Joe Bernard successfully land solid fuel model rocket after 7 years (video)
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The mechanism to throttle the solid rocket motor is simple and ingenious - ceramic "jaws" underneath constrict to block a portion of the exhaust plume (an idea borrowed from Josh at Simple Robotics). Here's a link to the juicy bit in an earlier video on it, although the whole thing is worth watching: https://youtu.be/8sksiYfkses?t=658