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Tracks vs wheels
Linked band track
One of the lessons from Stryker in Afghanistan is that they are too road bound which creates regular predictable routes, which makes them more vulnerable to IEDs.
When juxtaposed with their relatively thin armor, the consequences are unfortunate:
What doesn’t work is the Stryker in Afghanistan, says Scales. The 5th Stryker Brigade, operating in southern Afghanistan’s Kandahar area, has taken heavy casualties, losing some 21 of the eight-wheeled vehicles and two dozen soldiers killed. “The vehicles have proven to be too thinly armored to survive the very large explosive power of Taliban IEDs and too immobile to maneuver off road to avoid them,” Scales writes.
I would also add that, for a given envelope, tracked vehicles are more space efficient, since the wheels on something like a Stryker are large, have significant travel, and the front (and sometimes rear) wheels sweep out a larger volume as an artifact of their pivoting to steer. (see picture)
Also, tracked vehicles are a lot better in urban conflict, because they can go over something like a junked car road block, while wheeled vehicles cannot, and because they can pivot steer, their maneuverability in close quarters is superior.
The downside of tracks is operational cost and road speed.
It’s why it’s rather cramped in Strykers.
Unfortunately, it appears that they are still fixated on some sort of “very quiet” track system:
“The lesson of contemporary wars is that IEDs can best be defeated by designing a vehicle capable of avoiding them,” he writes, in other words a vehicle that can go off road across rough terrain so that it isn’t limited to predictable routes. That means the future GCV must be tracked. It must also be quiet enough to be somewhat stealthy, Scales argues, which would imply a rubberized band track.
This is an area that I worked on extensively on the FCS-RMV, since, as a recovery vehicle, it would have to perform field repair, and from this perspective, band track, basically a continuous rubber band is a complete disaster.
First, with link track, every vehicle can carry a few extra links, and if there is damage to one, or two, they can repair it themselves. Additionally, they can short track, shorten the track by pulling links, and reroute the it so that one or more road wheels are not in the path.
By contrast, if a band track is broken, the crew can’t repair it, the replacement has to take part as a whole (as opposed to feeding the track a link at a time around the drive and road wheels), and it’s a unit, which when stored is huge, as in large enough that you need a truck to carry it to where ever you need to go to do the repairs.
There is a solution, called segmented band track, which splits the difference, so, for example, as opposed to rigid links, the tread would be made with (for example) 10 flexible treads that are linked together with pins (bottom pic), which splits the difference.
It is hoped that this will combine the simplicity of transport of link track with the light weight, lower noise, lower vibration, less wear on the road, and higher performance of continuous band track.
I will say that one of the things that should be avoided, at least on the basis of my experience with the FRMV specifically and the FCS-MGV generally, is to make a fetish of commonality between different vehicles performing different roles.
In the FCS program, almost every vehicle carried significant weight and cost penalties as a result of having a common chassis.
Commonality in systems is good, but if you take it to chassis design, you have start increasing weight and cost of the systems to attain this.
*Future Combat Systems – Manned Ground Vehicle.