Helicopter rockets (or "helirocs") have really contrary flight modes! They
boost up on rocket power (A to G motors, one or two stages allowed) and
windmill to Earth as gently as thistledown (in theory anyway!) on autorotating
aerosurface or aerofoil blades stored/folded inside or around the outside of
the rocket during ascent, and then deployed by the rocket motor expulsion
charge. Timing, with up to 3 flights per entrant, is as in the Boost/Rocket
Glider event. These are technically challenging and interesting models to
build and fly; and this year the world's most ambitious heliroc, the "Roton"
Reusable Launch Vehicle is to start its test flights. The results and images
from the 1999 heliroc event will be sent to the "Roton" developer, the Rotary
Rocket Company in the USA, for comparison!