Vehicle & Technical > Military
What size of wheels do I need for a 80,000 lbs military vehicle off road?
Peter Dow:
--- Quote from: sMUDge on August 11, 2010, 01:58:36 ---Interesting project.
Go back to basics though, what will this vehicle be used for :-k Having served in all the places you mention, I see no job for it. It's too big as a fighting vehicle, no load space so not a logistics vehicle, perhaps as a Force Protection vehicle :-k
Though currently in Afghan, the Taliban seem to be shifting from IED to SRSAF, so no real use there either.
You say personnel carrier, but what formation? 18 blokes fully bombed up wouldn't fit, 10+ kit would, so a section strength vehicle, but then bin the seats in the trailer part & make that storage for the blokes kit :clap:
Looks good though mate :dance:
--- End quote ---
Thanks.
The basic idea was a MRAP-type vehicle, like the Mastiff 2 but specialised for Afghanistan. The roads are really bad in Afghanistan and those vehicles that did well in Iraq, in terms of protecting people from mines and IEDs, are struggling with the "roads" such as they are.
So it seems to me we need the same heavy-weight armour for the IEDs (and if our forces stop driving about in heavy armour the Taliban will go right back to using IEDs to get the kills) but we also need off road ability. Which means we need to look at the tyres - more tyres, maybe bigger tyres.
While I was designing for off road and stability, I thought up a few new ideas as well - telescopic rear axle - rotation about the spot - armoured trailer - remote weapons stations on the roof - and so on.
Now the fact is whether you or I see a need for the MRAPs in Afghanistan - they are using them - and rolling over, getting stuck, and that leaves them vulnerable. So we need better vehicles.
Maybe something more like the Stryker would be better for getting around in Afghanistan - it already has got loads of wheels?
Well as for room for kit as well, take the Mastiff 2, advertised as 2 crew + 8 passengers. Like 8 soldiers plus kit do you reckon? Or do they have to put all their kit in another truck?
The HUMPBAC tries to make more room for passengers by extending the driver cabin over the front axle in a "Cab over" configuration.
So I think 11 is fair for the front section and 7 for the trailer, based on the size of the Mastiff 2 anyway.
How much kit does an infantry man need - "fully bombed up" as you put it?
The thing is advertising the HUMPBAC concept as only 10 plus kit they will wonder how come you have a bigger vehicle but can't carry more?
Plus anyway I need to keep at least one guy in the trailer to operate the tail gun.
Peter Dow:
--- Quote from: dxmedia on August 11, 2010, 09:43:59 ---20" rims with probably 44" tyres (12.00's (12.00r20) are common millitary size)
I say that cus I've got a set at the bottom of the garden ;)
The millitary stick to generally the same wheel and tyre size so that they can be interchanged between vehicles in case of issues.
--- End quote ---
Thanks . With your clue I found a manufacturers data sheet for tyres - Continental.
The 12.00 R 20 they say is 1122 mm or 44.2 inches outer (diameter?) which has a maximum load 8,000 Kg per axle.
They also do a 14.00 R 20 (has a "MIL" pattern code) 1238 or 48.7 inches which has a maximum load of 10,000 Kg per axle.
You can also get about double those values if you use a double tyre fitment, which must be 4 tyres per axle instead of just the two.
So it looks like you can get more out of the 14.00 R 20 and maybe that is quite a common military size too?
Peter Dow:
--- Quote from: Grumpy on August 11, 2010, 11:10:00 ---Your gonna need more wheels it's going to ground it's self quite easily
--- End quote ---
Thanks for the tip. This is what I feared.
What do you mean ground? Do you mean get stuck? Well that is what I am asking about off road.
You see the load is one thing.
80,000 lbs is 36287 Kgs. So that is actually too much for 3 axles even using the biiger 14.00 R 20 tyres, unless I was to use double tyre fitment - not sure how easy that is for wheels that steer - seen it on rear drive wheels.
So I am thinking more of 5 axles now, 3 on the front vehicle and 2 on the trailer, just for the load.
5 axles even at 8,000 Kg per axle for the 12.00 R 20 tyre that would take the load up to a maximum of 40,000 Kg - more than the HUMPBAC needs.
So 5 axles looks better for the load.
But what I am really wondering is how much weight can you put on a soft off road surface per axle or per wheel?
When the tyre company says "8000 Kg" per axle, that is on a road. If you are in mud the tyre would be fine, it would just bog down and you would get stuck, right?
So come on, you guys are the experts on mud and off road. How much weight could you put on a 12.00 R 20 on mud or sand or dirt or whatever and still drive OK?
I suppose it depends on the mud, on the sand or the dirt - how wet it is, how loose and so on? Can you give me an estimate?
dxmedia:
--- Quote from: Peter Dow on August 11, 2010, 14:39:13 ---
--- Quote from: dxmedia on August 11, 2010, 09:43:59 ---20" rims with probably 44" tyres (12.00's (12.00r20) are common millitary size)
I say that cus I've got a set at the bottom of the garden ;)
The millitary stick to generally the same wheel and tyre size so that they can be interchanged between vehicles in case of issues.
--- End quote ---
Thanks . With your clue I found a manufacturers data sheet for tyres - Continental.
The 12.00 R 20 they say is 1122 mm or 44.2 inches outer (diameter?) which has a maximum load 8,000 Kg per axle.
They also do a 14.00 R 20 (has a "MIL" pattern code) 1238 or 48.7 inches which has a maximum load of 10,000 Kg per axle.
You can also get about double those values if you use a double tyre fitment, which must be 4 tyres per axle instead of just the two.
So it looks like you can get more out of the 14.00 R 20 and maybe that is quite a common military size too?
--- End quote ---
Close but no cigar ;)
For twin tyres think of about 1.5X the stamped weight rather than 2X, think it's to do with how the side walls buldge when they are inflated and under load - and to stop the bulges touching (causes heat and blow outs).
If I can be arsed later - I've some G388's which are commercial offroad spec tyres, I'll have a look at what's on the sidewall of them for a comparison to the continentals - they are goodyears.
Grumpy:
At present your vehicle could not go over a hump as the chassis would rest on the hump between the wheels and ground itself and result in loss of traction to the driving wheels and would be a sitting duck , shorten the vehicle or add more wheels, simples!
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