Apparently nobody expected this, based on the simnews comments thread.

I have a preview of the R&D tool for personal weapons, including preliminary equations, tech parameters, etc. The specifics of tech parameter scaling hasn't been figured out yet, but it will generally be a percentage improvement for multiplicative parameters and a constant improvement for additive parameters. The R&D preview tool can be found here.

This tool mimics the objective of the final design process: enter whatever parameters you want, and observe the resulting stats and production costs. There are probably some major issues with balance and scaling right now, but it is possible to design the A-280 with it (it was scaled around building an A-280, though, so I'm not sure that it can design OTHER weapons currently in game). The tool will periodically be updated without announcement (but a changelog may be maintained on the tool itself and on the discussion thread). If you plan on doing R&D down the line, it would be good to familiarize yourself with how this tool works, as it will form the basis of the eventual in-game UI for creating new entity datacards.

The feedback/discussion thread for the specific details about the equations and values is located in the suggestions forum, not the simnews comments thread.