A promissory note is not the proper vehicle to use for what you're proposing - and a 20x return is HUGE....way too much!

You'd be amazed at how many times you don't actually need "money" but rather ingenuity to start a business, and also there are a number of grants available from various sources and/or bartering opportunities that can be structured with existing business's for what you need.

I'd be happy to help you explore options - please feel free to call upon me. I've started many businesses of my own over the last four decades, and spent many years assisting others after that - when I was in commercial lending.

It sounds to me like you've got the desire, and you've put some time in - quantifying that is necessary so that you appear to have some skin in the game may prove very useful to you as it will likely improve your chances of persuasion.