RIP Kevin O’Brien, AKA “Hognose”

Kevin, the prolific and incredibly knowledgeable writer behind the Weaponsman blog, passed away yesterday after suffering a heart attack last Friday. His brother, Brendan, has written a post for the site describing Kevin’s life and death.

Weaponsman has been a daily read of mine for years now, with an eclectic mix of witty commentary on firearms, military affairs, fieldcraft, history, and other topics. If any of that sounds interesting then please head over and take a look through the site’s archives, just don’t blame me for all the time you’re about to lose.

Hognose, as he was known to his readers, spoke with the experience of a long military career in the special forces. His site accumulated a community of commenters from around the world, many with similarly deep experience in a variety of fields related to military and firearms matters. Often as much could be gleaned from their commentary as from Hognose’s original posts. I was honored to participate in some of those discussions, as much as I often felt like a neophyte interrupting the discourse of masters.

No one can replace him, but I think I may dust off this ancient blog and start writing on some topics relating to my own professional areas of competence as a naval historian/operations analyst. It seems like a mere ember springing up in the bed left by a recently extinguished bonfire, but if others are similarly inspired then perhaps, together, we might go some way towards maintaining the illumination Kevin sought to provide the world.

Thank you, Hognose. You will be remembered.

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Halfway to Anywhere

When reading popular descriptions of our solar system, one often comes upon descriptions of its sheer vastness. We are to be sent reeling by various analogies to grapes and billiard balls and the distance between US cities, with the upshot being that anything of interest out there is separated from everything else by a gulf of emptiness vaster than we can comprehend. This is true in every way except, perhaps, the most important.

Robert Heinlein, one of the fathers of science fiction, quipped that “once you’re in orbit, you’re halfway to anywhere.” He had a very specific (and nearly literal) interpretation in mind for “halfway” when he said that, and it wasn’t about point-to-point distance. Heinlein was referring to the “Delta-V” required to reach various locations in the solar system.

Delta-V is most generally defined as the change in velocity (both speed and direction) needed to reach one point in space from another. So, to reach a stable Earth orbit (over 100 km from sea level) you must be moving at over 7.9 km/s. In reality, losses due to air resistance on the way up mean that your rocket needs to thrust long enough that, were it in ideal vacuum, it would have changed its velocity by at least 9 km/s. For reference, the super-fast SR-71 spyplane maxes out at 950 m/s and few rifle bullets can crack 1 km/s.

Spaceships and launch vehicles are not rated by “speed” in the sense of the greatest speed they can maintain, which is a meaningless concept in the frictionless environment of space anyway.They are rated  by their maximum Delta-V, which determines what kind of maneuvering they can do and where they can go. In a very real sense, it is more reasonable to talk about somewhere like Mars as being a “speed” away from Earth than to talk about its geometric distance from us. It is the Delta-V between it and us that determines what sort of vehicle can reach it.

When measured by Delta-V the solar system shrinks a great deal, as I’ve illustrated in the diagram below. It shows the Delta-V required to reach the planets of our solar system from Earth. The first leg, from the Earth’s surface up to 8 km/s,  is shown roughly to scale, with the atmosphere petering out almost to nothing by 100 km (the lowest practical orbit as judged via the Kármán line). As you can see, from the Delta-V perspective Earth orbit is just about halfway to anywhere, or at least anywhere in the inner solar system. It’s only a third of the way to the gas-giants.

Click to Enlarge

Data courtesy of the ever-outstanding Atomic Rockets site. Click to Enlarge

It’s immediately noticeable that the planets aren’t in their typical order here. This is largely because the big gas giants, Jupiter and Saturn, have very deep gravity wells. This makes getting down to a 100 km orbit around them very expensive in terms of Delta-V. The requirements are greatly reduced (by around 20%) if you aim for one of their moons and don’t bother going down into the central planet’s gravitational death-grip.

There is one way in which this is misleading, and that is transit time. The chart lists the Delta-V for a minimum-energy “Hohmann” transfer between the Earth and the target world. The downside to this is that it is the slowest way to get there: 9 months to Mars, nearly 3 years to Jupiter, and half a century to Pluto.

You can always get there faster, but only if you build more Delta-V into your spaceship. Willing to spend 35 km/s instead of 5.8? You can get to Mars in 20 days instead of 9 months. 50 km/s will get you to Jupiter in only a year. Better yet you can get to its moon, Ganymede, in the same time with only 30 km/s – the higher the energy of your trajectory the greater the gains from not going so deep into the gravity well.

The fly in the ointment is that you aren’t getting 35 km/s out of a spaceship with chemical rocket engines. Even with the highest theoretical performance that would require 2400 tons of fuel for every ton of ship. Assuming you want to send more than a probe, it almost certainly means you’re going nuclear – either as a power source for a plasma propulsion system or as the engine itself in the case of a nuclear thermal rocket or fusion drive. The good thing is that such propulsion systems are within our technological reach, in some cases since the ’60s.

Blue Glow: A Rocketpunk Adventure

I’m currently running an RPG set in a world based on the classic Golden-Age science fiction of R.A. Heinlein, H. Beam Piper and others. It takes place in the year 2103, but the 2103 imagined in 1960 rather than the 2103 we expect. Men with slide-rules navigate atomic rockets on expeditions to scout strange new worlds for colonization under the aegis of the Solar Guard. I’ve taken pains to make the science and engineering as realistic as possible, with the exception of the frantic handwaving necessary for FTL, not to mention primitive computers in the 22nd century.

The Flag of the Solar Guard

The Flag of the Solar Guard

I’m maintaining a website that covers the basics of the game here. My in-person players are cast as officers of the Solar Guard exploration cruiser Avalon, while I have two remote players who respectively take the role of the Solar Guard’s secretly self-aware mainframe computer, Astrovac, and the leadership of a genocidal alien race called the “Chlor.” The first arc of the plot ended with a surprise orbital bombardment attack by the Chlor upon several peripheral human colony worlds. The current arc focuses on the crew’s assignments during the resultant war.

In keeping with my nature, I’ve worked up a topical analysis of Avalon’s engineering aspects, as well as a CAD model to illustrate the players’ home-away-from-home to them. The site also has some fun filk pieces very much in the space-opera spirit.

The system is pretty loose, with a very general basis in the mechanics of Sufficiently Advanced but with the scale brought down to a more human level and less dice rolling.

Walter Mitty Syndrome

I play plenty of video games, watch movies, read books, and world-build pretty compulsively. All these things are acts of mental escapism, something all humans do to some degree, but even I found the degree of Walter Mitty-ism present (and tacitly endorsed) in this Play Station commercial disturbing:

Discuss.

The Beginning of the End

On this day in 1914 Gavrilo Princip assassinated the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, and his wife, Sophie, on the streets of Sarajevo. Princip and his co-conspirators were recruited and organized by the “Black Hand,” an organization headed by the Chief of Serbian Military Intelligence.

Gavrilo Princip during his imprisonment. Too young to receive the death sentence in Austria, he was instead sentenced to 25 years. He died of tuberculosis in 1918.

The Austro-Hungarian empire responded with an ultimatum to the government of the Kingdom of Serbia. The demands made in this ultimatum were impossible for the government of Serbia to meet (likely by design), and so after a month of desperate diplomatic wrangling and confusion between the great powers, the Empire declared war on July 28. Russia, as protector of the Slavic people and unwilling to see the Empire expand its power in what was viewed as Russia’s sphere of influence, began to mobilize.

A day later, Germany began to mobilize in support of their Austrian allies and in anticipation of the intervention of Russia’s ally, France. Germany invaded Belgium on August 2 as part of their planned outflanking of the French, and two days later Great Britain declared war on Germany in response to their violation of Belgian neutrality. The Great War had begun.

It is darkly amusing in hindsight that Franz Ferdinand was unpopular with the government of his uncle, Emperor Franz Joseph I, partly on the grounds that he favored a more cautious approach to the Empire’s relations with Serbia.

Archduke Franz Ferdinand, heir presumptive to the throne of the Austro-Hungarian Empire.

 

Sophie, Dutchess of Hohenburg and wife of Franz Ferdinand.

Inquisitorial Blackship “Anatolia”

My fiancée and I have been working for some time on a novel set in the Warhammer 40K universe, specifically about an Imperial inquisitor named Alexandra North. Last night I had a sketchbook handy and decided to freehand a drawing of her ship, a Firestorm-class frigate named Anatolia after the birthplace of the Emperor.

Anatolia

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The Anatolia is broadly similar to the standard Firestorm frigates serving in the navy: loaded mass of 64.4 megatons, maximum acceleration of 0.2 g, mass ratio of 1.55, delta-V of ~130 km/s. She differs in having a larger reactor and a much larger bow lance (soft X-ray laser), on par with those carried by battleships. The lance has a very low rate of fire, around one shot every 10 minutes, due to Anatolia’s limited capacity to eliminate the waste heat of the titanic weapon. It does, however, allow her to open an engagement with a shot capable of punching through the shields of opponents double her mass.

Despite some slight perspective distortions due to being a freehand drawing with minimal construction lines, I’m pretty happy. I haven’t sketched more than a quick landscape (usually for RPGs) in years. I’m also pleased with the fact that there is not a single piece of “greeble” on the entire ship. Everything from the big hexagonal phased-array radar panels to the anti-ordnance turrets to the statues of the Primarchs and Emperor has a purpose, functional or symbolic.

Pacific Rim: Why Giant Robots Are (Usually) Silly

I’ll start this off by saying I really like Guillermo del Toro’s body of work, and that his characteristic blend of physical effects and CGI really shows in the quality visuals I’ve come to expect from his films. These two trailers for the upcoming Pacific Rim indicate that it will not be an exception to this rule.


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