Moving on Sand - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 249

Fig. 22.5 A stuck vehicle of Bagnold's Long Range Desert Group
being prepared to unditch. Mats have been laid in front of the front
wheels and a sand channel is about to be pushed under the right rear

wheel. Note that the practicality of access to the underside of a vehicle
leads to large numbers of people standing around while only one or
two actually are doing work: this is entirely typical. Crown Copyright

On steep dunes, vehicles should be aimed along the
direction of steepest slope: failure to do so means that the
downhill tires will see higher load than the uphill ones and
dig in further, steepening the angle. This positive feedback
can lead to getting stuck or worse, a rollover.

Tracked vehicles, of course, perform well in sand—the
large contact area of the tracks leads to a relatively low
ground loading, and tracks can have deep tines to dig into
soft ground (although this leads to heavy wear on regular
road surfaces). The sand crawler in Star Wars is an inter-
esting fictional variant. However, fuel consumption of such
vehicles is very high and, because of the differential steer-
ing, their driving requires special training.
A compromise that is effective in desert environments is
the half-track, wherein the rear wheel is replaced by a short
track giving low ground loading and high traction, but
steering uses conventional front wheels. A famous example
of such a vehicle is the Sd.Kfz 250/3 half-track, nicknamed
'Greif' used as a command vehicle by Erwin Rommel in the
Africa campaigns in World War II. This vehicle, festooned
with 'bedframe' rails (actually, a radio antenna) was much
seen

22.3 Vehicles for Dune Driving

For the professional purpose of just getting to a dune site,
vehicle availability, reliability and cost are considerations
that may overrule performance in sand. And in many cases,
long traverses on dirt roads or similar terrain may be
required to get to the dunes. Thus the distinction should be
recognized between vehicles used on dunes as a compro-
mise, and vehicles designed specifically (or even only) for
dunes, usually for recreation purposes. In both cases, some
obvious modifications are the incorporation of convenient
external access to shovels and sand channels for unsticking
(see later), and carriage of spare tires, water and fuel
containers.

in propaganda photographs (see Fig. 1.13 ), with

Rommel using binoculars.
In fact, half-tracks made landmark advances in desert
exploration. After some initial reconnaissance by regular
cars and by airplane, a French expedition was dispatched