I have seen a lot of designs from the real world that use the basic chassis of one vehicle like say a tank or an APC/IFV to mount all sort of derivatives that barely resemble the original save for the frame that holds the tracks. And that got me thinking. So I am here to question you about my thoughts.

Could a chassis (so basic body under the hull level, tracks, suspension etc.) be designed so that it can accommodate just about anything from a light (well heavy actually) APC to an IFV and finally a MBT?

The design would be such that it would contain a standardized body with only minimal structural RHA with all the actual armor being modular and unique to the design. For example, for the tank you would put the engine in the back and add on a glacis plate whilst for an infantry carrier you would use the rear space for seating and add the engine in the front. The chassis would contain all the structural mountings for anything from 5t of armor to something like 50t of it or god knows how much you want to add on.
Naturally by add on and modular I mean factory modular and not field modular. You will still need extensive factory work to attach all the armor but its better than building a while new frame from scratch.

The drive train, so the tracks and suspension would be the same except for having two versions designed, one for front and one for rear engine placement.

The crew compartment would be the same across all models and included in this basic setup, however the equipment inside would naturally have to change. Still, the basic seating layout, fire extinguishers, cooking equipment, air conditioning etc. would all be standard.

Turrets and other accessories like sensors and gunners sights would be unique to each vehicle and not standardized. However the basic driver/commander equipment would be the same. Especially the drivers sights.

Now, I have no NSish delusions about perfect modularity and stuff like that. You won't be able to just take a raw body and slap what ever you want on it. I understand that some adjustment betwen models will be needed. However the end idea is to have one chassis cover all my armored vehicles so that I can devote only one really large factory to making these with one production line as opposed to using may production lines all tailored to different vehicles employing many times more machines and people. Than these bodies would be shipped to the individual vehicle factories for a slight refit and than a new vehicle what ever it might be would be constructed on top of them.

Do you think this is feasible? And if so, what do you think of the idea in general.

you'll find the chassis requirements for an IFV and MBT would be quite different, and the costs for making a design that meets both needs to be excessively expensive with a poorly performing end product.

you're better off using tank chassis for recovery vehicles and the like, and havin separate ifvs with matched p/w ratios and offroad/on road speeds. might be able to get away with using either or for an artillery carriage.

there are always exceptions to the rule - namely the merkava - but usually separate vehicles are a better option, especially on the NS scape.

don't take my word as gospel truth though, as always personal research is quite valuable so long as it's a valid source and you're not blind to evidence contrary to what you're looking for.

This is more or less what i have been thinking of for the last week or so

I regret not being able to shed any light on the matter

Moving engine from back to front would prolly be overcomplicated, I would leave the engine up front for all configurations to simplify matters

Moving engine is probably a no-no

That's why I noted there being two variants. In reality you would get something like Chassis Universal A built at plant A for front engine and Chassis Universal B built at plant B for rear engine with the two not being interchangeable. However they would get lumped together in the writeup since that's the only distinguishing feature.

Could you explain why?

Also, I forgot to mention an important thing. I do not subscribe to the western logic of light IFV's. My design for an infantry carrier will pack 8 men in a 50+ ton vehicle with a remote controlled turret firing a full power cannon and enough armor to shrug off anything short of an MBT killer and take on a T-72 on equal terms while the infantry dismounts to fight.

If I do make a light 10-15 ton APC this will not be used for it due to what you mentioned.

I am open enough to come and ask here. And willing to listen. So go on please.

IFVs generally hae higher internal volume requirements than do tank chassis. Consequently that usually leads to a higher deck, which means more stuf to armor. For an ifv that's fine, they aren't expected to get into protracted engagements with opposition heavy armor. but a tank doesn't need the same internal volume in the chassis; it's preferable to have a smaller lighter tank so ideally you want to minimize wasted volume since that adds to necessary armor mass.


If you are going to use a common platform, stick with a front engined design. it's pretty much the only way you'll get this to work.

closest to your requirement is btmp-80 with remote turret. but that's seats only 5, and they're jammed in like sardines.

I don't really understand. The width of the body has to be the same due to rail track and road width concerns. And Tanks are usually at 8+ meters long just like IFV's. The only thing different is the height as you said but that would not be a problem becouse the design would not actually include top armor or a top hull level. In essence, the design would be a metal box open at the top and in the front where the glacis plate should be. It would really just be a frame to hold the road wheels with a crew compartment added into it and a set of standard sensors and stuff for the driver. The front in particular would be wide open so that you can either mount a large engine and armor in front of it or a low sloped glacis plate. The box would only be as high as it needs to be for an MBT and when I want to make an IFV out of it I would extend it upward by adding an extra metal box.

I imagine this looking like an MBT but drilled out entirely so that there is nothing betwen the tracks save for the floor plates. Than a crew compartment added in the mid-front behind where the glacis should be and thats it.


Also, what kind of space do I need for infantry anyway? I figured that a 45cm wide seat should be quite enough for a man to sit in. And I don't need them stretching around inside or anything.

Edit: Link to a neat image that sort of describes it.
http://www.robotgear.com.au/Cache/Files/Pr...Wheel%20Set.jpg

They also need room for their weapons, packs, and all their gear.

That sort of design brings up serious strength concerns.


Consider for a moment which is stronger, a closed box or open box of the same height.

Also consider the geometry and configuration of the only RL design that does something similar to what you're looking for

The box would get closed eventually. It would just happen at a later stage when one choses just how high it is supposed to be.

you still get the same strength and resiliency concerns when those welded elements are put ubder the weight of armor. not only are you adding a top section but you are also adding a vertical element extension, and that's your point of failure - that's where you'll get issues with maximum weight abd structural failures.



i still say you should use exclusively front engined designs if you're gonna use an extendable design base - it gives you more freedom to work with those types of concerns with deck height and strength while lowering development costs and logistical footprint. also having the front closed off with the engine in there means you have
more structure where you have the most forces acting, making it stronger and more resilient, while improving how much armor you can use up front. you can also do some other merk tricks like using the engine and fuel as armor and such.

In that case I guess the project is scrapped. The tradeoff of a very cheap mobility kill and lack of a proper glacis plate for the MBT just ain't worth it.

Thank you for all your input.

BTMP-84 best IFV:

They also need to be able to stand (or at least stoop without needing noodle spines) and move out two-by-two in order to physically dismount.

The Israelis have done just about everything to an armored vehicle you can think of, look at what they've done to old tanks for APC/etc conversions.

Namer-Merkava is probably the most dramatic example of this. Namer would probably serve as a decent base for a slew of other conversions as well.

Of course, they turned Centurions into the Puma, Nakpadon, and Nagmachon, and T-54/T-55s into Achzarit as well. (and there's the Magach line, and the lolzy Super Sherman thing)



That said, look at Namer and Achzarit, and consider them carefully. That's what you'd probably get. Look at Merkava as well, that's what your tank would probably look like.

Well, since we are switching to the IFV design lets make this thread about that than.

My initial drawings (and yes I did do initial drawings) give me roughly 3.5 meters of internal space length vise for the infantry compartment. Given 500mm seats per user that gives me 4 seats per side and a meter and a half to spare.

That's the thing, I think you can get away with IFV conversions of Namer, though they'll be much heavier and more expensive than the IFVs you're used to seeing.

Just for the record. I am attempting to avoid anything that has anything to do with anything that has once by no fault of its own been forced to see a glimpse of anything that came from Israel.

That and I am making a thing from scratch since that lets me optimize it better for the exact conditions I am looking for.

well, they done gone and proved the validity of using an MBT chassis for an APC conversion (they just haven't bothered doing IFV/etc conversions of that chassis) so, yeah. There's your idea from the OP.

Then again, they use APCs, Tanks, IFVs, rocket carriers, etc in their army, so you might want to reconsider their inclusion in your army if you're taking that tack.

(I hear their Air Force has been using "fighters" lately too....)

I meant that more along the lines of I won't use anything that is just a carbon copy of their tech but with just a bit added on for flavor. Just like I won't copy anyone elses tech but make my own solutions.

If you recall my input on the round selection thread back in ground tech where you guys finally convinced me to go with 7.5 Swiss becouse I thought 7.62R or 7.62x51 were both too much used. Same thing applies.

If you're going with something similar to the Namer but want heavy firepower, give it an ~30mm armored RWS with the only hull penetration being the gun magazine.

BMPT-84.

Achzarit was prototyped with a 30mm unmanned turret/heavy RWS. There's a photoshop of it around, but the idea is the same. Reduced capacity by one troop if I remember.

desant on churchills

I was thinking of something more along the line of mounting an oscillating turret with a full power 100-120mm gun on accompanied by a 30mm dual feed autocanon and a 14.5 HMG for heavy support. Than a RWS with a commanders 14.5 on top for extra work.

Say hello to massive top weight, massively reduced internal capacity, and no gain over a more flexible APC/Tank pair.

Why reduced internal space? I figured that a turret is a turret.
Since this thing would basically be a tank with the glacis plate replaced by the engine (1 meter shorter at least if not more) and the back lifted it should not have that much of a space loss.

Top weight would be an issue yes. But I figure that the weight of the armor (say hello to 50 tons worth of it at least since I want this to rival a T-72 in open combat) would balance it out.

And the gain would be that my infantry platoons can take on tanks in open battle.
Although at this point I am leaning toward not issuing them to each squad but instead issuing one squad per platoon (possibly the command squad) with one of these and the other 3 with greatly up armored BMP-3 equivalents.

A turret's not just dropped on top of the turret ring, a modern turret has a whole mini-superstructure beneath it to turn and remain fixed. Especially if it uses a carousel autloader.

That's not the point of IFVs. You're thinking of tanks.

Glacias replaced by the engine? Glacias plates are not that thick, and engines are not that thin.

Really, you can be a tank or carry infantry, you can't do both.

Infantry tanks to be exact. The thing is a tank with infantry inside. The infantry dismounts and it drives around like a tank providing massive firepower to them.

Tactically speaking the closest thing to how I intend to employ this is a tank desant off a T-34.

Well yes but since this thing is designed as a tank from the start it would be provided for. My sketch leaves for 3 sections, a 1.5 meter front section for the engine and body (I think I can put the engine and some armor in a 1.5 meter long space), a 3.5 meter center section for the turret fitting and a 3.5 meter section for the passengers toping out at 8.5 meters. Also, the rounds would be stored in the rear of the turret in one of those autoloaders that feeds from the back (my brain is stuck about the name).

Bustle autoloader.
For space concerns, consider this:
http://mdswebmaster.com/UK/MDS2008/flv/new...2d4b1704821695b

Well yes but its not like this thing would be any smaller than a real tank turret. It just won't infringe on inside space any more than a real tank turret would. And I am using a hull longer than real world tanks.

won't improve over the btmp-84

also 7m rule

That rule is for gun barrel length not for hull length. Or at least I think it is.

lol

Use a Merkava, or a BMPT-84.

Thing is, I need a full load of 8 infantry and equipment inside. That is one thing I can't compromise on.

Then use an APC, or an IFV with a smaller gun.

As proven in WW2, a short 75mm gun is more then capable for what is needed, HE throwing, and you could probably mount one in a large enough vehicle with 8 dismounts.

Consider, however, how many IFVs have 8 dismounts. Very few.