Lightsails versus sailboats

October 2019

Q. A well-designed sailboat here on Earth can go faster than the wind. Could a spacecraft propelled by a lightsail surpass the speed of light if given enough time to accelerate, notwithstanding Einstein?

Draft a response of no more than 250 words and email it by midnight Eastern time on Oct. 7 to aeropuzzler@aiaa.org.

From the September issue:

PIGSKIN PREVIEW: We asked you what 19th-century British inventor William Hale and your favorite football quarterback have in common. AIAA senior member Trip Barber, co-founder of the Team America Rocketry Challenge, reviewed your submissions.

WINNER: William Hale and football quarterbacks share an understanding of aerodynamic spin stabilization. Hale invented the “rotary rocket,” which used exhaust gases to apply torques that spun the rocket on its longitudinal axis. This spin gives the rocket an angular momentum pointed along the longitudinal axis, which makes it harder for disturbance torques to affect the attitude of the rocket. Similarly, quarterbacks apply spin to footballs when they throw them; this is called “throwing a spiral” in football jargon. This spin stabilizes the ball’s orientation as it flies, keeping its axis with the smallest cross-sectional area (and thus, the least aerodynamic drag) oriented along its velocity vector in order to maximize the throwing distance and accuracy.

Nat Guy
AIAA member
Software research and development lead
Astroscale Japan Inc. , Tokyo
nathaniel.guy@gmail.com