There are 2 StratRaft versions (V1 & V2), with similar lenticular based aerostat arrangements, designed in late 2002 for long endurance operation at high altitude. They either could be manned or remotely piloted and autonomously operated.
Their creation was undertaken through LTA Solutions, now integrated in Luffships Ltd (LSL), providing the basis for subsequent omni-directional (O-D) buoyant aircraft developments.
Both versions were arranged to serve as geo-stationary or roving dirigible buoyant aircraft (airships) in the stratosphere at say 20 km altitude, be able to orientate or face any direction, carry telecommunications and other equipment, and be able as carriers for launch/recovery of UAVs (drones) or other small craft.
They would be very big aircraft in the stratosphere due to expansion of the LTA inflation gas, not a problem with V1’s lower aerostat variable geometry method or V2’s simple 100% ballonet, enabling almost any height to be accessed and maintained. However, with V1’s variable geometry aerostat, it can be much smaller at ground level (easier to manage).
They both may be configured to operate at any altitude in the atmosphere. At a small size they therefore could fulfil duties as manned or unmanned types at a low altitude (say 150 to 300 m – 500 to 1000 ft) for as long as needed. They were designed for launch/capture from small sites anywhere.
Compared with unidirectional (UD) airships intended for such purposes, both StratRaft versions are more simply configured, adopting balloon (instead of traditional airship) technology in a cost effective way. They also remain upright in a natural way throughout flight, as balloons do; difficult for UD types to achieve from the physics of buoyancy causing the LTA-gas to flow to the highest end when pitched.
This remains a problem for UD airships at low altitude until the gas expands to largely fill their aerostats, which it does as atmospheric pressure drops through ascent. Further information from report: StratRaft – a Stratospheric LTA-Aircraft, only available from contact.
There currently are no plans to develop StratRafts. However, if people who would like to have or support development register interest for such capability then LSL would consider this.
