The StratRaft with two versions, as illustrated below, was conceived 2002 to provide upper atmosphere (pseudo satellite) high altitude platform (HAP) services.
StratRaft versions V1 & V2 are similar lenticular based dirigible aerostat arrangements for long endurance unmanned HAP ops. They either could be remotely piloted or autonomously operated.
Their creation was undertaken by LTA-Solutions Ltd’s (LTA-S, now integrated in LSL) founder, providing the basis for subsequent omni-directional (OD) 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, surveillance and other equipment, and be carriers for launch/recovery of UAVs (drones).
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 100% ballonet, enabling almost any height to be accessed and maintained. However, with V1’s simpler 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 120 to 300 m (400 to 1000 ft), for as long as needed. They were designed for launch/capture from small sites anywhere. Their upper surface also is ideal for solar panels to get free energy from the sun.
Compared with unidirectional (UD) airships intended for such purposes, both StratRaft versions are more simply configured, adopting balloon (instead of traditional airship) technology in cost effective ways. 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.
It should be appreciated that such BA could be a stepping stone for future use to either be the launch platform aloft for small space craft or indeed become the vehicle, as the atmosphere thins sufficiently to enable greater velocity that continues into space.
LSL currently has no plans to develop StratRafts. However, if people who would like to have or support development register interest then LSL would be pleased to consider plans for them.