First published in the Science and Engineering forum of the For Freedom Forums

Posted: Monday 26th July 2010 05:00 pm

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

Wikipedia wrote: 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.

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 travelling 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. Idea

The CATAMARAN Vehicle - an MRAP which doesn't roll over!

Conjoined All-Terrain Anti-Mine Ambush Repellent Armoured Next-generation (CATAMARAN) Vehicle
Quote: 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.

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 vehicle 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 vehicle - my idea and you heard it here first. Copyright Peter Dow, 26th July, 2010.

Considering the wheeled version of the CATAMARAN Vehicle only for now.

My proposal is that 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.

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

Well there must be many ways of doing this but here is one suggestion.

The diagram shows how the connecting bars bolt on to the vehicle on one side. The other side is symmetrically the same.

  1. The lug welded to the vehicle side (left) bolts to the clevis (at "A" in the diagram) and before the nut is tightened the clevis can rotate.

  2. The clevis slots in and bolts to the box section (at "B" in the diagram). The clevis is able to rotate here too before the nut is tightened because the clevis is narrower than the inner dimension of the box section, height-wise in the diagram, though breadth-wise the fit is snug to allow the bolt to tighten when required without bending the box section.

  3. The connecting bar slots snugly inside the box section (snug both height-wise and breadth wise) and they bolt together (at "C" in the diagram) using holes drilled so that when the connecting bar is butting firmly up to the clevis it bolts together. The butting remains firmly the same independent of the rotation of the clevis inside the box section because the end of the clevis is shaped according to a circular arc centred around the bolt hole.

The procedure to connect the two Y-sides vehicles together is that you manoeuvre one vehicle to a position where you can loosely connect the bolts at points A and B so that the box section while fixed to the vehicle has some movement in two degrees of rotational freedom and the connecting bar is sliding inside both box sections at either end but not able to fall out.

This means that the vehicles will be separated by slightly more than the distance that they will finally be fixed at and typically a variable distance apart from front to back, bottom to top. There are too many variables to expect anything else.

If the Y-sides are too far apart then the connecting bars will fall out of the box sections; too close and the connecting bars won't fit between the ends of the clevises.

OK so you fit all the connecting bars like that then winch the vehicles together using two winches, firstly using winch anchor points low down near the wheels - low so as to mostly drag the vehicles together, not just tilt them over!

This will bring the vehicles together until you can slot in the bolts and put the nuts on in the lower connecting bars anyway.

Then you move the winch to higher winch attachment points near the middle and get enough tension on the winch line to bring the vehicles parallel and you can then slot in all the bolts in and tighten up all the nuts!

The connecting bars are not designed to be all parallel to each other. Some need to be at angles so as to form rigid triangles both horizontally and vertically for stiffness.

The "deluxe" or "transformer" version of the CATAMARAN vehicle could have the Y-sides connected by telescoping connecting tubes which could be extended by hydraulics and shortened by winches to allow the driver 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 and have powered steering as well!

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

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

The CATAMARAN Vehicle twin-hull design does increase somewhat the total area and weight of the hull armour for the same protected area in the horizontal plane.

Steel safety cables complement the connecting bars or tubes to provide additional hold between the two Y-sides to prevent the two Y-sides being blasted apart.

There is not much more area in the horizontal plane for the explosive force to react with in the CATAMARAN Vehicle because the space between the two hulls is mostly empty space with just connecting bars or tubes and steel cables!

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

The CATAMARAN Vehicle - an MRAP which doesn't roll over!

Posted: Thursday 29th July 2010 01:54 pm

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 operational 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.

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 Idea

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.

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

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.

Posted: Saturday 31st July 2010 12:08 pm

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

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

Posted: Sunday 1st August 2010 02:32 pm

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.


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