heavy lift towed transport balloon concept heavy lift transport airship concept

LTA Solutions

A private practice for lighter-than-air aircraft

Lenticular (L) Aerostat Luffships

Knowing that spherical (S) and other bulbous aerostat forms (such as the natural {N} shape of hot-air balloons) have relatively high aerodynamic drag compared with classic cigar (C) shaped forms, but that associated unidirectional (UD) characteristics make things rather difficult when trying to hold station without turning into wind for load exchange in variable weather, an alternative low drag form retaining omni-directional (O-D) characteristics is desirable to reduce power requirements and enable long range if flown under continuous power. Even so, it should be noted that balloons normally fly powerless (drifting without airspeed, so zero drag despite their bulbous form) and to a certain extent are navigable using various weather patterns at different altitudes for conveyance in directions desired, sailing instead of plying the sky.

Surprisingly, although the lenticular (discus shaped) form was known to have low drag properties, early developers went straight from spherically shaped free balloons to dirigible types with a longitudinal cigar shaped aerostat practically without any developments with the lenticular form until the late 20th century. By this stage, classic UD airships with a close coupled gondola arrangement and tail surfaces for stability and control were established – influencing the way new developers adopting the lenticular form arranged things.

This, now with virtual reality methods to show things in a notional way, led to types that were hybrid (H) in nature (potentially able to utilise significant aerodynamic lift) but without properly solving aircraft stability issues. Due to the way things evolved, there also was a shortage of available data concerning aerodynamic characteristics of the L form at the size necessary for an LTA aircraft’s aerostat, where developers adopting this form should have invested in research to gain awareness.

For background and further information about lenticular airships, see the downloadable paper An Exposition about previous types.

Luffships (StratRaft, AeroRaft and further derived types) with an L form aerostat utilise low suspended weight (like free balloons) to provide strong pendulum stability that counteracts aerodynamic instability instead of fins at a rear position. Control of both behaviour and movement through the air then is with thrust, which (with today’s technology) will be automated; but where free balloon flight may be used routinely at any stage.

Click on a link above to explore different L form Luffships designed or on one of the following links to return to previous O-D Luffships or the general Luffships page.