In this section, I will present my study, trying to find if there's any cryptographic pattern in the primer.
1- Letter Frequency* EnglishThe drone story takes place, for the most part, in USA. So the initial guess is that, if there's any code, it's written in English.
Therefore, my study will be made firstly in this language.
However, it would certainly be interesting to see what happens when the substitution is made in others languages, such as Spanish, French, German, Italian, Turkish, etc.... And I will try to do it in a second time.
While some special letters are used in some languages (�, ö, ç, ô, etc....), most of the languages are using a 25+ basically similar alphabet characters, which is the exact number of the whole "drone alphabet", including all the flipping and mirroring possibilities.
This can be considered as a clue for the primer to be written is a "human-made" language, or at least, built in the same way...
According to
Wikipédia, here's the relative distribution of the letters in English:

That gives:
ETAOINSHRDLCUMWFGYPBVKJXQZNotes that the order is not exactly the same of those of the Linotype Machine:
"etaoin shrdlu" (eh-tay-oh-in shird-loo), was believed to be the twelve most common letters in the English language. The word came from linotype typesetting machines. The first, left row of six keys on a linotype machine produce the word "etaoin". The second, left row of six keys produce the word "shrdlu". The linotype machine keys are labeled: "etaoin-shrdlu-cmfgyp-wbvkxj-qz". The letter 'h' appears more often in every day speech and writing than it does in a list of dictionary words.
SOURCESome other variation could be made, such as the "letter frequency in press reporting", or "letter frequency in religious writings", etc... These frequencies are slightly different than in the common English language.
And here's the Digraphs frequency, based on a panel of 40.000 words:
SOURCE* Drone language
And the digraphs distribution:
