Re: [FYI] World's Longest page on tracks vs wheels

>At 8:46 PM +0100 1/10/02, Oerjan Ohlson wrote:
>Kinda-sorta. The ground pressure problem hasn't disappeared 
>completely, but with centralized tyre pressure control (you can 
>adjust the pressure of each individual tyre from inside the vehicle) 
>etc. it has been reduced quite a bit for modern wheeled vehicles.

The Argies couldn't get their Armored cars to go anywhere in the 
Falklands but on the roads. Dropping the tire pressure or not. The 
Scorpions were not limited to the roads at all on the boggy terrain.

>An interesting article from Armor magazine some time ago (don't 
>remember which issue offhand, but can check): During the UN 
>operation in Macedonia, some of the US posts guarding the 
>Serbian-Macedonian border were supplied by the neighbouring Finnish 
>troops during the snowy period - because the Finnish SISU wheeled 
>APCs were able to negotiate the snow and get to the posts, while the 
>US tracked M113s either got stuck or turned into gigantic sleighs 
>(and the weather was too poor for helos to fly out to the posts) :-/

The Fins probably did something specific to get those to work in the 
cold weather and in snow. That is their environment. Likely they are 
very very light.

>>50's and 60's Armoured cars are a good comparison to the M113 given 
>>their relative common 'birth dates'.
>
>They're a good comparison to the original M113, sure. Not so sure 
>that they're a good comparison for the M113A3 or the LAV-III, both 
>of which are rather more modern :-/
>
>>>3) The gripe which gets the most attention on the page is the 
>>>claim that the LAV-III has vastly inferior protection than the 
>>>vehicle the ranter pits as its rival, the M113A3. Here he is quite 
>>>wrong, and presents an impressive array of misleading data; I hope 
>>>that he is being misled by them rather than attempting to mislead 
>>>others. Let's take a closer look at this gripe:
>>
>>I agree here. You can make a more heavily armoured Armoured Car. ie 
>>the Italain Centauro (25 Tons) and South Africa's105mm armed 
>>Rooikat AC. They aren't MBT class, but better than the M113 or the 
>>LAV for that matter.
>
>Well, yes. But my main point is that the web site author says "14mm 
>armour on the LAV and 38-44mm armour on the M113A3, therefore the 
>M113A3 is obviously vastly better protected" without realising that 
>14mm sloped high hardness steel gives a very similar level of 
>protection against small arms fire and shrapnel as 38mm vertical 
>aluminium alloy gives :-/
>
>>The maintenance issue with tracks vs wheels has come way down with 
>>the newer technology tracks.
>
>Does the latest M113s have the newest tracks, though?

United Defense is making them.

>
>>Tensioning a bunch of tracks wouldn't be so bad, but they still 
>>take a lot of work when you have to change one or replace one. I 
>>could probably change a tire on the Ferret if I had to by myself. I 
>>couldn't do a M113's track by myself. I do however wonder about how 
>>many lubrication points the M113 has vs each wheel station on the 
>>LAV. If the LAV has lots of bevel boxes, that's a lot of stuff to 
>>keep topped up.
>
>IIRC it has a central lubrication system, but that may be mere 
>hearsay so don't quote me on that. Even if it is true, I don't know 
>if it works in practise :-/
>
>>As far as mine resistance, I'd point to the South African's as 
>>experts in survivable Wheeled vehicles. The Ratel and Buffels both 
>>are very mine resistant.
>
>They are also *very* tall compared to other AFVs - their mine 
>resistance comes mainly from the boat-shaped hull (deflects the 
>blast to the side instead of absorbing it) and the high ground 
>clearance.

Which is what any mine resistant vehicle has to do. The ferrets 
aren't bad given their age and size. The slope at each wheel station 
certainly helps.

>
>Could be the front as well - it is much better sloped than the sides 
>and rear, so would give better protection against horisontal hits 
>even with the same thickness. After all, the glacis plate on an M1A2 
>Abrams is only 55mm thick ;-)

On the ferret, it is thicker to the front. On the 
Abrams...well....you go on thinking that...I suspect its likely 
thicker.

>
>Yep. You know this, I know this, but the web site author thinks that 
>the Army has gotten the "protection against 14.5mm ammo" mixed up 
>with "protection by 14mm steel" :-/ (Do you think he'd accept 
>National Defense Magazine as a more reliable source than Driver's 
>Magazine? Or would he just claim that NDM is as gullible as the rest 
>of the Army...?)

Hmm, dunno.

>
>Er... Which of the two above statements isn't going to be - the 
>entire hull being made of a single thickness of plate, or the front 
>plates being thicker?

I don't know of any armoured vehicles with the same thickness all 
around. Its far too heavy. I could see the sides, rear and top being 
that 14mm. Given my ferret is 12mm on most aspects, a 14mm side and 
rear seems reasonable for the LAV III.

>>>Armour penetration is usually measured in mm RHA, ie. the distance 
>>>which the projectile penetrates into a standard Rolled Homogenous 
>>>Armour plate with a Brinell hardness number in the 350-380 range - 
>>>I've seen several definitions :-/ The higher the number, the 
>>>harder the metal; the harder the metal, the harder a bullet has 
>>>penetrating it - very simplified, but essentially correct for the 
>>>plate thicknesses and projectile calibers we're talking about.
>>
>>*mumble about slope of the armor face*
>
>I got to the main slope effects further down in the original post 
>:-) And I *did* say that the above mention was very simplified <g>

thats why I only mumbled. :-)

>Agreed. But see the SISU vs M113 anecdote above in this post <g>

Hmm. Why the SISU would be able to get through and US HEMMTs and 
other things wouldn't is a good question. I'd like to see the 
anecdote in greater detail.

>>4. Long time history in the Inventory allows for better 
>>institutional knowledge and history. (if it ain't broke, don't fix 
>>it).
>>5. Band tracks have fixed most of the complaints against tracks.
>
>Does the M113A3 have band tracks?

They can. We're talking about a proposed purchase. They could fit 
every LAV-III with a toilet, a cooker and a fridge if they wanted 
too, but they likely won't do all of those. M-113's don't have 
cookers now, but the army is starting to field those. The same goes 
for basic automotive components like band tracks. By the time all the 
LAV's or M113A3's or what have you are in the field, United Defense 
will have fixed the Band Track problems.

>Interesting - this is the first time I've heard anyone call the M3 
>"Devers"... most scouts/ cavalrymen I've talked to refer to it as 
>the "Bradley CFV" (as opposed to the M2 Bradley IFV).

Its one of those what they called it during development.

>If it is light and air droppable, then it is fairly easy to make 
>float (floating also requires a relatively light vehicle). AFAIK the 
>Bradley is neither airdroppable nor amphibious, though - OK, they 
>used to say that it can swim, but the swim gear was withdrawn from 
>service to prevent anyone from actually trying to use it <g>

Bradleys don't swim because the whole project suffered from design 
bloat. They kept adding things to it that they went over their 
allowable weight for amphib operation.

--
Ryan Gill	  |	   |	     rmgill@mindspring.com
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