Boy, I can highly recommend deepl.com for translation. The 30-day free trial requires a $10/mo subscription but is really easy to cancel at any time with no charge. Since I only needed this document translated I didn't keep the subscription. But it was super easy to use and I think it did a pretty good job. Translating pdf-to-pdf. It did a good job at keeping the document formatting, including the photos and figures, and even a good try at the equations.
Unfortunately, Adobe did a terrible job converting the translated pdf into an editable docx. The formatting went to hell and it completely blew away the equations. Does anyone know of a better pdf to doc translator? Or is there a good in-pdf editor? Either/both free, of course. I'm not really worried about the equations - I'll probably end up grabbing them as images from the original text.
The rest of the text translation to be corrected is kind of fun, and educational (remembering the little I'd studied of Russian very long ago). 'Model-copy' is find/replace changed to scale model; Rice. to Fig; athlete to modeler; a few things like that. Change some prepositions and conjunctions, and sometimes some other changes in sentence structure and it reads pretty well. Overall it should be pretty easy, but the formatting is the biggest block - I have a lot to learn in LibreOffice.
The book is really much deeper than I had first imagined. Sort of a combination between "Handbook of Model Rocketry" and "Topics in Advanced Model Rocketry", only squared. It really doesn't apply only to Scale. I'll attach a pdf of the Table of Contents of the first volume, and you'll see what I mean. (Note, I still haven't fixed a few odd terms you'll find on that ToC; i.e., 'benchmarking' = scale judging.)