https://phdino.com/ New Lab Notes and the weekly Dino Challenge from PhDino, the engineering calculators on a Windows 95 desktop. en https://phdino.com/lab/rocket-equationhttps://phdino.com/lab/rocket-equationSat, 17 Oct 2026 12:00:00 GMTAn interactive explainer of the rocket equation: why rockets are mostly propellant, what reaching orbit costs, and why staging and efficient engines change everything. https://phdino.com/challenge/1https://phdino.com/challenge/1Sat, 17 Oct 2026 08:00:00 GMTPhDino's weekly Dino Challenge No. 1, "Niki's top gear": one engineering puzzle a week, solved with the calculators, with the worked answer the following week.