| abstract |
A compound aerostat employing a primary lifting mixture of helium and methanol in a first enclosure and a secondary lifting mixture of ammonia in a second enclosure. Both enclosures are contained within a single envelope. The methanol in the primary enclosure gradually condenses out as the altitude increases yielding a decreasing lift with altitude up to the stratosphere to provide passive altitude stability to the system. An absorbent, metallic lithium is provided within a separate container and connected to controllably absorb the ammonia and thereby control the displacement of the secondary enclosure. The process is reversible with the application of heat by means of propane combustion or solar heating. Other absorbents are LiNO3, LiCl and CaCl2. This controllable displacement system can compensate for solar superheat and snow and ice accumulation and facilitate long endurance flights, especially in the troposphere. |