🚀 go-pugleaf

In article <ida.726295295@atomic> ida@atomic (David Goldschmidt) writes:
>... It was a square design, which surprised me; the
>heliogyro design, developed by R. H. Macneal ... has several advantages,
>including stability (its spinning), and ease of deployment...

The stability produced by that spin is actively undesirable if you have
a maneuverability requirement.  A sail designed to be deployed in Earth
orbit, in particular, has to do 90-degree turns twice per orbit (to get
full advantage of sunlight in the "downwind" half of the orbit and
minimize losses during the "upwind" half).  JPL got away with it because
their design was launched to escape by conventional propulsion.

The heliogyro is also a very flexible structure for its sail area, with
extra dynamics problems arising from those long thin blades.  (This is
also another area where the spin hurts, because the blades see constantly
changing Sun angles to complicate their dynamics.)

Mind you, there is a whole lot to be said for easy deployment.  Deployment
is a big problem for solar sails.
-- 
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  henry@zoo.toronto.edu  utzoo!henry