"Do wheeled tanks make sense (as opposed to tracked)?" Topic

I know nothing about the physics or the engineering side of things, but of late I've seen a lot of wheeled vehicles that I really like the look of. However I can't shake some lingering sense that having tires is somehow less useful than tracks.

Either something to do with weight distribution or vulnerability or mobility or something. Is that true, or are there examples or principles that suggest that wheeled tanks would make some sense.

And I mean tanks proper. Basically if you took whatever you wanted to be the baseline tracked tank in your sci-fi world, would there be a reason to build the thing with wheels instead of tracks?

IIRC wheels do offer some advantages: speed, range (costs less fuel to turn them…), ease of maintenance, cheaper to run logistically, typically more quiet. But there are disadvantages: mobility (even with 8 wheels there is IIRC less ground contact compared to tracks), vulnerability to combat damage are two big ones. So the best thing to do is develop a role that concentrates the advantages while limiting the disadvantages. This is why you see wheeled vehicles more often in light vehicles, like scouts, APCs and occasionally tank destroyers, but not in MBTs or other "heavy" forces.

Damon.

Tanks with wheels are not new. They do make sense. With combat urbanizing more and more eventually the need for open country tracks will diminish… until we fight it out on the Moon or the swamps of Venus.

The Italians seem to think so:

link

I like it, and their IFV.

I imagine over 50%, or so of the terrain they are intended for, they'll work fine, since the ground is probably packed hard, there are roads, etc.

Cross-country, in boggy, soft terrain, they'll be in trouble.

Given the road networks in most countries though, it's probably not as big an issue as it was back in WWII.

Mako – the Italians have the C1 Ariete as their heavy armor. The Centauro is a "tank destroyer" with the main gun equal to the Leo 1. However, the armor is only good against 14mm rounds on the sides and 25mm rounds at the front. That means it could go up against infantry and buildings but if there's a tank involved, it will be in serious trouble unless it hits first.

In short, it's a MOWAG Piranha or LAV-25 on steroids, but the engine is constantly breaking down so you're going out with the expectation that you'll be hauling one or more vehicles back to base by mission end.

Wyatt

They're also not as hard on the roads as tracked vehicles generally are, although that's partly because many rollers tend to weigh quite a bit less to begin with. That's a factor to think about if you expect to be driving around wrecking your infrastructure rather than doing your fighting on the other guy's highways.

In an SF context, and depending on your economic, technological and space-transport parameters, so assuming some degree of economic isolation: Any planet with a wheeled heavy equipment industry will find it cheaper to re-purpose wheeled chassis than to develop a tracked vehicle industry. For tracks to pay off, you need a lot of sustained, symmetric wars with enemies who could bring tracks (and heavy armor) to the table.

As far as vulnerability, IIRC the Saladin (for all practical purposes, a wheeled light tank) was supposed to be able to run with three of its six wheels disabled/destroyed so long as at least one on each side was still working.

A single track link breaks or you throw one and a tank is a pillbox with potentially hours of backbreaking work to get the thing fixed.

Tanks require a lot more maintenance hours per hour, are a lot less fuel efficient, chew up the landscape and are noisier (as has been pointed out)

That said, tracks have it all on ground pressure and overall load carrying capacity. You are going to have to work really hard to get a viable wheeled drive-train for a 60 ton AFV.

Tracks are appallingly expensive to maintain. So much so that the military routinely puts tracked vehicles on tractors or trains to transport as little as 100 miles.

And tracks demolish asphalt roads in a hurry.

Therein lies the prime reason for not being totally invested in tracks.

When I was riding Amtracs in the USMC, I recall we had regular dog-and-pony shows to drum up support for changing the suspension system. They told us to remind the general that it was costing approximately $1 USDMillion per year to maintain the vehicles, which at the time were just shy of their 30th birthday.

Note: they are still in use today! And the original MSRP was about $1 USDMillion a piece!

The answer is still 'no.' Tanks are for the open country where their advantages over wheeled vehicles are clear: better mobility over rugged terrain, less susceptible to be bogged down, etc. Tanks are not ideal for urban warfare where they are vulnerable to close quarter ambush. Wheeled vehicles like the Stryker are better suited for that.

Isn't part of the appeal of wheeled vehicle also the weight involved? A similar vehicle is lighter with a wheeled chassis as opposed to a tracked vehicle. This become important today due to the desire for airlifted armor.

I imagine in scifi all the things that make wheeled vehicles appealing today might be even more important.

1) Lighter means less weight in payloads.

2) Simpler to maintain means easier to find parts and effect repairs on colony worlds.

3) Less damaging to infrastructure – an even bigger deal when the nearest supply of building materials might be light years away.

-Eli

Great, thanks for the thoughts folks. Lots and lots of things I hadn't thought about.

Seems like wheeled vehicles would make SOME sense at least for a somewhat industrialised colony world that's trying to break away from the motherworld. Civilian factories can switch to wheeled production faster, assuming they lack a heavy metals industry then their doctrine might form around lighter, faster vehicles.

I'm thinking you could (with the usual suspensions of disbelief) have a colony purposed around extracting unobtanium on a deeply hostile planet. Around the unobtanium mines/nodes/forests/whatever grow vast domed cities, which produce their own underground food but, until recently, relied on water from the mother world. Say they recently developed ice-extraction from their giant moon, on which they also used wheeled vehicles.

Perhaps, as they revolt, their doctrine comes to form around lighter vehicles that don't cause as much infrastructure damage in their megacities, can be transported by air between the cities/moon more easily, and are easier to maintain and fuel up.

Heck, maybe the terrain outside the domed cities is generally hard-packed ground for whatever astronomical reason, and unobtanium might be a super metal, though I'm more inclined to posit it as a fuel source or some sort of growing crystal stuff used in electronics.

Or am I stretching plausibility WAY too far? I'm certainly more a space opera type than a physics type, to be sure, and at the end of the day there's just a lot of wheeled vehicles that look cool, but I'd like to pretend I could offer at least a couple of reasons for them.

A tracked vehicle can almost always get off the road,except in some extreme Terrain. Roads mean ambushes and mines. If your vehicle cant leave the road in an ambush you are dead. If you cant leave the road to get around the big hole in the road from a mine, you are stuck.

In Afghanistan they found out that those 6 and 8 wheeled armored vehicles got stuck all the time and needed a tracked vehicle to unstuck them. Also a tank works really well against insurgents too. A 120mm round does wonders on a wall that even a .50 bounces off. Most convoys that have a tank along are not attacked.

Yeah its nice to cruise down a road, but it is even nicer to be able to get off the road and outflank your enemy.

Consider also the recoil on a large piece of ordenance. Firing a cannon on a 20 ton armoured vehicle is different then on a 60 ton vehicle. A 120mm gun rocks a 70 ton M1A2. Even if you could somehow mount a gun that large on a Stryker, what happens when you fire it over the side of the vehicle? There is a reason you mount big guns on big vehicles.

Aren't there tanks that have the ability to drive without their tracks (as a result of having driven road wheels rather than a driver sprocket)?

I swear there was a Russian APC/IFV that could operate with or without tracks.

If that was the case, you could take the tracks off for delivering the vehicle to where it was needed and then 'simply' fit the tracks when it gets there.

Best of both worlds.

In (IIRC)Robert Frezza's 'Small Colonial war' trilogy, they used wheeled AFVs, (some with autocannon, some with heavier weapons) and there was a comment to the effect that for 'colonial war', a platoon of these had the same transport and logistic 'footprint' as a single tank, very important when your logistic train extends light-years.

There hasn't been a tank with driven roadwheels in a while. Since Christie's designs of the 1930s, IIRC.

The SdKfz 254 had deployable roadwheels, but was really a tracked vehicle.

The new Strykers may finally equal the offroad capabilities of the Abrams/Bradley family. The new strykers are hybrids, pushing 600+hp onto the ground. It gives them a power:weight as good as or better than the tracks, and central tire inflation lets you decrease your ground pressure if you need to.

One small trench and the wheeled vehicle comes to halt.

Tanks proper? No wheels. Tanks have to be heavy as possible (to allow for LOTS of armor), in order to be heavy and still move you need to distribute the ground pressure as much as possible, so tracks are a requirement over wheels.

Light armored vehicles can use wheels, and perhaps that will be the future of armor, but they are not tanks in the strictest sense.

Tanks are for the open country where their advantages over wheeled vehicles are clear: better mobility over rugged terrain, less susceptible to be bogged down, etc.

So I guess that's why all commercial ATVs are tracked, because wheels just can't manage it.

Light armored vehicles can use wheels, and perhaps that will be the future of armor, but they are not tanks in the strictest sense.

Depends on how you are setting your definition. If you make the definition to be "a tracked vehicle with heavy armour" then the answer is no, they are not tanks, but that definition rather begs the question.

However, if you set your definition as "a well-defended vehicle with good cross country mobility that is capable of tactical offensive operations, the answer is yes, a wheeled vehicle can be a tank.

Even today there are wheeled military vehicles with very good cross country mobility. It's also true of course that wheeled vehicles can be heavily armoured, the G6 currently deployed today in the South African military weighs over 46 tons and with six wheels has very good cross country mobility. Part of the weight is of course the big howitzer but it is also heavily armoured to defend itself from counterbattery fire and direct fire as well, in case the units are exposed to direct enemy action.

In the future defence may be a matter of fields or active defences rather than armour, so weight may not be as much of a consideration.

To conduct tactically offensive military operations the vehicle has to be able to advance and acquire targets without changing direction, so it must have a turret or some other multi-directional weapon. (This of course is why the German turretless vehicles of WWII were not designated as panzers. They were very effective when used defensively, their designed role, but when they were emplyed as tanks they fared poorly.)

Vulnerability of drive train is also a wash, more or less. In fact, the MRAPs developed recently probably have better mobility than a tank once they suffer a mobility attack, not worse. They were designed to take a hit and drive on a blown tyre, and often did so in fact. In a tank takes a mobility it is immobilized.

So the answer in this, as in all things, is, it depends.

Generally tracked vehicles have better cross-country, off-road capabilities than wheeled. As has been already mentioned. And after serving active duty in 3 Mech Bns and commanding an M113 Mech Co. ('87-'89), and being attached to an M60 Tank Bn … I can truely say tracked AFVs require a lot more maintenance that anything with wheels. Something also to consider, when Tanks first came about in WWII to now, generally there are more urban areas and roads today then in 1916 … Especially in the 3rd World … However, there is still a lot of desert out there, as well as jungle and forests. And we know from a tactical standpoint deserts allow you much more maneuver space than in jungle. Ran operations in both as well as Europe and Korea … And again, in general, you'll use roads when available if for no other reason then speed … until you close with the enemy and get into combat formations …

One small trench and the wheeled vehicle comes to halt.

Depends on whether you're talking about a 4x4 or an 8-wheeler.

I don't think the LAV25 particularly notices trenches less than 1.5m wide, for example.

And if you're talking about replacing serious tanks, well, you need at least 8 wheels if not 10 or 12.

@ Guests:
Since you are thinking about an SF setting, has the culture of that future developed "Gravitic" technology (a.k.a. anti-gravity devices). If so, then maybe "tanks" would have gravitic device aboard that would negate the need for "external" propulsion and suspension systems. The downfall of that is that if the gravitic systems were KO then the whole vehicle comes to a crashing halt. Additionally, a gravitic technology would require very specialized maintentance depending on deeply technical you wanted to make this "Science Fantasy" technology.

Just a thought.

Andy Welkley
"Your Phrendlee Hevy Phyzx T-chrr"

The wheel vs track question doesn't need to be either or. The BT series of Russian fast cavalry tank could run on tracks on rough ground. Then, they could quickly remove the tracks and run on the tires on roads.

en.wikipedia.org/wiki/BT_tank

link

right back to the Half track Idea :) best of both worlds, and you can have a mix of 2 to 8 driven wheels + a tracked drive

I guess it also depends upon your world, or moon too, e.g. its gravity.

A low-grav world, or moon will present less of an issue for wheeled vehicles, since they'll be relatively lighter, so less likely to bog down.

Therefore, you can add more armor on them too, without worrying about it too much.

I think Lion in the Stars has a point about the number of wheels. A 70 tonne main battle tank with (say) 14 double wheel axles (7 each side – around the same number of wheels/cogs as on most MBTs) would have 28 tyres on the road. If they are all driven (say, electric transmission to each wheel) that's:

A) a lot of rubber and drive/traction on the road;

B) a lot of redundancy to get shot off (see comments on Saladin) and

C) only just over a tonne per wheel and less than three tonnes per axle. Which is probably less than a Striker.

Also – if they are skid steered like a tracked vehicle (see Argocats) – the wheels can have a very secure attachment to the body and be fitted with close armour covering the top half of them (like they do currently on a tracked vehicle) as they don't need to swing out to turn the vehicle.

Team that with the no-inflation, honeycombe rubber tyres recently mentioned on a seperate TMP thread that I can't find at he moment and they would wear out tarmac an awful lot less and probably be quiet(er) and still more reliable/fuel efficient.

I think it could work.

John T

Alright – over 2 tonnes per wheel – so I can't count! – About the same as a Styker (16 odd tonnes and eight wheels)

John T

John mentioned something that I was going to bring up, the honeycomb tires.

Those tires can be made out of a metal-rubber mix, and they tend to distribute ground pressure far better than current tires (they are around 24" wide is one reason).

They are also harder to damage than regular tires.

And putting 14 to 16 of them on a MBT coud see a workable alternative.

But something that the tires still won't do is to travers a lot of terrain where tracks are needed.

But there is a solution to this as well.

The rubber-track.

Several different varieties of rubber-tracks have been in development.

They allow for tracked vehicles to use roads without destroying them, and they allow for the robust all-terrain capabilities that tracks offer.

Plus, they are many hundreds of pounds lighter than metal-tracks, and a tank can carry a pair of spare tracks that can be changed by the crew if one is broken (They also have splicing kits that are like giant staplers).

The Rubber Tracks also are made to go over driven road-wheels, so that even if the track is broken, the tank can still move.

Once you get 14 tires on something, well you should have just gone with tracks in the first place. The cost is going to be about the same and the mechanical complexity is probably worse if all the wheels are powered (and if they are not then they are not much use).

Once you get 14 tires on something, well you should have just gone with tracks in the first place.

Don't most tank wheels have rubber tyres on them? Solid ones, I mean? The all wheel drive might be an issue but not if it's electric, I think (esentially the main engine (say a turbine) then becomes a constant velocity electrical generator. The lack of strain on it means that it can be more reliable and the power stored in batteries and then fed to the individual drive hubs.

John T

Yes, they are solid rubber, called road wheels. Improves the ride, needs less maintenance then steel road wheels, even lowers the noise signature a little bit …

Dynaman doesn't that then suggest 18 wheeler tractor trailers should be tracked? Not a very efficient way to haul things around.

I think it's more about purpose and function, it's almost similar to our debate about the idea of hover tanks. For most combat wheeled vehicles are probably more useful and functional and tracks become more of a support platform offering heavier armor and firepower in modern engagements. But when you have infantry armed with weapons that can take out the tanks why risk losing a more expensive vehicle when you got the cheaper cannon fodder vehicles for the enemy to shoot at first.

The track tanks excel at one purpose really, assaults. Backed up with infantry they take positions, but are kind of useless at holding them, that whole easy to ambush thing is a problem. This is where the wheeled AFV come back into play.

An old simple military saying, " Armor seizes, Artillery destroys, Infantry holds … "

Dynaman doesn't that then suggest 18 wheeler tractor trailers should be tracked? Not a very efficient way to haul things around.

Completely different function. Tractor trailer rigs move cargo over improved roads, and the wheels are there for load capacity. Also, they are 2-3x as long as a tank.

For a tank to do all terrain, all (or at least) most of the wheels need to be powered, and several (more than just 2) would need to be steerable. I can't see that you could just reverse wheel driections and steer it like a treaded tank – you'd tear off the wheels at either end for sure.

Of course, as part of historical accuracy and national pride ( :D) I should point out the hybrid vehicles called 'Self-deploying" tanks.

In WW2, the General motors NZ engineer Mr. Schofield came up with an idea to build inexpensive armoured vehicles that could operate on roads as well as wheeled ones, with the ability to have tracked mobility rapidly. He developed the Schofield Tank and two other prtotypes, which were eventually sent to Britain for evaluation; they were impressive vehicles for the time, and the British army was in fact impressed. ( Illustrated here YouTube link )

Sadly, the evaluation took too long; They were never built as American tanks were too plentiful and the war was drawing to a close at that point in any event. Still, they *did* function and so they are a consideration.

Once you get 14 tires on something, well you should have just gone with tracks in the first place. The cost is going to be about the same and the mechanical complexity is probably worse if all the wheels are powered (and if they are not then they are not much use).

Depends on what your driveline system is. If it's mechanical, then, yeah, complexity goes up. If it's an electric motor in each wheel hub, then you're basically just bolting another box onto the chassis and running power and possibly air for the CTI system to it.

The US Army is getting all over series-hybrid designs (like railroad locomotives use) with wheel-hub motors.

The initial LAV-25s had 300 horsepower. Strykers got a bigger engine and are close to 550 or 600 horsepower. If you went to a series-hybrid design, you could have a Stryker with 1200 horsepower delivered to the ground.

They make sense in my games because they look so cool.

Tee hee – they make sense because nine out of ten wargamers don't use muddy terrain or soft ground or ditches on anything like the same frequency as they occur in real life!

What about wheeled vehicles like the crawlers from the movie 'Soldier'?

Considering that those started life as open-pit MINING dumptrucks, they aren't really fast. They're just about unstoppable, though, because of the huge tires and insane approach angles.