The AeroRaft was designed as a development step of the StratRaft in early 2003 to be a dirigible piloted motorised lenticular (L form) Luffship working in the lower atmosphere, conceived to serve as an aerial crane for medium range transport (say 2000 km) of outsized and/or heavy (100 tonne) mainly indivisible payloads with precise point to point pick-up & delivery operations without mooring. The design also permits transport of general freight, livestock or goods of any type loaded into a lightweight container, which the AeroRaft simply would pick up, transport and then put down as an under-slung load.
Its low suspended gondola module was deliberately arranged to provide strong pendulum stability (keeping the aircraft upright) like free balloons. The design incorporates an optional rotordyne (a large outer fan system) to generate aerodynamic lift in either direction (up or down) for payload carriage purposes or to counter excess buoyancy in a naturally balanced way. Separate propellers at strategic positions provide motivation plus stability and control.
Itís recognised that the rotordyne is a risk issue, which is why itís an optional item; where it needs a separate programme for development (to establish a reliable working system). This may be at a smaller scale and without fitting around an aerostat. If fitted around the suspended module below the aerostat instead, then it could still be used to help balance the differences between buoyancy and overall weight. However, when fitted around the aerostat, efficiency is expected to improve significantly due to: benefits from greater disc size/lower rotordyne speed, reduced aerostat blockage interference and (in fact) extra induced aerodynamic lift from flow effects over the aerostat that then result. Otherwise, much more power is necessary to achieve the same effect Ė affecting performance and safety.
It appears that thereís a need for such aircraft in regions that lack infrastructure and/or have unstable conditions preventing other transport vehicles over certain periods each year. Itís also been said that, once a demonstrator shows it can do the work claimed, unlimited funds would be made available for development Ė but is a chicken & egg affair! Review the 'Derived Types' following to see how significantly smaller versions have been arranged to support (reducing risk) the AeroRaft's future development.
SkyLifter took the lead in 2008 to source funds for development and had strategic plans to produce versions of the design (derived types), starting with small entry level Luffships based on the AeroRaftís arrangement without its Rotordyne. SkyLifter's intention was to eventually produce types able to serve serious aerial crane duties after proving the technology. Whilst progress was made, SkyLifter hasn't so far been able to get the serious support necessary for such aircraft development.
However, CargoLifterís CL75 AirCrane (see paper - available from contact) did prove to a certain extent that the proposal is viable; where the AeroRaft leverages experience from it.