"Strapping rockets onto the back of a helicopter is not the type of approach we're looking for. The engineering community is familiar with the numerous attempts in the past that have not worked. This time, rather than tweaking past designs, we are looking for true cross-pollinations of designs and technologies from the fixed-wing and rotary-wing worlds. The elegant confluence of these engineering design paradigms is where this program should find some interesting results."
A modern refactoring of certain old projects, like the Hiller Flying Platform, could yield some excellent results.
So, DARPA is ready to write checks for just technical plans just as engineering presented just on paper for very challenging problems. And they intend to evaluate the plans, just from what is on paper. So, the check comes before any prototype, alpha, beta, users, revenue, traction, proof of product/market fit, etc. And the DARPA batting average is not awful. The VC industry might see from this DARPA practice that such things are possible.