Extrapolating from Modern Warfare Tactics into Interesting SF Weapons

Strain Of Thought

Active Member
Apr 15, 2009
A long time ago I came up with a robot character that I've yet to use in an actual story. I used to draw it a lot, though, and I got okay at it. Here is an old picture of it:

Strain-of-Thought's Gallery

Most of the description under the picture is outdated or irrelevant to this discussion, so don't worry about it. Just look at the picture to get a sense of the anatomy.

There are a number of things that don't work about the design, chiefly the leg joints, and recently I've been thinking about the character again and feeling like trying to redesign it, and give it a lot more detail. Which requires re-evaluating what the design is for, and a deeper understanding of the military tactics the design is supposed to exploit.

My supposition was this: Ground combatants in a hard science fiction setting on dry, lifeless, low gravity, geologically inactive celestial bodies- the most common kind- will have very limited cover. This will make it difficult to approach within striking distance of entrenched enemies, or to employ guerrilla tactics, and therefore there will be a niche for units that can conceal within minimal cover, then get out of it, approach to engagement distance, attack, and then get back into it very quickly. So, hey: man-sized frog-like jumping robots! In low gravity, they could leap over hills, presenting a small, rapidly moving target as they came into view, and depending on their armament either firing between jumps or perhaps even firing in mid-air.

I can think of several reasons this might not work, and I'd appreciate the thoughts of any armchair generals (or, if I am insanely lucky, actual military personnel on this forum) on how plausible this idea is.

The first and most obvious objection I can think of is that (man-sized) legged robots, even with major technological advances, still won't compete economically with robot tanks. The comparative effectiveness of the two weapons would depend on the relative values of armor, cover, heavier armaments, larger ammunition stocks, and the adaptability to various terrains. I have very little data for any of those points; for example, I have no idea what role cover plays in main battle tank tactics. Do tanks even try to hide behind things? For the robots to be cost effective a small, unarmored robot with minimal ammunition would have to be as effective as a much larger tank because the minimal technological sophistication needed for the leg components is going to be much higher than that needed for a simpler, much heavier wheeled or treaded vehicle.

A huge issue is terrain types. I know that tanks are ineffective in urban and mountainous environments, and one reason for this is that there is so much cover available that the tank's armor advantage is neutralized, while the tank itself is too unwieldy to take advantage of the type of cover present. But I don't know how they relate to cover in other types of terrains. I know that another reason is that there are limits even to a heavy treaded vehicle's ability to overcome the road obstacles common in urban and mountainous environments, making more maneuverable units more effective, but I don't know where the threshold for obstacle difficulty lies and I don't know how those obstacles compare to the sorts of terrains available on other celestial bodies. Boulder-strewn plains feature prominently in NASA photos but I'm suspicious that that is because NASA specifically seeks out such sites due to geological interest and that they are in fact uncommon.

There are other potential issues but I think that's enough for now. Comments appreciated; I'm very interested in hearing any thoughts you all may have.


resident pedantissimo
Staff member
Aug 10, 2005
West Sussex
It all comes down to the balance between defensive and offensive weaponry. The tank/mobile fortress cannot be concealed, so its armour must be tough enough to withstand the full force of mobile weaponry, which might well be ground to ground nuclear missiles with target seeking and recognition. Your killer frogs could be made much more fragile, but with far more evasive capability, and probably cheaper than the missiles themselves, swamping the defences. Sort of like battleships being eliminated by aircraft.

But then, how much firepower could a hopper use? Unless they were suicidal(antimatter power pack, get close to target, release containment fields) they'd be good antipersonnel, or preparation for infantry, but no big gun.

The excess complexity of the legs (not actually too major) would hardly be a problem if they are mass produced, and cheap. Spares would be universal (unless they kept upgrading the model), and, unlike the tank, losses would be acceptable, even expected.


Jul 16, 2010
Another thing to consider, when talking about the economic feasibility of a war on another planet, is the extreme cost involved in moving material from the surface of a planet into space. Because of this cost, any tank/robot would have to be either manufactured on the planet in question or would have to be extremely lightweight. Also there are a couple of video games that have played with the concept of having light weight infantry men who where able to jump in to combat using a jump pack. They were similar to having paratroopers. The fact that they could jump out of combat as quickly as they jump in would make it an excellent surprise attack weapon. Also if there target has some kind of shield, then it would likely take a great deal of power which would keep them from powering there shields all the time. That would make your robot design very valuable.


New Member
Aug 16, 2010
I agree with the above, you have to take in account the economic feasibility of a war on another planet. And transportation, ect. Unless you take the easy way out and just give them teleportation devices or some sort of warp jumps. (Don't know if this would work in a hard sf setting though, coz the detail to describe such a device would be so long)

But, another thing I must stress is the weakness of such robots when they attempt to do things other than harry and ambush the enemy. If you tried to use them in a prolonged confrontation without heavy support then they would probably be wiped out easily.

But, they sound pretty feasible since they are being used as ambushers and such. I think it would work.