Papp wasn't about to give away the secret of his engine. I don't think he understood how it really worked anyway. What he did demonstrate was the explosiveness of the noble gases. That's where my interest in lenr from the alpha chain begins. Such a reaction is not likely to be chemical.😎
The mention of thorium is interesting. Papp said he added 4 grams of thorium to each cylinder, which translates to the generation of 70 alpha particles per second for pure thorium or up to 420 per second for. seasoned thorium. As far as I know the Rohners did not add thorium. No thorium no reaction.
If you would just read through their website you would see several mentions of thorium or radioactive substances. Fake news.