To answer your question Alex, From memory, the initial...

To answer your question Alex,

From memory, the initial shareholder disclosure stated that excess cash would be used to pay down the loan.
From this statement, I think we pretty much all got the impression that the machines would be paid down over a loan period of less than 12 years, which would be the rate of paydown based on minimum loan payment.

However, later Mike clarified that the loan will be paid down over 12 years. So these two statements are/were inherently opposed.

My take is that the positive cash flow from FBRs share of profits within the JV WAAS entity will be made available for FBR for OPEX, CAPEX, production and R&D Spend.

Payback period is completely different. Payback period gives the number of years it will take to essentially pay off the initial investment, if the investment were in fact paid off with all positive cash flow. Payback period is not impacted/effected by strategic decisions to pay down the loan faster or slower.
If the machine makes $10 in positive free cash flow per year and the machine costs $100 to product, then payback period would be 100/10=10 years.

There are many uncertainties but reading between the lines and based on my expectation of machine cost I think I calculated a true payback period of somewhere around 1.8 years based on free cash flow projections from FBR and some modifications based on my assumptions around utilisation, etc.

Of course, again, this isn't an exact science. Investors need to be risk averse and manage their own expectations because we are talking about the unknown future.

Not investment advice. Do your own research, etc etc.