[email protected] wrote:
> A linear actuator may have enough torque to turn 2 halves. Or a
> combination of multiple actuators???
Sorry to burst any bubbles ... but I don't think the Warthog would ever
be an effective support vehicle in the hobby ... despite it's novel appeal.
Specifically, common skid-steering (forward on one track and reverse on
the other) will *NOT* work because as soon as you reverse one of the
tracks on the tractor or trailer, the pivot joint will lock over in one
direction and the vehicle will prevent itself from completing the turn.
That's how we originally tried to steer the Goer and it was an
immediate failure. Even though it used wheels instead of tracks and the
trailer wheels were free-wheeling, the lateral friction of the wheels
was enough to stop it dead in a turn.
The Goer and ZD3000 both use a modified skid-steer control (called
tractor steering) that simply cuts off power to the inside tractor wheel
when turning, allowing the inside wheel to free-wheel during the turn.
That allows the single outer wheel to turn the tractor and the
free-wheeling trailer follows it around the turn.
Unfortunately, I don't think such a modified skid-steer control will
work at all for the Warthog. Since a track has far greater rolling
resistance than a wheel, a single track on the tractor will not be able
to turn the tractor by itself, let alone with a tracked trailer behind
it. We've proven this many times on the battlefield when a tank track
stops working for some reason. In those cases, the tank continues to
move along with only a slight curve to it's direction. Basically, the
free-wheeling track acts like an outrigger, helping to keep the tank
going straight.
That eliminates both forms of skid-steering commonly used, so what's
left? The only approach I can think of that has any chance of working
is to use the same approach that the real vehicle uses: computer
controlled operation of all four tracks. Specifically, when you want to
turn the vehicle, the computer starts varying the relative speed of all
four tracks to (a) cause the tractor to go in a given direction and (b)
keep the tractor-trailer angle constant during the turn. This is *not*
as easy as it sounds, because the trailer has to start and stop turning
*after* the tractor does (so it will travel along the same path).
Moreover, the amount of time depends on the actual speeds of the vehicles.
As a veteran software developer, I wish "good luck" to anyone that
develops the required software. Even if they do get it working, the
resulting vehicle will under-perform all other support vehicle designs,
rendering such clever programming virtually worthless. Specifically, the
use of relative track speeds to turn the vehicle also means that the
turning-radius of the vehicle is significantly increased. Tanks have a
zero turning radius because of full skid steering. The Goer and ZD3000
have a slightly larger turning radius using tractor steering. Wheeled
vehicles using conventional steering have a greater turning radius,
limited by the angle of the steering wheels. By far, the worst turning
radius would be the Warthog.
When it comes to a tracked support vehicle, I think that the best (and
perhaps only) choice is the FV103 Spartan as evidenced by SV015 built by
Mike Mangus. With a zero turning radius, go-anywhere performance and
heavy-hauling capacity, I don't see any other vehicle matching it in the
support vehicle category ... including the venerable Goer and UN Peace
Keeper. It costs more to build and operate, but over time I think it
will prove to be the most effective support vehicle design. But, that's
just a personal observation based on a relatively small amount of design
and battlefield experience.
Frank "A high-speed Spartan would change the game" Pittelli
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