I don’t know if I mentioned it, but I had a hernia repaired a couple weeks ago, and I’ve been having some post-surgery complications. I’ve also been writing an op-ed for the WSJ, and answers to FAQs for the Reason project. We’re going to Vegas on Monday for the AIAA ASCEND meeting, where we’ll be all week.
For those concerned, though, I should be fully recovered and back up to speed by next weekend.
Yikes. Thankfully I’ve never had a hernia.
I just finished watching an interesting control-system video and thought that it might have some applications to vibration damping in rockets, especially in terms of making a mechanical system that can be tuned to knock out a particular resonant frequency.
https://www.youtube.com/watch?v=FhmLb2DhNYM
The concept depends on understanding that mass and inertia are not the same if you toss in a mechanical advantage, making a small mass move a much greater distance at a higher speed. More simply, the short end of a free-floating lever reacts to an applied force as if it had a larger mass than it actually does, because the long-end of the lever has to sweep through a large distance.
His first “inerter” was a rack and pinion spinning a flywheel, a concept I once thought of using on a direct blow-back rifle bolt to increase the apparent mass of the bolt without adding excess weight to the gun, but the resulting torques would make the gun act wonky unless you add more complexity to create multiple torques that cancel each other, at which point the parts count gets ugly.
He ended up using a ball screw with the nut spinning a flywheel, and that’s what F-1 race teams ended up using.
Rand, I am sorry to hear that your hernia repair did not go well.
Thanks, Paul, but I don’t want to overstate the issue; I’m sure I’ll be fine in another week or two. I developed a seroma at the site, and it’s just annoying having to drain it until it closes up and finally heals. Many people my age have much more serious health issues, if they’re even alive. I’m thankfully and astoundingly healthy, once this is fixed.
Best wishes for a quick and complete recovery