Military Theory: A Technical Analysis of War of the Worlds' Equipment, Strategy & Operations20 Dec 2019 4
"No one would have believed in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's and yet as mortal as his own; that as men busied themselves about their various concerns they were scrutinised and studied, perhaps almost as narrowly as a man with a microscope might scrutinise the transient creatures that swarm and multiply in a drop of water. …Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us. And early in the twentieth century came the great disillusionment." – War of the Worlds
Reverse Engineering the Martian War Machine – The Heat Ray and HMS Thunder Child
This article is a “history” of H.G. Wells classic science fiction novel, “The War of the Worlds”, as if it actually happened, complete with technological assessments, logistical evaluations and strategic analyses. Naturally, the first subject will be prominent given the vast technological superiority of the invading Martians.
One incident in particular from the book can serve as the basis for this technical analysis: the encounter between three Martian war machines and HMS Thunder Child as described in book one, chapter seventeen. The battle, which is depicted as taking place off the mouth of the River Blackwater in Essex, was the only known incident in the war where Humans defeated the Martians. When the Martians arrive at the coastline, HMS Thunder Child is laying offshore with other ironclads of the Royal Navy escorting shiploads of refugees fleeing the Martians. The Martians wade out into the ocean in pursuit of the refugee fleet.
Defending the refugees, HMS Thunder Child steams directly at the three Martian tripods now wading out into the offshore waters. Initially confused as to what the craft could be, the Martians at first attack it with a canister of poisonous black gas. The canister bounces harmlessly off Thunder Child’s hull as it continues its advance. The Martians then retreat shoreward and higher ground to gain firing advantage with their heat rays. A blast from the heat ray of the first Martian tripod penetrates the ship’s hull but fails to damage the ship’s steering gear or engine. HMS Thunder Child then rams the first Martian which crumples and collapses. HMS Thunder Child fires its guns, but does not score any hits (though a shell almost hits a fellow steamer). It continues to steam towards the second Martian, though its interior is now on fire. The second Martian fires its heat ray into the heart of Thunder Child just before impact. Thunder Child then explodes into flaming wreckage. The explosion staggers the Martian and the ship’s impetus allows the now dead Thunder Child to ram the Martian full on, destroying the second Martian. The clouds of steam generated by the heat ray obscure what happens next. When the clouds clear, neither Thunder Child nor the third Martian can be seen as the Royal Navy ironclads take up guard positons shoreward of the refugee fleet.
HMS Thunder Child was an ironclad torpedo ram, based on the very real HMS Polyphemus. This was the only ship of this class commissioned by the Royal Navy (1882, two other ships were ordered but never built). An ironclad torpedo ram such as HMS Polyphemus was a rather odd hybrid vessel whose tactical use on the open sea was never quite figured out by the admiralty. Unlike HMS Thunder Child, it had no deck guns, relying on five torpedo tubes and 18 torpedoes with a maximum range of 600 yards. Its class of ship, and the tactic of ramming itself, was soon rendered obsolete by the introduction of quick traversing and quick fire guns (ramming only proved effective against ships already dead in the water, in any case). Its design specifications and construction plans describe its steel plate armor as “deck 3 inches’ compound armor, hatch coamings 4 inches, conning tower 8 inches”. The Martian heat ray is described as penetrating this like a “white hot poker through paper”.
So, what can this information tell us about the Martian heat ray?
Begin first with metallurgy. Carbon steel has a temperature of vaporization (the temperature at which steel boils) of approximately 3000 degrees C. By comparison, the surface of the sun is approximately 5,500 degrees C. Carbon steel also has a specific heat value (the amount of energy needed to raise one kilogram of steel by one degree C) of 502.4 Joules / (kg * deg C).
Assuming the heat ray was of a relatively large diameter (up to a 1 foot - based on description of the heat ray’s large camera-like projector and its effects on troops in the field) it would have to vaporize 905 cubic inches of carbon steel to punch through its thickest 8" armor plating. This is equivalent to 257 lbs of steel or 116.6 kg.
(Note: I ask the reader’s forgiveness for switching back and forth between English and Metric units. Wherever possible I will use Metric, but both the values and characteristics of a Royal Navy ship of the late 19th century are given in English as are some comparative characteristics of modern American military vehicles).
To reach this vaporization point, the heat ray would have to deliver 175 million joules = [502.4 Joules / (kg * deg C)] * 116.6 Kg * 3000 deg C. Assuming vaporization can occur in one second or less (“white hot poker through paper”), this is equivalent to 175 megawatts minimum. So, we can assume that a Martian tripod was equipped with an approximately 200 MW power plant.
Assuming the Martians did not use any exotic physics, this puts the Martian tripod's power plant in the range of currently available small modular nuclear reactors (SMRs), which are classified as reactors that generate 10 MW to 300 MW. The dimensions of these reactors vary with design and output, with some requiring housing as small as 6m x 6m x 30m. Assuming continued advances in reactor design, even smaller and more compact reactors will soon be available. Certainly, it is feasible for such an advanced compact reactor to fit in the cowling at the top of a Martian tripod (described as being 10 stories high with a cowling described as being the size of a small house or large boiler on top of its three legs). We can further assume that the tripods are not powered by extreme power sources like fusion or anti-matter. A tokamak fusion reactor may be more efficient than a fission reactor, but its need for confining magnetic fields and associated super structure makes it impractically large compared to a compact SMR whose power output would be more than sufficient.
But how would the Martians fair against the mightiest Human war machine of the early 20th century, the Dreadnaught-class battle ships with their massive (by Human standards) fire power and heavy steel armor? I’m cheating here just a bit since the book was published in 1898 and HMS Dreadnought wasn’t commissioned until 1906. Then again, though Wells never gives the precise year of the Martian invasion, it was sometime “early in the 20th century”. We can be assumed the Martian invasion to have taken place in the first decade of the 20th century just as the Dreadnought-class warships were coming on line.
Unfortunately, HMS Dreadnaught had “only” 11-inch thick steel plate armor. It would have lasted no longer against the Martian heat ray than HMS Thunder Child. Its 12-inch guns on the other hand had a maximum range of 16,450 yards (9.3 miles or almost 15 km). This gives HMS Dreadnaught the chance to fire one or more broadsides against the Martians. However, at an elevation of approximately 30 meters (10 stories), the horizon to a Martian observer would extend 19.6 km (12.2 miles). Again, the unfortunate HMS Dreadnaught could not hide beyond the horizon out of reach of a line of sight weapon like the Martian heat ray. But being a larger ship firing at a greater distance, HMS Dreadnaught could conceivably take out several Martian tripods before its demise.
Fast forward a century, and how does the Martian heat ray compare to the battlefield lasers now entering service? The ATHENA laser system deployed by the US Army in 2015 utilized a 30-kW laser capable of setting thin skinned vehicles like trucks on fire or shooting down a drone at a range of one mile. The newer THEL systems have twice the power. Lasers installed on US Navy destroyers have power ranging up to 150 kW. The US Air Force AC-130 aircraft used in an anti-missile role are also equipped with lasers in the 150-kW power range. None of these weapon is in the same class as the 200 MW Martian heat ray. The only comparable lasers are free electron lasers under development with power estimated in the 1 MW range or the theoretical nuclear pulse powered satellite lasers proposed for President Reagan’s Strategic Defense Initiative, SDI (aka “Star Wars”).
Assuming that the Martians had fire control and target acquisition technology at least as advanced as our own, their heat ray could also be easily employed in a similar anti-projectile role (making the protective “force fields” shown in both “War of the Worlds” movies unnecessary). The energy of the heat ray would simply trigger any explosive shell or explode the propellant of any missile fired at them, as well as incinerate any helicopters, drones or aircraft in their line of sight. Not even the 350 mm (almost 12 inches) thick depleted uranium mesh-reinforced composite armor of the M-1 Abrams tank would provide a significant defense.
Odds are, the Martians tripods and their heat rays from over 100 years ago, would still be able to dominate even a modern battlefield, inflicting death and destruction with relative impunity.
Reverse Engineering the Martian War Machine – Power to Weight Ratios and Movement
Martian war machines were 30-meter high tripods. The top 3 meters (10 feet) consisted of an enclosed cowling that housed the operator, along with its (his? her?) instrumentation and equipment, power plant and environmental controls. The legs of the tripods measured 27 meters (90 feet) in length with their movement while walking potentially affecting the height of the war machine and the elevation of the occupant inside.
Actual movement of the tripod's legs were a more fluid version of a man on crutches (2 legs, then 1 leg, then 2 legs then 1 leg, etc.). The closest living analog would be a more graceful three-legged dog. The estimated power plant would certainly be sufficient to provide enough energy for movement at speeds of up to 60 miles per hour (96.5 kph) - the tripods are described as moving at a speed equivalent to a fast locomotive in Wells' day. By comparison, the top off-road speed of an M-1 Abrams tanks is half the speed of a Martian tripod (only 30 mph). However, that fact that the Martians' heat ray requires such a huge amount of energy would explain why the tripods must stop to fire, they probably didn’t have enough energy to move and fire simultaneously.
Their length of stride would be limited by the need to maintain a stable posture with the angle between the legs no more than 60 degrees (or 30 degrees to the vertical). In this position, each leg (or pair of legs) would form the hypotenuse of a triangle with the adjacent segment being the vertical and the opposite segment being the ground surface. With the sin of 30 degrees being 0.500, each step would be equal to 90 feet (2 x 0.500 x 90 feet). A speed of 60 mph is equal to 1 mile per minute, or 88 feet per second. Therefore, when moving at top speed, a tripod would have to take a stride every second.
The leg movements themselves are complicated by the need to maintain an even elevation for the tripod’s operator. At midstride, with all the legs in alignment the cowling would be at its maximum height of 90 feet. However, the cosine of 30 degrees is 0.866 the height of the cowling would fall to approximately 78 feet (24 meters). That’s a rise and fall of 10 feet (3 meters) with each step, which occurs every second at top speed. The occupant could not be subject to such shaking, in effect being dribbled like a basketball to heights of ten feet, especially on a plant whose gravity is 2.5 time greater than the operator’s home world. Therefore, the legs themselves must change length while walking, being shorter at mid stride and longer at the end of the stride to keep the cowling and its occupant level. This could be done by segmented legs that bend further as needed to achieve the required length, telescoping legs the extend and contract during movement, or curled legs that wind and unwind with each step. However, no detailed description of this movement is given.
The cross section of the leg struts themselves would best be circular. The tripod will be constantly changing direction and speed, and a circular cross section does not present a directional and variable moment of inertia (like an I-Beam would, for example). Which brings us to the applied loads on the leg struts and the question of how much a tripod weighs.
The cowling’s superstructure is described as being as big as a one-story house. House movers will transport loads between 80,000 and 160,000 lbs. Assuming a small house of 100,000 lbs what would be the equivalent weight of such a structure made from more advanced material than pine wood framing (pine having a density of 0.54 g/cc)? There are two potential materials that could be used to construct the tripod, traditional carbon steel (7.7 g/cc, 15 times the density of wood) and more advanced carbon fiber composites or even nanotubes (1.56 g/cc, 3 times the density of wood). Assuming the same ratio of shell/wall and interior structure to open space as the house being used as the baseline (Martian bodies/heads are exceedingly large and there will be the need for control equipment and instrumentation). In round numbers, a carbon fiber cowling would weigh approximately 300,000 lbs, while the steel version would weigh 1,500,000 lbs.
However, the main load would be the tripod’s power plant. As mentioned before this would be equivalent to a 200 Mw small modular reactor. These vary in size, weight and dimension but an average weight of 500 tons (when loaded with fuel rods) can be assumed for the power plant. This adds another 1,000,000 lbs. to the weight on the legs. So, the total weight of the carbon fiber cowling would be 1,300,000 lbs. (almost 600,000 kg) and the steel cowling would be 2,500,000 lbs. (almost 1,200,000 kg). So, again in round numbers, each leg would carry about 200,000 kg if made of carbon fiber and 400,000 kg if made of steel.
Note: I am making some simplifying assumptions here. As the legs move from a vertical upright positon to a complete stride, the weight loadings of the cowling and the reacting loads on the leg’s feet would become oblique instead of axial, inducing further bending moments in the legs. Also ignored are concentrated point loads at bending joints or the additional weight from leg extension machinery.
Also, the only military action taken by Martian flying machines was the spreading of poisonous gas. At a weight of 500 tons, the power plant needed for the heat ray would have been too heavy to mount on an aerial platform.
We can now estimate the diameter of each leg using a buckling formula for column loadings. This formula is gives the relationship between the applied weight load and the following: the length of the leg, the leg’s internal strength characteristics (as defined by the material’s modulus of elasticity) and the geometric moment of inertia defined by the leg’s cross sectional area. The strength modulus of advanced carbon fiber nanotubes is estimated to be about 138,000,000 psi (950 GPa) while steel has a modulus of 29,000,000 psi (200 GPa) – making carbon fiber nanotubes 23.5 stronger per unit weight than steel. Arranging the formula to determine the required cross sectional moment of inertia, carbon steel would require 1580 in^4 – a circle with a radius of 45 inches (1.14 meters, a cross sectional area of 4.08 meters^2). The carbon nanotubes would require only 166 in^4, or a circular radius of 14.5 inches (0.37 meters, a cross sectional area of 0.43 meters^2). A steel construction is not practical.
The additional volume of each carbon nanotube leg would be 11.61 cubic meters. At a density of 1.56 g/cc (1560 kg/M^3) each leg would weigh 18,112 kg or over 54,000 kg total. With the cowling and power plant’s estimated weight of 600,000 kg, along with other equipment, furnishings, appurtenances, weapons (gas canisters, tube gun and the heat ray projector), the total weight of a Martian tripod could be approximately 700,000 kg (1,543,000 lbs or 772 tons). Its 200 MW power plant would generate 268,200 HP, giving a power to weight ratio of almost 350 HP/ton. By comparison, an M-1 Abrams tank weighs 62 tons and is equipped with 1,500 HP engine giving it a power to weight ratio of 24.2 HP/ton. Clearly the Abrams is out classed.
Lastly there is the issue of the feet. During its stride, the tripod balances one either one or two legs as it advanced forward like a man on crutches. At some point in this cycle either its entire weight or half of its weight is being transmitted through the legs and into the ground below. The bearing capacity of the soil therefore becomes a critical concern. This can vary from 33 kg/cm^2 for hard rock to 0.5 kg/cm^2 for soft clays. At the maximum one legged load of 700,000 kg, walking on rock would require a circular foot pad of 21,212 cm^2 (a radius of 82 cm, or a diameter of 1.66 meters). To navigate the other extreme, soft clay soils, its foot pad area would have to be 1,400,000 cm^2 (a radius of 667 cm, or a diameter of 13.3 meters – probably too large for practical movement.
While a tripod would certainly have the power to pull its legs out of the muck, this does illustrate that it has certain terrain limitations. Wet and marshy conditions are something not encountered on a desert planet like Mars. It seems that a strong rainstorm would be better at slowing the Martian’s advance than any Royal artillery battery. So, any Human survivors of a successful Martian invasion should hold up in jungles, marshes and peat bogs – instead of the London sewer system. What is left of Human civilization could possibly survive in the heart of the Amazon or the Congo.
The Economics and Logistics of Interplanetary Invasion
It’s not clear how many tripods and associated equipment were loaded into each cylinder fired at Earth. As many as five tripods are described as rising out of the impact crater, along with earth moving equipment, a handling/construction machine and the parts for a flying machine. Also included are the Martian crew, and provisions (live Martian bipeds) The weight of the cylinder’s payload would be almost 6,000,000 kg.
The cylinder itself is described as bluntly bullet shaped with a maximum diameter at the base of 30 meters. That’s about the height of a war machine, allowing them to be stored in an upright and assembled position. Space would also be required for crew, fuel used for re-entry braking, equipment and instrumentation. The length of the cylinder is never described (its nose being buried in earth after landing) but is probably not longer than 150 meters, for a total volume of about 106,000 m^3. Assuming an average 1/10 meter thick ablation shell with insulation layers, the cylinder’s structure would take up about 2,000 M^3 with 104,000 M^3 of interior storage volume. If made of carbon nanotubes, the cylinder’s hull would weigh another 3,000,000 kg. With the addition fuel taking up half its storage volume (assumed to be metallic hydrogen with a density of 600 kg/M^3, see below) the weight of fuel for reentry would be another 31,000,000 kg. This makes the total weight of the cylinder, fuel and payload equivalent to 40,000,000 kg. By comparison the total weight of the largest man made rocket, the Saturn V of the Apollo moon missions, was 2,800,000 kg.
Launch from Mars would be much easier with its gravity of only 0.376 g - escape velocity on Mars in about half that of Earth (5.03 km/sec vs. 11.186 km/sec). Human astronomers observed what appears to be ten separate explosions on the Martian surface which they later take to be guns firing the cylinders. Though beloved of both Verne and Wells, using guns to launch spacecraft is not used for any number of reasons - not the least of which is the high initial acceleration at launch that would turn any occupant into chunky salsa, Martian or otherwise. Assuming the Martians lack exotic physics such as artificial gravity or negative gravity generators to dampen the forces of acceleration, a rail gun launch would seem to be the best explanation.
The energy required to launch 1 kg into Earth orbit is 32,900,000 j (or 9.14 kW hr). A launch from Mars would require 12,370,400 j per kg due to its lesser gravity. Therefore, a Martian cylinder would require almost 5 x 10^14 j with additional energy required to transfer to Earth orbit, decelerate and land. Some type of aerobraking in Earth’s atmosphere could be possible but there is no mention of Martian cylinders appearing in Earth’s skies like streaking meteors. On the other hand, there is the use of green colored propellant to reduces its velocity upon entry. Landing would not be an impact crash in any case as it would kill the occupants or even create an extinction level event.
Certainly, altitudinal jets would continue the cylinder’s deceleration when in Earth’s atmosphere unit it was safe enough to make a sliding landing in the English countryside. Given that cylinders are lacking in aerodynamic gliding properties, landing would depend entirely on engines. The fuel required for reentry would have to be extremely powerful and efficient. One fuel meets these requirements, metallic hydrogen. A substance only recently created in the laboratory, its energy content is such that an engine utilizing metallic hydrogen would have a specific impulse of 1700 sec compared to standard rocket fuel of 460 sec.
The total energy required per cylinder launch and landing could be as high as 1 x 10^15 j. By comparison, the energy needed to launch a Saturn V into orbit was almost 9 x 10^12 j, or less than one hundredth of the energy needed to launch a Martian cylinder even from its lower gravity. And the Martians launched at least 10 such cylinders.
The Martians would have to be a truly advanced civilization to command energy levels of this magnitude. For a Martian civilization to treat a cylinder launch as the same percentage of total available energy as the Saturn V launches were to total American energy consumption, they would have to be rated as well above a Type 1 civilization on the Kardashev scale. Humanity is currently about a Type 0.7 and probably won’t obtain Type 1 status for another 100 to 200 years.
What about supply on the ground? How did the Martians provision themselves? They lived off the land by ingesting Human blood. Given the oddities of Martian physiology (no internal digestive organs for example) their source of nourishment would be blood from their cattle bipeds (whose brain cases were large enough to allow for intelligence – a horrible fate for any intelligent species) - and us. And this practice may be the source of the disease that killed them. An advanced civilization like the Martians would not be ignorant of the existence of microbes. In their pre-invasion study of Earth its possible they could have at least determined the chemical signatures of various types of microbes in the Earth’s biosphere. And they could have easily filtered the air they breathed. What they did not count on is that certain microbes are only found in the Human body’s microbiome.
This resolves the Martian disease question: It was something they ate.
The Invasion Strategy and Operational Goals
As mentioned above, 10 cylinders, each containing up to five tripods were launched at Earth and landed in the English countryside outside of London. Locations of seven of the landing sites are known (Horsell Common, Addlestone, Pyrford, Bushey Park, Sheen, Wimbledon, and Primrose Hill).
A mere 50 war machines seem inadequate for the purposes of occupation. But then the Martians had arrived to exterminate, not occupy. As stated in previous parts, a 100 feet tall Martian tripod would have a line of sight to the horizon of almost 20 km with the ability to incinerate anything that moves within their field of view - or poison with gas if in hiding. Each tripod would have a zone of control equal to a diameter of 40 km. Five such tripods could form a line of battle 200 km long. The entire invasion force could form a continuous front of 2,000 km. The longest distance between points in the UK (Lands End, Cornwall to Duncansby Head in the far northeast of Scotland) is 968 km. So the Martian invasion force could literally sweep Great Britain with a continuous line of advance from one end to the other. Nothing on the island would escape them.
But why the UK? There are several advantages to landing in Great Britain to establish and invasion beachhead. As an island, it could be completely swept clean of defending Humans without having to worry about interference from contiguous lands. Great Britain was also one of the most technologically advanced societies on Earth with the greatest concentration of industrial capacity and technological prowess, and its defeat would augur well for future complete conquest of the planet. But most importantly, London was the largest city on the planet and therefore the largest single concentrated source of food available to the Martians. Perhaps the Martians thought of their invasion more as a hunting expedition of inferior food animals than as a military campaign.
The UK also offered the perfect place both geographically and logistically to establish a solid base of operations for subsequent advances across the globe. The initial invasion force of 50 tripods would be analogous to the first divisions that landed on the beaches on D-Day. The main invasion force would follow on through.
Aside from hunting and domesticating Humans for food, their long-range plans most likely included terra-forming (or more accurately “ares-forming”) the Earth to resemble the environment of their home planet. To that end they deliberately introduced the red weed as an invasive species. This Martian plant quickly overwhelmed the local ecosystem but also in time succumbed to Earth microbes. Had this initial first wave been successful, Great Britain would have been transformed into a human cattle pen whose other native species would have been driven to extinction by invading Martian life forms.
The fate of the planet would have been the same after the second wave had arrived.