The catamaran tank - an MRAP which doesn't roll over

[Peter Dow]

MRAP (armored vehicle)

Mine Resistant Ambush Protected (MRAP) vehicles are a family of armored fighting vehicles designed to survive IED attacks and ambushes. IEDs cause the majority (63%) of US deaths in Iraq.
...
A June 13 report by the Marine Corps Center for Lessons Learned indicated concerns about MRAP vehicles rolling over in combat zones.

The V-shaped hulls of the MRAP give it a higher center of gravity and the weight of the MRAP can cause the poorly built or maintained roads in rural Iraq or Afghanistan to collapse.

Of the 66 MRAP accidents between Nov. 7, 2007 and June 8, 2008, almost 40 were due to rollovers caused by bad roads, weak bridges, or driver error.

In many of the rollovers troops were injured, and in two separate incidents five soldiers have been killed by rolling over into a canal and getting trapped under water. The report said 75% of all rollovers occurred in rural areas often when the road is above grade and a ditch or canal full of water is next to it.

OK so that is the problem and there is an obvious vehicle modification to counter the roll-over problem which is to fit stabilisers, adopting the same concept employed in a child's bicycle.

[PLAIN]http://img3.imageshack.us/img3/3770/stabilisedmrap.jpg

The simplest and cheapest way to do this would be have bolt on stabilisers which could be partially unbolted to fold up when not required while driving on good flat roads but where the additional width of the stabilisers would cause problems, such as when traveling along narrow roads, needing to negotiate dense traffic such as in urban roads.

The high-tech and expensive solution would be stabilisers which fold-up or deploy automatically using hydraulics at the touch of a driver's button.

However, when you compare the expense of a good solution to the expense of lives lost by MRAP rollovers then it is a small price to pay.

OK that idea is adapting the existing MRAPs but here is an idea for a completely new design of MRAP.

The catamaran tank - an MRAP which doesn't roll over!

[URL]http://www.visailing.com/newsletter/charter-chatter/issue-5/yacht-charters-images/bareboat-catamaran.jpg[/URL]
A catamaran - the inspiration for a twin-hulled armoured vehicle

The catamaran tank or catamaran MRAP or catamaran armoured vehicle or catamaran armored vehicle - you heard it here first!

One idea I have for a completely new design to counter ground-blasts yet retain stability would be a double-hull or catamaran tank.

To explain, let us describe most simply the current MRAP vehicle design as an M-shape, looking at the vehicle from the front or the rear, with a high middle, and a V-shaped hull, armoured to deflect the blasts.

Well the concept of the catamaran tank is to replace the M-shape with something more like a Y''Y-shape which is a lot wider for stability and so may not be so good in narrow streets or traffic admittedly.

The central double quotes in the Y"Y-shape represents a line of strong blast-chimneys up through the middle of the vehicle, from front to rear, which some of the blast could go up without splitting the vehicle in two.

This twin-hull, double-hull MRAP would give two distinct cabins on the left and right of the vehicle and however high you need the vehicle to get distance from a ground blast then make the Ys bigger and so further apart which keeps stability.

The leg of the Ys could have blast ventilation holes so that blast gas under the vehicle can escape to the sides as well as up the central chimneys. The more ways the blast gas can escape from under the vehicle the less force the blast will apply against the vehicle itself.

The bottom of the Ys could be either wheels or tracks depending on what ground conditions you are designing the vehicle for and need to cope with.

This dear forum members is the catamaran tank - my idea and you heard it here first. Copyright © Peter Dow, 26th July, 2010.

 

[Skrambles]

Tanks with training wheels? I'm not sure if I should laugh or cry, but the hand drawn pic next to the pink bicycle is pure genius.

All I can say is that if a tank had training wheels, a banana seat, and pink streamers, I would still want to drive it.

 

[DaveC426913]

All I can say is that if a tank had training wheels, a banana seat, and pink streamers, I would still want to drive it.

:Whips out Photoshop:

 

[mgb_phys]

SUVs are built like tanks, SUVs roll over, therefore tanks roll over.
Now if you had the tanks built by porsche...

 

[Peter Dow]

Considering the wheeled version of the catamaran tank only for now.

Maybe the left and right sides while separated are 4 wheeled vehicles which you can drive independently, call those "half-vehicles" Y-sides.

The Y-sides are tall and narrow and even less stable than an MRAP while separated but loading and unloading on and off transport and manoeuvring the sides in position to connect together the stability is sufficient.

Then, when you come to bolt the two Y-sides together there are a number of choices as to how wide apart the left and right hand Y-sides are fixed.

I'll type in some figures so you can see what I mean.

Say, the separated Y-sides are 4 feet wide.

Well for example, the connecting bars or tubes could hold the left and rights Y-sides together separated by these example widths:

• 1 foot, Y1Y so the total width is 4 + 1 + 4 = 9 feet - no wider than a Cougar MRAP and so as stable as todays MRAPs and narrow enough for urban roads and traffic.
  
• 4 feet, Y4Y so the total width is 4 + 4 + 4 = 12 feet, the same as an M1 battle tank, good for country roads, stable but narrow enough to get across most bridges no problem.
  
• 8 feet, Y8Y so the total width is 4 + 8 + 4 = 16 feet, super-stable for open cross country off road where the extra width is no problem for crossing bridges or fitting on roads because there are no roads maybe nothing more than a dirt track of uncertain width itself, maybe nothing but rough ground and rivers need to be forded or not crossed at all and then the extra stability is purely a bonus with no disadvantage of extra width.

The vehicle could even carry the different lengths of connecting bars or tubes for the crew to swap round to change vehicle width which they can do themselves anywhere they can find a flat piece of ground - no special facilities required.

[PLAIN]http://img199.imageshack.us/img199/2750/connectingbars.jpg

When you change configuration you are changing the connecting bars between the two Y-side vehicles.

So the mechanic or the trained crew would

• unbolt and remove the connecting bars you want to change
• drive one of the Y-sides to about the right new position for the new bars
• attach the bars and tighten them up to bring the Y-sides to the right distance apart.

The deluxe version could have a hydraulic telescoping connecting tubes to change vehicle width at the touch of a button!

When the two Y-sides are connected together, the steering mechanisms of the two Y-sides are mechanically coupled together, somehow! There could be power steering as well!

The catamaran tank still has V-shaped hulls to deflect the blast. It just has 2 V-shaped hulls, each of half the width of a single V-shaped hull.

The catamaran tank can have the same total area of V-shaped hull measured in the horizontal plane as a single-hulled MRAP!

For the same area in the horizontal plane, the hulls of the catamaran tank and the MRAP have quite similar surface areas and weights.

[PLAIN]http://img696.imageshack.us/img696/4210/catamarantank.jpg

To lessen the blast forces tending to split the two V-shaped hulls apart, the Vs can be angled slightly to form a vertical blast chimney.

[PLAIN]http://img186.imageshack.us/img186/3058/verticalblastchimney.jpg

There is not much more area for the explosive force to react with in the catamaran tank because the space between the two hulls is mostly empty space with just connecting bars or tubes!

The benefit is this - it doesn't roll over!

The catamaran tank - an MRAP which doesn't roll over!

 

[Peter Dow]

For the same area in the horizontal plane, the hulls of the catamaran tank and the MRAP have quite similar surface areas and weights.

...

To lessen the blast forces tending to split the two V-shaped hulls apart, the Vs can be angled slightly to form a vertical blast chimney.

Just to be clear, these two are mutually exclusive options. You can have one or the other but not both.

I am going with the vertical blast chimney which means the catamaran twin-hull design I propose does increase somewhat the total area and weight of the hull armour for the same protected area in the horizontal plane.

MRAP luggage compartments / trailers / passenger trailers

MRAP luggage compartments / trailers / passenger trailers are something I want to feature in my new design.

It isn't really a "catamaran" feature particularly because a mono-hull MRAP could have a luggage compartment, outside the armour-protected volume and trailers are already available for today's MRAPs. A trailer is a trailer, right?

But I hear complaints from many sources about passenger cabins not being spacious, can't afford to make them smaller and so on.

The thing is, if you always put the gear the troops are carrying (heavy guns and ammunition etc.) in a trailer it saves space in the passenger cabin right?

So then the armoured passenger cabins could be made smaller, and the gear stored in a non-armoured volume, either a luggage compartment - a boot or a trunk which can be low, lowering centre of gravity, or in a trailer, which also takes the weight off the MRAP wheels which helps to prevent road collapse.

So for all kinds of reasons I am thinking that pulling a luggage trailer and a non-armoured boot/trunk should be integral to a good MRAP design, not just an optional extra.

So why don't MRAPs use trailers more, when road collapse, heavy weight on the wheels is such a problem?

I know that to use or not to use a trailer is an operation decision that the military make but if anyone knew if trailers were a bad idea for some reason, then would you please point that out.

OK for existing MRAPs (some of which don't have a fixed gun) I can see why the passengers want to keep their weapons with them so that they can dismount guns blazing.

Frankly, a "no fixed gun" APC is a really bad design in my opinion. Even one gun is too little in my opinion.

Defence against ambush is why you need fixed guns on every APC roof.

My design would include a minimum of one gun on each side of the catamaran MRAP.

Actually, I would like 4 guns on top; that is possible and if you read on I will explain how.

Only the guns and video cameras (2 per gun, one wide-angle, the other telescopic sights) need to be on the roof. There is no need for a gunner up top in a gunner's turret with all the high up weight and instability that causes.

The gunner can be sat in the cabin with the rest of the crew and fire and aim the gun from below.

Think of a submarine periscope in terms of turning and aiming the gun, although the gunner would remain seated in one position if he (or she) views the gun camera views on a LCD display. Push buttons to change camera view and push button to fire.

For reloading "the periscope" can come down to allow the gunner to reach the gun to reload in safety.

2 or 4 guns, medium machine guns can be up top and because there is no armour up there, it could work out with a lower centre of gravity than one gunner with an armoured turret.

Of course an armoured passenger trailer would have guns of its own as well.

There is no reason why passengers cannot always carry a handgun which takes up no space. That and cover from fixed guns should be sufficient I would have thought.

Sure I could imagine a scenario when you'd really like to fire a guided missile the second you open the passenger door.

Well you still could do that and carry weapons inside in a smaller cabin if you were not carrying a full load of passengers.

MRAP armoured passenger trailers

In fact, why not have an armoured trailer with a V-shaped hull (or two V-shaped hulls for a catamaran trailer) and carry some of the passengers there?

Then you could really reduce the weight of the MRAP - a much smaller front cabin, much less volume needing protecting in the front vehicle, spreading the weight across more wheels.

I think the armoured passenger trailer idea is a winner, catamaran or no catamaran and it is a concern that existing MRAPs don't use this concept already.

 

[Mech_Engineer]

I think you need to nail down your ideas further before you post them; this whole stream-of-consciousness design process is very annoying.

In short, I think your "catamaran MRAP" idea is poorly conceived, and has far too many detriments to make it a viable alternative to the current MRAP's.

 

[Peter Dow]

[PLAIN]http://img168.imageshack.us/img168/1212/catamaranvehicle640.jpg
Conjoined All-Terrain Anti-Mine Ambush Repellent Armoured Next-generation (CATAMARAN) Vehicle
© Peter Dow
The CATAMARAN vehicle concept is the original idea of Peter Dow of Aberdeen, Scotland and was published on 26th July 2010. All copyrights are retained by Peter Dow.

http://scot.tk/forum/viewtopic.php?t=496"

 

[Mech_Engineer]

Conjoined All-Terrain Anti-Mine Ambush Repellent Armoured Next-generation (CATAMARAN) Vehicle
© Peter Dow
The CATAMARAN vehicle concept is the original idea of Peter Dow of Aberdeen, Scotland and was published on 26th July 2010. All copyrights are retained by Peter Dow.

Claiming "copyright" over your pictures/concepts is both pointless and redundant. If you want to retain rights to the concept you have to apply for a patent; if you want to retain rights to the name you need to register for a trademark. Copyright is implicit in any work you personally make, and only gives you the right to retain ownership of the pictures/sketches/designs you've personally made of your concept, but it doesn't prevent someone from using your idea to design and market their own version of it. They can even use the same name/acronym, it can even look EXACTLY the same, as long as they didn't use/modify any of your original work to do it.

By the way I'm curious- who owns the copyright to the picture of the MRAP and turrets you used in the somewhat hideous poster you made? I'm betting you didn't take the picture yourself...

Read these:

Copyright - "Copyright is the set of exclusive rights granted to the author or creator of an original work, including the right to copy, distribute and adapt the work."
http://en.wikipedia.org/wiki/Copyright

Trademark - "A trademark or trade mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or services from those of other entities.
http://en.wikipedia.org/wiki/Trademark

Patent - "A patent is a set of exclusive rights granted by a state (national government) to an inventor or their assignee for a limited period of time in exchange for a public disclosure of an invention."
http://en.wikipedia.org/wiki/Patent

Keep in mind as well that it falls upon the owner of the patent/trademark to defend that patent/trademark. If someone infringes on your patent (can be very difficult and costly to prove, less so for a trademark I suppose) it is your responsibility to bring a civil lawsuit against them (you'll have to pay for the lawsuit); the government that granted you the patent/trademark will not act on your behalf to defend them.

 

[Mech_Engineer]

Now that I've got the legal stuff out of the way, there's the topic of insurmountable technical flaws in your design:

• TOO WIDE. It won't fit on smaller caro planes standard MRAP's and HMMWV's do, and they'll take up too much precious cargo space for their usefulness. Won't fit down city streets, won't be able to navigate through trees or forests, won't won't won't.
• The turning radius and overall maneuvability will be completely atrocious due to the width/length ratio and number of wheels you have.
• You would need two synchronized powerplants (one for each "outrigger") to drive all of the wheels equally, ruling out the possibliity of a simple diesel engine with mechanical drivetrain. More complexity, more cost, less usefulness.
• Your concept is flawed because although the center is mine-resistant (because nothing's there!) the "outriggers" will be logical targets and need to be mine hardened in the method standard MRAP's are anyway; completely negating the usefulness of your twin-hulled concept.
• Huge remote-controlled turrets at the corners?! Too much complexity, possibility of shooting each other, I could go on and on. Why at this point don't they just drive a Stryker?

 

[Peter Dow]

Now that I've got the legal stuff out of the way, there's the topic of insurmountable technical flaws in your design:

• TOO WIDE. It won't fit on smaller caro planes standard MRAP's and HMMWV's do, and they'll take up too much precious cargo space for their usefulness. Won't fit down city streets, won't be able to navigate through trees or forests, won't won't won't.

What part of

Say, the separated Y-sides are 4 feet wide.

Well for example, the connecting bars or tubes could hold the left and rights Y-sides together separated by these example widths:

• 1 foot, Y1Y so the total width is 4 + 1 + 4 = 9 feet - no wider than a Cougar MRAP and so as stable as todays MRAPs and narrow enough for urban roads and traffic.
  
• 4 feet, Y4Y so the total width is 4 + 4 + 4 = 12 feet, the same as an M1 battle tank, good for country roads, stable but narrow enough to get across most bridges no problem.
  
• 8 feet, Y8Y so the total width is 4 + 8 + 4 = 16 feet, super-stable for open cross country off road where the extra width is no problem for crossing bridges or fitting on roads because there are no roads maybe nothing more than a dirt track of uncertain width itself, maybe nothing but rough ground and rivers need to be forded or not crossed at all and then the extra stability is purely a bonus with no disadvantage of extra width.

didn't you understand?

• The turning radius and overall maneuvability will be completely atrocious due to the width/length ratio and number of wheels you have.

There will be two special turning gears, clockwise and anti-clockwise which have one side's gears in reverse and the other side's gears in a equivalent low-geared first gear. (See my post below) The rear wheel steers coupled to the front steering in the opposite direction of turn.

Therefore it will be able to turn on the spot like a tank.

• You would need two synchronized powerplants (one for each "outrigger") to drive all of the wheels equally, ruling out the possibliity of a simple diesel engine with mechanical drivetrain. More complexity, more cost, less usefulness.

Yes two engines for sure.

An interesting challenge because I don't think separate left and right engines has been tried too many times before.

My guess is that it'll work just fine without any linkage beyond connecting the two engine throttles together to work off the same throttle control and making sure the cables are properly adjusted.

Clearly, if one throttle cable is too loose or one engine is misfiring then you'd get more power from one engine and one side of the vehicle would want to go faster tending to turn the vehicle.

It is exactly the same issue as making sure your braking on both sides are balanced. If the brake-pads or tyres on, say, the left hand side of a vehicle are worn then when you brake, the car will tend to turn to the right. Same kind of thing.

• Your concept is flawed because although the center is mine-resistant (because nothing's there!) the "outriggers" will be logical targets and need to be mine hardened in the method standard MRAP's are anyway; completely negating the usefulness of your twin-hulled concept.

There are many connecting bars or tubes in the centre to keep the two sides together and stiffly so.

Actually I expect the connecting bars to be most vulnerable to a blast directly under the centre but I suppose that depends on how thick they are and whether the weight is worth making them so strong?

It might be a better solution just to let the connecting bars get bent or some broken and simply replace the connecting bars after a blast? It would be nice if the two halves are strongly enough connected so they don't go flying off in opposite directions after a typical predictable blast under the middle.

If the bars do fail first then they will have done their job in a similar way to the crumple zone of a car.

The concept is to provide increased and very useful stability against roll-overs which makes the MRAP not very useful off road.

• Huge remote-controlled turrets at the corners?! Too much complexity, possibility of shooting each other, I could go on and on.

Medium machine guns (weighs about 10Kg I think) 2 cameras, wide-angle and telescopic view (cameras are small and light these days). Manual aim controls (simple and light up top) or powered aiming (motors up there will add weight) (either would work), push button to change camera view, and fire. What is so "huge" and complex about that?

There can be stops added which prevent the guns pointing at parts of their own vehicle.

• Why at this point don't they just drive a Stryker?

Well Stryker is not preferred to MRAP I guess because Stryker doesn't have quite the mine resistance of MRAP.

I like Stryker's sloping front armour. It would be nice to put a slope in MRAPs' front and rear armour - but with a central axis edge like a ship's bow maybe? Maybe I will draw that one day - thanks for the inspiration.

 

[Peter Dow]

The CATAMARAN vehicle can rotate on the spot!

It is proposed that the CATAMARAN vehicle will have impressive manoeuvring and tight turning abilities, despite its size - including an ability to rotate on the spot as tracked tanks can do.

The trailer, although optional, when it is fitted, it will be attached to the powered and driven front of the vehicle by hinges allowing the front and rear parts of the vehicle to pivot relative to each other in the vertical plane thus keeping the driven rear wheels on the ground but the hinges will not allow any relative movement to the left or right, so as to keep the body and the wheels in alignment.

There are 3 pairs of axles -

1. front wheel drive steered axles, (left and right)
2. rear wheel drive fixed axles, (left and right) and
3. trailer wheel steered axles, (left and right).

The trailer wheels will steer coupled to the front wheels but in an opposite clockwise / anti-clockwise sense to the front wheel.

Each Y-side of the vehicle will have 4-wheels driven so with "4-wheel drive" on both the left and right Y-sides, one might note that the whole vehicle has 8 driven wheels, not just the 4.

CATAMARAN Vehicle Steering Geometry Normal steering
[PLAIN]http://img808.imageshack.us/img808/2019/catamaransteeringnormal.jpg

What this arrangement allows is that even with the trailer fitted, the vehicle can be reversed easily. Normally trailers are a nightmare to reverse. The CATAMARAN vehicle will be a dream to reverse.

In addition the CATAMARAN vehicle can rotate about a spot in the middle between the powered rear wheels. It achieves this special ability by virtue of certain design features -

• A first gear which is a low gear for manoeuvring and has a gearing ratio precisely the same as the reverse gear
  
  Two additional rotational gear modes -
  
• Clockwise - when the left side gearbox of the vehicle is automatically put into first gear and the right side gearbox of the vehicle is automatically put into reverse gear.
  
• Anti-clockwise - when the left side gearbox of the vehicle is automatically put into reverse gear and the right side gearbox of the vehicle is automatically put into first gear

When either clockwise or anti-clockwise gear is selected, the mechanical coupling normally engaged between the left and right hand steering is automatically disengaged and the left hand wheels are automatically turned to hard right hand turn lock and the right hand wheels are automatically turned to hard left hand turn lock; those two hard turn lock stops are designed so that the steered wheels are pointed in the correct direction for vehicle rotation.

Whenever either of the two rotational gear modes is deselected and the gear shift is put into neutral, the mechanical coupling between left and right hand steering is re-engaged and the wheels returned to the appropriate direction as determined by the driver's steering wheel which was redundant during the selection of either of the rotational gears.

CATAMARAN Vehicle Steering Geometry Rotational steering
[PLAIN]http://img688.imageshack.us/img688/2732/catamaransteeringrotate.jpg

 

[Peter Dow]

The CATAMARAN Vehicle vs. the MRAP. Which is better?

The CATAMARAN Vehicle vs. the MRAP. Which is better?

Compare and contrast the features of the CATAMARAN Vehicle against the MRAP it is designed to replace.

• The CATAMARAN vehicle is not taller than an MRAP with a gun turret.
  
• Yes the CATAMARAN vehicle will be taller including the height of its guns than an MRAP without a gun turret but the CATAMARAN vehicle's automatic guns are quite light and don't raise the height of the centre of gravity much and maybe has a lower centre of gravity than an MRAP with a gun turret with armour and gunner up top as well.
  
• The CATAMARAN vehicle can be the same width as an MRAP when configured narrow, such as Y1Y at 9 feet wide. It can be narrower, the same width or wider than a tank to suit the roads or terrain.
  
• The CATAMARAN vehicle will be as fast as an MRAP without the trailer on a straight road. It will be much faster off road, with or without trailer, because it won't roll over and a rolled over MRAP is a slow as you can get; you'd be faster on a donkey!
  
• The CATAMARAN vehicle will be as well armoured as an MRAP.
  
• The CATAMARAN vehicle will have as much internal cargo space without the trailer and more internal cargo space with the trailer compared to an MRAP.
  
• The CATAMARAN vehicle offers the possibility, depending on the width configuration, of additional external cargo space by strapping certain loads, which don't require armoured protection, to the connecting bars in between the two halves of the vehicle.
  
• The CATAMARAN vehicle will very manoeuvrable even with the trailer attached so its length is no big deal.
  
• The CATAMARAN vehicle will have more firepower than an MRAP. Two roof mounted machine guns without the trailer, 4 guns with the trailer.
  
• The CATAMARAN vehicle is "ambush repellent". whereas the MRAP is only "ambush protected".
  
• Terrorists going up against a CATAMARAN vehicle with RPGs and the like is a more risky proposition for them because the defenders have got 2 or 4 pairs of eyes watching for ambushes with their fingers on triggers to fight the attackers off.

Conclusion

The CATAMARAN vehicle is a better vehicle than MRAPs for any conflict where MRAPs are now the vehicle of choice.


CATAMARAN Vehicle & trailer - 6 machine guns, 16 seats!

[PLAIN]http://img27.imageshack.us/img27/9519/catamarangunswieghtpeop.jpg

The image shows some vital statistics for my proposed CATAMARAN vehicle, only one Y-side is pictured.

The front powered and driven vehicle seats a maximum of 10, 5 in either Y-side.

Each side seats 5 =

• 1 - one driver or reserve driver or front passenger +
• 2 - one front gunner and one rear gunner +
• 2 - two passengers

The trailer seats a maximum of 6, 3 in either Y-side

Each side seats 3 =

• 2 - two passengers +
• 1 - one tail gunner

So the vehicle with trailer attached seats a maximum of 16, 8 in either Y-side.

Each side seats 8 =

• 1 - one driver or reserve driver or front passenger +
• 3 - one front gunner, one rear gunner and one tail gunner +
• 4 - four passengers.

The driver can be either on the left or on the right Y-side and then the reserve driver or front passenger would be on the right or left Y-side, respectively.

Weight distribution

The image also shows the ideal weight distribution in relation to the axles.

Each square represents the same weight and length which is

• one eighth of the weight and length of the combined vehicle with trailer,
• one fifth of the weight and length of the front powered and driven vehicle and
• one third of the weight and length of the trailer.

Designing the vehicle to have this weight distribution helps to keep the vehicle well balanced in terms of equal weights over each axle which allows for the same suspension and tyres to be used through-out and maintains this balance with or without the trailer attached.

 

[Mech_Engineer]

[*]The CATAMARAN vehicle can be the same width as an MRAP when configured narrow, such as Y1Y at 9 feet wide. It can be narrower, the same width or wider than a tank to suit the roads or terrain.

It takes more than width to determine off-road performance. Rollover resistance is basically a ratio of track width to CG height and so a wider vehicle is more resistance to rolling over, but wider also means more difficult to maneuver and just as there are many situations that width helps, there are also situations where width hurts you. Driving through trees, city streets, etc.

[*]The CATAMARAN vehicle will be as fast as an MRAP without the trailer on a straight road. It will be much faster off road, with or without trailer, because it won't roll over and a rolled over MRAP is a slow as you can get; you'd be faster on a donkey!

I think you're overstating the number of rollover incidents that have occurred in MRAP's. They don't roll over as soon as you go off-road, but they do take special operator training to make sure the operator understands the vehicle's limitations. The fact is they're no less safe than any other large armored vehicle that is designed high off the ground.

[*]The CATAMARAN vehicle will be as well armoured as an MRAP.

Not possible without adding significant weight. Your concept splits the passenger compartment in two, which means you need almost twice as much armor as a standard MRAP. Each passenger compartment will require armor on both the left and right sides.

[*]The CATAMARAN vehicle will have as much internal cargo space without the trailer and more internal cargo space with the trailer compared to an MRAP.

Also not possible, since you're saying the narrowest configuration of your vehicle will be the same width as a standard MRAP, yet you have a large gap in the middle of the vehicle. The wider configurations have the same size passenger compartments, only the beams holding them together change.

[*]The CATAMARAN vehicle will very manoeuvrable even with the trailer attached so its length is no big deal.

Not true, because overall vehicle length is still a large limiting factor in a zero-turning-radius vehicle (and I'm not convinced your vehicle can be designed to be a ZTR). To be a ZTR, the wheels have to be able to turn 90 degrees which precludes the use of a standard axle and makes the design much more complicated.

[*]The CATAMARAN vehicle will have more firepower than an MRAP. Two roof mounted machine guns without the trailer, 4 guns with the trailer.

Firepower is not the limiting factor here, if they need more firepower they call in an airstrike or drive a Stryker or an Abrams. Still, remotely operated roof turrets are an option being installed on current MRAPs and HMMWVs.

[*]The CATAMARAN vehicle is "ambush repellent". whereas the MRAP is only "ambush protected".

Because of the more firepower? Current MRAPS are coming available with remotely operated roof turrets as well, so I don't think you're right on that.

[*]Terrorists going up against a CATAMARAN vehicle with RPGs and the like is a more risky proposition for them because the defenders have got 2 or 4 pairs of eyes watching for ambushes with their fingers on triggers to fight the attackers off.

One 360 degree turret is just as good as 4 120 degree turrets as long as the attack is only coming from one side. What you're trying to argue is that your vehicle will be basically an urban warfare tank, and that just isn't the case because you've made choices that prevent its effective use in Urban settings (such as the width).

The CATAMARAN vehicle is a better vehicle than MRAPs for any conflict where MRAPs are now the vehicle of choice.

No, for all the reasons I have stated.

 

[Peter Dow]

Telescopic rear axle armoured vehicle - easy!

OK well I have to admit there are a few problems with my CATAMARAN vehicle design.

• Heavier armour for the same volume protected
  
• The inner sides required to be armoured and connected together and that all adds weight. Precisely how much more weight is difficult to predict but a significant thickness of additional armour required certainly

Therefore I am now turning to a different and easier idea to solve the roll-over problem for MRAP armoured vehicles - telescopic rear axles.

Telescopic Rear Axles. Extended - Wide.
[PLAIN]http://img444.imageshack.us/img444/2698/telescopicrearaxles.jpg

Telescopic Rear Axles. Collapsed - Narrow.
[PLAIN]http://img3.imageshack.us/img3/7483/telescopicrearaxlesnarr.jpg

Hydraulic cylinders components are available to be adapted for this purpose.

The axles would need to be braced vertically to stop them bending under the weight of the vehicle.

Certain design concepts I have previously described for the CATAMARAN vehicle which I do want to retain for the telescopic rear axle design, such as

• Trailer wheel steering
• Armoured passenger trailer
• Rotation on the spot
• Roof mounted remote-controlled machine guns
• 5 : 3 ratio, 5 (vehicle) : 3 (trailer), weight and length distribution

Therefore the telescopic rear axle design although it is perhaps a less radical and innovative mono-hull design than the CATAMARAN Vehicle design, nevertheless it has many excellent features which greatly enhance the performance over the standard MRAP.

 

[Peter Dow]

My new Armoured Personnel Carrier design.

Armoured Personnel Carrier Designed by Peter Dow.

Features

• Front vehicle seats a maximum of 11 people
• Armoured passenger trailer seats a maximum of 7 people
• Vehicle with trailer seats a maximum of 18 people
• Roof mounted remote-controlled machine guns
• Trailer wheel steering
• Telescopic Rear Axle & Wheels
• Rotation on the spot
• Even axle weight distribution
• 5 : 3 weight & length ratio, 5 (vehicle) : 3 (trailer)

[PLAIN]http://img217.imageshack.us/img217/7015/armouredpersonnelcarrie.jpg

 

[Peter Dow]

My new Armoured Personnel Carrier design.

Armoured Personnel Carrier Designed by Peter Dow.

Features

• Front vehicle seats a maximum of 11 people
• Armoured passenger trailer seats a maximum of 7 people
• Vehicle with trailer seats a maximum of 18 people
• Roof mounted remote-controlled machine guns
• Trailer wheel steering
• Telescopic Rear Axle & Wheels
• Rotation on the spot
• Even axle weight distribution
• 5 : 3 weight & length ratio, 5 (vehicle) : 3 (trailer)

[PLAIN]http://img217.imageshack.us/img217/7015/armouredpersonnelcarrie.jpg[/QUOTE]

It takes more than width to determine off-road performance. Rollover resistance is basically a ratio of track width to CG height and so a wider vehicle is more resistance to rolling over, but wider also means more difficult to maneuver and just as there are many situations that width helps, there are also situations where width hurts you. Driving through trees, city streets, etc.

That's why my new APC design features variable width as standard with a telescopic rear axle and wheels.

Not true, because overall vehicle length is still a large limiting factor in a zero-turning-radius vehicle

You mean a long vehicle on a narrow bridge say? Even if it could rotate on the flat it couldn't in a confined space. Useful elsewhere though.

(and I'm not convinced your vehicle can be designed to be a ZTR).

Why not? If it can be done then my designs can do it.

To be a ZTR, the wheels have to be able to turn 90 degrees which precludes the use of a standard axle and makes the design much more complicated.

No the wheels don't need to turn quite the 90 degrees - in my design anyway! Not if the left hand wheel gets turned to a hard right turn and the right hand wheel turns to a hard left turn.

Do you understand? The wheels cannot be turned to that position while they are engaged with the driver's steering wheel and engaged with each other via the steering rod. The wheels need to be disengaged and turned independently from each other in opposite directions by a powersteering mechanism which can do that kind of thing.

The angle the wheels need to be at is described by the tangent at a circle centred on the point of rotation but each wheel turns by less than 90 degrees every time. For a very long narrow vehicle the angle approaches 90 degrees. For a short wide vehicle, the angle could be much less than 90 degrees.

See this diagram I produced for the CATAMARAN.

[PLAIN]http://img688.imageshack.us/img688/2732/catamaransteeringrotate.jpg

So if the left hand side drives in reverse and the right hand side drives an equivently geared "first" gear then the car will rotate anti-clockwise.

Whereas if the right hand side drives in reverse and the right hand side drives an equivently geared "first" gear then the car will rotate clockwise.

So it is certainly complicated - not to control but to engineer. New powersteering and gearing needs to be implemented. But the wheels don't turn by more than 90 degrees. Not in my design anyway. Maybe other designs do it differently, as you suggest, turning the wheels away past 90 degrees on one side and using the one gear?

Well the design I am describing I adopted for the CATAMARAN which already had two engines and two gear boxes so putting one in first gear and the other in reverse gear was no more difficult really. With a single engine, gearbox and transmission, it would need to be redesigned from conventional vehicles.

So maybe the Zero Turning Radius design you were thinking about is more conventional for zero turning radius machines?

Firepower is not the limiting factor here, if they need more firepower they call in an airstrike or drive a Stryker or an Abrams.

No for an ambush the best is if you see them first or at the same time and they don't get the advantage of surprise and if you have your weapons to hand as soon as the enemies. Therefore air strikes etc are much too late.

Still, remotely operated roof turrets are an option being installed on current MRAPs and HMMWVs.

Great! You should post some images of the models concerned with remote turrets in place.

One 360 degree turret is just as good as 4 120 degree turrets as long as the attack is only coming from one side. What you're trying to argue is that your vehicle will be basically an urban warfare tank, and that just isn't the case because you've made choices that prevent its effective use in Urban settings (such as the width).

A well planned ambush will try to get the victims (our vehicle) in a crossfire from different angles.

With my new design with a conventional mono-hull body, this can do well with two machine guns up front and one on the trailer.

Well I hope you like my new design better.

 

[Mech_Engineer]

Well I guess no one else is willing to jump in on this conversation, but overall your "concept" (it isn't a "design," you haven't actually designed anything) is lacking in technical detail with respect to how the telescoping axle would work. Overall I don't think a telescoping axle could reasonably be designed for such a large heavy vehicle, especially if you want it to be powered as well. Suffice to say it would be a very complex design to solve a relatively small problem IMO.

As I said before it won't be possible to make your concept a ZTR vehicle with conventional axles. "Normal" steering axles only have a maximum turning angle of around 45-50 degrees, no where close to what would be required for a ZTR application. In addition, you would have to be able to drive two wheels in the same axle in opposite directions, further complicating the design. Overall, the best way to make a large vehicle a ZTR is to drive wheels on opposite sides of the vehicle in opposite directions (e.g. tank tracks), but it's a PITA to do with a wheeled vehicle with axles.

Rather than changing the track width of the vehicle (which I think is too complex to implement), it might be possible to utilize an active suspension system with hydraulic or pneumatic rams that attempt to keep the vehicle as level as possible in off-camber situations. Such a system would be fairly easy to adapt to an existing truck in place of their shock absorbers. A few gyros or accelerometers could sense vehicle tilt and match with an appropriate level of adjustment. It would at least provide a higher level of resistance to rollovers, although nothing can be 100% effective. In the end, it's prudent to assume/require a certain level of driver knowledge and skill regarding the vehicle they're operating.

 

[Mech_Engineer]

Notice this parahgraph about tactical mobility tradeoffs with the Stryker:

Tactical mobility
...

Some criticism of the Stryker continues a decades-long ongoing debate concerning whether tracked or wheeled vehicles are more effective. Conventional tracks have superior off-road mobility, can pivot a vehicle in place, and are more resistant to battle damage. Wheeled vehicles are easier to maintain, and have higher road speeds. The US Army chose the Stryker over tracked vehicles due to these advantages.

An additional issue is that rollover is a greater risk with the Stryker relative to other transport vehicles, due to their higher center of gravity. The high ground clearance, however, is likely to reduce the damage caused by land mines and improvised explosive devices on the vehicle.
...

http://en.wikipedia.org/wiki/Stryker#Mobility

You'll notice, the Stryker has a level of rollover risk as well due to its high CG yet due to the tactical advantages afforded by a higher stance they are considered acceptable risks. It's my opinion that the higher rollover risk of an MRAP is outweighed by it's much better protection from IED's.

 

[Peter Dow]

Air Powered Steering for rotation about the rear axle

As I said before it won't be possible to make your concept a ZTR vehicle with conventional axles. "Normal" steering axles only have a maximum turning angle of around 45-50 degrees, no where close to what would be required for a ZTR application.

Here is an idea. If you need to, please review http://en.wikipedia.org/wiki/File:Ackermann_New.jpg" .

OK my idea is you replace parts of the steering rod with pneumatic pistons, either side of the connection to the steering column as follows (I hope you can see my diagram, Imageshack stopped serving the earlier image I posted here on rotational steering - annoying when it let's me down.)

[PLAIN]http://img833.imageshack.us/img833/9913/rotationalsteering.jpg

There is an air tank topped up by an air pump which when its valve is turned on inflates the pneumatic pistons now integral to the steering rod. (This should only ever be done while the vehicle is at rest and the driver has selected clockwise or anti-clockwise gear - some kind of safety cut out.)

The air pressure quickly rises (that is why you use air, not hydraulics, it is so much faster if you supply from an air pressure reservoir - there is not a need for huge force, just speed, so pneumatics is the driver of choice I think) and when the air pressure exceeds a critical amount, retaining catches, which normally hold the pistons firmly closed against all manner of road bumps, suddenly break open and the pressurised air forces the pistons open against a spring and the steering rod lengthens to a maximum and the wheels are turned inwards to their respective stops - hard right hand turn for the left hand wheel and hard left hand turn for the right hand wheel, ready for rotation.

It is clear to me that the 45-50 degrees or so maximum turning angle you are talking about is limited by the steering rod at full stretch - not by the wheel bumping into the axle - so 75 degrees in this diagram looks easy.

When you want to revert to normal steering, the system simply releases the air pressure in the pistons and the pistons close with the spring and the pistons snap shut into their retaining catches ready for normal steering.

As you can see this is for rotation about a point mid-way between the rear axle. It is only when I add on my trailer to my armoured personnel carrier that the vehicle does zero turning radius, strictly speaking.

Hence I have always called it "rotation on the spot".

So do you think that would work? I would doubt that is the way that lawnmowers do zero turning radius.

 

[Peter Dow]

APC with walk-through connecting trailer

Introducing HUMPBAC - an armoured personnel carrier with a connecting doorway from the rear of the vehicle to walk through into the armoured passenger trailer. Tickets please!

HUMPBAC
Hinged Under-floor-Mine-Protection Battle-ready Armoured-personnel Carrier
Copyright © Peter Dow, 7th August, 2010.

[PLAIN]http://img833.imageshack.us/img833/4264/humpbac780.jpg


HUMPBAC Features

• Trailer bolts firmly to the rim of the vehicle forming a rigid joint
• Rear section of vehicle is hinged to articulate the trailer's vertical motion
• Movement of hinged rear section accommodated by a hump in the roof
• Vehicle rear door can serve as a connecting doorway to the trailer section
• Front vehicle seats a maximum of 11 people
• Armoured passenger trailer seats a maximum of 7 people
• Vehicle with trailer seats a maximum of 18 people
• Roof mounted remote-controlled machine guns- front, top & tail gun
• Trailer wheel steering
• 6-wheel drive
• Telescopic Rear Axle & Wheels
• Rotation on the spot
• Even axle weight distribution
• 5 : 3 weight & length ratio, 5 (vehicle) : 3 (trailer)