With modern technology would it be possible to build an HG Wells style Martian tripod?

Question

With modern technology would it be possible to build an HG Wells style Martian tripod?

It should approximate to one of the HG Wells war of the worlds style tripods at roughly 30m high and have a “heat ray” that consists of some form of flame thrower with a 100m range. It needs to be capable of movement across open terrain for 100 miles at 10mph and carry a cargo in the pod of 5 tonnes. It needs to be able to cope with light tree cover and shrubs, but won't be expected to cope with very dense and tall forest. No need for tentacles.

If 30m is too ungainly or impractical for the 100 mile trip at 10mph how long could the legs reasonably be?

Note I realise that such a tripod would be very vulnerable to modern weapons, but such concerns are out of scope for this question (although might be the subject of of a follow up question).

Answer 1

When it comes to 'possible', a War of the Worlds tripod should be achievable with near-future technology, pretty much just the R&D required to actually build the thing. While it wouldn't be the most efficient vehicle, it is quite plausible that it could make a 100 mile trip at 10 miles per hour. It's not an impossible distance for a modern internal-combustion powered vehicle.

When it comes to vehicles, the larger they are, the more inertia they tend to have. Even if a tripod didn't attempt to lift its feet over light tree cover and shrubs, the weight of a twenty-odd metre long leg capable of supporting the tripod's entire weight would be strong and heavy enough to simply push through such light vegetation with just a little care.

The main problem with a tripod is that it would be unstable while moving. However, many animals manage with an even more unstable two-legged gait. With a sufficiently trained neural network controlling the legs, a tripod ought to be able to remain upright under most circumstances.

As for a 'heat ray', there are all sorts of possibilities for that... a flame thrower or an infra-red laser immediately come to mind. Neither are particularly good weapons... but it's achievable.

Of course, this ignores the matter of practicality... but then the OP wasn't concerned about that.

Answer 2

Probably Doable

Currently the tallest robot built to date that walks on legs is an 18 meter tall, 25 ton, bipedal Gundam replica in Yokohama Japan. Although this robot is not quite as tall or heavy as your goal, I think it is close enough to say that you could plausibly make your idea able to stand. The tricky part though is moving. The electric motors that make robotics possible do not scale up well; so, in order to make the Yokohama Gundam able to walk, they had to make it move very slowly using significant mechanical advantages. Many videos out there of it walking are sped up to make it look more impressive, but when you actually see it in action, it is SLOOOOOW. Nowhere near your 10kph goal.

Furthermore whereas a biped's feet takes turns stepping, and a quadruped's feet take turns stepping in pairs, the only way to evenly distribute the load of a triped while it walks is to take a 3-phase step which inheirantly takes longer than a 2-phase step. So, a tripedal robot will if all other factors are the same walk 50% slower than a comparable biped or quadruped.

All this said, there may be some saving grace in the design of a Tripod, that a Gundam does not have. For starters, Tripods have less unnecessary top weight. They have no giant arms or articulated head or any of the flashy decorative elements. It's just a simple football on legs which should help with reaching your taller goal, and even though a triped is naturally slower than a biped, there is something to say for the design because it always has 66% of its legs engaged with the ground instead of 50% which should help some with the structural concerns. Lastly, it uses segmented, tentacle like legs; so, instead of needing a giant, high torque actuator to slowly turn a joint by many degrees, you could use many smaller actuators that only need to turn by a fraction of a degree each to achieve a faster motion through compounding rotation. While these legs require a lot more moving parts and would be harder to maintain, they may actually help your giant robot move much faster than a simpler human like leg. Especially since you can create a smooth stress to motility curve across the whole length of the leg instead of just at the 3 points of articulation.

There are also some promising statistics available in crane load capacities. While cranes don't "walk", there are some important specs where cranes are involved that make tripods sound perfectly reasonable. The average weight of a 30 ton capacity truck crane is 18-30 tons and they come with booms that average 30-40m in length meaning that we know for a fact that something like a robotic leg exists with the power to lift, hold, and about 2 times its own weight 30+ meters in air. Moreover, cranes are normally made using cheap, low carbon steels. These are fine for cranes because cost is a bigger concern than weight, but there are much stronger materials you could use, if you can bear the cost. High yield steels like those used in mining equipment paired with high tensile strength tungsten alloy cables could be used to make legs that are 3 times as strong for thier weigh as a traditional crane boom which would allow you to build legs that can endure the higher impact of walking. So, if you think of a Tripod as 3, 5-ton crane arms, each with a 15+ ton capacity, turned upside-down, then you could reasonably expect to be able to build a 30 ton Tripod that can endure a brisk walk with at least 15 tons to spare on cockpit, armor, and weapon systems.

The Heat Ray is the Easy Part.

We actually have these already. A 1 kilowatt High Energy Laser (HEL) can kill a human faster than they can get out of the way, and the US Military already has 300 kilowatt lasers that are compact enough to fit on an armored fighting vehicle. While the 300kw laser and its whole power system is probably a bit heavy for a tripod to carry (it's exact weight, or combined weight of it and its combat vehicle does not appear to be public knowledge), much older 50kw lasers could fit on a 16 ton Stryker Armored Fighting Vehicle; so, even using relatively old HEL technology, a 30 ton Tripod that is about 1/2 leg weight and 1/2 head weight would leave you enough tonnage to essentially turn this whole thing into a HEL armed Striker with legs instead of wheels. A HEL in this size/power range is still adequate be a threat to most lightly armored combat vehicle, slow moving aircraft, or if turned against people, it could cause a human's flesh to boil and burn with explosive force while permanently blinding everyone who happens to be anywhere nearby.

Answer 3

I think the tripods could work but they may be a bit different to the machines that are typically drawn on 'War of the Worlds' book covers. The robots in the MIT and Boston Dynamics labs are very different to the experimental walking machines of the fifties. They have a sense of balance. They use tendons and elasticity to store the energy when a foot comes down, and use it to spring up again, much as we do. So, how might the tripods move? They may have two legs with knees and feet, and a third leg that could be used for balance much like a monkey or a squirrel uses its tail. It could run with a slow, floating gait on its 30 meter legs while keeping the pod in steady motion. It could put down the third leg when it needed to stand still.

No-one has tried to make a walking robot that high with elastic legs. 30 meters is six times times higher than a giraffe or a pole-vaulter's pole. It is hard to extrapolate any mechanical system to something six times bigger, but I see no obvious barriers either.

It would look creepy as heck when it ran. But it could be fast. An ostrich can do 45 MPH. This is the same shape but with a third leg instead of the neck and wings for balance.

Now to the Heat Ray. This could be a Phalanx Gatling gun firing tracer rounds. That would look like a continuous stream of flame to a Victorian soldier, rather than a gun firing very quickly. The Heat Ray was a separate unit that was handed from one tripod to another, which also fits. The gun would be heavy when loaded, and not something that a tripod could run with. So, they stop, put down their third leg and lock them so it makes a stiff structure, pick up the loaded gun, fire it, and then put it down again for reloading.

Good old H.G. He leaves enough gaps in his description that we can fill in the blanks. I don't know if this is what he had in mind, but it works for me.

Answer 4

It wouldn't be possible with these specifications, but with some changes, it would be plausible

There was a project similar to tripods in the 60s, the "Pedipulator", a machine that walked on two 3.65m inarticulated legs. This concept only had a prototype that did not walk but balanced on two legs using the pilot's balance.

With today's technology, it would be possible to create an artificial balance system using the tripod's internal computers.

I suppose that the assistance of drones to map the path would be more practical and useful than placing sensors on the tripod with its long legs in the way, as well as having the advantage of being able to scan the area to find dangers against the fragile tripod.

But the main flaw of the "Pedipulator" that the tripods would also have is the high center of gravity, so it would be impossible to carry 5 tons as it would distance the center of gravity and also increase the pressure on the legs (causing the tripod to sink into a floor soft enough), it would only be practical if the load was towed. Plus, the 100-foot legs would only add to the center of gravity problem. (All this assuming that the tripod would be made to be used under Earth's gravity).

The project that succeeded the "Pedipulator" was the "Walking Truck", a truck with legs instead of wheels. It is powered by a 90 horsepower gasoline engine that drives a pump for a high press hydraulic system with the servos being hydromechanical, without any electrical elements. This created several problems, but the main one was that the hydraulic fluid did not allow the vehicle to run autonomously. But by using electric servos powered by a diesel engine, the tripod would be practical would have more autonomy, and also be easier to maintain.

To maximize the size of the legs, the layout of the legs on the tripod can make them longer, so the tripod can have long legs like a giraffe while standing still and bend its legs like a spider to walk with more stability and faster.

Regarding the speed, it would depend on the dynamics of the movement of the legs, and as stated above they could be like the legs of the "Walking Truck" with two joints similar to those of humans with a triaxial joint (similar to the coxofemoral joint) attached to the body and a monoaxial attached to the leg (similar to the knee), with the 3 legs being equal, facilitating maintenance and production, keeping the two segments the same size as in most animals.

When the tripod entered a walking mode, its monoaxial joint would be placed at a higher altitude than its respective triaxial joint (similar to a spider), thus allowing the tripod to run faster.

The relationship between the size of the legs and speed is a difficult question, but if the tripod walks alternating flexing the second segment of the front legs while extending the entire rear leg for support, its speed would depend on the relationship between the size of the moved limb of the legs. with the angle of your movement, in addition to the steps/minute.

So I suppose that the size of the segments could be something around 5m (with each end having an excess of a few centimeters to connect with the joint), then the height of the leg would be 10m and a few more centimeters for a structure similar to the feet. Assuming that the tripod was made with reliability in mind, not performance.

The movement angle of the monoaxial joint should be approximately 45° to maintain stability, while the triaxial joint acts as a suspension.

Finally, if he performs a movement cycle every second with the proportions mentioned above, it is possible for him to do 10mph.

Answer 5

50/50

The problem is the energy source. In The War of the Worlds the tripods energy source is briefly discussed. Mostly in the context that research on it blew up two separate affords.

Mechanically, there is nothing inherently impossible about them. Yet it is important to remember the historical concept in which Wells thought them up. Tripods are Martian Land Ironclads. They were created for a time in which Air power was fiction and artillery precision a coincidence. Keep in mind, the OG Tripods did not have shields. These Tripods would melt against a modern military.

Of course, we dont know your exact context but it is important to keep in mind. The Tripods worked because they were made for a specific time and heavily inspired by real concepts. A modern iteration of the Tripod idea would most certainly be some sort of Aerial Vehicle with standoff munitions.

Getting back on topic, the Energy Source. We have no idea what could possibly power them. Nuclear is to heavy, so is Gas. Wells seems to indicate they use some sort of portable power, a battery. Which is probably the only realistic option. If you have a high critical current Superconductor you could make a battery with absurdly high energy densities. Way more than any power plant. But of course, you are caring a mini nuke as your energy source.

The Heat-Ray was, at least if my recent read through can be believed, not a flame thrower. It was described as a Laser. Including a parabolic mirror. That is obviously not very hard to do in principle. It all comes back down to Energy. The Tripods Heat-Ray can cut into / through an Ironclad with minimal exposure time. We are talking about a TWh laser here. At which point the air around you will become a real problem as it might begin combusting. Personally i think a more realistic version of the Heat-Ray would be a device that can send out a Ray across a wide spectrum. Since you dont need TWh to vaporize humans with microwaves.