Abstract:
The need for high-speed high-payload craft has led to a considerable interest in
vehicles capable of bridging the gap between conventional ships and aircraft. One
such concept uses the forward motion of the craft to create aerodynamic forces on
a wing-like structure, and hence, alleviate the overall drag by reducing the wetted
area.
This research focuses on the use of suitably shaped multihull geometries to
achieve e cient aerodynamic lift for high-speed sea vessels. The problem is rst
studied in two dimensions using a simpli ed analytical approach and CFD modeling.
The work is then extended into three dimensions and a nal aerodynamic
model is produced for a complete hull form, including the e ects of hydrodynamic
surfaces above the water. The aerodynamic analysis demonstrates that signi cant
e ciency can be achieved through careful shaping of the side hull and cross deck,
with lift-to-drag ratios of nearly 50 for a complete aerodynamic hull con guration.
Further analysis is carried out using a hybrid vehicle stability model to determine
the e ect of such aerodynamic alleviation on a theoretical planing hull
vessel. Comparisons are made using the Savitsky planing model, and from this it
is found that the resistance can be almost halved for a fty metre, three hundred
tonne vehicle with aerodynamic alleviation traveling at 70 knots.
A comparative study is made for the hybrid vehicle with regards to size, speed
and weight, whilst attempting to match the proportion of aerodynamic lift with
speed to a theoretical optimum. From this the likely con gurations for future
development are identi ed.
