DARPA should already know that this is not a new concept. A guy by the name of Alan Gerbino has come up with essentially the same thing some time ago and holds patents on the rotor disk assembly - "Retractable Lifting Blades for Aircraft."
Gerbino Flight Systems
Their promo spot should answer a lot of questions:
Their team is working on the prototype now in California.
Gerbino Flight Systems
Their promo spot should answer a lot of questions:
Their team is working on the prototype now in California.