Page 41 - Theory and Design of Air Cushion Craft

US hovercraft development 25

been used as an ambulance vehicle in the region between Tomsk and Kolpashevo from
1985, and in 1987 a passenger service was established with three Pumas between
Tomsk and Krasny Yar, a 100 km route along the Volga river.

Amphibious craft

The US Government has supported the development of air cushion technology pri-
marily through its military applications. Americans like to use the aeroplane and car
as passenger transport both for long and short range journeys, but have paid less
attention to the development of high speed marine vessels as water transport for pas-
sengers. For this reason the development of US military hovercraft represents the
main development of the US hovercraft. The US Armed Forces initially aimed to
apply air cushion technology to amphibious patrol vessels. In the early 1960s a num-
ber of experimental craft were built and tested, using air jet curtains, and later skirts,
following the lead in the UK. Interestingly, one of the larger test craft, the SKMR-1,
used twin fixed ducted propellers for propulsion, a system which is most commonly
used today, due to its efficiency.
In the late 60s and early 70s versions of the British SR.N5 were built under licence
from BHC by Bell Aerospace, and used in military service in Vietnam. Post Vietnam,
the main objective became direct over-the-shore delivery of personnel as a new gen-
eration of amphibious landing craft. It was considered that the coast line which could
be used as a landing area would increase from 17% for conventional landing craft to
70% for ACVs. For this reason the US Navy realised that the ACV should play a
major role in amphibious warfare to decrease combat casualties, and would be a
break-through tactic for amphibious warfare as an alternative to using helicopters for
personnel transfer. The US navy decided to construct two competitive prototype air
cushion craft, the Aerojet General JEFF(A) and Bell JEFF(B), as test craft for this
concept of amphibious assault warfare. Each craft weighed about 160t and carried up
to 60 tonnes of cargo. The costs of the craft at that time were eighteen million US dol-
lars each. The craft could accommodate both tanks and soldiers. The craft engineer-
ing schedule was as shown in the table below.

Primary design 1970
Review and summary of engineering design 1972
Detail design and construction preparations 1971-1975
Construction in factory 1972-1976
The installation of components for subsystems 1975
Delivery to naval test base 1977
Inspection of systems v 1976-1987
Craft bollard test " • 1978
Craft trial 1978
Crew training 1977-1978
Various warfare systems trials, which included tests in Alaska, in Arctic conditions 1977-1984

The US Navy approved the tests and decided to use the prototype craft JEFF(B) as
the basis for the amphibious landing craft series LCAC (Landing Craft, Air Cushion).
The Navy signed a contract with Bell Textron Aerospace Corporation for building 12