In this world, the vehicles are effectively re-engineered insects; enlarged bio-manufactured nervous systems used instead of engines; factory grown lightweight chassis / [wheels]. The fuel station could be an algae pit or something similar.

My question is basically, if you could redesign an insect's shape and size to be similar to that of a small 4x4, how much fuel would it require to get say 200miles? what kind of oxygen intake it would it need to function? and, as a bonus question, what kind of technology (or biotech) could be used to command the vehicle?

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    $\begingroup$ Welcome to the site Aloysius Anise, please take the tour and read up in our help centre about how we work: How to Ask We have a one question per question policy, could you edit your's to fit in. Just as a suggestion, I'd break yours into two seperate question threads, the second being about control systems - but it's up to you. $\endgroup$ – Bitter dreggs. Mar 9 '19 at 13:36
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    $\begingroup$ Looking through the answers I think your question needs some edits for clarification. I get the idea that you call it an insect as it has multiple limbs (wheels in this case apparently) and an exo-skeleton (the chassis). Unfortunately the mention of insect makes people think its an actual current day insect but scaled up, rather than a living and breathing 4x4 people can hitch a ride in. $\endgroup$ – Demigan Mar 9 '19 at 15:04
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    $\begingroup$ So what is wrong with a horse? it doesn't have all the design problems of an insect. $\endgroup$ – John Mar 9 '19 at 15:16
  • $\begingroup$ You are effectively asking us to determine the fuel consumption of an undescribed vehicle of unspecified construction, powered by engines of an unknown type and carrying an undefined payload. And in addition you are asking us how to design the steering column of that nebulous vehicle. You may also want to clarify the intended meaning of chassis over open bracket wheels close bracket. BTW, you do understand that gasoline and diesel fuel are organic materials, yes? $\endgroup$ – AlexP Mar 9 '19 at 17:10
  • $\begingroup$ @John: And considering a horse gives us a ballpark fuel consumption. Average horse eats about 15-20 lbs of hay per day. (Plus a bit of grain, occasional apples & carrots, &c). So figure that, not pushing things, you can do 200 miles in 5 days, or around 1 bale of hay. (Last week grass hay was $16.95/bale, alfalfa $15.75.) $\endgroup$ – jamesqf Mar 10 '19 at 6:06

if you could redesign an insect's shape and size to be similar to that of a small 4x4,


Square cube law. When you double the ceitter's length, its volume is increased 8x, but its surface areas are increased only 4x.

Which is why insects, with their tracheal respiratory system, can't grow past a few inches for the very largest ones. Thwy would suffocate by growing larger. Last time they were longer than a foot our atmosphere had much more oxygen in it.

If you do manage to grow an animal to be as big as a car, it won't be an insect. If you did start with an insect, the zerg you'll be making will not be an insect anymore.

  • $\begingroup$ But he mentions he builds them. A 4x4 doesnt collapse under its own weight, and all that seems to have changed is that the engine and electronics of the vehicle are replaced with a living being. $\endgroup$ – Demigan Mar 9 '19 at 14:58
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    $\begingroup$ Not just the breathing system the legs won't support its weight either. $\endgroup$ – John Mar 9 '19 at 15:14

An insect, as it is commonly defined, cannot be scaled to the size you desire. They use trachea in their respiratory system, which cannot be scaled up to much greater size unless the oxygen content of the atmosphere goes up. And even then there will be limits.

So you are probably left with a reptile or mammal, even if genetic engineering gives it tough armor. For the fuel use of those, it will be very roughly comparable to the fuel an ox or an elephant needs to travel 200 miles. One could imagine that genetic engineering improves the efficiency of the digestive system, after all the other changes that were made. It will also depend on the energy content of the food.

As a wild guess, several hundred pounds for 200 miles.

  • $\begingroup$ Since its a re-engineered insect build with modern-day materials such as metals, a trachea would be easily replaced. $\endgroup$ – Demigan Mar 9 '19 at 15:01
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    $\begingroup$ @Demigan, then it isn't an insect any more, just a GM lifeform with a small percentage of insect DNA. $\endgroup$ – o.m. Mar 9 '19 at 15:26
  • $\begingroup$ Since the question is already about a 4x4 type vehicle with a living engine, how could you assume it would be a full insect? Ofcourse this is "Just a GM lifeform with a small % of insect DNA"! I dont think that the exact knowledge of what constitutes an insect is common knowledge and that such lack should be taken into account, especially with the surrounding context. $\endgroup$ – Demigan Mar 9 '19 at 16:33


I am tired of square cube and the whole insects can't be scaled up thing. I want a 4 x 4 bug. By 4 x 4 I assume something like a Jeep. A jeep is roughly 2 x 2 x 3 meters I think. How to make a bug that big?

I was going to start with a mighty coconut crab, but instead we will start with Arthropleura the largest land dwelling invertebrate ever.


Arthropleura species ranged in length from 0.3 to 2.3 metres (0.98 to 7.55 ft)[2] and a width up to 50 centimetres (1.6 ft).[3] Arthropleura was able to grow larger than modern arthropods, partly because of the greater partial pressure of oxygen in Earth's atmosphere at that time and because of the lack of large terrestrial vertebrate predators.

As is this big bug has got the length. Now the other dimensions which we will achieve without violating the square cube law. We will put it on stilts, Opiliones style. These are the harvestmen, or daddy longlegs. They have got a lot of leg.

daddy https://www.livescience.com/24020-new-long-legged-arachnid-discovered.html

By the ruler I think that long leg is 15 cm and the body 0.5, so a leg to body ratio of 30:1. We will give our Arthropleural legs like that. The millipede body plan is better for this because the legs will presumably be supporting some weight, and so more is better.

With 2 meter body that gives us legs of 60 meters. That seems a little extreme and so to keep things sane we will take the legs back down to just 10 meters. Of course they would be as thin as human fingers. You would have something like an extreme version of one of my favorite bugs, the house centipede.

The 4x4 would have longer legs and more of them, being a millipede. Air intakes (spiracle equivalents) for the legs would help with oxidative metabolism out in the periphery.

enter image description here

Scoffer square cube fans might protest - the Arthropleura needs more oxygen than the atmosphere can provide! So your riders provide extra oxygen, which they carry in tanks.

And the question: fuel. I used a calorie calculator https://www.omnicalculator.com/sports/calories-burned. and asked about a 10kg individual (the big bug); assume 200 miles at 10 mph = 20 hours running equivalent. It needed 1420 kcal which is about a Wendy's triple cheeseburger, fries, small Frosty and Diet Coke. Acknowledged - this calculator is for humans, which might be more metabolically wasteful than a millipede. Also this calculation is without a passenger. I think it might make more sense for the big bug to pull a chariot rather than have someone sit on its back; the legs provide lots of traction but people are heavy.


It has of course already been done in science fiction, in the excellent TV series Lexx.

Lexx is a science fiction television series that follows the adventures of a group of mismatched individuals aboard the organic spacecraft Lexx. They travel through two universes and encounter planets, including a parody of the Earth. https://en.wikipedia.org/wiki/Lexx

enter image description here

Lexx is the mother-ship. It can spawn Moths for use as landing craft.

The Lexx spawns these Moth ships for use as landing craft, but they are also indispensable for travel INSIDE the Lexx. ... ... ... Mindless humanoid drones cultivate the Moths and ready them for flight... Lexx can create dozens of Moths at a time when needed, and as a last resort Lexx can actually eat the existing Moths when food is not available. https://3dwarehouse.sketchup.com/model/ce40a04ccd7616e11dd0274343216065/Moth-Ship?hl=en

enter image description here

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    $\begingroup$ Why is it organic spacecraft seem to be a TV trope almost exclusive to the antipodes (Farscape anyone)? ~ Oh! and I never realized (or at least didn't remember) the Lexx was a guitar, thanks or the pic :) $\endgroup$ – Pelinore Mar 9 '19 at 15:33

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