evidence may be Russian behavior itself. As a senior Pentagon official argued, “And one of the reasons we know … [Ukraine’s air defenses are] working is because we continue to see the Russians wary of venturing into Ukrainian air space at all and if they do, they don’t stay long … And I think … that speaks volumes …”

Napoleon did not recommend the study of battles, but of campaigns

Saturday, September 24th, 2022

Napoleon did not recommend the study of battles, but of campaigns:

Campaigns before the twentieth century are in many ways the opposite of case studies. The latter thrusts us into a specific scenario, at a certain time and place, with a certain number of troops and resources, and with an immediate objective in mind. In set-piece battles of yore, as in modern operations, most of a commander’s mental efforts took place before things even begin: gathering an intelligence estimate of the enemy, selecting the best scheme of maneuver, matching troops to task, arranging logistics, etc. Once the action commenced, there were only a limited number of decision points where he could influence the course of events—to grossly simplify, the results came down to a series of rolls of the dice. This naturally focuses our attention on the mechanism of victory: what predetermined course of action gives the best probability of success in a scenario, accounting for a limited range of possible enemy responses.

Campaigns, on the other hand, were fundamentally more open-ended. When armies marched out of their winter cantonments for the season, they did not always know in advance which fortress to attack or where to fight a decisive action. Even when they did have a definite objective in mind, the entire challenge lay in precipitating conditions which would allow them to accomplish it; just as often, however, enemy action or the accidents of fate forced them to reconsider their intermediate steps or even the final objective itself.

This open-endedness created a very different decision-making structure. Plans had to account for a far greater degree of uncertainty, and the ability merely to remain in the field as a coherent force was at least as important as the pursuit of an objective. Sheer accident could moot one’s present course—Napoleon’s own staff was famous for issuing a steady stream of countermanding orders as circumstances evolved—and it was quite common for armies to stumble into a decisive engagement without realizing it. In short, decision-making was a far more continuous process.

This remained true even when both sides were clearly heading toward a decisive clash. Most of a commander’s focus had to remain outside the object itself: heeding his own vulnerabilities, considering the enemy’s intervening actions, ensuring that he was not detracting from his own efforts elsewhere, and getting enough men and supplies to the right place. And looming above all that was the risk of failure: what would the immediate consequences be? Was there a safe line of retreat? How would failure change his overall position? Naturally enough, the decision whether to engage in battle was just as important as the battleplan itself.

These questions shine through in narratives and memoirs from past campaigns. Many sources record war council debates over objectives, contingencies, marching routes, and supply considerations. It is by engaging with these debates and working through the decision-making process that a student can develop an intuition for the principles of war—not as a list of rules, but as a way of conducting operations in the face of uncertainty and risk. Even when the sources don’t reveal a commander’s thoughts, it can be just as instructive to try to figure out what he might have been thinking, or whether a failed action might have been somewhat justified by some non-obvious factor.

At its best military history is like a problem set with a partial answer key.

Thirty-one percent of the gun owners said they had used a firearm to defend themselves or their property

Tuesday, September 20th, 2022

The largest and most comprehensive survey of American gun owners ever conducted, based on a representative sample of about 54,000 adults, 16,708 of whom were gun owners, suggests that Americans use firearms in self-defense about 1.7 million times a year:

The overall adult gun ownership rate estimated by the survey, 32 percent, is consistent with recent research by Gallup and the Pew Research Center. So is the finding that the rate varies across racial and ethnic groups: It was about 25 percent among African Americans, 28 percent among Hispanics, 19 percent among Asians, and 34 percent among whites. Men accounted for about 58 percent of gun owners.

Because of the unusually large sample, the survey was able to produce state-specific estimates that are apt to be more reliable than previous estimates. Gun ownership rates ranged from about 16 percent in Massachusetts and Hawaii to more than 50 percent in Idaho and West Virginia.

The survey results indicate that Americans own some 415 million firearms, including 171 million handguns, 146 million rifles, and 98 million shotguns. About 30 percent of respondents reported that they had ever owned AR-15s or similar rifles, which are classified as “assault weapons” under several state laws and a proposed federal ban. Such legislation also commonly imposes a limit on magazine capacity, typically 10 rounds. Nearly half of the respondents (48 percent) said they had ever owned magazines that can hold more than 10 rounds.

Those results underline the practical challenges that legislators face when they try to eliminate “assault weapons” or “large capacity” magazines. The survey suggests that up to 44 million AR-15-style rifles and up to 542 million magazines with capacities exceeding 10 rounds are already in circulation.

Those are upper-bound estimates, since people who reported that they ever owned such rifles or magazines may have subsequently sold them. But even allowing for some double counting, these numbers suggest how unrealistic it is to suppose that bans will have a significant impact on criminal use of the targeted products. At the same time, widespread ownership of those products by law-abiding Americans makes the bans vulnerable to constitutional challenges.

Two-thirds of the respondents who reported owning AR-15-style rifles said they used them for recreational target shooting, while half mentioned hunting and a third mentioned competitive shooting. Sixty-two percent said they used such rifles for home defense, and 35 percent cited defense outside the home. Yet politicians who want to ban these rifles insist they are good for nothing but mass murder.

[…]

Thirty-one percent of the gun owners said they had used a firearm to defend themselves or their property, often on multiple occasions. As in previous research, the vast majority of such incidents (82 percent) did not involve firing a gun, let alone injuring or killing an attacker. In more than four-fifths of the cases, respondents reported that brandishing or mentioning a firearm was enough to eliminate the threat.

That reality helps explain the wide divergence in estimates of defensive gun uses.

[…]

About half of the defensive gun uses identified by the survey involved more than one assailant. Four-fifths occurred inside the gun owner’s home or on his property, while 9 percent happened in a public place and 3 percent happened at work. The most commonly used firearms were handguns (66 percent), followed by shotguns (21 percent) and rifles (13 percent).

Smart bombs payout immediately by requiring a fraction of the ordnance

Thursday, September 1st, 2022

Austin Vernon discusses the economic logic of smart bombs:

US smart bombs like the GPS-guided JDAM and the laser-guided Paveway cost somewhere between $10,000 and $30,000 to manufacture. They are nearly 100% accurate in hitting a target, while unguided bombs are stuck with single-digit accuracy numbers. Unguided dumb bombs cost $2000-$3000 per bomb. Smart bombs payout immediately by requiring a fraction of the ordnance.

It is worse than that, though. A fighter jet like the US Navy’s F-18 costs over $10,000 an hour to operate, not including tankers. A B-52 bomber costs $70,000 an hour. Attacking targets using dumb bombs requires ten times the sorties at a significant cost premium and exposes planes and pilots to more risk.

[…]

Modern smart bombs fired by aircraft can provide support and screening for fast advancing mechanized columns instead of artillery. In the early Afghanistan conflict in 2001, the US deployed zero artillery because of its weight and logistics challenges. Combat aircraft were able to cover US ground forces against light Taliban forces.

In the 2003 invasion of Iraq, armor columns brought much less artillery than in 1991. Aircraft took over the strategic mission, leaving counter-battery fire and all-weather close fire support to artillery forces.

[…]

Smart weapons also have standoff capability. An unpowered JDAM bomb can glide over 25 km.

[…]

Drones are a continuation of the precision-guided munition paradigm. Smart bombs can make a plane 20x more effective. Drones are force multipliers across the board. The Army and Air Force have been drone leaders but need to continue to invest in drones across the spectrum. They need large, expensive drones that can operate far from bases and inexpensive micro-drones that can disrupt enemy formations or intercept enemy micro-drones. Modern warfare is an o-ring industry because enemies exploit gaps relentlessly.

Each Starship launch has the same payload as three B-52s

Wednesday, August 31st, 2022

Recent talk about hypersonic missiles got me wondering whether SpaceX’s reusable rockets would lend themselves to this role. Austin Vernon suggests that SpaceX’s Starship is America’s Secret Weapon:

B-52s flying from Barksdale AFB to complete a mission in East Asia incur a marginal cost of $50/kg to deliver bombs. Starship’s cost is cheaper and can put weapons on target in less than thirty minutes. Each Starship launch has the same payload as three B-52s.

[…]

The supply line would be a natural gas pipeline and a rail line providing fuel and projectiles to a domestic launchpad instead of ships crossing oceans.

I hadn’t considered this though:

Orbital weapons still need intelligence to tell them where to go. Starship’s sister system, StarLink, provides an answer. StarLink is a constellation of thousands of small Low Earth Orbit satellites that gives customers low latency broadband internet. It uses sophisticated phased-array radios that allow ground terminals to track satellites traveling thousands of miles per hour.

As Casey Handmer points out, StarLink can use its radios to do high fidelity synthetic aperture radar (SAR). SAR is already one of the primary ways militaries find enemy ships, and researchers have used it to track planes. It could also see ground vehicles.

While the US already has satellites capable of doing this, they are expensive and limited in number. Individual StarLink satellites cost a few hundred thousand apiece to build and launch on Starship. One of the first things China would do in war is shoot down our military satellites with anti-satellite missiles. That is a problem with bespoke satellites but not with Starlink. Anti-Satellite missiles cost tens of millions of dollars. Each Starship launch could drop off hundred of StarLink satellites. The Chinese would have to expend incredible resources to keep StarLink offline.

A satellite constellation provides other bonuses. Our GPS satellites are both hard to replace and sensitive to jamming. StarLink can provide GPS coordinates (with a few meters less accuracy), and its phased array radios make it difficult to jam.

The upshot is StarLink gives the US survivable sensing, communication, and navigation capabilities.

The military can’t afford iPhone-level software

Tuesday, August 30th, 2022

As consumers, we are spoiled by how easy our phones are to use, Austin Vernon notes, and critics expect the military to have software as capable as our phones:

If you examine the numbers, it quickly becomes apparent that the military can’t afford iPhone-level software. Apple, Google, Microsoft, and Facebook had combined operating expenses of over $600 billion in 2021. The military’s total budget is around $750 billion.

The mass of all the physical products these companies sell is probably less than one Ford-class aircraft carrier, and the number of SKUs is relatively limited. And remember, a defining feature of the software business is that marginal cost is near zero. It costs about the same to design high-quality software for 100 F-35s as for 200 million copies of the plane.

The Rotating Detonation Engine is an extension of the Pulse Detonation Engine, which is an extension of The Pulse Jet Engine

Wednesday, August 24th, 2022

The concept behind rotation detonation engines dates back to the 1950s:

In the United States, Arthur Nicholls, a professor emeritus of aerospace engineering at the University of Michigan, was among the first to attempt to develop a working RDE design.

In some ways, a Rotating Detonation Engine is an extension of the concept behind pulse detonation engines (PDEs), which are, in themselves, an extension of pulsejets. That might seem confusing (and maybe it is), but we’ll break it down.

Pulsejet engines work by mixing air and fuel within a combustion chamber and then igniting the mixture to fire out of a nozzle in rapid pulses, rather than under consistent combustion like you might find in other jet engines.

In pulsejet engines, as in nearly all combustion engines, igniting and burning the air/fuel mixture is called deflagration, which basically means heating a substance until it burns away rapidly, but at subsonic speeds.

A pulse detonation engine works similarly, but instead of leveraging deflagration, it uses detonation. At a fundamental level, detonation is a lot like it sounds: an explosion.

While deflagration speaks to the ignition and subsonic burning of the air/fuel mixture, detonation is supersonic. When the air and fuel are mixed in a pulse detonation engine, they’re ignited, creating deflagration like in any other combustion engine. However, within the longer exhaust tube, a powerful pressure wave compresses the unburnt fuel ahead of the ignition, heating it above ignition temperature in what is known as the deflagration-to-detonation transition (DDT). In other words, rather than burning through the fuel rapidly, it detonates, producing more thrust from the same amount of fuel; an explosion, rather than a rapid burn.

The detonations still occur in pulses, like in a pulsejet, but a pulse detonation engine is capable of propelling a vehicle to higher speeds, believed to be around Mach 5. Because detonation releases more energy than deflagration, detonation engines are more efficient — producing more thrust with less fuel, allowing for lighter loads and greater ranges.

The detonation shockwave travels significantly faster than the deflagration wave leveraged by today’s jet engines, Trimble explained: up to 2,000 meters per second (4,475 miles per hour) compared to 10 meters per second from deflagration.

[...]

A rotating detonation engine takes this concept to the next level. Rather than having the detonation wave travel out the back of the aircraft as propulsion, it travels around a circular channel within the engine itself.

Fuel and oxidizers are added to the channel through small holes, which are then struck and ignited by the rapidly circling detonation wave. The result is an engine that produces continuous thrust, rather than thrust in pulses, while still offering the improved efficiency of a detonation engine. Many rotation detonation engines have more than one detonation wave circling the chamber at the same time.

As Trimble explains, RDEs see pressure increase during detonation, whereas traditional jet engines see a total pressure loss during combustion, offering greater efficiency. In fact, rotation detonation engines are even more efficient than pulse detonation engines, which need the combustion chamber to be purged and refilled for each pulse.

[...]

According to the Air Force Research Lab, RDE technology could make high-speed weapons much more affordable, which is of particular import following a recent Defense Department analysis that indicated the hypersonic (Mach 5+) weapons in development for the Air Force may cost as much as $106 million each.